Note: Descriptions are shown in the official language in which they were submitted.
CA 02233713 1998-04-15
LADDER EXTENDER
FIELD OF THE INVENTION
The present invention relates to a ladder extender. More particularly, the
present invention
relates to an adjustable ladder extender which can be affixed to one or more
side rails of a ladder
to allow the use of the ladder on uneven surfaces or terrain.
BACKGROUND OF THE INVENTION
Ladders are commonly used for a number of applications to reach desired
heights. However, to
ensure that a ladder is used safely, it ideally should rest on a surface that
is substantially flat (i.e.
horizontal), or else the stable, upright position of the ladder may be
comprised, i.e. the ladder
may tip over, fall, etc... and the safety of the user and of bystanders may be
put at risk.
In order to allow for the use of a ladder on sloping terrain, a number of
ladder extenders,
levellers, adapters, attachments, etc... are known in the prior art. Notably,
US patent no.
4,073,367 to Wright, US patent no. 5,265,699 to Phoumisavanh, US patent no.
4,802,471 to
Cordell, US patent no. 4,766,976 to Wallick, Jr , US patent no. 1,631,513 to
Berry. These
levellers, or adapters generally comprise an adjustable extension which can be
extended and
locked at a desired position.
However, the levellers taught by the above prior art use only one type of
locking means (i.e.
braking means) on the frame (i.e. for locking the extension arm of the
leveller at a desired
position), with the result that, if the locking means fails during use,
particularly under important
loads, no back-up locking means exist. In addition, the absence of an
additional type of locking
mechanism as a back-up, means that when the existing locking mechanism begins
to wear as a
result of repeated use, there is no factor of safety to ensure that the
leveller continues to be safe.
Sudden and catastrophic failure may ensue without warning. Further, the
levellers taught by the
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CA 02233713 1998-04-15
prior art comprise locking means which typically utilizes a friction or clutch
type of locking
mechanism. This type of locking means has a distinct disadvantage in that it
may inadvertently
be released through the application of accidental force thereto, thereby
releasing the extension,
and causing the ladder to tip over. Further, the force of the friction locking
means of the prior art
may not be adjusted to different loads.
In addition, the levellers taught by the above prior art often require the
drilling of holes into the
side rail of the ladder in order to install the levellers onto the side rail.
The need for drilling of
holes in the side rail means that installation of the levellers is slowed due
to this additional step,
and causes physical damage to the ladder. In additions, such levellers can not
be adjusted rapidly
to other ladders.
Further, some of the above prior art provides for a leveller which frame is
not directly affixed to
the side rail of the ladder, which therefore means that these extenders are
less firmly affixed to
the side rail of the ladder.
It would therefore be advantageous to provide an alternatively configured
ladder extender.
It would be advantageous to provide an alternatively configured ladder
extender comprising a
dual locking means comprising two separate and distinct locking means (i.e.
two separate and
distinct types of braking mechanisms) disposed on the frame of the ladder
extender. It would
therefore be advantageous if the dual locking means would comprise a
frictional locking means
and a compression locking means.
It would also be advantageous to provide a ladder extender which allows for
quick adjustment
of the projection arm to different environments of use.
It would also be advantageous to provide a ladder extender which is quick to
install onto the side
rail or rails of a ladder, without the need for drilling holes into the side
rail to affix the frame
thereto.
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CA 02233713 1998-04-15
It would further be advantageous to provide a ladder extender comprising a
tension adjusting
mechanism to adjust the braking strength of the frictional locking means.
Various other features of the invention will become obvious to one skilled in
the art upon reading
of the specification herein.
SUMMARY OF THE INVENTION
The present invention, in accordance with one aspect, provides for a ladder
extender for
releasably affixing to a side rail of a ladder, said extender comprising
a frame
fixation means for releasably affixing said frame to said side rail, and
a proj ection arm slidably engaged in said frame
dual locking means for releasably locking said proj ection arm at a desired
position,
said dual locking means comprising
frictional locking means and compression locking means.
In accordance with another aspect of the present invention, there is provided
for a ladder extender
for releasably affixing to a side rail of a ladder, said extender comprising
a frame
fixation means disposed on said frame for releasably affixing said frame to
said side rail
a projection arm slidably engaged in said frame, and
dual locking means disposed on said frame for releasably locking said
projection arm
with said frame at a desired position ,
said dual locking means comprising
frictional locking means for releasable, frictional locking engagement of said
projection arm, and
compression locking means for releasable, compression locking engagement of
said projection arm against said frame.
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CA 02233713 1998-04-15
In accordance with a further aspect, there is provided for a ladder extender
for releasably affixing
to a side rail of a ladder, said extender comprising
a first frame component and a second frame component
fixation means disposed on said first and said second frame components for
releasably
affixing said first and second frame components to said side rail
a projection arm slidably engaged in said first and second frame components,
and
dual locking means disposed on said first frame component for releasably
locking said
projection arm with said first frame component at a desired position ,
said dual locking means comprising
frictional locking means for releasable, frictional locking engagement of said
projection arm, and
compression locking means for releasable, compression locking engagement of
said projection arm against said first frame component.
The frictional locking means of the present ladder extender may also comprise
a friction force
adjustment mechanism. Also, the fixation means of the ladder extender of the
present invention
may comprises clamp locking means for releasable locking engagement of said
frame against
said side rail. The frame (or frame components) of the present ladder extender
may comprises
a guide portion for receiving the proj ection arm therein and an engagement
groove for receiving
the side rail therein.
In accordance with a further aspect , there is provided for a ladder
comprising at least two side
rails spaced apart by a plurality of ladder rungs
the improvement wherein said ladder comprises a ladder extender releasably
affixed to
a said side rail,
said ladder extender comprising
a frame
fixation means disposed on said frame for releasably affixing said frame to
said side rail
a projection arm slidably engaged in said frame, and
dual locking means disposed on said frame for releasably locking said
projection arm at
a desired position,
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said dual locking means comprising
frictional locking means for releasable, frictional locking engagement of said
projection arm, and
compression locking means for releasable, compression locking engagement of
said projection arm against said frame.
In yet a further aspect, there is provided for a ladder extender for
releasably affixing to a side rail
of a ladder, said extender comprising
a first frame component and a second frame component
fixation means disposed on each of said first and said second frame components
for
releasably affixing each said first frame component and said second frame
component to said
side rail
an elongated proj ection arm simultaneously, slidably engaged in said first
and second
frame components, and
dual locking means disposed on said first frame component for releasably
locking said
projection arm at a desired position,
said dual locking means comprising
frictional locking means for releasable, frictional locking engagement of said
proj ection arm, and
compression locking means for releasable, compression locking engagement of
said projection arm against said first frame component,
said first and second frame components each comprising a guide portion and an
engagement
groove for respectively receiving therein said projection arm and a portion of
said side rail
said fixation means comprising a screw having opposed first and second ends
and a
threaded shank therebetween in threaded engagement with a threaded hole
disposed in
each of said first and second frame component,
said screw being displaceable from a first position wherein said first opposed
end
engages a portion of said side rail such that said portion of said side rail
is
releasably, fixedly impinged between said first opposed end and said
engagement
groove, to a second position wherein said first opposed end is disengaged from
said side rail
CA 02233713 1998-04-15
said elongated proj ection arm comprising a longitudinal recessed groove
disposed on a lateral
side thereof, said elongated projection arm further comprising a pivoted foot
member
said frictional locking means comprising a clutch plate disposed on said first
frame
component, said clutch plate having a centrally disposed aperture configured
and
disposed to receive said projection arm therein, said aperture comprising at
least one
rough edge
said clutch plate being spring biased against said first frame component
between
an engaged position such that said at least one rough edge frictionally
engages a
side wall of said proj ection arm such that said proj ection arm is in
releasable,
frictional locked engagement with said clutch plate, to a disengaged position
wherein said clutch plate is disposed free from frictional engagement with
said
projection arm
said frictional locking means further comprising a friction force adjustment
means
said compression locking means comprising a fastening bolt having opposed
first and
second ends and a threaded shank therebetween disposed through an opening in
said first
frame component, said first opposed end comprising an enlarged head configured
to be
disposed within said recessed groove, said second opposed end being in
threaded
engagement with a threaded turning handle, said fastening bolt being
displaceable
between a first position wherein said enlarged head engages said recessed
groove such
that the projection arm is impinged between said enlarged head and said first
frame
component such that said projection arm is in releasable, compression locking
engagement against said first frame component, to a second position wherein
said
enlarged head is disengaged from said recessed groove.
The ladder extender of the present invention may be used with a number of
ladders, such as for
example rigid and moveable ladders, commonly known as straight ladders,
extension ladders,
stepladders, etc... The ladders may have two, or more side rails spaced apart
by a plurality of
ladder rungs, and these side rails may be configured and disposed in any
manner, such as for
example parallel to each other.
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Generally, the ladder extender of the present invention may be used to provide
a ladder with
additional range andlor improved versatility. In order to improve the
versatility of a ladder, for
example, for use on uneven terrain, on inclined surfaces, on stairs, etc...
the ladder may be fitted
with a ladder extender adj acent the lower extremity of one or more side
rails. Therefore, in order
to keep a ladder substantially upright on sloping ground, the ladder extender
may be affixed
adj acent the lower extremity of the downward side rail, i.e. the side rail
which, if the ladder is
placed upright, does not touch the downwardly sloping ground. Once the
extender is releasably
affixed to the downward side rail, the proj ection arm may be extended below
the lower end of
the side rail and releasably locked into position, such that the projection
arm may come into
contact with the downwardly slopping ground, and provide footing for the
ladder.
The ladder extender may also be used to increase the range of a ladder, for
example in order that
the ladder may reach a greater height than usual. For this application, the
ladder may be fitted
with a extender on the upper end of one or more of the side rails of the
ladder, i.e. adjacent the
end of the side rails normally up in the air. Alternatively, a ladder may be
fitted with an extender
on both the upper and the lower ends of the side rails.
As mentioned above, in accordance with one aspect of the present invention,
the ladder extender
may comprise a frame, which may be configured and disposed to be releasably
attachable to a
side rail of a ladder. The frame may therefore comprise fixation means to
releasably affix the
frame to the side rail. The ladder extender may further comprise a projection
arm slidably
disposed through the frame, and dual locking means disposed on the frame, for
releasably
locking the projection arm and the frame together.
In accordance with the present invention, the reference to the expression
"dual locking means"
is to be understood to mean that two different types of locking means may be
used, namely a first
locking means and a second, distinct locking means. The second locking means
is to be different
from the first locking means, and may achieve its locking fiznction through a
different mechanical
principle than the first locking means.
The dual locking means may therefore comprise a frictional locking means (i.e.
a friction brake)
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CA 02233713 1998-04-15
and a compression locking means (i.e. a compression brake).
In accordance with the present invention, the reference to the expression
"frictional locking
means" is to be understood to comprise any mechanism disposed on the frame,
which may be
able to be in releasable frictional locking engagement with the proj ection
arm, in such a manner
to cause frictional braking force to be applied to the projection arm, so as
to oppose the
movement of the projection arm. The application of sufficient frictional
braking force to the
proj ection arm by the frictional locking means may therefore releasably lock
the proj ection arm
and the frictional locking means together. In other words, the mechanism of
the frictional locking
means, when in contact with the projection arm, creates friction therebetween
which brakes the
movement of the proj ection arm to a stop.
Frictional locking engagement is understood to means that one surface (i.e. of
a the frictional
locking means, or of a component thereof) may be made to rub against, bite
into, or j am into, or
the like, into a second surface (i.e. of the projection arm) such that
relative motion of the two
surfaces may be completely inhibited through the effect of friction.
The frictional locking means of the present invention may take on any desired
aspect, and may
be configured and disposed in any suitable manner, keeping in mind its purpose
of being brought
into frictional locking engagement with the proj ection arm in such a manner
as to releasably lock
the projection arm in its desired position. It is understood that the
frictional locking means may
be disposed, (i.e. anchored) on the frame.
The frictional locking means of the present invention may, for example,
comprise a clutch plate.
In order to create adequate frictional braking force, the clutch plate and the
proj ection arm may
be configured and their respective materials selected to enhance the creation
of friction when the
clutch plate is brought into contact with the proj ection arm. The clutch
plate may, for example,
be configured to comprise one or more rough edges, (i.e. not smooth) which
will rub against and
bite into the proj ection arm causing it to j am into the proj ection arm, and
"catch" therein.
As may be understood, in order that the clutch plate be in releasable,
frictional locking
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CA 02233713 1998-04-15
engagement with the engagement arm, it may be brought to rub against, j am
into or bite into the
projection arm through the application of adequate force. Thus, as may be
understood, the clutch
plate may be biased against the proj ection arm through any suitable means.
The biasing action
may be as a result of the configuration and disposition of the clutch plate
itself, or may be as a
result of a biasing means, such as, for example, a spring.
In accordance with a particular embodiment, the clutch plate may, for example,
be configured
and disposed as an elongated plate having a centrally disposed aperture
therethrough, sized and
configured to receive the projection arm therein. The inside edges of the
aperture may be rough
(i. e. not smooth), so as to create adequate friction when brought into
contact with the outside
edges of the proj ection arm. The clutch plate may be anchored to the frame of
the ladder extender
and may also be biased away from the frame by a biasing means, such as for
example a spring.
Thus as may be understood, the proj ection arm may be disposed through the
aperture of the
clutch plate, and the spring may cause the clutch plate to be biased against
the projection arm,
whereby at least one edge (i.e a rough edge) of the aperture of the clutch
plate may bite into, rub
against, be in contact with etc... the projection arm, thus releasable,
frictionally locking the
projection arm in place in relation to the frame.
The clutch plate, in its resting position, may therefore be biased against the
proj ection arm.
However, in order to allow for the proj ection arm to be adjusted to different
positions, the clutch
plate may be displaceable from its first (i.e. resting) position, wherein the
clutch plate is biased
against the projection arm, to a second position (through for example the use
of manual force)
wherein the clutch plate is free from the proj ection arm. Thus, as may be
understood, in the first
position, the clutch plate may bite into (rub against, catch etc...) the
projection arm and be in
releasable frictional engagement therewith, thereby preventing movement of the
proj ection arm.
In the second position, the clutch plate may no longer be in frictional
engagement with the
projection arm, and therefore the projection arm may be slidably displaced
within the frame.
It is understood that in accordance with a further aspect of the present
invention, the clutch plate
may be configured in any other manner so as to effect a releasable, frictional
locking engagement
with the proj ection arm. Further, more than one clutch plate may be used.
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The frictional locking means may also comprise a friction force adjustment
mechanism (i.e.
tension adjusting mechanism), whereby the biasing force of the clutch plate
against the projection
arm may be varied. For example, in accordance with an embodiment wherein the
frictional
locking means comprises a clutch plate biased by a spring, it would be
advantageous to provide
for the force of the spring to be adjustable to different loads. The
frictional force adjustment
mechanism may therefore comprise a threaded screw disposed on (i.e. anchored
to) the frame,
which may also act to anchor the clutch plate to the frame. Thus, when the
threaded screw is
made to shorten or lengthen, there may be a corresponding change in the travel
distance of the
spring, thereby causing the biasing strength of the spring to also change
accordingly.
Consequently the biasing force which may be applied to the projection arm may
also be adjusted.
As mentioned above, the dual locking means, in addition to comprising a
frictional locking
means, may further comprise a compression locking means. In accordance with
the present
invention, the reference to the expression "compression locking means" is to
be understood to
comprise a mechanism disposed on the frame, which, through the application of
force, (for
example, manual force) may cause the projection arm to be releasably pushed or
pulled into
engagement against the frame of the ladder extender. The compression locking
means may
comprise an element which impinges on the proj ection arm, such that the
compression arm may
be releasably locked together or against the frame. The compression locking
means may create
enough compression locking force such that the projection arm and the frame
may be releasably
locked together in a clamp-like or vice-like engagement.
The expression "clamp-like or vice-like engagement" is understood to mean that
the proj ection
arm, or a portion thereof, may be compressively sandwiched between the frame
and the
compression locking means, such that resistance to relative motion between the
projection arm
and the frame may be completely inhibited. As a result, the projection arm and
the frame may
be releasably locked together.
The compression locking means of the present invention may take on any desired
aspect, and
may be configured and disposed in any suitable manner, keeping in mind its
purpose of
releasably locking the proj ection arm in a clamp-like or vice-like engagement
against the frame.
CA 02233713 1998-04-15
In order to produce a clamp-like or vice-like engagement, the compression
locking means and
the projection arm may each be configured and disposed, and their respective
materials of
construction selected to enhance the clamp-like or vice-like engagement
therebetween.
The compression locking means of the present invention may, for example,
comprise a fastening
bolt, screw, rod, etc... which may extend through an opening disposed in the
body of the frame.
The shank of the fastening bolt may be threaded. The diameter of the opening
through the frame
may be larger than the outside diameter of the bolt, or alternatively, the
opening may be threaded
and sized to threadingly engage the threads of the bolt. The fastening bolt
may take on any
desired aspect, and may be configured and disposed in any suitable manner,
keeping in mind its
purpose to engage the proj ection arm (which is slidably disposed through the
frame), either by
pushing against it, or by pulling on it through for example the application of
manual force.
Through this pulling or pushing, the projection arm may be caused to be in
releasable locked
engagement against the frame in a clamp-like or vice-like manner.
In accordance with a particular aspect of the present invention, the
compression locking means
may comprise a fastening bolt having first and second opposed ends and a
threaded shank
extending through an opening disposed in the body of the frame. The diameter
of the opening
may be larger than the threads of the fastening bolt. The first end, or inside
end of the fastening
bolt (i.e. the end disposed inside the frame) may comprise an enlarged head
which may be
configured and disposed to engage the projection arm. In accordance with this
particular
embodiment, the enlarged head, or any other part of the threaded bolt, may be
made to pull on
the proj ection arm so as to cause the proj ection arm to be brought into
releasable locking
engagement against the frame in a clamp-like or vice-like manner, as explained
below. As a
result, the proj ection arm, or a portion of the proj ection arm, may be
releasably sandwiched
between the enlarged head of the threaded bolt and (a portion of) the frame.
The second opposed end of the fastening bolt (i.e. the end disposed outside of
the frame) may
be fitted with a handle, or wing nut etc... in threaded engagement with the
threads of the shank
of the fastening bolt. The clamping (or vice-like) action of the compression
locking means may
be caused by the handle, which when turned clockwise on the end of the
fastening bolt, (for
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CA 02233713 1998-04-15
example, through the application of manual force), may cause relative movement
of the enlarged
head and of the handle toward each other, i.e. the fastening bolt may be
threaded inside the
handle. Thus, the length of the shank disposed inside the frame may be
progressively shortened.
After a number of turns of the handle, the shank may have been sufficiently
shortened such that
the enlarged head may begin to push a portion of the projection arm against
the frame. After a
further number of turns, the enlarged head may exert enough force on the proj
ection arm, such
that the projection arm is releasably sandwiched between the frame and the
enlarged head. It is
understood that the tighter the handle is turned, the more firmly the enlarged
head of the
fastening bolt may cause the portion of the proj ection arm to be compressed
against the frame,
thus firmly keeping both in a clamp-like or vice-like engagement.
In addition to the fastening bolt and handle, the compression locking means
may also comprise
washers, rings, and other components necessary to accomplish the compressional
locking motion
of the compression locking means.
As mentioned above, in addition to the dual locking means, the ladder extender
of the present
invention may ftu ther comprise a frame, which frame may take on any
configuration keeping in
mind that it may fulfill a number of functions. In particular, the frame may
provide anchoring and
support points for the dual locking means. The frame may also be sized and
configured to be
releasably attachable to a side rail of a ladder. In addition, the frame may
be configured and
disposed to guide and support the projection arm.
The frame may therefore be provided with a guide portion through which the
proj ection arm may
be slidably engaged. The guide portion may, for example, comprise a closed
channel through
which the proj ection arm may slide. Conversely, the guide portion may not
enclose the proj ection
arm, but may nonetheless be configured and disposed to guide the movement of
the proj ection
arm, and also to provide support therefore. As may be understood, the
configuration of the guide
portion frame may generally correspond to the configuration of the proj ection
arm, such that the
projection arm may slide within the guide as smoothly as possible, in order to
facilitate the easy
adjustment of the projection arm to its required or desired position.
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Additionally, the frame may also be provided with an engagement groove
configured and
disposed to receive therein a side rail of the ladder. The engagement groove
may, for example,
be U-shaped, and be open along one side to allow the side rail to be placed
therein.
In accordance with the present invention, the dual locking means may be
disposed (i.e. anchored)
on the frame. The frame may therefore be configured and disposed such that
both the frictional
locking means and the compression locking means may be anchored on the frame,
and such that
each may concurrently exert its locking (i. e. braking) action on the proj
ection arm.
In accordance with a particular aspect of the present invention, the frame may
comprise two (or
more) similarly configured, spaced apart frame components, each of which may
be affixed to the
side rail of a ladder. The guide portions (as described above) of each of
these frame components
may be co-axially aligned (when the frame components are each affixed to the
same side rail)
such that the projection arm may be simultaneously engaged therein. In this
configuration, the
guiding and supporting ability of the two-component frame may be enhanced,
while reducing the
material needed to construct the frame. It is understood that in accordance
with this particular
embodiment (wherein the frame comprises two frame components), the dual
locking means may
be disposed (i.e. anchored) on one of the frame components, while the second,
spaced apart
frame component may serve to only guide and support the projection arm.
However, each of the
frame components may have its own fixation means for fixation to the side rail
of the ladder.
It is understood that in an alternative configuration comprising two or more,
spaced apart frame
components affixed to the side rail, each frame component may comprise its own
dual locking
means (for releasably locking the proj ection arm), and its own fixation means
(for releasable
attachment of the frame component to the side rail). Alternatively, one frame
component may
be disposed with the friction locking means, and a second spaced apart frame
component may
be disposed with the compression locking means.
As mentioned above, in order to releasably affix the ladder extender of the
present invention to
the side rail of a ladder, the frame may be provided with fixation means. In
order to provide fast
and easy fixation of the ladder extender to the side rail, the fixation means
of the present
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invention may not require the drilling of holes into the side rail of the
ladder. By eliminating this
need for drilling, the installation of the leg extender may be facilitated by
reducing an
unnecessary step, and damage to the ladder may be avoided. Also, once the leg
extender is no
longer needed, it may be more easily removed from the side rail, and quickly
affixed to another
ladder.
The fixation means may therefore comprise a clamp locking means. The
expression "clamp
locking means" is understood to comprise a mechanism disposed on the frame,
which, through
the application of force, may cause the side rail (of the ladder) to be
releasably pushed or pulled
into engagement against the frame of the ladder extender. The fixation means
may, for example,
comprise an element which impinges on the side rail, such that the side rail
may be releasably
locked together with the frame. The application of sufficient force may
releasably lock the side
rail and the frame together. The fixation means may therefore comprise a
compression type
locking means, similar in principle to the compression locking means of the
dual locking means
used to releasably lock the projection arm and the frame together.
In accordance with a particular aspect of the present invention, the fixation
means may comprise
the engagement groove of the frame, which may be configured and disposed so as
to wrap around
the side rail of the ladder. In addition, the fixation means may also comprise
threaded screws,
(such as for example, tap screws or the like) which may be in threaded
engagement with threaded
holes provided in the frame of the ladder extender. As may be understood, in
accordance with
this particular aspect, the engagement groove of the frame and the fixation
means may be
configured and disposed so as to act as a C-clamp which may be made to
releasably wrap around
a side rail and releasable affix the side rail therein.
In order to install the frame of the ladder extender to a side rail, the side
rail may be disposed in
the engagement groove of the frame, and the tap screws may be turned
counterclockwise in their
respective threaded holes, causing them to advance therein. After a sufficient
number of turns
(depending namely on the size of the side rail, of the tap screws etc...), the
forward end of the tap
screws may begin to push against the side rail of the ladder. After a
sufficient number of turns,
the end of the screws may eventually engage against the side rail, and further
cause the side rail
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to be releasably sandwiched between the frame, and the end of the tap screws.
The application
of sufficient force will allow the frame (and therefore the ladder extender)
to be firmly, releasably
affixed to the side-rail such that movement of the ladder extender in relation
to the ladder may
be precluded.
It is understood however that fixation means may comprise other mechanisms
than tap screws.
For example, the fixation means may comprise a lever, which may be coupled to
a cam disposed
inside the engagement groove of the frame. The lever may be rotated, which may
cause the cam
to be forced against a side rail disposed in the engagement groove. The
application of sufficient
force to the suitably sized and configured cam may releasably sandwiched the
side rail between
the inside of the engagement groove, and the cam.
As mentioned above, the ladder extender may also comprise a proj ection arm.
The proj ection arm
may disposed to be slidably engaged with the frame of the ladder extender, and
more specifically,
within the guide portion of the frame, if one is provided. The projection arm
may take on any
required or desired configuration keeping in mind its function of providing
additional reach
between the end (lower or upper) of a side rail of a ladder, and a surface to
be reached. Thus the
proj ection arm may have a generally elongated configuration, and its cross
section may have any
number of shapes. For example, the projection arm may be configured as a flat
bar, round bar,
or otherwise shaped element, either hollow or fizll, or as an angle, or as any
number of extruded
shapes. Further, the projection arm may have any desired number of recesses or
projections
which may increase the strength and rigidity thereof, while also reducing its
weight. The
presence of a recess or of a projection may also facilitate the locking of the
projection arm in its
desired position by the frictional locking means, the compression locking
means or both. for
example, the projection arm may comprise a recessed groove along a
longitudinal side thereof,
which may be sized and configured to accept the enlarged head therein.
The proj ection arm may also comprise a foot element disposed at the extremity
thereof. The foot
element may serve the purpose of providing a wider and safer interface between
the projection
arm and the surface to be reached, for example, a sloping surface. Further,
the foot element may
also be provided with an anti-slip surface on the underside thereof, which may
help to prevent
CA 02233713 1998-04-15
slippage. The foot element may be integral with the proj ection arm itself, or
alternatively, may
consist of a separate element connected to the proj ection arm through a ball
joint, a swivel joint,
or any other suitable connection.
In use, the proj ection arm may be releasably locked in a selected position
such that a desired
portion of the proj ection arm may extend beyond the ladder extender. Thus if
a ladder is to be
used, for example on sloping terrain, the frame of the ladder extender may be
affixed adj acent
a lower extremity of one of the side rails of the ladder. The side rail may be
disposed in the
engagement groove, and the fixation means activated to releasably affix the
frame to the side rail.
With the dual locking means in its disengaged mode (i.e. not locking the
projection arm), the
projection arm may be slidably extended beyond the frame such that it may
extend below the end
of the side rail and come into contact with the sloping ground. As may be
understood, the release
position of the dual locking means is understood to mean that the clutch plate
may be disengaged
from the projection arm such that its sides do not bite into the projection
arm. Also, the
compression locking means may be in its disengaged position such that the
sides of the
projection arm may not engage the frame.
Once the proj ection arm has been extended a desired distance below the
extremity of the side rail,
so as to engage the slopping surface, the dual locking means may be engaged,
namely the
frictional locking means and the compression locking means are made to engage
the proj ection
arm, thus releasably engaging the projection arm fixed to the frame.
The ladder extender of the present invention may be of any suitable metal,
such as steel,
aluminum, or a combination of any required or desired materials.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings, which illustrate example embodiments of the invention,
Figure 1 is a schematic view of a ladder extender affixed to a side rail of a
ladder.
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CA 02233713 1998-04-15
Figure 2 is a side elevation view of an alternative embodiment of ladder
extender 10 having a one
component frame 17, shown without a proj ection arm therethrough. Ladder
extender 10 is shown
not attached to a side rail of a ladder.
Figure 3 is a top plan view of the alternative ladder extender 10 of Figure 2,
showing frame 17
without a projection arm therethrough. Ladder extender 10 is shown not
attached to a side rail
of a ladder.
Figure 4 is a side elevation view of the ladder extender 10 of Figure 3 shown
unattached to a side
rail of a ladder, showing the frame 17 having a projection arm 15 disposed
therethrough.
Figure 5 is a further side elevation view of the ladder extender of figure 4,
showing the clutch
plate 25 of the frictional locking means in its disengaged position.
Figure 6 is a sectional view along section 6-6 of figure 4, showing a top plan
view of the ladder
extender not attached to a ladder, wherein frame 17 has a proj ection arm 15
disposed
therethrough.
Figure 7 is a sectional view along section 7-7 of figure 4.
Figure 8 is a sectional view along section 7-7 of figure 4, and additionally
showing a section of
a side rail affixed in the engagement groove 40 of frame 17.
Figure 9 is a schematic view of a ladder extender 10 having a one-component
frame 17 affixed
to a side rail 3 of a ladder 1.
DETAILED DESCRIPTION OF THE DRAWINGS
Refernng to Figure 1 there is shown a schematic view of a ladder extender,
generally designated
by reference number 10, disposed adj acent the lower extremity 6 of side rail
3 of ladder 1.
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CA 02233713 1998-04-15
Ladder 1 is shown having opposed side rails 2 and 3 being spaced apart by
rungs 4 and 5. The
ladder extender 10 of Figure 1 is shown comprising a two part frame, namely a
first frame
component 17 and a spaced apart, second frame component 16. Second frame
component 16 is
shown affixed to lower extremity 6 of side rail 3, while first frame component
17 is affixed to
side rail 3 and is shown spaced apart from second frame component 16. Proj
ection arm 15 is
shown simultaneously disposed through each frame component 16 and 17. First
frame
component 17 and second frame component 16 are each affixed to side rail 3 of
ladder 2 in such
a manner that the projection arm 15 may be simultaneously disposed through
each of them,
namely their guide components (as shown in Figures 3 and 6) are substantially
axially aligned.
First frame component 17 is shown comprising a dual locking means, namely
frictional locking
means comprising clutch plate 25 (to be further explained in Figures 2-6), and
compression
locking means comprising turning handle 35 (to be further explained in Figures
2-7). Clutch plate
25 is shown in its second or disengaged position, as shown in Figure 5. Second
frame component
16 is shown without any locking means, i.e. it only serves to guide and
support projection arm
15 therethrough.
Figure 1 further shows ladder 1 being used on downwardly slopping terrain 7.
In order to keep
ladder 1 in a substantially upright position, the proj ection arm 15 of the
ladder extender 10 is
shown to extend by a distance 8 below the lower extremity 6 of side rail 3.
The projection arm
15 is further shown as having a foot element 18 attached to its lower
extremity 19 through pin
20. Foot element 18 is also shown having a non-slip surface 14 on the
underside thereof which
serves to better grip downwardly sloping ground 7. Although not shown, side
rail 2 of ladder 1
may also be fitted with a ladder extender similar to that shown at 10.
Figure 2 is a side elevation view of an alternative embodiment of ladder
extender 10 having a one
component frame 17, shown without a proj ection arm therethrough. Ladder
extender 10 is shown
not attached to a side rail of a ladder.
As explained above, one of the functions of frame 17 is to provide support for
the dual locking
means, namely the frictional locking means generally designated by reference
number 21 and the
compression locking means, of which turning handle 35 is a component, to be
further described
18
CA 02233713 1998-04-15
in Figure 3. As may be seen, the dual locking means, namely the frictional
locking means 21, and
the compression locking means 29 are disposed (i.e. anchored) on frame 17.
The frictional locking means, generally designated by the reference number 21
comprises a
clutch plate 25, which is anchored at one end 22 by the head of threaded screw
27. Clutch plate
25 is biased upwardly at its opposed end 23 by spring 26. Therefore, clutch
plate 25 is
displaceable in a generally arcuate mariner as indicated by motion arrows 24a
and 24b, either
upwardly by the action of spring 26, or downwardly, such as for example,
through the application
of manual force. Clutch plate 25 is shown in its first, or resting position
(i.e. when spring 26 is
extended), and is displaceable to its second position (shown in figure 5) when
manual force is
applied downwardly in the direction of motion arrow 24b.
Clutch plate 25 comprises an elongated opening 30 therethrough which, as
shown, is generally
aligned with guide portion 31 disposed through frame 17 (as further described
in Figure 3).
Opening 30 comprises a first edge 37, and an opposed second edge 36 disposed
on the narrow
ends of opening 30. Edges 36 and 37 are to be configured so as to be able to
bite into, or catch
the sides of the projection arm 15 to be shown in figure 4. For example, edges
36 and 37 may be
rough (i.e. not smooth).
The frictional locking means 21 further comprises a friction force adjustment
mechanism (i.e a
tensioning means), namely nut 28 and threaded screw 27. Nut 28 is shown to be
in threaded
engagement with threaded screw 27, and is shown engaging surface 11 of frame
17. The friction
force adjustment mechanism can vary the tension of spring 26, and consequently
the force
applied thereby to clutch plate 25. As may be understood, when nut 28 is
turned in a clockwise
or counterclockwise direction, the threaded screw 27 is caused to be raised or
lowered. Therefore,
when threaded screw 27 is raised, the tension in spring 26 is reduced, with a
corresponding
reduction of the biasing force on clutch plate 25. When threaded screw 27 is
lowered, the reverse
occurs.
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CA 02233713 1998-04-15
Figure 3 is a top plan view of the alternative ladder extender 10 of Figure 2,
showing frame 17
without a projection arm therethrough. Ladder extender 10 is shown not
attached to a side rail
of a ladder.
Ladder extender 10 is shown comprising the dual locking means disposed (i.e.
anchored) on
frame 17, namely frictional locking means, of which clutch plate 25 is a
component, and
compression locking means generally designated by reference number 29.
Compression locking
means 29 comprises a fastening bolt 32 having opposed first and second ends,
whose threaded
shank extends through an opening (not shown) in the wall of frame 17. In
accordance with the
embodiment shown in Figure 3, the threaded shank of fastening bolt 32 is not
in threaded
engagement with the opening through the wall of frame 17. The first opposed
end, (i.e. inside
end) of fastening bolt 32 is provided with an enlarged head 33 disposed within
the guide portion
31 of frame 17. Turning handle 35 is in threaded engagement with the threaded
shank of second
opposed end (i.e. the outside end) of fastening bolt 32. A washer 34 is
disposed on the threaded
shank of the fastening bolt 32 against the inner face of turning handle 35.
Turning handle 35 can
be turned clockwise, through for example, the application of manual force, and
consequently,
may be tightened on the shank of the fastening bolt 32. The tightening of
turning handle 35 on
the threaded shank of fastening bolt 32 causes the length of the threaded
shank disposed inside
the guide portion 31 to be shortened, i.e. causes the relative displacement of
enlarged head 33
and of turning handle 35 toward each other. Therefore, enlarged head 33 is
displaced in the
direction of motion arrow 38, and turning handle 35 is displaced in the
direction of motion arrow
39. Consequently, washer 34 is also pushed by the turning handle in the
direction of motion
arrow 39.
As may be understood, the clockwise turning of turning handle 35 creates the
clamp-like or vice-
like action of the compression locking means on the proj ection arm (as shown
in figure 7), as
head 33 is displaced in the direction of motion arrow 38, and as turning
handle 35 (and washer
34) are displaced in the direction of motion arrow 39.
Clutch plate 25 is shown comprising opening 30 therethrough, which opening 30
is substantially
aligned with guide portion 31 disposed through frame 17. Opening 30 comprises
first edge 37
CA 02233713 1998-04-15
and second edge 36.
Frame 17 also comprises an engagement groove 40 which is sized and configured
to receive a
side-rail of a ladder (shown in Figure 8). Tap screw 50 is in threaded
engagement with an
opening in the outside wall of frame 17 (not shown). Therefore tap screw 50
may be turned
clockwise and advanced through the threaded opening so as to sandwich the side-
rail of a ladder
(as shown in Figure 8) between the extremity 51 thereof and surface 52 of
frame 17. The
application of sufficient force will cause the tightening of extremity 51
against the side rail, as
shown in figure 8. As may be understood, in accordance with the embodiment
shown in Figure
3, engagement groove 40 and tap screw 50 are configured and disposed so as to
create a C-clamp
shaped enclosure for receiving the side rail of a ladder therein
Figure 4 is a side elevation view of the ladder extender 10 of figure 2,
showing frame 17 having
a portion of a proj ection arm 15 disposed therethrough. As may be seen, proj
ection arm 15 is
simultaneously disposed through opening 30 of clutch plate 25, and through
guide portion 31 of
frame 17 (as shown in Figures 2 and 3).
The clutch plate 25 shown in Figure 4 is in its first, or resting position,
whereby it is in releasable
locked engagement with proj ection arm 15. As may be understood, spring 26
biases clutch plate
25 upwardly in the direction of motion arrow 24a such that the edge 37 (and
also edge 36) of
opening 30 (as shown in figures 2 and 3) are in frictional engagement with
sides 13 and 12
respectively of projection arm 15. Thus as may be understood, the friction
created by this
engagement causes the projection arm to be in a releasable frictional locking
engagement with
clutch plate 25, and indirectly, with respect to the frame 17. Spring 26 is to
have sufficient force
such that projection arm 15 and clutch plate 25 are in locked engagement,
whereby movement
of projection arm 15 in the direction of motion arrow 18 is stopped..
Projection arm 15 is further shown having a longitudinally disposed recessed
groove 41 disposed
on a lateral side thereof.
21
CA 02233713 1998-04-15
Figure 5 is a further side elevation view of the ladder extender of figure 4,
showing the clutch
plate 25 of the frictional locking means in its second or disengaged position.
The clutch plate 25 shown in Figure 4 has been displaced in the direction of
motion arrow 24b
through, for example, the application of manual force. Clutch plate 25 is
therefore in its second,
or disengaged position, whereby it is not in contact with proj ection arm 15.
As may be seen, as
a result of the clutch plate being displaced downwardly in the direction of
motion arrow 24b, first
edge 37 (and also opposed second edge 36) have been displaced away from sides
13 and 12 of
proj ection arm 15, and therefore, proj ection arm 15 is no longer in
frictional engagement with
clutch plate 25 of frictional locking means 21. Proj ection arm (if not locked
into position by the
compression locking means), is therefore free to move up and down within frame
17 in the
direction of motion arrow 18.
Figure 6 is a sectional view along section 6-6 of figure 4, showing a top plan
view of the ladder
extender not attached to a ladder, wherein frame 17 has a proj ection arm 15
disposed
therethrough.
As may be seen, the dual locking means, namely the frictional locking means
21, and the
compression locking means 29 are disposed (i.e. anchored) on frame 17. As may
also be seen,
proj ection arm 15 is substantially hollow and comprises a recessed groove 41
along a lateral side
thereof. Recessed groove 41 is configured to be able to accept therein the
enlarged head 33 of
fastening bolt 32. Enlarged head 33 is to be configured so as to be non-
circular, and will engage
its side edges with side members 41 a and 41b of recessed groove 41. When the
head 33 is in
contact with the inside face of side members 41 a and 41b, enlarged head 33,
(and consequently
fastening bolt 32), will be held against turning about their longitudinal axis
when handle 35 is
turned. As may be understood, when turning handle 35 is rotated, head 33 is
held against turning
by the inside walls of recessed groove 41, causing the threaded shank of
fastening bolt 32 to be
threaded inside the turning handle 35.
As may be seen, projection arm 15 is sized to substantially fit within opening
30 of clutch plate
25, and also within guide portion 31 of frame 17, (as shown in Figures 2 and
3). Clutch plate 25
22
CA 02233713 1998-04-15
is shown to be in contact with the projection arm 15 along edges 37 and 36 of
opening 30. It is
however understood that the configuration of opening 31 may be such that more
than edges 37
and 36 of the opening may be in contact with the projection arm, namely along
the longitudinal
edges of projection arm 15. Conversely, only one edge, for example, edge 37,
may be in contact
with proj ection arm 15.
As shown in Figure 6, the compression locking means generally designated by
reference number
29, is not in compression locking engagement with proj ection arm 15. Enlarged
head 33 is shown
not engaged with the inside walls of recessed groove 41.
Figure 7 is a sectional view along view lines 7-7 of figure 4. Compression
locking means,
generally designated by reference number 29, is shown to be in releasable
compression locking
engagement with proj ection arm 15. As may be seen when comparing Figures 6
and Figure 7,
turning handle 35 has been turned on fastening bolt 32 a sufficient number of
times so as to have
caused relative displacement of turning handle 35 and enlarged head 33 toward
each other, i.e.
turning handle 35 has been displaced in the direction of motion arrow 39. This
displacement of
turning handle 35 has caused washer 24 to also be displaced in the direction
of motion arrow 39,
so as to abut outside surface of wall 43. The motion of turning (i.e.
rotating) the turning handle
35 has also caused fastening bolt 32 to be threaded inside turning handle 35,
thereby shortening
the length of its shank disposed inside recessed groove 41. As may be seen,
enlarged head 33 has
been displaced inside recessed groove 41 in the direction of motion arrow 38.
Thus as may be
understood, the compression locking engagement of the proj ection arm 15 is
caused by the
sandwiching of wall 42 of projection arm 15 between enlarged head 33, wall 43
of frame 17 and
washer 34. The application of sufficient force will cause the compression
locking engagement
of the projection arm 17 against the frame 17.
Figure 8 is a sectional view along lines 6-6 of Figure 4, and further shows a
side rail 60 of a
ladder being disposed in the engagement groove 40.
Figure 8 shows the frame 17 of ladder extender 10 affixed to the side rail 60
of a ladder. As may
be seen, engagement groove 40 and tap screw 50 are configured and disposed so
as to create a
23
CA 02233713 1998-04-15
C-clamp shaped enclosure for receiving the side rail of a ladder therein. The
clamp locking
means may therefore be the combination of the shape of the engagement groove
40, the tap
screws 50, and surface 52. The fixation of the ladder extender 10 to side rail
60 is accomplished
by placing the frame 17 over and around side rail 60, i.e. disposed in the
groove of the C-clamp
shaped enclosure, namely inside engagement groove 40. Threaded screw 50 is
threadingly
engaged with the threaded opening in the wall of frame 17, and when threaded
screw 50 is turned
clockwise, will advance and be displaced in the direction of motion arrow 61,
until extremity 51
abuts side rail 60. The application of sufficient turning force to threaded
screw 50 will cause side
rail 60 to be held firmly in a clamp or vice-like manner between surface 52
and extremity 51,
thus precluding the need for drilling a hole in side rail 60. Although not
shown, more than one
tap screw 50 may be used to engage side rail 60 within engagement groove 40.
Figure 9 is a schematic view of a ladder extender 10 having a one-component
frame 17 affixed
to a side rail 3 of a ladder 1.
Figure 9 shows a schematic view of a ladder extender, generally designated by
reference number
10, disposed adj acent the lower extremity 6 of side rail 3 of ladder 1.
Ladder 1 is shown having
opposed side rails 2 and 3 being spaced apart by rung 4. Frame 17 is affixed
to lower extremity
6 of side rail 3.
Frame component 17 is shown comprising a dual locking means, namely frictional
locking
means comprising clutch plate 25 (as explained in Figures 2-6), and
compression locking means
comprising turning handle 35 (as explained in Figures 2-7). Clutch plate 25 is
shown in its
second or disengaged position, as shown in Figure 5.
Figure 9 further shows ladder 1 being used on downwardly slopping terrain 7.
In order to keep
ladder 1 in a substantially upright position, the projection arm 15 of the
ladder extender 10 is
shown to extend by a distance 8' below the lower extremity 6 of side rail 3.
The proj ection arm
15 is further shown as having a foot element 18 attached to its lower
extremity 19 through pin
20. Foot element 18 is also shown having a non-slip surface 14 on the
underside thereof which
24
CA 02233713 1998-04-15
serves to better grip downwardly sloping ground 7. Although not shown, side
rail 2 of ladder 1
may also be fitted with a ladder extender similar to that shown at 10.
