Note: Descriptions are shown in the official language in which they were submitted.
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E~R~NCY CABLE BRAKE
FIELD OF THE lNV~NlION
The present invention relates, in general, to suspension type
cables which will normally be subjected to a substantially constant
tension being applied to them during service thereby increasing the
chances of these suspension cables becoming broken due at least in
part to such constant tension being applied to them over an
extended period of time and, more particularly, this invention
relates to an improved emergency cable brake type apparatus which
is specifically designed to both quickly seize and then retain such
suspension cable in the event that such suspension cable should
become broken and in this manner substantially minimize any
detrimental and/or potentially hazardous sudden movements of the
suspension cable and, still even more specifically, the instant
invention relates to an improved emergency cable brake type
apparatus which will both seize and hold the suspension cable
portion of a balanced weight assembly that provides the requisite
amount of constant tension on both the overhead messenger wire and
contact wire portions of an overhead suspended catenary system that
supplies the electrical energy necessary to operate certain known
types of passenger transit railway vehicles in the event at least
one of such messenger wire portion or such contact wire portion of
such catenary system should become broken for any reason.
BACKGROUND OF THE lNv~N~lION
It is generally well recognized in the suspension cable art,
that there are a number of applications in which steel and/or other
type metal cables will be subjected to a more or less constant
tension being applied to them during their normal service. The
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steel cables which are attached to elevator cars for enabling the
movement of these cars between adjacent floors in a building and
the cable which forms at least a portion of the balanced weight
assembly utilized to maintain a substantially constant tension on
both the messenger wire portion and the contact wire portion of an
overhead suspended catenary system that enables the necessary
electrical energy to be delivered to certain known types of
passenger transit type railway vehicles are only two examples of
such cables, presently known by applicant, that will be subjected
to a relatively constant tension being applied to them during
service.
It is likewise well known, for example, that these elevator
car suspension cables must always possess at least the capability
of supporting not only the overall gross weight of a particular
elevator car but, also, these suspension cables are quite often
required to support the additional weight of one or more passengers
and/or some form of freight which is being transported therein.
Consequently, even though these elevator car suspension cables
are subjected to a relatively constant tension, the tension that
is being applied to them during their normal operation will,
obviously, vary from time to time due to both the number and the
weight of such passengers and/or the weight of such freight being
carried by the elevator car.
On the other hand, the balanced weight assembly which is
normally utilized to maintain the tension on each of the messenger
wire portion and the contact wire portion of an overhead suspended
catenary system will normally provide a substantially constant
tension. The prior art type balanced weight assemblies which are
used in this particular application may include either an integral
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type weight portion or a stack of individual type weight portions.
In either case these weight portions are usually both suspended
from and supported by a steel cable which has a predetermined
diameter.
Additionally, the suspension cable is, normally, looped
through a pulley system connected to a yoke member which in turn
is connected to one end of both the messenger wire portion and the
contact wire portion of the catenary system.
The specified weight ratio that is provided between the more
or less typical balanced weight assembly known to be in use at the
present time and the catenary system which is suspended overhead
will, generally, be on the order of approximately 1:3.
Furthermore, in this known type of catenary system, either the
integral type weight portion or the stack of individual type weight
portions of such balanced weight assembly will be essentially free
to travel in each of an upwardly and downwardly direction. Such
upward or downward movement of such balanced weight assembly will
readily compensate for either the contraction or the expansion of
both the messenger wire portion and the contact wire portion of
such overhead suspended catenary system. The noted contraction and
expansion of such catenary system, normally, being encountered due
to the fluctuations in the temperature.
Additionally, in each of the applications discussed above, the
suspension cable is being subjected constantly to a rather large
amount of flexing. Such flexing of the cable will, in general,
tend to cause a certain amount of fatigue in the cable. This will
be especially the case over an extended period of time.
In addition, in the application for providing a substantially
constant tension on an overhead suspended catenary system, the
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suspension cable for the balanced weight assembly portion of such
catenary system is more often than not constantly exposed to the
outdoor elements during service.
In one particular overhead suspended catenary system that is
connected to supply the electrical energy required for a passenger
transit type railway vehicle installation, which is known by the
applicant to be in operation at the present time, the constant
tension that is being maintained on such messenger wire portion of
such catenary system is on the order of approximately 4,000 lbs.
and the constant tension that is being maintained on the contact
wire portion of such overhead catenary system is on the order of
approximately 3,000 lbs.
Therefore, in order to accomplish these constant tension
values the overall weight of the weight stack portion of such
balanced weight assembly will be 1/3 of about 7,000 lbs. or on the
order of about 2,333 lbs.
It is, likewise, known by the applicant that in such overhead
suspended catenary system discussed above, the weight stack portion
of such balanced weight assembly is movably disposed at a position
located a few feet above the ground level. Consequently, prior to
the development of the present invention, if an undesirable event
should occur in which both of such messenger wire portion and the
contact wire portion of such suspended catenary system should
become broken, then at a minimum the weight stack portion of such
balanced weight assembly would be capable of free falling down to
the ground.
Obviously, should the weight stack portion of the balanced
weight assembly fall to the ground a considerable amount of damage
could occur to the pole during the fall as well as to the weights
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which form the individual weight stack portion itself. Of even
more importance, it is conceivable that these weights could cause
either a serious or possibly even a fatal injury to anyone who
might happen to be in their way as they are tumbling down to the
ground.
SUMMARY OF THE lNV~NllON
In a first aspect, the present invention provides an improved
emergency cable braking type apparatus which is capable of being
utilized in a number of specific, but different, applications. The
emergency cable brake apparatus, of this invention, includes a
housing structure. A cable gripping means includes a first portion
thereof immovably secured within and to such housing structure and
has a second portion thereof pivotably secured within and to such
housing structure. The second portion of such cable gripping means
is designed to cooperate with such first portion of the cable
gripping means in a manner to both grip and hold such cable when
the tension on such cable is suddenly removed. There is a trigger
means having a first portion thereof rotatably secured within such
housing structure for sensing any undesirable and relatively sudden
acceleration of such cable. A second portion of such trigger means
is pivotably connected to a predetermined surface of such first
portion of the trigger means. This second portion of such trigger
means engages a third portion of the trigger means which is
pivotably connected to such housing structure and is engagable with
the cable gripping means for releasing such cable gripping means
into a position such that any further free fall of such cable is
stopped.
In a second aspect of the present invention, there is provided
in an overhead suspended catenary system, having both a messenger
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wire portion and a contact wire portion connected at one end
thereof to a yoke-like member and a balanced weight assembly
connected to said yoke and a pole member to provide a predetermined
amount of substantially constant tension on such messenger wire
portion and such contact wire portion of such catenary system, the
improvement therewith of a cable type brake apparatus as described
above.
OBJECTS OF THE lNv~N~l~ION
It is, therefore, one of the primary objects of the present
invention to provide an improved emergency cable brake type
apparatus which is effective in both seizing and holding a
suspension type cable upon determining a break has occurred.
Another object of the present invention is to provide an
improved emergency cable brake type apparatus which can be readily
adapted to a number of different applications in which a suspension
type cable is utilized.
Still another object of the present invention is to provide
an improved emergency cable brake type apparatus which is
relatively simple to install.
Yet still another object of the present invention is to
provide an improved emergency cable brake type apparatus which will
require a m; n; m~ 1 amount of maintenance.
A still further object of the present invention is to provide
an improved emergency cable brake type apparatus which will be
relatively inexpensive to manufacture.
It is an additional object of the present invention to provide
an improved emergency cable brake type apparatus which is
particularly well suited for use with the suspension cable portion
of a balanced weight assembly that is designed in such a manner so
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as to maintain a substantially constant tension on both a messenger
wire portion and a contact wire portion of an overhead catenary
system that supplies the electrical energy required to operate
certain types of passenger transit vehicles.
A further object of the present invention is to provide an
improved emergency cable brake type apparatus which can be rather
easily retrofitted to an existing suspension cable portion of a
balanced weight assembly forming a part of an overhead suspended
catenary system.
Still yet another object of the present invention is to
provide an improved emergency cable brake type apparatus which can
be easily adapted to a number of different applications that may
require the use of a number of different cable sizes.
A further object of the present invention is to provide an
improved emergency cable brake type apparatus which includes a
self-locking feature incorporated therein.
In addition to the several objects and advantages of the
present invention that have been discussed in some detail above,
it is conceivable that various additional objects and advantages
of the improved cable type brake apparatus will become more readily
apparent to those persons who are skilled in the relevant cable
braking art from the more detailed description of the invention
which follows, particularly, when such detailed description is
taken in conjunction with the attached drawing Figures and with
the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view which illustrates a presently
preferred embodiment of a housing structure of an emergency cable
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brake type apparatus according to a presently preferred embodiment
of the invention;
Figure 2 is a side elevation view of a presently preferred
embodiment of the emergency cable brake type apparatus of the
present invention with the cover removed from the housing
structure;
Figure 3 is a perspective view which illustrates a presently
preferred embodiment of the emergency cable brake type apparatus
illustrated in Figures 1 and in a position before it has been
triggered to seize a cable and with the cover removed;
Figure 4 is another perspective view of the emergency cable
brake type apparatus illustrated in Figures 1 and 2; and
Figure 5 is a schematic diagram which illustrates the present
invention as it is used in a suspension cable portion of a balanced
weight assembly that is designed in such a manner so as to maintain
a substantially constant tension on both a messenger wire portion
and a contact wire portion of an overhead catenary system that
supplies the electrical energy required to operate certain types
of passenger transit vehicles.
BRIEF DESCRIPTION OF THE PRESENTLY
PREFERRED EMBODIMENTS OF THE lNV~NlION
Prior to proceeding to the more detailed description of the
present invention, it should be noted here that, for the sake of
clarity, identical components which have identical functions have
been identified with identical reference numerals throughout the
several views illustrated in the drawings.
Additionally, it should be noted here that even though, for
the purposes of understAn~;ng the invention, such improved
emergency cable brake type apparatus will be described in detail
as it will relate specifically to use in a suspension cable portion
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of a balanced weight assembly that is designed in such a manner so
as to maintain a substantially constant predetermined tension on
both a messenger wire portion and a contact wire portion of an
overhead suspended catenary system that is provided in order to
supply the electrical energy requirements for the operation of
certain known types of passenger transit vehicles, the applicant,
also, contemplates use of the present invention in a number of
other cable brake type applications and these other applications
are, likewise, considered to be within the spirit of the instant
invention and the broad scope of the claims.
Now reference is made, more particularly, to Figure 5 of the
drawing Figures. Illustrated therein is one end of a catenary
system, generally designated 10. Catenary system 10 is suspended
overhead and is known to be in use in a mass transit installation
at the present time. As is known, such overhead catenary system
is provided in this installation to supply the necessary
electrical energy to the railway type passenger transit vehicles.
Such catenary system 10 includes each of a messenger wire
portion 12 and a contact wire portion 14. One end of each of the
messenger wire portion 12 and such contact wire portion 14 is
attached to a plate-like yoke member 16 adjacent respective ends
thereof.
In order to suspend such catenary system 10 overhead, there
is provided a pole member 18, which has a portion of a balanced
weight assembly, generally designated, 20 attached thereto adjacent
the upper end thereof. Such balanced weight assembly 20 includes
at least one and, preferably, a plurality of pulley members 22
(three such pulley members are illustrated) and their associated
brackets 24 around which a cable 26 is strung. A first end 28 of
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such cable 26 is secured to the yoke member 16 at a predetermined
point located intermediate the one end of such messenger wire
portion 12 and the one end of such contact wire portion 14 which
are attached to such respective ends of the yoke member 16.
Attached to the cable 26, adjacent the second end 30 thereof
is a weight stack portion 32. Such weight stack portion 32 of the
balanced weight assembly 20 provides a predetermined amount of
substantially constant tension to be applied to such catenary
system 10.
Now reference is made, more particularly, to Figures 1
through 4 of the drawings. Illustrated therein is one of the
presently preferred embodiments of the invention in which such
improved cable type brake apparatus, generally designated, 40 is
pivotally attached to such pole 18. The cable brake apparatus 40
is disposed on the pole 18 at a point located intermediate that
portion of such balanced weight assembly 20 attached to the upper
end portion of such pole 18 and the weight stack portion 32. In
this embodiment of the invention, the pivotal attachment of the
cable brake apparatus 40 to the pole 18 is achieved by at least one
and,preferably, by a pair of mounting brackets 34 (upper and lower)
attached to such pole 18 and a bolt 36 disposed through both such
upper and lower mounting brackets 34 and the housing structure 38
of such emergency cable brake apparatus 40.
In addition to the housing structure 38, such emergency cable
brake apparatus 40 further includes a cable gripping means,
generally designated 50. Cable gripping means 50 has a first
portion 42 thereof immovably secured within and to such housing
structure 38 and a second portion 44 thereof pivotably secured
within and to the housing structure 38. The second portion 44 of
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such cable gripping means 50 being cooperable with such first
portion 42 of the cable gripping means 50 for both gripping and
holding the cable 26 when such tension on such cable 26 is suddenly
removed.
The final essential component of the emergency cable brake 40,
according to the present invention, is a trigger means, generally
designate 60, having a first portion 46 thereof rotatably secured
within such housing structure 38 for sensing any undesirable and
sudden acceleration of such cable 26. A second portion 48 of such
trigger means 60 is pivotably connected to a predetermined
surface 52 of such first portion 46 of the trigger means 60. Such
second portion 48 of the trigger means 60 engages a third
portion 54 of such trigger means 60 which is pivotably connected
to the housing structure 38 and engagable with such cable gripping
means 50 for releasing such cable gripping means 50 so that further
free fall of such cable 26 is stopped.
According to the presently preferred embodiment of the
invention of the improved emergency cable brake apparatus 40, the
housing structure 38 includes a pair of slot-like openings 56
and 58 formed therein to enable such cable 26 to pass through such
housing structure 38. Additionally, in this embodiment, such
housing structure 38 further includes a cover member 62 which is
at least one of removable from such housing structure 38 and
pivotable away from such housing structure 38 to enable the cable
brake apparatus 40 to be installed after such cable 26 has been
installed.
The improved emergency cable brake apparatus 40 further
includes a guide pulley 64 rotatably secured within and to such
housing structure 38 closely adjacent a predetermined one 56 of the
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pair of slot-like openings 56 and 58 for guiding such cable 26
through the housing structure 38 in a desired path.
The first portion 42 of such cable gripping means 50 includes
a groove-like portion 66 disposed closely adjacent a first side of
such cable 26 in the presently preferred embodiment and the second
portion 44 of such cable gripping means 50 is at least one cam-like
member having a predetermined surface 68 engagable with an opposed
second side of such cable 26. Preferably, the predetermined
surface 68 includes a plurality of knurled surfaces.
In addition, it is also presently preferred that such second
portion 44 of such cable gripping means 50 includes a pair of cam-
like members 44 and that the cable brake apparatus 40 further
includes a means 70 for connecting such at least one cam-like
member to a second one of such pair of cam-like members 44.
In the embodiment being described, such first portion 46 of
the trigger means 60 is, preferably, a pulley member 46 engaged
with one side of such cable 26. The second portion 48 of such
trigger means 60 is a plurality of paddle-like members 48 pivotably
secured to one surface 52 of such pulley member 46 and the third
portion 54 of such trigger means 60 is a release arm 54 having a
portion 72 thereof engaged in a slot formed in a portion of such
cable gripping means 60.
As discussed above, the function of the Balance Weight
Assembly is to apply a constant tension to the contact and
messenger wires during changing atmospheric conditions, i.e.
ambient temperature changes. It accomplishes this via a balance
weight stack which applies a constant force to the contact and
messenger wire. During normal operation, due to contraction and
expansion, the counter weight stack moves up and down according to
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the temperature of the contact and messenger wires. Under cold
conditions, it is in the upper position and during hot conditions,
the lower position. This assembly allows the tension of the
contact and messenger wires to be constant under varying ambient
temperatures. The cable brake, during normal operation, allows for
the cable to pass through the unit without resistance. The
tripping mechanism monitors the acceleration of the cable. When
the messenger and/or contact wires fail, the tension load releases
and causes the weights to free-fall to the ground. The cable brake
is used to prevent the weights from impacting the ground. The
cable brake consists of two major components. One, the mechanism
that senses the acceleration of the wire rope, and two, the
gripping mechanism that stops the cable. Figures two and three
show the trigger mechanism, idler pulley, release arm, cams,
linkage, wedge block, ice scrapers, and reset handles. All of
which is mounted in a housing. Under normal operating conditions,
the cable moves up and down through the assembly turning both the
tripping pulley and the idler pulley. Excessive ice is removed
from the cable via two ice scrapers mounted on the top and bottom.
When a contact and/or messenger wire failure occurs, the
acceleration of the cable through the unit is sensed by the trigger
mechanism. The trigger mechanism, in conjunction with the release
arm, frees the cams and allows them to fall into place and engage
the cable. The cam movement and the trigger mechanism is based on
gravity, which removes any need for adjustment and also minimizes
the chances of product failure over its lifetime.
In operation, the trigger mechanism senses the down
acceleration of the cable which cause centrifugal forces to act on
a set of paddles attached to the trigger pulley. As the cable
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acceleration increases from zero to 1-G, the paddles overcome
gravitational forces and swing outward. The centrifugal energy of
the paddles is transferred to the release arm through impacts on
the release arm pegs. The release arm pivots out from the cam slot
and frees the cams. The cable is gripped by two linked cams that
engage the cable after being released by the trigger. The amount
of cam-cable engagement, the cam material, and the dimensional
profile of the cams lend to the amount of friction generated by the
cams. The amount of friction required to stop the weight stack is
dependent on the speed in which the mechanism is triggered and the
condition of the cable.
Additionally, the present invention has the capability for ice
removal provided by the two pulleys. This is due to the slight
offset path of the cable routing through the cable brake. The
cable brake is self-aligning to the cable due to the size of the
idler pulley. The cable brake can be retrofitted into any existing
balance weight assembly with minimal effort. And, since the major
acting force on the components is gravity, mi n i m~ 1 maintenance
effort is required.
It is evident from the above description of the invention that
the emergency cable brake prevents the balance weight assembly's
counter weights from falling to the ground during a contact or
messenger wire failure. This prevents pole foundation damage and
minimizes overhead cantenary hardware damage due to the effects of
impact loads of the free-falling counter-balance weight. The
invention also provides a relatively maintenance-free component
which is easy to install and reset once tripped. This allows
installation crews, inspection crews and repair crews to minimize
their efforts during operation of the cable brake. Further, the
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invention will minimize the damage to the pulley cable when the
messenger and/or contact wires have failed. ~ini~izing the damage
to the cable caused by friction reduces the hazard of this failing
during operation. Finally, the invention provides a positive,
swift means of sensing the abnormally high acceleration of the
weights but ignore normal movement. This allows the cable brake
to react to the falling weights quickly, reducing the amount of
energy the cable brake must dissipate.
Although a number of presently preferred and various
alternative embodiments of the instant invention have been
described in detail above in conjunction with the several drawing
Figures, it should be noted and understood that various other
modifications and adaptations of the improved emergency cable brake
type apparatus can be envisioned by those persons who are skilled
in this particular art without departing from either the spirit of
the invention or the scope of the appended claims.
