Note: Descriptions are shown in the official language in which they were submitted.
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Personal Height Rescue Apparatus
This invention relates to a personal height rescue apparatus to lower a person
to safety after being arrested and suspended at height following a fall whilst
attached
to fall arrest equipment. In particular, this invention relates to a personal
height
rescue apparatus that is physically associated with a person whilst working at
height
as well as in the event of the person being arrested following a fall from
height
whereupon the personal height rescue apparatus enables such a person to be
lowered
to safety whether to the ground or some other safe level.
Personnel working at height are normally required to wear a body harness.
The body harness is entwined around parts of the wearer's body in order to
ensure that
the wearer's body is held securely within the body harness. The body harness
is
typically attached to one end of a lanyard and the other end of the lanyard is
then
attached to a secure anchorage. An alternative arrangement is where the body
harness
is attached to a line that can be extracted from or retracted into a drum that
can rotate
within a housing that is then attached to a secure anchorage. Extraction of
the line
from the drum is normally achieved by pulling the line whereas retraction of
the line
into the drum occurs automatically due to the action of a torsion spring
tending to
rotate the drum to retract the line. If the line is extracted from the drum
quickly, as
would be the condition in a fall event, pawls within the housing engage on the
drum
and stop the drum from any further rotation until the load on the line due to
the
pulling action is removed. The secure anchorage could be any appropriate
anchorage
on a structure or building or it could be part of ,a further fall arrest
system such as a
cable system whereby the secure anchorage may be able to move along the length
of
the cable whilst the anchorage is securely attached to said cable thereby
allowing
access to areas within the proximity of the length of the cable. In any fall
arrest
arrangement, it is usual for an energy absorber to be attached between the
body
harness and secure anchorage and for deployment of such an energy absorber to
be
achieved within a given load limit in order to limit loading on the body of
the faller.
Many lanyards have a flat rectangular cross section and the energy absorber is
incorporated by folding and then stitching together a part of the length of
the lanyard
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such that when the lanyard is subjected to a sufficient tensile loading
between either
end, the stitching progressively breaks causing the effective length of the
lanyard to
extend whilst such tensile loading is sustained thereby absorbing energy. The
energy
absorber associated with the line extracted from or retracted onto a drum is
often
incorporated between the drum and its housing by allowing the drum to rotate
to
extract line from-the drum after the pawls have engaged on condition that the
tensile
loading on the line exceeds a threshold limit that is less than the given
limit for
loading on the body of the faller. The threshold load is often mechanically
detennined by friction applied between the drum and it's housing whereby the
drum
can rotate if, and as long as, the load on the line is sufficient to overcome
the resisting
load due to the friction.
Fall arrest systems and equipment generally allow a person to access the edge
of a building or structure where there is a possibility of a fall occurring.
In the
unfortunate event that someone should accidentally fall, the fall arrest
equipment
arrests the fall of the faller leaving the faller suspended at height close to
the edge of
the building or structure. The faller is secured within a harness that is then
attached to
lanyard or retractable line that is then attached to a secure anchorage.
During the fall
arrest process, the energy absorber located between the faller and the secure
anchorage will normally deploy depending on the fall energy that needs to be
absorbed thereby limiting the load on the faller's body. Whilst the faller is
safely
arrested and the load applied on the faller's body is limited, the physical
demands
placed on the human body during a fall event are nevertheless significant
particularly
if the faller is light in weight or is in a relatively poor' state of health.
However, there
are further serious complications experienced by a faller suspended at height
in a
harness following the fall event. Motionless suspension in a harness for even
a very
short time, sets up a blood venous pooling effect, which becomes dangerous
leading
to unconsciousness and eventually death in as little as ten minutes. Various
research
studies have been carried out confirming the dangers of motionless suspension
and
there is now general agreement that it is vital to rescue and recover a faller
as quickly
as possible to avoid the onset of serious life threatening complications.
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There are various methods currently used for rescuing fallers but none of
these
is generally satisfactory. The most common method is to call out the -fire
services.
The speed of response depends on a number of factors such as where the fall
has
occurred and its distance from the nearest fire services depot, the
availability of fire
service resources at the time of the fall incident and whether the nearest
fire services
depot has the specialist equipment such as mobile platforms and lifting
equipment for
rescuing a person suspended at height. The specialist equipment tends to be
relatively
expensive and used less often than, the standard fire fighting equipment and
is usually
only available at a selection of fire service depots.' All these factors make
it difficult
to predict how long the fire services will take between being alerted to a
fall event and
being in a position to begin to lower the suspended person to the ground.
Generally,
the response times vary widely between about 10 minutes at best and up to as
much as
an hour. A further problem can be to gain access to the specific location on
the
perimeter of a building where a fall has occurred. Many buildings are sited
close to
neighbouring buildings or there are obstructions such as barriers all of which
impede
speedy access of the appropriate height rescue equipment to a fall location.
Another rescue method is for a rescuer equipped with descending apparatus to
be lowered, or to lower himself', alongside the faller and to attach the
faller's harness
to the descending apparatus. The rescuer then cuts the faller's lanyard
usually with a
knife, so that the faller's weight is transferred to the descending apparatus.
Having
cut the faller's lanyard, the rescuer descends with the faller. This method
has several
disadvantages not least of which is the need for the rescuer to expose himself
to
significant risks. The rescuer will also need to have received substantial
technical and
physical training in order to carry out this rescue method. The training is
generally
expensive and so tends to be limited to a select few thereby increasing the
possibility
that a person properly qualified to carry out such a rescue procedure may not
be
immediately available at the time of a fall event.
A further rescue method is to attach the faller's harness to a lifting
apparatus
such as provided in GB2376009 and to lift the faller back to the top of the
building or
to the original location of the cable fall arrest system. This method presents
a number
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of problems. Firstly, the harness attachment point of a person suspended at
height
after being arrested from a fall is likely to be two or more metres below the
edge of
the building. Any attempt to attach lifting cable to the attachment point from
a
position at the top of the building will typically compromise the safety of
the rescuer.
GB2376009 shows a substantial and convenient anchorage point in the form of an
over hanging beam. In thost typical locations where personnel work whilst
attached
to fall arrest systems or equipment there is unlikely to be a convenient and
appropriate
anchorage sufficiently elevated above both the faller and the edge of a
building to
enable the suspended faller to be lifted clear of the edge before being
recovered to the
level from which the fall occurred. The time needed to erect such a beam
following a
fall event would be significant. However, even if the faller were to be
successfully
raised and recovered, there is still the problem of transporting him or her
easily and
safely to the ground in order to enable him or her to access appropriate
emergency
services in the likely event that he or she has sustained injuries.
In either of the aforementioned rescue methods, not including the method
using the fire services, there is a need to locate and transport the rescue
system
apparatus to the site where the fall has occurred and to unpack and prepare
the
apparatus before the rescue process can begin. Since the need to undertake a
rescue is
thankfully rare, there is considerable potential for problems that could cause
further
delays such as locating the rescue apparatus, ensuring that the package
containing the
apparatus is complete and that the rescue equipment is properly maintained.
Also, as
already mentioned, the rescue methods generally require a high level of
personnel
training and so there is the need to ensure that there is always an
appropriately
qualified rescuer at hand when height access work is being carried out.
Taking all the above factors into account there is considerable advantage in
arranging the rescue apparatus to be an integral part of the faller's personal
equipment
so that the apparatus is immediately available at the site of the fall and
ready to be
operated on by the faller and/or a rescuer.
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Accordingly, one object of this invention is to provide a personal height
rescue apparatus that is a part of the personal equipment associated with a
person
working at height so that, if the person should fall and be arrested by fall
arrest
equipment, the rescue apparatus is capable of withstanding dynamic fall arrest
loading
and is then ready for use after the fall has been arrested, to lower the
person to the
ground or other safe level. It is also an object of this invention that the
personal
height rescue apparatus should be lightweight and compact in order to have
minimal
impact on the mobility of personnel using the equipment and also for the
personal
height fescue apparatus to be economic to produce. =
A further object of this invention is provide a personal height rescue
apparatus
that enables a person to be lowered to the ground or other safe level without
delay
after a fall has been arrested. The invention may be operated on by the faller
equipped with the apparatus, albeit with provision for the apparatus to be
operated by
or in conjunction with another party such as a rescuer. Operation by a rescuer
would
be important if the faller were unconscious. Also, it may be necessary to be
helped by
one or more rescuers in order to avoid obstacles and to navigate with respect
to wind
effects during descent. Alternatively or additionally, the personal height
rescue
apparatus may be operated automatically after a person has been arrested from
a fall,
particularly if the person has sustained injury or is rendered unconscious
during the
fall. Injuries including head injuries can be common especially with fall
arrest
equipment that has significant elasticity such that the faller suffers a
number of fall
oscillations before coming to a standstill and where each oscillation adds to
the
potential for the faller to collide with surrounding objects.
According to the present invention there is provided a personal height rescue
apparatus comprising a load element with means for attaching to one end of a
safety
line such as a lanyard or other type of safety line, the other end of such
safety line
being attached to a secure anchorage such as a building or other structure,
and also
comprising a harness attachment means for attaching to a safety harness that
is worn
by a person, and a connector with releasable means and means for releasing the
releasable means whereby the connector is securely connected between the load
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element and the harness attachment means and, in the event that the person is
arrested
following a fall from height, the connector has at least sufficient strength
to maintain
its connection to both the load element and harness attachment means in order
to
withstand loads between the load element and harness attachment during the
process
of the person being arrested from the said fall, and further comprising a
length of
flexible elongate that is securely attached atone end to the load element and
a part of
its length is held in a store, and also comprising at least one speed control
means that
is disposed within the personal height rescue apparatus such that it controls
the speed
that the length of flexible elongate can move relative to the said harness
attachment
means, such that in the event that the person falls and the fall is arrested,
the fall arrest
loads between the load element and harness attachment means are sustained by
the
said connector with releasable means so that the person is then suspended at
height,
and subsequently, in order to lower the person to safety after the fall has
been
arrested, the means for operating the connector's releasable means is acted on
such
that the connector is released thereby releasing its connection between the
load
element and the harness attachment means so that the load between the load
element
and the harness attachment means is then transferred to the length of flexible
elongate
causing the flexible elongate to be deployed from the store at a speed
relative to the
harness attachment means that is controlled by the at least one speed control
means,
thereby lowering the person at a controlled speed of descent.
In most embodiments the personal height rescue apparatus has a casing that
provides a convenient base for attaching and housing components. In typical
embodiments both the harness attachment means and speed control means are
attached to the casing so that the casing effectively provides the attachment
between
both these components. Also, a casing provides a convenient housing for
storing the
length of flexible elongate and for protecting it from the environment and
possible
accidental damage. A casing is also useful for storing the connector with
releasable
means together with part or all of the mechanisms that may comprise the means
for
releasing the connector.
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Loads imparted between the load element and harness attachment means
during the process of arresting a fall from height are typically significantly
higher than
the loads when lowering the person after being statically suspended following
the fall
arrest event. An energy absorber between the person and the secure anchorage
limits
the load on a person's body in fall arrest event. The magnitude of the
required load
limit varies between international jurisdictions. In Europe that maximum limit
on the
person's body is 6kN whereas in the United States of America the limit is
noanally
4k.N. Therefore, applying a safety factor of two times, the connector with
releasable
means would need to be able to withstand loads across it of at least 12kN.
However,
once the connector has been released, the tensile load in the flexible
elongate will be
substantially equivalent to the static weight of the man being lowered being
typically
around lkN. Therefore, applying a generous factor of safety of as much as 4
times to
account for deceleration effects of any braking during descent, the flexible
elongate
and any speed control means for controlling the speed of deployment of the
flexible
elongate relative to the harness attachment means will only need to withstand
tensile
loading between the load element and the harness attachment means of up to 41N
instead of a higher dynamic fall loading of up to 12kN, so that the personal
height
rescue apparatus can be relatively compact and light in weight
Whilst the use of a load element with releasable connector is advantageous for
enabling both the flexible elongate and any speed control means for
controlling the
speed of deployment of flexible elongate to avoid dynamic fall arrest loading
in a fall
situation and therefore to be compact and light in weight, the invention may
also
include embodiments with a releasable arrangement that primarily prevents any
speed
control means from operating under such dynamic fall arrest loads. Such
dynamic fall
arrest loading may be prevented from being imparted to any speed control means
by
various methods such as applying a releasable stop or brake to the flexible
elongate or
to the means for deploying the flexible elongate, instead of using a
releasable
connector acting on a load element to which one of the flexible elongate is
attached.
For example, such an embodiment may comprise a length of flexible elongate
whereby its first end is attached to a drum and a substantial part of its
length is
helically wound onto said drum and its second end is attached to a safety line
or is
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attached directly to a secure anchorage, the drum being mounted on and free to
rotate
about a central axle, the central axle being securely attached to a structure
that is
securely attached to or may be integral with the harness attachment means, and
further
comprising a releasable stop or brake with release means for releasing the
stop or
brake such that the releasable stop or brake may act on the drum to prevent it
from
rotating until the stop or brake is released, and also comprising the at least
one speed
control means for controlling the speed that flexible elongate may be deployed
relative to the harness attachment means, such that in the event that a person
falls and
the fall is arrested, the flexible elongate is prevented from deploying from
the drum by
the releasable stop or brake thereby also preventing dynamic fall arrest
loading
between the flexible elongate and the harness attachment means from being
imparted
to the at least one speed control means. After the fall has been arrested, the
releasable
stop or brake may be released by operating its release means such that the
load
between the flexible elongate and the harness attachment means is then
transferred to
the at least one speed control means thereby enabling deployment of flexible
elongate
from the drum in order to lower the person at a controlled speed of descent to
the
ground or other safe level. Operation of the release means to release the stop
or brake
may be similar to any of the preceding and subsequent embodiments associated
with a
releasable connector including manual, automatic and remote release. The
disadvantage however with applying a stop or brake to the flexible elongate or
to the
means for deploying flexible elongate from its store is that dynamic fall
loads may be
imparted to at least part of the length of flexible elongate and, in an
embodiment such
as that using a drum for the store, dynamic fall loads are also imparted to
the drum, its
axle and the structure connecting the axle to the harness attachment means
resulting in
these components needing to be relatively substantial and therefore likely to
be
heavier and less compact than using a load element with releasable connector
where
dynamic loading is only imparted between the load element and the harness
attachment means and is not imparted to the flexible elongate. The size and
weight of
the flexible elongate may be optimised by arranging for the part of the
flexible
elongate that is subjected to the higher dynamic fall loads to have a
proportionately
higher cross sectional area or to consist of more than one parallel length of
flexible
elongate.
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In any or all embodiments of the personal height rescue apparatus the
invention could include the above mentioned energy absorber that limits load
on the
person's body whilst being arrested from a fall and where the load limitation
is
required to be less than 6kN in Europe and less than 4kN in the United States
of
= America. Typically, the energy absorber would be incorporated in either
the
connector between the load element and the harness attachment means or between
the
load element and the connector or between the harness attachment means and the
connector.
Operation of the means for releasing the connector may be achieved by
manual operation, ideally by the person being lowered after a fall. In many
situations,
the personal rescue apparatus will be located behind the faller's head during
suspension after a fall so that the release control means are extended to
reach a
convenient location for operation by the faller. A typical means of operation
is
provided by a pull cord linked to an appropriate mechanism for activating the
release
of the connector. It is common for regulatory authorities to require the
release of a
connector in a safety critical situation, where the release could be activated
accidentally, to have two or more distinct actions in order to complete the
release
function. Therefore, whilst the release means could be operated with a single
operator
action such as pulling a cord once, various other release operation
embodiments are
possible that provide more than one distinct action. A simple manual release
operation embodiment could be to provide one pull cord requiring only one pull
action to release the connector but where the cord is accessed by opening a
pouch
such that opening the pouch and pulling the pull cord are then two distinct
actions. A
further release operation arrangement could utilise two or more pull cords
that need to
be pulled together, sequentially or sequentially but in a prescribed order of
sequence
in order to release the connector. Another release operation arrangement may
be to
use only one pull cord that is pulled a prescribed number of times before
releasing the
connector. Other safety measures can be applied that only allow successful
operation
of the means to release the connector when a person is suspended after being
arrested
from a fall rather than during or before the fall event. Again, many different
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embodiments are possible. For example, the release mechanism may only be
operable
within a predetermined range of magnitudes of load between the load element
and the
harness attachment means, in order to be only releasable when loads equate to
the
weight of a person suspended. Another embodiment may have a release mechanism
that is only releasable when a substantially static load between the load
element and
the harness attachment means has been sustained for a predetermined duration
of time
or where such substantially static load equates to the weight of a person
suspended
and has been sustained for a predetermined duration of time.
If the faller is unable to operate the connector release means due to injury
or
unconsciousness as a result of a fall event, the personal height rescue
apparatus may
include one or more facilities for enabling the connector to be release by a
rescuer or
helper. This may be achieved by using an additional releasing means that
extends to
the ground or some other safe level after a person is arrested from a fall,
or, by
attaching extensions to the faller's own manual release means that can then be
operated by a rescuer of helper or, by using a device such as a pole with a
hook at one
end whereby the hook can be used to activated a releasing means, or, by any
other
suitable means. A further alternative is for a rescuer equipped with a
personal rescue
apparatus to lower himself or herself alongside the unconscious faller and to
operate
the faller's manual release means on behalf of the faller.
In some embodiments, it may be beneficial to operate the connector releasing
means automatically particularly if the person suspended after an arrested
fall has
sustained injury to the head and has become unconscious. It is generally
important to
= ensure that automatic release of the connector cannot occur until the
process of
arresting a fall from height is complete in order to avoid the possibility of
relatively
high dynamic loads during such a fall being transmitted to the length of
flexible
elongate and the at least one speed control means. Embodiments with automatic
release means for releasing the connector may include a release means that
releases
the connector automatically in response to a load applied between the load
element
and the harness attachment and where such a load has a magnitude within an
upper
and lower limit typically relating to the weights of the heaviest and lightest
users
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respectively of the personal height rescue apparatus. Also, such an automatic
release
" nieatiS Mayiiidlude a means for delaying release of the connector for a
short period
such as 30 seconds after the initial sensing of load between the said upper
and lower
load limits, in order to enstie that activation occurs after the fall event is
completed.
Many falls include not only the initial fall but also subsequent dynamic
motion
usually due to elasticity in a fall arrest system causing a faller to bounce
before
coming to a standstill and so it is important to ensure that the connector is
only
released when or after dynamic motion in the vertical plane has substantially
ceased.
As a further safeguard against the release means being activated accidentally
the
release means to release the connector may be arranged such that the release
means
cannot be activated until loads within the said upper and lower limits of
magnitude
between the load element and harness attachment means have been sustained
within
such limits of magnitude for a specified period of time such as 30 seconds.
Typically,
if the time period that loads are sustained, within the specified upper and
lower limits
of magnitude, is less than the specified time period such as 30 seconds, then
the
activation process would cease as if load between the load element and the
harness
attachment means had not been applied. In other embodiments, the activation
process
would cease as if no load had been applied if such loads reduce below a
specified
lower limit. However, if such loads increase beyond a specified upper limit
then the
activation process may be halted and subsequently resumed if and when such
loads
fall below the specified upper limit. Such an automatic release means may be
achieved mechanically using a mechanical device for providing a specified time
= delay.
A more sophisticated automatic release means for releasing the connector may
be achieved using typically standard electronic components to electrically
activate an
actuator that then releases the connector. Such an actuator may be an
electrical motor,
solenoid, pyrotechnic device or any other suitable type of actuator.
Pyrotechnic
actuators are widely used in the automobile industry for activating safety air
bags and
to pretension seat belts and have an excellent record for long-term
reliability in a wide
variety of environments. They also have the advantages of being detonated by a
relatively small electrical current whilst producing high levels of mechanical
energy
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after detonation that is then available to release the connector. A potential
problem
with relying on electrical power in a safety critical device is to ensure that
there is
sufficient electrical power available when it is needed. Electrical power is
typically
drawn from a battery or other suitable portable store of electrical power
incorporated
with the personal height rescue apparatus. In order to minimise electrical
power use,
the electronic circuit including the battery may be arranged such that it
remains open
without any power being drawn on the battery until there is a load applied
between the
load element and the harness attachment means as would occur when a person is
suspended after a fall arrest event. The magnitude of the load would typically
be
greater than a specified lower limit in order to minimise the possibility of
the circuit
being closed inadvertently. The magnitude of the lower limit may usefully be
related
to the weight of the lightest user of the personal height rescue apparatus.
When the
load between the load element and the harness attachment means is above the
specified lower limit, the electronic circuit would then be closed such that
electrical
power from the battery is available to activate the actuator. In order to
ensure that the
electrically activated actuator only releases the connector after a fall event
has been
completed and the faller is substantially motionless, a standard electronic
timer could
be used to provide a predetermined time delay such as 30 seconds between the
electronic circuit being closed and the actuator being activated to release
the
connector such that if the load between the load element and the harness
attachment
means were removed or its magnitude were below the said lower limit, then the
electronic circuit would be opened and the activation process would cease as
if the
load had not been applied. In some workplace applications, relatively high
loads may
be applied between the load element and the harness attachment means when a
worker
may use his harness, lanyard and secure anchorage to restrain his position
whilst
working particularly on a steeply inclined surface. A relatively heavy worker
may
apply restraint loads between the load element and the harness attachment
means that
could exceed the said lower limit of load magnitude and therefore activate the
electronic circuit. Whilst this situation is unlikely, the electronic circuit
may
incorporate a sensor that senses the load between the load element and the
harness
attachment means or senses acceleration forces of the personal height rescue
apparatus during a dynamic fall event such that the connector is only released
after a
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relatively high threshold limit of load magnitude has been surpassed. This
would
affectively ensure that the connector is only released after a relatively
severe fall event
where a faller might sustain injury or be rendered unconscious. Such a
personal
height rescue device would have a manual release means in order to enable the
faller,
in a less severe fall event, to operate his own manual release. The manual
release
means may be a simple electrical switch_to activate the electrical actuator or
it could
be a mechanical arrangement or any other suitable arrangement. Means for
sensing
loads above the relatively high threshold limit may also be provided
mechanically.
In any embodiments whereby the release means for releasing the releasable
connector or releasable stop or brake is operated automatically or where the
operation
is manual by means of an extended pull cord, the personal height rescue
apparatus
may be located at any position between a person wearing a harness and the
secure
anchorage on a structure or building to which the person is attached because
there is
no requirement for the personal height rescue apparatus to be in close
proximity to
such a person. For example, the personal height rescue apparatus may be
attached
directly to a secure anchorage rather than to the person's harness so that the
secure
anchorage bears the weight of personal height rescue apparatus. In such an
embodiment where the personal height rescue apparatus is attached directly to
a
secure anchorage it may be preferable for the harness attachment means, that
would
otherwise be attached to the harness, to be attached to the anchorage and for
the load
element and/or flexible elongate to be attached to the safety line disposed
between the
person's harness and the secure anchorage so that only flexible elongate moves
away
from the secure anchorage when the flexible elongate is deployed thereby
reducing
the possibility of deployment being compromised by obstacles in the descent
path.
In any of the preceding or subsequent embodiments using electrical energy,
further back up release means could be provided mechanically in case the
electrical
release means should fail for any reason.
A useful addition to any of the preceding or subsequent arrangements using
electrical energy may be the inclusion of an electronic sounder that could be
activated
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to give an audible warning that a person has fallen. Such a sounder could also
be
useful for indicating that power is being drawn from the battery. An
electrically
operated sounder could also be added to any preceding or subsequent mechanical
arrangements but where such a sounder is energized by a source of electrical
energy
such as a battery. Alternatively, a sounder could be provided mechanically in
a
variety of arrangements including adapting the at least one speed control
mechanism
such that its operation is clearly audible as a warning that someone is
descending after
a fall arrest event.
An alternative embodiment of this invention using typically standard
electronic components is to enable release of the connector to be carried out
remotely
by a rescuer or helper. In an injurious fall event where the faller requires
medical
attention it can be desirable that a rescuer or helper activates the faller's
release means
and is then ready to receive and administer assistance when the faller reaches
the
ground. An embodiment of the invention is therefore for a rescuer or helper to
be
equipped with a typically standard wireless sender so that the rescuer or
helper can
send a wireless signal to a wireless receiver incorporated in the faller's
personal
height rescue apparatus such that the signal can initiate electrical
activation of an
actuator such as an electric motor, solenoid, pyrotechnic device or some other
suitable
actuator in order to release the connector. As before, the electrical power
may be
provided by a battery or some other suitable electrical power store and, in
order to
minimise electrical power use, the electronic circuit including the battery
may be
arranged such that it remains open without any power being drawn on the
battery until
there is a predetermined threshold of load applied between the load element
and the
harness attachment means as would occur in the event of someone being
suspended
after a fall. A time delay device may also be included to ensure that the
connector is
not released until after the fall event is substantially complete. The faller
may also be
equipped with a wireless sender in order to activate his own release means if
he is not
injured or unconscious after a fall. This could be advantageous if, in another
situation, roles reversed and the faller became the rescuer and he could then
utilize his
own wireless sender to perfoim a remote rescue. Alternatively, the faller
could
activate his own release means with a simple manually operated electrical
switch
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connected directly to the electronic circuit in his personal height rescue
apparatus or
activate his release mechanism with some other suitable release means such as
a
mechanical release means that is independent of any electronic circuit.
In typical embodiments, this invention has a speed control means that
automatically controls and limits the speed of descent of a-person. However
other
embodiments may also have a further speed control means that can be operated
manually by the person being descended in order to reduce the speed of descent
and
may also have the means to stop their descent if required. This further speed
control
means may have the ability to be operated on by a rescuer in addition to or
instead of
being operated on by the person being descended. Operation by a rescuer would
be
useful in the event that the person being descended were unconscious. Both
automatic and manual speed control means are notwally in close proximity for
convenience. In practice, it has been found that pulling or releasing one or
more
control lines is an appropriate method of operating the manual speed control
means.
However, it is debatable as to whether speed should be reduced by the action
of
pulling or releasing the one or more control lines. Pulling is a conscious
action and is
therefore often best associated with reducing speed particularly if the person
is
unconscious in which case it is vital to lower the person to safety as quickly
as
possible. For convenience and to minimise potential for confusion, operation
of the
manual speed control means is often, but not necessarily, shared with
operation of the
releasing means for releasing the connector. In a further typical embodiment
of a
manual speed control there is provided a means for manually operating a speed
control means to stop the deployment of flexible elongate at any stage in the
descent
process and to remain stationary without needing any sustained or further
operation of
the manual speed control means after having stopped. This is useful in a
situation
where a rescuer equipped with the personal height rescue apparatus needs to
lower
himself alongside a person who is unconscious and suspended after having been
arrested from a fall and who is also equipped with a person height rescue
apparatus,
and where the rescuer needs to remain stationary alongside the faller and to
have both
hands and any other faculties available free in order to release the faller's
connector
release means. The manual speed control having stopped deployment of the
flexible
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elongate can then be operated on at an appropriate time to release the braking
mechanism and resume deployment of the flexible elongate from the store.
However, in sophisticated embodiments, actuation of the braking means
could be arranged electrically as has already been referred to with respect to
electrical
actuation of the connector releasing means. As with electrical actuation of
the
connector releasing means, electrical actuation of the manual speed control
means
could be controlled by sending signals wirelessly from a controller located
with the
person descending and/or with a rescuer.
The invention will now be described by way of example only with references
to the accompanying diagrammatic figures, in which:
Figure 1 shows a personal height rescue apparatus according to a first
embodiment of the invention worn by a person;
Figure 2 shows a reverse view of the embodiment in Figure 1 rotated about a
vertical axis;
Figure 3 shows the embodiment in Figure 1 worn by a person suspended after
being arrested following a fall;
Figure 4 shows the view in Figure 3 but with the connector having been
released and the person in the early stage of descent;
Figure 5a shows a partially cut away view of the embodiment in Figure 1;
Figure 5b shows an elevation partially cut away of Figure 5a;
Figure 5c shows a partially cut away view of Figure 5a in a first level of
operation;
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Figure 5d shows a partially cut away view of Figure 5a in a second level of
operation;
Figure 6a shows a partially cut away view of Figure 5a with a first
alternative
connector release mechanism;
Figure 6b shows Figure 6a in a first level of operation;
Figure 6c shows Figure 6a in a second level of operation;
Figure 7a shows a partially cut away view of Figure 5a with a second
alternative connector release mechanism;
Figure 7b shows Figure 7a in a subsequent level of operation;
Figure 7c shows Figure 7b in a further level of operation;
Figure 8 shows a partially cut away view of a third alternative connector
release mechanism;
Figure 9a shows a partially cut away view of a fourth alternative connector
release mechanism;
Figure 9b shows an elevation partially cut away of Figure 9a;
Figure 10 shows a personal height rescue apparatus according to a second
embodiment of the invention worn by a person;
Figure 11 a shows a partially cut away view of the invention in Figure 10;
Figure 1 lb shows an elevation partially cut away of Figure 11a;
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Figure 12a shows a partially cut away view of the apparatus in Figure 10 with
an alternative method of releasing the deployment of flexible elongate;
Figure 12b shows a partially cut away view of the apparatus in Figure 12a in a
second level of operation;
Figure 13a shows a partially cut away view of the invention applied either to
Figure 1 or Figure 10 showing a possible automatic release mechanism;
Figure 13b shows a partially cut away view of the invention in Figure 13a;
Figure 13c shows a partially cut away view of the invention in Figures 13a and
13b in a second level of operation;
Figure 13d shows a partially cut away view of the invention in Figures 13a
through to 13e with a mechanical time delay arrangement;
Figure 13e shows a partially cut away view of the invention in Figure 13d in a
second level of operation;
Figure 14a shows a view of the invention with an alternative arrangement for
the lanyard, harness and rescue line attachments in a first level of
Operation;
Figure 14b shows a view of the invention in Figure 14a in a second level of
operation;
Figure 14e shows a side view of the invention in Figurel4a including a
housing in a first mode of a person falling;
Figure 14d shows a side view of the invention in Figurel4a including a
housing in a second mode of a person falling;
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Figure 14e shows a side view of the invention in Figurel4a including a
housing in a third mode of a person falling;
Figure 15a shows a partially cut away view of the invention with a centrifugal
dynamic servo braking arrangement;
Figure 15b shows a view of part of the invention in Figure 15a;
Figure 16a shows a partially cut away view of the invention in Figures 14a
through to Figure 15b inclusive in a first level of operation with a brake
operated by
the pull cord that also releases the connector;
Figure 16b shows a partially cut away view of the invention in Figures 16a in
a second level of operation;
Figure 17a shows a side view of the invention in Figures 14a through to Figure
16b inclusive:
Figure 17b shows a front view of the invention in Figure 17a;
Figure 18a shows a view of a part of the invention having an extension to the
pull cord for operating the release of the connector that extends to the
ground, or other
safe level when a person is arrested from a fall;
Figure 18b shows a cut away view of the invention in Figure 18a;
Figure 18c shows a view of a first component of the invention in Figure 18a;
Figure 18d shows a view of a second component of the invention in Figure
18a.
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In Figure 1, the first embodiment of the personal height rescue apparatus is
shown as worn on the back of person 1 whilst carrying out ordinal/ work duties
at
height. Person I wears a harness 2 that is securely attached to bracket 3 in
Figure 2
by means of straps 4 and 5 of harness 2 being passed through aperture 6 in
bracket 3.
Straps 4 and 5 are also passed through guides 7 and 8 that are part of or are
attached
to the personal height rescue apparatus housing 9 in order to hold the
personal height
rescue apparatus in position on harness 2. In Figure 1, a safety line such as
a lanyard
is shown attached at one end to a load element such as an eye 11 by means of a
typical attachment device shown as karabiner 12 whilst the other end of
lanyard 10 is
attached to a secure anchorage provided by a fall arrest system or single
point
anchorage. Eye 11 and bracket 3 are strong components connected together so
that
any load imparted on lanyard 10 is transferred across the connection between
eye 11
and bracket 3 to harness 2. In the event that person I. should fall, the
severity of his
fall and the resulting load imparted on his body would largely depend on his
weight
and the distance through which he falls before being arrested between the fall
arrest
anchorage and his harness 2. However, regulatory authorities recognise the
limitations of load that the human body can sustain before causing serious
injury and
therefore require that persons working at height should be equipped with an
energy
absorber between the harness and fall arrest anchorage that limits load on the
harness
irrespective of the severity of a fall. Such an energy absorber is typically
integrated
into lanyard ID or a further device commonly known RS a fall arrester that is
attached
between the harness and the fall arrest anchorage and absotbs energy by means
of
friction. The load limits required by regulatory authorities vary
internationally, In
Europe, the load on the harness is limited below 6kN where as, in the United
States of
America the load on the harness is limited below 4kN or 8kN. Regulatory
authorities
also generally require that safety equipment components should be designed to
withstand 15kN in Europe and 22kN in the United States of America. Therefore
both
eye 11 and bracket 3 and the connection between, them need to Sustain loads of
at least
15kN or 22kN in the event of a person being arrested after a
Figure 3 shows person 1 equipped with the first embodiment of the personal
height rescue apparatus in a typical posture after having been arrested
following a fall.
CA 02566705 2013-08-09
The combination of person Ps body tending to slump towards the parts of
harness 2
supporting his body together with the tendency for harness 2 to undergo some
stretch
particularly during the preceding fall event, both result in straps 4 and 5
becoming
realigned around bracket 3 such that load generated as a result of and after a
fall event
is sustained by bracket 3. Load on bracket 3 is transferred across its
connection with
eye 11 through to lanyard 10 and then to the secure fall arrest system or
single point
anchorage. The personal height rescue apparatus is therefore able to withstand
fall
arrest loading between the harness 2 and bracket 3, between bracket 3 and eye
11 and
between eye 11 and lanyard 10.
When person 1 has come to rest afler being arrested following a fall and is
suspended at height applying a substantially static loading across bracket 3
and eye 11
equivalent to person weight, the personal
height rescue apparatus is now ready to
be deployed to lower the person to the ground or other safe level. Deployment
is
typically initiated by releasing a first connection between eye 11 and bracket
3 that
sustaies load during the fall arrest phase of a fall event and replacing the
connection
between eye II and bracket 3 with a second connection including flexible
elongate
that can be deployed to lower the person. Figure 4 shows person 1 having
actuated
the release of the connection between eye 11 and bracket 3 so that the
connection is
transferred to flexible elongate 21 allowing eye 11 to move away from casing 9
and
therefore bracket 3 to which harness 2 is attached.
Figures 5a through to 9a show the first embodiment hi greater detail and with
alternative means fbr actuating the release of the connection between eye 11
and
bracket 3.
In Figures Sa and 5b, retention members such as pins 13 and 14 are cylindrical
shafts with axes perpendicular to, and both pins being, supported between
parallel
plates that are part of casing 9. Both. pins 13 and 14 are also located in
bracket 3 so
that bracket 3 is securely attached to both pins 13 and 14. Bracket 3 may also
be
securely attached to casing 9. However, pin 14 differs from pin 13 in that pin
14 has a
recessed section such as a flat portion 18 and is also able to rotate with
respect to
casing 9 such that flat portion 18 is also able to
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rotate about the axis of pin 14 with respect to casing 9. Eye 11 has abutments
15 and
- - = 16 that each bear on pins 13 and 14 respectively such that eye 11 cannot
move in the
direction of arrow 17 when flat portion 18 is in the radial attitude as shown
in Figure
5a.
Lever 30 is rigidly attached to pin 14 such that rotation of lever 30 also
results
in rotation of pin 14. Lever 32 is in the same plane as lever 30 and is able
to rotate
about axle 33 and has torsion spring 34 that tends to urge rotation in a
clockwise
direction relative to Figure 5a such that lever 32 is notinally abutted
against stop pin
35 in its static position. Levers 30 and 32 are linked by means of pin 31 that
is rigidly
attached to lever 32 and which is also constrained within slot 36 on lever 30
such that
radial movement of pin 36 about axle 33 will result in radial movement of both
lever
30 and also pin 14 with respect to casing 9. Pull cord 37 is a length of
flexible
elongate attached at one end to lever 32 and with its other end being located
in a
convenient position on person l's harness. Pull cord 37 is shown as being
enclosed in
sheath 38. Sheath 38 is typically a tubular sheath that protects pull cord 37
and is
strong in tension in order to prevent pull cord 37 from being pulled
accidentally such
as during a fall arrest event. Clip 39 securely attaches sheath 38 to casing
9. In
Figure Sc, pull cord 37 is shown as having been pulled substantially in the
direction of
arrow 40 thereby rotating lever 32 in an anticlockwise direction about axle 33
causing
lever 30 to rotate with pin 14 in a clockwise direction about pin 14 relative
to casing 9
such that flat portion 18 also rotates in a clockwise direction. When flat
portion 18
has reached the degree of rotation as indicated in Figure Sc, abutment 16 of
eye 11 is
able to rotate free of pin 14 about abutment 15 bearing on pin 13. In Figure
5d, eye
11 is shown as having disconnected from both pins 13 and 14.
In order to avoid the possibility of accidental release other than following
suspension after being arrested from a fall, it is common to require two
distinct
actions in order to complete actuation of the release mechanism. In its
simplest form,
this may be achieved by requiring person 1 to access a pouch possibly secured
with a
temporary fastening method such as Velcro before pulling on pull cord 37 to
activate
release. ,
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On releasing eye 11. in order to lower person 1 after being suspended
following a fall being arrested, the weight ofpersen 1 is then transferred to
a flexible
elongate element such as a flexible elongate 21. In Figure 5a, flexible
elongate 2/ is
a length of flexible elongate that is securely attached at one end to eye 11
and at its
other end it is attached to end stop 22. From its attachment to eye 11,
flexible
elongate 21 is passed through two guides 19 and 20 and is then helically wound
in an
anticlockwise direction relative to Figure Sa around cylinder 23 and cylinder
23 is
rigidly attached to easing 9. Cylinder 23 reduces tensile loading on flexible
elongate
21 between the point at which the flexible elongate is wound onto cylinder 23
from
eye 11 and the point at which it leaves cylinder 23. This is substantially as
a result of
radial friction between the surface of flexible elongate 21 and the radial
surface of
cylinder 23. Figure 5a shows flexible elongate having been wound through
approximately two revolutions around cylinder 23. However, the number of wound
revolutions will depend on the coefficient of friction between the surfaces of
flexible
elongate 21 and cylinder 23. On leaving cylinder 23, flexible elongate 21 is
helically
wound in a clock wise direction relative to Figure 5a around drum 24 and drum
24 is
able to rotate about axle 25 and axle 25 is scoured to casing 9. On one axial
end of
drum 24 there are six pins shown including pin 26a and pin 26g protruding from
the
surface of drum 24 whereby all six pins are radially equi-apaced about axle
25. 1n
Figure 5c, speed control lever 4115 a weighted lever that can pivot about axle
42 and
has a profiled aperture 43 through which the six pins including pins 26a and
26g
protrude from the surface of drum 24. When eye 11 is released and the weight
of
person 1 is transferred to flexible elongate 21, flexible elongate slips
around cylinder
23 and rotates with drum 24 about axle 25. The tension in flexible elongate
21,
substantially equivalent to the weight of person I, is reduced as already
mentioned as
flexible elongate leaves cylinder 23 and is passed around drum 24. As drum 24
rotates with flexible elongate 21, speed control lever 41 is forced to move in
opposite
radial diteetioris with an arc defined by the juxtaposition of aperture 43
with the six
pins including 26a and 26g. Since the rotation of drum 24 generates movement
of
speed control lever 41 about axle 42, there will be a limit whereby inertial
resistance
caused by the movement of speed control lever 41 Will resist and therefore
reduce or
limit the speed of rotation of drum. 24 and thereby limit
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the speed that flexible elongate is deployed from drum 24. The use of cylinder
23 in
order to reduce tensile load on flexible elongate 21 enables speed control
lever 41 to
be relatively compact. Whilst speed control lever 41 is shown as one means for
limiting speed of deployment of flexible elongate 21 from drum 24, any other
suitable
means for controlling speed could be used.
Moving from drum 24 away from eye 11, flexible elongate 21 is passed
between guides 44 and 45 before being packaged in a store area as shown in
Figure
5a. Typically, 44 and 45 are arranged such that they bear slightly on flexible
elongate
21 to provide some tension between flexible elongate 21 leaving the store area
and
being wound onto drum 24. At the stored end of flexible elongate 21 there is
an end
stop 22 that is securely attached to the end of flexible elongate 21 such that
in the
event of the store being depleted whilst lowering person 1, end stop 22 would
become
trapped between guides 44 and 45 and thereby prevent flexible elongate 21 from
leaving casing 9.
Flexible elongate 21 may be a modern high strength polymer rope. In
practice, it needs to withstand a substantially static tensile loading
equivalent to the
weight of person 1 being typically around lkN. However, applying a generous
factor
of safety of about 4 times this could be increased to at least 4kN. Various
high
strength fibre ropes are widely used and it is common for rope with a cross
sectional
diameter of as little as 4mm to have a breaking load of as much as 18kN.
Therefore,
flexible elongate 21 could be such a high strength rope so that it can be
stored
compactly with sufficient length to lower a suspended person safely whilst
also being
lightweight. Compactness and lightweight are important factors bearing in mind
that
the personal height rescue apparatus is worn by personnel at all times whilst
working
at height. However, flexible elongate 21 may be any other suitable material
including
steel cable or wire or polymer tape or webbing.
In Figure 5d, lever 32 has a protruding pin 46 such that when lever 32 is
rotated about axle 33 in an anticlockwise direction relative to Figure 5d, pin
46 bears
on surface 47 of speed.control lever 41 thereby limiting the radial scope of
movement
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of speed control lever 41 about axle 42 and resisting the rotation of drum 24.
Therefore, whilst pull cord 37 when pulled substantially in the direction of
arrow 40
to a first level releases eye 11 allowing eye 11 to move away from casing 9 as
flexible
elongate 21 is deployed, pull cord 37 can also be pulled to a second level
that resists
or stops radial movement of speed control lever 41 thereby slowing and, if
necessary
stopping, the descent of person 1. In some embodiments, both the
aforementioned
first and second levels to which pull cord 37 is operated could be the same
such that
the brake is applied at the same time as the connector is released.
Figures 6a through to 6c show a first alternative arrangement for releasing
eye
11 whereby pull cords 50 and 51 are required to be pulled in a specific
sequence with
pull cord 50 preceding pull cord 51. This is to reduce further the possibility
of
accidentally releasing the mechanism prematurely. In Figure 6a, lever 48 is
attached
to lever 32 such that it can rotate relative to lever 48 about axle 54. Lever
49 is able
to rotate about axle 53 and has a protruding pin 52 that is rigidly fixed to
its surface
and which bears on surface 56 of lever 49. Also, lever 49 has abutment 55 that
bears
on lever 48. Therefore, if pull cord 51 is pulled substantially in the
direction of arrow
51a, lever 48 is prevented from moving due to protruding pin 52 bearing on
surface
56 of lever 48. This also applies if both pull cord 50 and 51 are pulled
concurrently
substantially in the direction of arrow 51a. However, if pull cord 50 is
pulled first, as
shown in Figure 6b, substantially in the direction of arrow 50a, lever 49
rotates about
axle 53 allowing protruding pin 52 to move away from surface 56 on lever 48
such
that lever 48 may then be moved by pulling pull cord 51 substantially in the
direction
of arrow 51a, as shown in Figure 6c thereby rotating lever 30 and releasing
eye 11.
The addition of torsion spring 105 at axle 53 tending to rotate lever 49 in a
clockwise
direction relative to Figure 6b, will only allow pull cord 51 to be pulled
both after and
whilst pull cord 50 is pulled to its extent.
Figures 7a through to 7c show a second alternative arrangement for releasing
eye 11 whereby pull cord 58 is required to be pulled substantially in the
direction of
arrow 58a and then released but whereby the pull and release sequence is
required to
be carried more than one time consecutively. The embodiment shown includes a
CA 02566705 2013-08-09
release mechanism requiring 3 consecutive pulls on pull cord 58 in order to
release
eye 11. In Figure 7a, lever 62 is rigidly attached to pin 14 and has a stop 64
that bears
on stop 65, stop 65 being attached to or part of easing 9. Torsion spring 66
is between
lever 62 and casing 9 such that lever 62 tends to move in an anticlockwise
direction
relative to Figure 7a towards stop 65. Lever 62 also has radial teeth that
engage with
pawl 61, pawl 61 being mounted on lever 59 such that it can rotate relative to
lever 59
about axle 63. Lever 59 is able to rotate about axle 60 and has pull cord 58
attached
to it. Axle 60 is attached to casing 9. Torsion spring 67 is between pawl 61
and lever
59 tending to urge cam 61 in a clockwise direction relative to Figure 7a
towards Lever
62. Torsion spring 68 is between lever 59 and casing 9 tending to urge lever
59 in a
clockwise direction relative to Figure 7a towards stop 65. Whoa pull cord 58
is pulled
substantially in the direction of arrow 58a for the first time, pawl 61
engages with the
first tooth of lever 62 and rotates both lever 62 and pin 14 through a limited
arc in a
clockwise direction, With insufficient load on eye 11 bearing on pin 14, the
friction
generated between eye 11 and pin 14 would be overcome by the strength of
torsion
spring 66 and so lever 62 would return to its original position when pull cord
58 is
released. However, in the event that eye Ills loaded with the weight of person
1
relative to pin 14, the friction generated between eye 1,1 and pin 14 would be
sufficient to overcome the strength of torsion spring 66 such that, after the
first pull of
pull cord 58, lever 62 and pin 14 would be and remain rotated relative to eye
II. A
further pull of pull cord 58 substantially in the direction of arrow 58a would
engage
cam 61 in the next tooth in lever 62 thereby rotating lever 62 through a
further arc of
rotation. Figure 7b shows the start of a third pull of pall cord 58
substantially in the
direction of arrow 58a and in Figure 7c the third pull is shown as being
completed
whereby flat 18 In pin 14 is turned sufficiently to enable eye 11 to escape.
This is a
particularly safe method of release because it requires distinct consecutive
pulls on
pull cord 58 and if the load on eye 11 is insufficient to counteract torsion
spring 661
lever 62 returns to its start position against stop 65.
Whilst Figures 7a to 7a show an embodiment requiring three consecutive pulls
of pull cord 58, other typical embodiments may require two or more pulls. For
example the movable retention member or pin may have one or more projections
and
26
CA 02566705 2013-08-09
be rotatable to engage/disengage said one or more projections with/from a
corresponding notch formed in the load element. Two or more such projections
may
be provided for successive engagement in said notch, the release means needing
activation two or more times in order to release the load element It.
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Figures 8, 9a and 9b show a third and fourth alternative method of activating
- the -ielease of eye 11 such that the release can only be activated between a
minimum
and maximum range of loads on eye 1.1 and whereby the range of loads
specifically
includes loads equating to the weight of a person but excludes light loads
such as may
be encountered during normal activities at height and also heavy loads such as
would
occur whilst arresting a fall. The embodiment in Figure 8 shows a simple
mechanism
that would resist eye 11 being released below a predetermined threshold of
load on
eye 11. Lever 71 is able to rotate about axle 70 and axle 70 is secure in
casing 9.
Lever 71 also has a protruding surface 74 that interfaces with a mating
surface on eye
11. Spring 73 is a compression spring between abutment 73a that is attached to
or
part of casing 9 and lever 71, and spring 73 has sufficient strength to push
lever 74
against eye 11 such that if surface 18 on pin 14 were rotated into a position
where eye
11 could otherwise escape, the engagement of protruding surface 74 on lever 71
would hold eye 11 in place up to a minimum threshold of magnitude of load
between
eye 11 and pin 14.
The embodiment in Figures 9a and 9b shows a mechanism that would resist
eye 11 being released above a predetermined threshold of load on eye 11. Lever
30 is
rigidly attached to pin 14 with flat surface 18 and there is torsion spring 81
tending to
urge lever 30 and pin 14 to rotate in an anticlockwise direction relative to
eye 11.
Both levers 75 and 82 rotate about the same axle 76 and torsion spring 80 is
arranged
between levers 75 and 82 tending to urge lever 82 to rotate in a clockwise
direction
relative to Figure 9a towards lever 75. Pull cord 79 is attached to lever 82.
Pin 78
protrudes from the surface of lever 75 and engages with a slot form in lever
30 such
that rotation of lever 75 about axle 76 also causes rotation of lever 30 about
pin 14. If
the load on eye 11 bearing on both pins 13 and 14 is higher than a
predetermined
maximum threshold limit, the friction generated between pin 14 and eye 11 will
be
greater than the strength of torsion spring 80 in the event that pull cord 79
is pulled
substantially in the direction of arrow 79a. In such circumstances, pull cord
79 would
cause lever 82 to rotate but lever 75 would be held by lever 30, which in turn
is held
by friction between pin 14 and eye 11. However, if friction between pin 14 and
eye
11 was insufficient to overcome the strength of torsion spring 80 as would be
the case
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CA 02566705 2013-08-09
if the load on eye 11 were below the predetermined upper threshold, then,
rotational
movement of lever 82 activated by pull cord 79 would turn lever 75 that would
then
turn lever 30 and pin 14 allowing eye 11 to escape. Both embodiments shown In
Figure 8 and also in Figures 9a and 9b may be combined to provide a mechanism
that
= will only allow release of eye 11 between a predetermined maximum and
tninIm.um
threshold of load on eye 11.
In Figures 10, 1 la and 11b, a second embodiment of the personal height
rescue apparatus is shown. In Figure10 the second embodiment is shown as worn
on
the back of person] whilst carrying out ordinary work duties at height. The
second
embodiment of the invention is the same as the first embodiment with respect
to
release mechanisms for releasing eye 11 and also with, respect to the method
for
attaching the personal height rescue apparatus to harness 2 with the use of
bracket 3.
The main differences are in the MUDS of storing and deploying flexible
elongate
whilst lowering a person alter having been suspended f011owing the arrest of a
f*111,
and also the means of controlling the speed of deployment of flexible elongate
and
therefore the speed of the person's descent.
In Figures 1 la and lib, flexible elongate 85 is a length of flexible elongate
element attached at one to eye 11 and passed through guides 87 and 88 before
being
helically wound onto drum 90 in a clockwise direction relative to Figure 1 I
a. The
other end of flexible elongate 8$ is securely attached to drum 90. Drum 90 is
rigidly
attached to pin 91. At one end of pin 91 there is a headed portion that is
able to rotate
within axial bearing 92, axial bearing 92 being scoured to casing 86, so that
both drum
90 and pin 91 can rotate together within axial bearing 92. Fin 91 also passes
through
tixial bearing 96 that is secured in structure 95, structure 95 being rigidly
attached to
or is part of easing 86. Beyond structure 95, pin 91 has a threaded portion
shown as
thread 93 that is typically right handed. Nut 94 is a specially formed nut
that has a
central threaded hole that is threaded onto thread 93 of pin 91. Therefore,
drum 90,
pin 91 and nut 94 can rotate together with respect to casing 86. Spiral spring
98 is
attached between nut 94 and pin 91 tending to urge nut 94 to rotate in an
anticlockwise direction relative to pin 91 snob that spiral spring 98 tends to
urge the
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thread on nut 94 to unwind with respect to thread 93 on pin 91. Speed control
disc 99
is a disc that is attached to structure 95 and retains a viscous material 100
such that the
viscous material is disposed between speed control disc 99 and nut 94. The
viscous
material is intended to cause a predetenuined drag between nut 94 and
structure 95
such that when drum 90 rotates in an anticlockwise direction relative to
Figure lla the
threaded part of nut 94 tends to wind onto thread 93 of pin 91 towards drum
90.
When pull cord 37 is pulled substantially in the direction of arrow 40 to
release eye
11, drum 90 rotates in an anticlockwise direction with respect to casing 86
and
relative to Figure Ila deploying flexible elongate 85 from drum 90. The
strength of
spiral spring 98 tends to unwind nut 94 with respect to pin 91 thereby
allowing drum
90 to rotate. However, when the rotational speed of drum 90 exceeds a
predetermined
limit, the viscous drag imparted by viscous material 100 between nut 94 and
structure
95 tends to overcome the strength of spiral spring 98 and cause the threaded
part of
nut 94 to wind onto thread 93 of pin 91 such that both pin 91 and drum 90 move
towards nut 94. Friction disc 101 is a disc made of a friction material that
has a
substantially predeteauined coefficient of friction between itself and the
mating
surfaces of structure 95 and drum 90 such that when pin 91 and drum 90 move
towards friction disc 101, and structure 95 and drum 90 interacts with
friction disc
101, the rotational speed of drum 90 is reduced until the strength of spring
98 exceeds
the viscous drag imparted by viscous material 100 thereby tending to unwind
the
threaded part of nut 94 with respect to thread 93 of pin 91 such that drum 90
tends to
move away from friction disc 101 thereby reducing resistance to the rotational
movement of drum 90. Ball bearing 97 separates nut 94 and structure 95 such
that nut
94 is prevented from becoming locked to structure 95. Without ball bearing 97,
nut
94 could become locked to structure 95 due to friction that would develop
between
their mating surfaces so that spiral spring 98 would be unable to overcome the
friction
and therefore be unable unwind nut 94 with respect to pin 91 when the
rotational
speed of drum 90 has reduced below a predetermined limit.
Hence, in the above embodiment, the rotational speed of drum 90 is
effectively controlled and the speed of descent of person 1 is effectively
limited. A
manually controlled brake could easily be added with a mechanism that simply
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applies drag to nut 94 in addition to the viscous drag applied by viscous
material 100.
Such a mechanism could then be linked to a pull cord, or other suitable
operation
means, in order to operate the brake by pulling the pull cord.
Whilst the automatic speed control applied to drum 90 is shown as being
applied by viscous material 100 causing drag on nut 94, the application of
drag could
be any other suitable means providing dynamic drag that is related to the
speed of
rotation of drum 90 thereby limiting the speed of descent of person 1 after
eye 11 has
been released. In the event that the length of flexible elongate 85 is
insufficient to
lower person 1 to a safe level, flexible elongate 85 would be prevented from
leaving
drum 90 as a result of its end being securely attached to drum 90. Also, the
flexible
elongate 85 could be any suitable material and cross section. However, in
practice, it
has been found that steel cable is both strong and compact when wound around a
drum. High strength polymer rope may be used particularly as it is strong,
compact
and lighter than steel cable. Polymer tape such as webbing may also be used.
Figures 12a and 12b show an arrangement that is similar to the arrangement in
Figures lla and llb except that the releasable connector acting on eye 11 is
replaced
with a releasable stop that prevents drum 90 from rotating and therefore from
deploying flexible elongate and imparting dynamic fall arrest loading to the
speed
control mechanism that controls the speed that flexible elongate is deployed
from the
drum, until the releasable stop is released. In Figure 12a a first end of
flexible
elongate 85 is fixed to drum 90 and then a substantial part of the length of
flexible
elongate is helically wound onto drum 90, its second end being securely
attached to
eye 101. Eye 101 is notable in that it does not have any substantial features
that could
prevent it from moving away from drum 90. As in Figures 11.a and 11b, drum 90
may
rotate about axle 91 whereby axle 91 is secured between parallel sides of
casing 86.
There is also a mechanism for controlling the speed of rotation of drum 90
similar to
that in Figures 11 a and 11b, although this is not explicitly shown. Pawl stop
104 is
attached to or is integral with lever 102 and lever 102 is able to rotate with
respect to
housing 86 about its axle 103 that is secured to and disposed between two
parallel
sides of housing 86. Tension spring 105 urges lever 102 to tend to rotate in a
CA 0 2 5 6 67 0 5 2 0 13 ¨ 0 8 ¨ 0 9
clockwise direction relative to Figures I2a and 12b. In a dynamic fall arrest
situation,
dynamic fall loads would be applied to eye 101 in a direction away from drum
90
such that the dynamic fall loads would be imparted to flexible elongate 85 and
therefore tend to cause the rotation of drum 90. However, in. order to prevent
drum 90
from rotating, in. an anticlockwise direction relative to Figures 12a and 12b,
and
thereby imparting relatively high dynamic fall loading to the speed control
mechanism, pawl stop 104 as shown in Figure 12a is engaged in a recess in the
form
of cut-out detail 106 in the rim of drum 90 stopping its rotation. A line
drawn
between axle 103 and the engagement surface between pawl stop 104 and cut-out
detail 106 is ideally substantially parallel to length portion 85a of flexible
elongate 85
such that tensile loading applied to length portion 85a is substantially
counteracted by
pawl stop 104 at its axle 103 thereby minimising loading between drum 90 and
its
axle 91. After a dynamic fall arrest situation is concluded, pull cord 37 may
be pulled
in the direction of arrow 40 thereby also pulling its attaohment 107 to lever
102
against the urging load applied by tension spring 105, such that lever 102
rotates in an
anticlockwise direction relative to Figures 12a and 12b until the degree of
rotation is
sufficient to release pawl 104 from its engagement with drum 90 at its cut-out
detail
106. Drum 90 is then free to rotate and thereby deploy flexible elongate R5
and at a
speed of deployment controlled by the speed control mechanism. Clearly, any of
the
preceding methods for operating the release means and releasing a releasable
connector in Figures 5a through to 11b could equally be applied to releasing
pawl stop
104. Also, there are many different arrangements that could be used for
stopping
flexible elongate 85 and/or its deployment means such as drum 90 from moving
during a fall being arrested thereby preventing dynamic fall arrest loads from
being
imparted to the speed control mechanism, A disadvantage with acting on the
flexibk
elongate or flexible elongate deployment means to stop movement of the
flexible
elongate instead of using a releasable connector acting on a releasable eye as
shown in
Figures 5a to 1lb, is that dynamic fall arrest loading is imparted to at least
part of the
length of the flexible elongate 85 particularly between eye 101 and the
initial helical
winding onto drum 90. In order to minimise the size and weight of the flexible
elongate, the relatively highly loaded part of its length could, although not
necessarily, have greater strength than the remaining part. This greater
strength could
be provided in various ways including
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simply increasing the cross sectional area of the flexible elongate along the
part of its
length that is relatively highly loaded or by specifying a stronger material
for this part
of its length. Alternatively, more than one length of flexible elongate may be
arranged in parallel and secured together along the part of the length of
flexible
elongate that is relatively highly loaded or the flexible elongate could be
looped
around an attachment to eye 101 such that the looped length is also wound
helically
onto drum 90 until the load is reduced by radial friction effects in order to
effectively
double the strength capability in the relatively highly loaded part of its
length.
Figures 13a to 13c show a means for releasing eye 11 automatically such that
release is activated when the load applied to eye 11 is within both an upper
and a
lower predetermined limit. When a person is equipped with the personal height
rescue apparatus in normal use, not involving a fall event, the person may use
his
attachment to a secure anchorage as means for restraining his position or to
recover
from a stumble or slip and so it is desirable in such circumstances that eye
11 is not
released. Therefore, the lower predetermined limit below which eye 11 cannot
be
activated will be typically determined by the weight of the lightest person
that is
equipped with a personal height rescue apparatus. A typical lower limit may be
about
400N. In order to ensure that the flexible elongate cannot be deployed until
the
process of being arrested from a fall is substantially concluded, the upper
predetermined limit of load will typically deterinined by the weight of the
heaviest
person that is equipped with a personal height rescue apparatus. A typical
upper limit
may be about 2000N.
In Figure 13a, pins 13 and 14 restrain eye 11. Pin 13 is fixed between
parallel
sides of casing 86. Pin 14 is cylindrical with a flat 18 along its length and
is fixed or
is an integral part of the larger diameter pin 110. Pin 110 is secured between
parallel
sides of casing 86 such that it can rotate about its central axis relative to
casing 86.
When a load is applied to eye 11 typically in the direction of arrow 111, eye
11 bears
on pin 14 tending to rotate the larger pin 110 in a clockwise direction
relative to
Figure 13a and casing 86, as a result of the location of pin 14 being offset
from the
centre of pin. 110. Figure 13c shows how such rotation of pin 110 eventually
results
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in eye 11 being able to escape the restraints provided by both pins 13 and 14.
However, in Figure 1-3a; friction between the interconnecting surfaces of pin
110 and
casing 86 is sufficient to prevent rotation of pin 110 if the loading on eye
11, typically
in the direction of arrow 111, is greater than a predeteimined upper limit of
about
2000N. Figure 13b shows a view of Figure 13a but outside one of the parallel
sides of
casing 86. Link 112ds secured at a first end to pin 113 such that it can
rotate about
pin 113 and its second end is attached to tension spring 114. Tension spring
114 is
also attached to casing 86 at attachment location 115 such that it urges link
112 to
move towards location 115. Pin 113 is typically fixed to or is an integral
part of pin
110 and the central axis of both pins are aligned. When eye 11 is lightly
loaded in the
direction of arrow 111, tension spring 114 urges pin 110 to bear on casing 86
such
that the friction between the interconnecting surfaces of pin 110 and casing
86 prevent
rotation of pin 110 if the loading on eye 11, typically in the direction of
arrow 111, is
less than a predetennined lower limit of about 400N. If, however, the loading
on eye
11 is within the upper and lower predetermined limits, loading between pin 110
and
casing 86 will tend to be relieved by the counteraction of eye 11 and tension
spring
114 such that the friction between pin 110 and casing 86 is relatively small
and pin
110 can therefore rotate in casing 86. Also, pin 113 can rotate relatively
easily in the
relatively small diameter hole in link 112.
Figures 13d and 13e show a means for delaying the release of eye 11 in
Figures 13a to 13c for a predetermined time interval. The embodiment in
Figures 13a
to 13c would allow eye 11 to be released when the load on eye 11 is between an
upper
and lower limit. However, this may occur during the process of arresting a
fall rather
than when the process is substantially completed. Therefore, it is desirable
to include
a time delay to ensure that a load between the upper and lower limits has been
sustained for a time interval typically of about 30 seconds to allow
sufficient time for
any dynamic fall arrest event to be concluded before releasing eye 11. In
Figure 13d,
lever ant 118 is fixed to or is integral with pin 110 and pin 14. When a load
is
applied to eye 11 typically in the direction of arrow 111 and within the
predetermined
upper and lower limits, lever arm 118 is urged to rotate with pin 110 in a
clockwise
direction relative to Figures 13d and 13e. At the end of lever arm 118 away
from its
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attachment to pin 110, lever arm 118 bears on roller 121 that can roll about
axle 122.
Axle 122 is attached to receptacle 123 and receptacle 123 is able to rotate
about pin
120, pin 120 being attached to or disposed between parallel sides of casing 86
such
that lever arm 118 urges receptacle 123 to rotate in an anticlockwise
direction relative
to Figure 13d. Sucker 124 is fixed to casing 86 and has a flexible diaphragm.
Receptacle 123 is pressed against sucker 119 in Figure 13d creating a vacuum
or
partial vacuum within sucker 119 such that receptacle is urged to adhere to
sucker
119. The action of lever arm 118 bearing on roller 121 tends to separate
receptacle
123 from sucker 119. Sucker 119 has a small hole through which air can leak
until,
after a predetennined period of time has elapsed, the vacuum in sucker 119 is
filled
sufficiently so that sucker 119 is no longer urged to adhere to receptacle
123.
Typically, receptacle 123 would be urged by a spring (not shown
diagrammatically)
towards diaphragm 124 to ensure that the vacuum or partial vacuum within
sucker
119 is maintained during normal use of the personal height rescue apparatus
and,
more particularly, that it can be reset if the load on eye 11 should vary
between and
outside the upper and lower limits. For example, this reset facility would be
required
if a faller were to oscillate or bounce after being initially arrested from a
fall, due to
any elasticity in the fall arrest equipment or system. The effects of bouncing
would
apply a wide range of loading on eye 11 that may be both within and outside
the upper
and lower limits.
In the preceding embodiments, both eye 11 to which the lanyard is attached and
bracket 3 to which the harness is attached are rigidly attached to housing 9
so that
when load is applied between eye 11 and bracket 3 in the event of arresting
someone
falling, housing 9 may be urged to rotate about bracket 3 as eye 11 and
bracket 3 tend
to align with the applied load. This is not generally a problem if a faller
falls feet first
(in a substantially upright position with head above body and body above feet)
because there is unlikely to be any rotation of housing 9 about bracket 3
towards the
faller's body and therefore little, if any, load imparted on housing 9.
However, if the
faller falls in a prone position with head, feet and body at substantially the
same level,
and the rescue device is mounted on the faller's back, housing 9 will tend to
rotate
- into the faller's back as eye 11 and bracket 3 are urged to align with
the applied load
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to arrest a fall. As the lower edge of housing 9 contacts the faller's back,
eye 11 and
bracket 3 will be restricted in the extent to which they can align with the
applied load
causing all three components to be loaded awkwardly, particularly housing 9.
The
rotation of housing 9 and its contact load on the faller's back may be
sufficient to
cause injury. The same applies if the faller should fall head first with body
and feet
above the head.
In practice, it is difficult to determine how someone will fall and so it is
necessary to
provide for all feasible eventualities. Figures 14a through to 14e show a
preferred
embodiment that provides for different modes of falling by allowing
articulation
between housing 9 and both the lanyard attachment means and the harness
attachment
means. Eye 11 in preceding embodiments is replaced with a load element in the
form
of first and second portions such as an eye 130 and an anchor 131.
In Figures 14a and 14b, both eye 130 and anchor 131 are each shown as folded
from
sheet material to form a loop in each and eye 130 has an elongated apeiture
130a
through which anchor 131 is passed so that both eye 130 and anchor 131 are
effectively securely attached to each other when elongated aperture 130a bears
on
loop 131a in anchor 131. Also, eye 130 Is able to rotate about the radial axis
of the
folded loop 131A in anchor 131. Folded loop 130b in eye 130 is provided to
enable a
removable fastener such as a to karabiner, typically at the end of a lanyard
or other
safety line, to be passed through loop 130b to achieve a secure attachment to
eye 130.
A harness attachment section in the form of a harness bracket 133 lies two
parallel
arms 133a and 133b spaced apart with an adjoining bar 133c that is
perpendicular to
each arm and securely fixed to or part of one end of each arm. Axle 134 is
attached to
the other end of each arm and is securely located In a load element securement
section
in the form of structure 135 such that harness bracket 133 can rotate with
respect to
structure 135 about the axis of axle 134. Anchor 131 is also effectively
secured to
structure 135 whereby cut outs 13th and 131; shown in Figure 14b in anchor
131,
engage with retention members in the form of a cylindrical stop 156 and cam
stop 137
respectively. Structure 135 is shown as being formed fltm a flat sheet of
material
CA 02566705 2013-08-09
with a back 135a and two parallel sides 135b and 135c perpendicular to back
135a
and forrne.d, for convenience, by folding two opposing edges of the sheet
material.
One end of cylindrical stop 136 is fixed to and with its cylindrical axis
perpendicular
to the plane of back 135a of
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structure 135. A front plate, not shown in Figures 14a and 14b, is positioned
with its
plane parallel to and spaced apart from back 135a of structure 135 and is
located in
apertures 135d and 135e. The other end of cylindrical stop 136 is then
securely fixed
to the said front plate so that structure 135 and the said front plate are
also effectively
rigidly attached to each other. Cam stop 137 is secured between structure 135
and
said front plate and is able to rotate about an axis parallel and apart from
the axis of
cylindrical stop 136. Therefore, in Figure 14a, eye 130 and harness bracket
133 are
both secured to structure 135 and able to rotate on substantially parallel
axes with
respect to each other and to structure 135.
Figures 14c to 14e show eye 130 and harness bracket 133 articulating with
respect to
housing 9 for different fall positions, eye 130 being loaded in the direction
of arrow
146 and bracket 133 being loaded in the direction arrow 147. In all Figures
14c to
14e, structure 135 is attached to and housed within housing 9. Figure 14c
shows an
alignment of eye 130 and harness bracket 133 with housing 9 assuming a
position that
would be typical if someone was to fall feet first and where there is no
significant load
on housing 9 since there is no tendency for housing 9 to rotate about harness
bracket
133 towards harness 2 and the faller's body. Figure 14d shows an alignment of
eye
130 and harness bracket 133 that would be typical if someone fell headfirst.
Whilst,
in Figure 14d, there is some tendency for housing 9 to rotate about harness
bracket
133 towards harness 2, the load on the faller's back is unlikely to be
injurious and can
be mitigated by the rounded form in the region of 9a on housing 9 to spread
load on
the faller's back. Figure 14e shows an alignment of eye 130 and harness
bracket 133
that would be typical of someone falling in a prone position with head, body
and feet
at substantially the same vertical level and where, as in Figure 14c, there is
no
significant load on housing 9 due to any tendency for housing 9 to rotate
about
harness bracket 133 towards harness 2 and therefore the faller's body. In
Figure 14e,
eye 130 leans on protruding abutments 135f and 135g on structure 135, as shown
in
Figure 14b, to avoid anchor 131 from being excessively loaded other than in
the
direction in which it may be eventually be released as in Figure 14b.
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In Figure 14b, cam stop 137 shares some similarities with lever 62 in Figure
7a. In its
normal radial position whilst a fall is being wrested, cam stop 137 presents a
substantially cylindrical surface to engage in cut out 131e in anchor 131,
However,
when cam stop 137 is rotated in an anti clockwise direction relative to Figure
14a and
to an extent as showo in Figure 14b, the cylindrical surface is rotated away
from cut
out 131c and replaced with a recessed section in the form of a flat cut away
portion
that allows anchor 131 and therefore eye 130 to escape from structure 135. Pin
138 is
located securely in anchor 131 and one end of flexible elongate 85 is
terminated
typically with the elongate formed in a closed loop and the loop restrained
with a
component such as a ferrule and the loop is then attached securely around pin
138.
In practice, it has been found that the method shown in both Figures lla and 1
lb for
housing flexible elongate 21 and controlling the speed of its deployment is
advantageous because friction disc 101 is the principal means for reducing the
rotational speed of driun 90 whereas viscous material 100 only acts as a servo
mechanism for controlling the force with which drum 90 is brought to bear on
friction
disc 101. This means that the viscous drag required by viscous material 100 to
control drum 90 is relatively small so that the servo mechanism can be
reiatively
lightweight and economic to manufacture. . However, viscous material can
present a
problem because of the tendency for its viscosity to change depending on its
temperature so that as the rescue apparatus is used to descend a person, some
heat
dissipated within the apparatus may transfer to viscous material 100 and
affect its
viscous drag characteristics. An alternative is to use a centrifugal brake
mechanism
and an embodiment of this is shown in Figures 15a and 15b.
As in Figures 1 La and 1 lb, the embodiment in Figure 15a has flexible
elongate 85
being helically wound onto drum 90. One end of flexible elongate 85 is
attached to a
component such as anchor 131 in Figures 14a and 14b and the other end is
securely
attached to drum 90, not shown in Figure 15a. Drum 90 is rigidly attached to
pin 91
and both are able to rotate within bearing surface 150 that is part of housing
9c. Pin
91 has a threaded region 93a that is engaged in a mating threaded region in a
specially
formed nut 94. Nut 94 passes through the centre of a spur gear, drive gear
151, and is
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frictionally adhered to drive gear 151 by means of brake lining ring 152 and
spring
washer 153 such that relative rotational movement between nut 94 and drive
gear 151
is prevented until opposing torque between nut 94 and drive gear 151 exceeds a
predetermined limit. Thrust bearing 154 minimises friction effects between nut
94
and housing 9c. When drum 90 and pin 91 rotate together in the direction of
tightening the mating screw surfaces between pin 91 and nut 94, nut 94 will
tend to
unwind with respect to pin 91 because there is no significant friction between
nut 94
and housing 9c due to thrust bearing 154. Therefore, as drum 90 rotates with
respect
to housing 9c, drive gear 51 will also tend to rotate in the same direction.
Drive gear 151 intermeshes with a spur gear, idler gear 155, and idler gear
155 is free
to rotate about spindle 161. Idler gear 155 intermeshes with a spur gear,
pinion gear
156. Pinion gear 156 is rigidly attached to spindle 157 and spindle 157 is
attached to
shoe drive aim 158 such that spindle 157 and shoe drive aim 158 are
constrained to
rotate together. As also shown in Figure 15b, shoe drive arm 158 is locate
between
shoes 159a and 159b and both shoes 159a and 159b can rotate within and about
the
cylindrical axis of cylindrical friction lining 160 that is housed in housing
9e, housing
9e being located between housing 9c and 9d such that rotation of drive gear
151 will
result in the rotation of shoes 159a and 159b. As shoes 159a and 159b rotate,
the
mass and rotation speed of each shoe will determine the magnitude of the
radial force
between each shoe and cylindrical friction lining 160 such radial force being
translated into a tangential braking force that is then translated through the
spur gear
train back to drive gear 151. The resultant drag on gear 151 will also apply
drag on
nut 94 such that ongoing rotation of drum 90 will tend to tighten pin 91 into
the
mating thread in nut 94. As pin 91 is drawn towards nut 94, drum 90 is also
drawn
towards friction disc 101, friction disc 101 being constrained not to rotate
with respect
to housing 9c, thereby reducing the rotational speed of drum 90. As the speed
of
drum 90 reduces further, the rotational speed of drive gear 151 and ultimately
the
rotational speed of shoes 159a and 159b reduces thereby also reducing the
centrifugal
drag tending to tighten nut 94 onto pin 91. Eventually, the centrifugal drag
will
reduce to an extent where the thread of nut 94 tends to unwind with respect to
pin 91
allowing drum 90 to move away from friction disc 101 and freeing drum 90 so
that its
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rotational speed can increase again. In this way, the centrifugal brake acts
as a
dynamic servo mechanism to regulate the braking force between drum 90 and
friction
disc 101 depending on the rotational speed of drum 90 and thereby controls the
speed
of deployment of flexible elongate 85 from drum 90. The significant advantage
of
this arrangement is that the centrifugal braking mechanism can be relatively
low
strength and lightweight because it is the friction between drum 90 and
friction disc
101 that is doing the principal work slowing the speed of drum 90. Because of
the
relatively small mechanical load demands on such a servo mechanism, it has
been
found that both drive gear 151 and idler gear 155 can typically be made from
plastic.
In preferred embodiments, it has been found that it is advantageous for the
mating
screw thread surfaces between pin 91 and nut 94 to be coated in a low friction
material and also for the thread to have a non standard extended pitch size to
increase
the tendency for nut 94 to unwind with respect to pin 91.
During the process of a person descending to the ground or to a safe level
with the
rescue apparatus, it is possible that the person could temporarily alight on
an abutment
in the rescue path and then undergo a secondary fall. In a worst case
scenario, a
secondary fall could involve some free fall where the person falls through a
vertical
distance without flexible elongate being deployed from drum 90. In such a
situation,
at the end of the free fall distance, rotation of drum 90 will accelerate
sharply and
quickly reach a speed that would engage the centrifugal servo brake and bring
drum
90 to bear on friction disc 101 with a relatively high force that could be
transmitted to
the person being descended as well as the rescue apparatus itself. To mitigate
against
this effect, as shown in Figure 15a, the predetermined frictional adherence
between
nut 94 and drive gear 151, as a result of spring washer 153 urging nut 94 and
drive
gear 151 to bear on brake lining ring 152, would be overcome and drum 90 and
nut 94
would rotate independently of drive gear 151 thereby ensuring that load on
flexible
elongate 85 never exceeds a predetermined limit effectively limiting load on
the
person and flexible elongate 85 to within a safe level typically around 2.5kN
or 3kN.
Input fall energy as a result of the free fall would be absorbed at least in
part by the
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multiple of load resisting rotational movement of drum 90 and the extent to
which
drum 90 turns
When a person is descended through a distance at a controlled speed, much of
the
energy absorbed as a result controlling descent speed will be translated into
heat.
Whilst this is not normally a problem, it is sensible to manage the
distribution of heat
within the rescue device particularly in the vicinity of plastic components.
In practice,
it has been found that heat can be effectively stored in drum 90 if it is made
from
aluminium and where friction disc 101 is constrained by housing 9c not to
rotate with
drum 90. Also, if flexible elongate 85 is made from galvanised steel wire, the
wire
itself can store heat and dispense it, albeit slowly, as the wire is deployed
from the
rescue device. Alternatively, if flexible elongate 85 is made from a fibre
rope that is
vulnerable to heat, housing 9c may be made from aluminium and friction disc
101
could be constrained by drum 90 to rotate with drum 90.
Figures 16a and 16b, with reference to Figures 14a, 14b, 15a and 15b show an
embodiment with a descent brake operated by pull cord 37 as well as the
function of
pull cord 37 activating the release of anchor 131. Figure 16a shows the decent
brake
being applied when pull cord 37 is released and Figure 16b shows the descent
brake
being released when pull cord 37 is pulled.
In Figure 16a, pull cord 37 is attached to one end of lever 166 and the other
end of
lever 166 is attached to and can rotate about pin 165 such that when pull cord
37 is
pulled, lever 166 rotates about pin 165. The position of pin 165 is fixed with
respect
to housing 9d. Lever arm 169 is also attached to and can rotate about pin 165.
Pin
170 is attached to both lever arm 169 and one end of brake lever 171 so that
both
lever aim 169 and brake lever 171 can. rotate about pin 170. Towards the other
end
of end of brake lever 171, brake lever 171 is constrained firstly between
brake ring
173 and then, closer to the end of brake lever 171, abutment 172. The
positions of
abutment 172 and the central axis of brake ring 173 are fixed with respect to
housing
9d and brake ring 173 is able to rotate within cylindrical housing 9f that is
typically an
integral part of housing 9d. The axis of rotation of brake ring 173 is the
same as the
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axis of rotation of shoes 159a and 159b in Figures 15a and 15b and brake ring
173 has
lugs 173a and 173b that locate between the ends of shoes 159a and 159b so that
brake
ring 173 and shoes 159a and 159b are effectively constrained to rotate
together on a
common axis. Pin 170 is urged to rotate in an anti clockwise direction about
pin 165
with respect to Figure 16a by torsion spring 174 such that brake lever 171,
because of
its movement being restricted by abutment 172, is urged to bear on brake ring
173 and
thereby apply load on brake shoes 159a and 159b to impede and stop their
rotation
- such that rotation speed of drum 90 is also reduced or brought to a
standstill slowing
or stopping deployment of flexible elongate 85.
In Figure 16b, pull cord 37 is shown in a position after having been pulled in
the
direction of arrow 37a such that lever 166 is rotated in a clockwise direction
with
respect to Figure 16b. Pin 168 is attached to lever 166 and is raised at one
end above
the surface of lever 166 such that it forms an abutment that acts on lever arm
169 at
contact surface 169a thereby tending to rotate lever arm 169 in a clockwise
direction
about pin 165 with respect to Figure 16b so that pin 170 and the end of brake
lever
171 attached to pin 170 are also rotated about pin 165 thereby allowing
movement of
brake lever 171 between brake ring 173 and abutment 172. Torsion spring 174
urges
brake lever 171 to rotate towards abutment 172 and away from brake ring 173.
Brake
shoes 159a and 159b are then free to rotate so that drum 90 is also able to
resume
deployment of flexible elongate 85. A spring not shown in either Figures 15a
or 15b
urges lever 166 to rotate in an anti clockwise direction about pin 165 with
respect to
Figures 15a and 15b such that when pull cord 37 is released after having been
pulled
in the direction of arrow 37a, lever 166 returns to its position as shown in
Figure 15a
and the brake is then reapplied.
Figures 16a and 16b, with reference to Figures 14a and 14b, also show a
preferred
embodiment for releasing anchor 131 by pulling pull cord 37. Lever 167 is
attached
at one end to pin 168 and is able to rotate about pin 168. Pin 168 is also
attached to
lever 166 such that lever 166, pin 168 and the said one end of lever 167
rotate
together in a clockwise direction about pin 165with respect to Figure 16a when
pull
cord 37 is pulled in the direction of arrow 37a. A spring not shown in either
Figures
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15a or 15b tends to urge lever 167 to rotate in a clockwise direction about
pin 168
with respect to Figure 16a. Pin 167a is fixed to the other end of lever 167
and
engages in a first tooth of cam stop 137. Cam stop 137 rotates about axis
137a, the
position of which is fixed with respect to housing 9d. Whilst arresting
someone
falling, cam stop engages in cut out 131c in anchor 131, in Figure 14b,
preventing
anchor 131 from escaping from structure 135. When pull cord 37 is pulled in
the
direction of arrow 37a, lever 167 and pin 167a apply a load on the said first
tooth of
cam stop 137 tending to rotate cam stop 137 in an anti clockwise direction
with
respect to Figure 16a. After this first pulling action of pull cord 37, cam
stop 137
remains engaged in cut out 131c in anchor 131. A spring, not shown in Figures
16a or
16b, tends to urge cam stop 137 to rotate in a clockwise direction about its
axis 137a
with respect to the said Figures so that cam stop 137 will tend to return a
first position
as shown in Figure 16a when pull cord 37 is released. However, when there is a
predeteimined level of load between someone's harness and eye 130 as would
occur
when a fall has been arrested, cam stop 137 would bear on cut out 131c in
anchor 131
and the frictional resistance between the contacting surfaces of cam stop 137
and cut
out 131c would be sufficient to stop cam 137 returning to its first position
after pull
cord 37 is released. In such an arrested fall situation, when pull cord 37 is
released,
pin 167a engages in a the second tooth of cam stop 137 so that another pull of
pull
cord 37 will rotate cam stop 137 through a further angle of rotation to an
extent where
there is no engagement of cam stop 137 with cut out 131c and anchor 131 can
then
escape as shown in Figure 16b. This method of releasing anchor 131 avoids
anchor
131 from being released unintentionally such as if pull cord 37 was
accidentally
snagged.
It should be understood that the brake as operated by pull cord 37 would
typically be
used after anchor 131 has been released and when a person is being descended.
Such
a brake function would be especially useful if someone was to descend from one
level
at height to another level rather than to the ground. For example, if a
person's fall had
been arrested on a high-rise building it would be useful if that person could
descend
and stop alongside a lower level to be rescued. However, in work at height
sites
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where the descent is relatively simple the pull cord brake facility may not be
needed
in which case it would be more economic to provide the rescue apparatus
without it.
Figures 17a and 17b show external views of the rescue apparatus incorporating
embodiments described in Figures 14a, 14b, 15a and 15b and also in 16a and 16b
that
may or may not include a brake as operated by pull cord 37.
In Figure 17a the harness straps of harness 2 passing through restrictor 185
and
around the harness bracket 133. Restrictor 185 is typically used with
harnesses to
prevent the rescue apparatus from slipping with respect to the harness. Eye
130 is
noirnally angled at rest as shown and a karabiner is then fastened through the
open
loop. Bracket 133 would nonnally be rotated with respect to housing 9d as a
result of
the weight of the rescue apparatus. However, for convenience when the rescue
apparatus is being carried in normal working conditions, it is typical for
bracket 133 is
to held in the position shown in Figure 17a usually by one or more straps
linking the
lower part of housing 9c or 9d to harness bracket 133.
In Figure 17b, the hidden lined circles indicate how drum 90, drive gear 151,
idler
gear 155 and pinion gear 156 would typically be located inside the apparatus
housing
components 9b, 9c and 9d. Fastenings 186 and 187 serve to locate structure 135
in
Figures 14a and 14b within housings 9c and 9d. Pull cord 37 is shown without
any
sheathe because the use of multiple pulls to activate the release of anchor
131 will in
many embodiments be sufficient to avoid accidental release before a fall has
been
arrested.
Reference has been made to the possibility of a person becoming incapacitated
whilst
being arrested from a fall to an extent that the person might be unable to
operate
release cord 37 manually and further reference has been made to a proposed
solution
whereby an extension of pull cord 37 may be dropped to the ground, or other
safe
level, during the process of arresting the fall enabling another person to
activate the
release mechanism instead and from the level to which the faller will be
descended.
Figures 18a, 18b, 18c and 18d show an example of an embodiment that provides
such
an extension to pull cord 37.
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Webbing 202 is a length of webbing strap that is typically a part of a
person's harness.
A loop shown as loop 202a in Figure 18b is faimed in webbing 202 with the
looped
axis parallel to the width of webbing 202 and loop 202a is then passed through
a
substantially rectangular aperture in one side of cylindrical drum 201. The
length of
the said aperture is at least as long as the width of webbing 202 and the said
aperture
width is bounded on each side by two opposing angled walls 201c and 201d that
are
attached to and typically part of drum 201. Pin 204 is a cylindrical pin whose
length
is typically similar to the width of webbing 202 and less than the length of
the said
aperture in drum 201. Pin 24 is placed within loop 202a with its cylindrical
axis
parallel to the folded axis of loop 202a. The width of the said aperture in
drum 201 is
less than the effective diameter of both pin 204 and loop 202a such that both
pin 204
and the loop 202a cannot normally return through the aperture in drum 201
without
first removing pin 204. Flexible elongate 200 is a length of flexible elongate
that is
helically wound onto drum 201 and fills drum 201 at least in the region of
loop 202a
such that both loop 202a and pin 204 are effectively located between flexible
elongate
200 and the said aperture in drum 201. 201e and 201f in Figure 18c are stops
that
retain pin 204 and prevent movement of pin 204 along its cylindrical axis.
Cover 203
is assembled onto webbing 202 through its slot 203c and it is then located
over drum
201 as a means for preventing flexible elongate 200 from escaping from the rim
of
drum 201. Abutments 203a and 203b in Figures 18b and 18d help to locate cover
203
into position with respect to drum 201. For convenience, cover 203 may be
attached
to webbing 202 at an attachment means 205 to stop it becoming easily detached
from
webbing 202. In practice, Velcro has been found to be suitable for attachment
means
205.
Flexible elongate 200, preferably made from a rope which is strong, relatively
small
diameter for compactness and light weight, is securely attached to or is part
of pull
cord 37 in Figure 17b. In practice, some modern fibre ropes with small
diameters as
little as 2.5mm have been found to provide adequate strength. The length of
flexible
elongate 200 is typically at least as long as flexible elongate 85 wound onto
drum 90
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in Figure 15a so that there is sufficient length to reach the ground or some
other safe
level after someone has been arrested from a fall.
When a person is arrested from a fall, the person's harneSs webbing straps are
loaded
significantly in tension as a result of restraining and arresting the fall.
When webbing
202 is loaded beyond a predetermined level typically in the opposing
directions of
arrows 206 and 207 in Figure 18b, angled walls 201c and 201d deflect under the
load
as a result of the tendency for loop 202a to straighten until the deflection
of walls
201c and 201d is sufficient to enable both pin 204 and loop 202a to escape
through
the aperture in drum 201. When pin 204 and loop 202a escape, drum 201 is free
to
fall away from webbing 202 and to descend to the ground, or other safe level.
As
drum 201 falls it also rotates as a result of flexible elongate being unwound
from the
drum. The rotation of drum 201 during its descent has been found to be
beneficial
because the drum tends to roll away from any obstructions in its path. When
drum
201 reaches the ground, or some other safe level, a person other than the
faller can
pick up the line and operate the fallers rescue apparatus. If flexible
elongate 200 were
relatively strong small diameter rope, it could be difficult for someone to
grip the rope
sufficiently filialy to operate the rescue apparatus release mechanism. Slots
201a and
201b in drum 201 enable the rope to be mechanically gripped on drum 201 on the
drum itself so that someone may handle drum 201 instead of flexible elongate
200 to
achieve the necessary grip and pulling tension.
In any of the methods for releasing eye 11 in any of the embodiments from
Figure 1 through to Figure 13e including any or all methods for releasing drum
90 in
Figures 12a and 12b and also for releasing eye 130 and anchor 131 in Figures
14a
through to 17b, a timer could be added so that if a release has not been
manually
carried out in a predetermined time period, the release mechanism could be
actuated
automatically. This would be useful if a person sustained injury whilst
falling and/or
being arrested and was therefore unable to operate the manual release control
to
release eye 11 or pawl stop 104. Alternatively, an additional extended manual
release
control may be used as provided in Figures 18a, 18b, 18c and 18d. Also, in any
of the
above embodiments, the personal height rescue apparatus could be attached to
any
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suitable harness or safety belt and in any location with respect to the person
wearing
the harness or safety belt. For example, the personal height rescue apparatus
could be
attached at the front of a person particularly if the person was undertaking
tasks that
required him or her to be facing the secure anchorage provided by the fall
arrest
system or single point anchorage.
Any above references to manual control could also mean control by any other
part of a person's body, limbs or head. The cord in any of the pull cords
referred to in
any of the preceding embodiment descriptions is typically a flexible elongate
and all
aforementioned references to flexible elongate refer to flexible elongate that
may be
made from any suitable material and with any suitable cross section.
The described embodiments differ in their details but they are linked by
common operating principles. Accordingly, it will be understood by the person
skilled in the art that the technical features described with reference to one
embodiment will natinally be applicable to other embodiments.
Where the invention has been specifically described above with reference to
these specific embodiments, it will be understood by the person skilled in the
art that
these are merely illustrative although variations are possible within the
scope of the
claims, which follow.
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