CA2233713A1 - Ladder extender - Google Patents

Abstract

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. The ladder extender comprises a frame, fixation means for releasably affixing said frame to said side rail; a projection arm slidably engaged in said frame, and dual locking means for releasably locking said projection arm at a desired position, said dual locking means comprising frictional locking means and compression locking means. The fixation means may be such that the side rail of the ladder need not be drilled or otherwise damaged to affix the frame thereto.

Description

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 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.

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.

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, 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 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.

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) 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 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.

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.

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 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.

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 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 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 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.

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.

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 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.

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 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.

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 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 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 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.

Claims (11)

1. 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 projection arm slidably engaged in said frame dual locking means for releasably locking said projection arm at a desired position, said dual locking means comprising frictional locking means and compression locking means.

2. 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.

3. The ladder extender of claim 2 wherein said frictional locking means comprises a friction force adjustment mechanism.

4. The ladder extender of claim 3 wherein said fixation means comprises clamp locking means for releasable locking engagement of said frame against said side rail.

5. The ladder extender of claim 4 wherein said frame comprises a guide portion for receiving said projection arm therein and an engagement groove for receiving said side rail therein.

6. 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.

7. The ladder extender of claim 6 wherein said frictional locking means comprises a friction force adjustment mechanism.

8. The ladder extender of claim 7 wherein said fixation means comprises clamp locking means for releasable locking engagement of said first frame component and said second frame component against said side rail.

9. The ladder extender of claim 8 wherein said first frame component is spaced apart from said second frame components and wherein said first and said second frame components each comprise a guide portion for simultaneously receiving therein said projection arm and an engagement groove for simultaneously receiving therein said side rail.

10. In 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, 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.

11. 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 projection 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 projection 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 said elongated projection 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 projection arm such that said projection 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.