Patent Publication Number: US-7222695-B2

Title: Ladder leveller

Description:
FIELD OF THE INVENTION 
   This invention relates to extension ladder attachments comprising a movable and adjustable stile extension that engages the ladder via hollow ladder rungs, for the purpose of using a ladder on uneven surfaces. 
   BACKGROUND OF THE INVENTION 
   Ladders are used extensively in construction and maintenance tasks on construction sites and in buildings by a variety of trades and home do it yourself people. Used both indoors and out, ladders are often needed in locations and positions where the footing upon which they rest is uneven. Indoor stairwells present a particular problem for painters, electricians, etc. for accessing walls and ceilings. Out of doors uneven ground around a building or structure upon which work is to be performed poses a significant challenge in terms of safe ladder use. Many solutions to this problem have been devised including ladders with independently telescoping legs of various design, and ladder attachments that incorporate telescoping legs for the purpose of leveling a ladder on uneven surfaces. 
   Applicant is aware of patents regarding adjustable ladders and ladder attachments that provide support to the ladder so that each leg may adequately engage the supporting uneven surfaces: 
   
     
       
         
             
             
             
             
             
           
             
                 
                 
             
             
                 
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   The fore-mentioned patents teach a variety of methods to make ladder legs adjustable in order to compensate for uneven supporting surfaces. Some require tools to attach the ladder leveling device, while others can be applied without tools. Some are mounted through the rung of a hollow rung ladder, while others are affixed to the outside of the rung or the main ladder frame or stiles. Some are easily removed while others are not. Some insulate the ladder primarily by means of a rubber foot pad, while others are not. Some are adjustable and positively secured, with some being easily quick and easy to adjust, while most are not. Many require permanent modification of the ladder being attached to. 
   SUMMARY OF THE INVENTION 
   The present invention provides the means to use a hollow rung ladder on uneven surfaces by attachment of one or more extendible legs to the ladder stiles. One common application where the invention may be used on uneven surfaces is in painting a hallway with a set of stairs in it. The present invention is readily attached to or removed from a ladder without the use of tools or modification of the ladder in any manner. Further the present invention once installed does not interfere with the operation of the ladder where the ladder is an extension ladder Or a step ladder. The present invention attaches to a ladder by passing threaded rods centrally through two adjacent hollow rungs on the lowest extent of the ladder stiles, and securely affixing the rod therein by insulated ladder collars that locate and seat in the ladder rung port, and on the surface of the stile at the ladder rung port. The insulated ladder collar is surfaced with grooves in a manner that provides an interlocking surface with a similarly surfaced extendible leg in the form of u shaped channel. The channel is mated against the ladder collars so as to attain the desired leg extension, and secured thereon by means of a quick-release locking bar, which is guided into position by a cylindrical groove on a locking bar guide. The quick release locking bar eases adjustment of the extendible leg, without the use of tools, while providing a secure means of attaching the ladder leveller to the ladder. This also allows for quick relocation of a single leveller leg from one side, that is stile, of the ladder to the other. 
   Thus in summary, the present invention may be summarized as a ladder leveller for mounting onto at least one stile of a hollow runged ladder, the leveller including, an elongate stile extension member at least one cross bar sized for mounting journalled through a hollow rung of the ladder, a locking pin extending from the at least one cross bar and cooperating locking bar. The extension member has a spaced array of apertures formed therealong, each aperture of the array extending through the stile extension member. 
   Cross bar mounts are mountable onto an end of the cross bars in mating engagement with an end of the hollow rung so as to secure the cross bars journalled in the hollow rungs. The cross bars and cross bar mounts extend co-axially from the cross bars and through any one of the apertures in the stile extension member so that the locking pin is exposed outwardly of the stile extension member oppositely disposed relative to the ladder when the stile extension member is abutted against so as to lie along, the corresponding stile. The locking bar is releasably mounted onto the locking pin when extending through an aperture in the stile extension member. The locking pin has locking grooves for interlocking with the locking bar. 
   Thus, with the cross bars mounted through corresponding hollow rungs, and with the cross bar mounts mounting the cross bars securely in the rungs, and with the locking pin or pins protruding outwardly of the stile, and with the stile extension member mounted along and adjacent the stile with the locking pin protruding through one of the apertures in the stile extension member so as to expose the locking grooves on the locking pin outwardly of the stile extension member, and with the locking bar mated onto the locking grooves on the locking pin, the stile extension member is releasably mounted to and along the stile so as to adjustably extend from a lower end of the stile. 
   Advantageously, the cross bars extend to opposite ends of the corresponding hollow rungs, and the cross bar mounts mount to opposite ends of each cross bar and corresponding rung, and the locking pins are mounted to, so as to extend oppositely from, the opposite ends of the each cross bar and corresponding rung. 
   The locking bar may be an elongate rigid member having slotted apertures therein spaced apart so as to coincide with spacing between at least two of the locking pins extending from the corresponding cross bars. The slotted apertures in the locking bar mount simultaneously over the two locking pins so as to engage the locking bar into releasable locking engagement with corresponding the locking grooves in the locking pins. 
   At least one stop may be mounted on the stile extension member and engageable with the locking bar to limit travel of the locking bar along the stile extension member as the locking bar is mounted into engagement with the locking pins. 
   Further advantageously, the cross bar mounts are electrically insulating and are mounted onto exposed ends of the cross bars, and the cross bars are of sufficient length to extend outwardly of the corresponding rung so as to expose ends thereof for mounting of the mounts thereto. The mounts mount between the stile extension member and corresponding stile to insulate one from the other. The mounts have outwardly disposed surfaces, disposed outwardly of the corresponding stile. The outwardly disposed surfaces are contoured for inter-locking engagement with a correspondingly contoured surface on the stile extension member so as to inhibit slipping of the stile extension member along the corresponding stile when the stile extension member is mounted thereto. For example, the contoured surfaces may be corrugated such as forming interlocking teeth. 
   The stile extension member may be a channel member, u-shaped in cross section, so as to form an elongate channel along the length of the member. The locking bar when mounted onto the locking pin is contained within the elongate channel. 
   In one embodiment, an elongate resilient latch bar is mounted at one end thereof onto the locking bar. The locking bar includes an aperture therethrough disposed underneath a free end of the latch bar. The aperture in the locking bar is sized to mate over the locking pin so as to allow the locking pin to extend therethrough. The latch bar has a mating aperture in the free end thereof for mating over the exposed locking pin exposed through the aperture in the locking bar. The free end of the latch bar is biased by a user lifting it away from the locking bar against a return biasing resiliency of the locking bar so as to mount the mating aperture onto the locking pin. The free end of the latch bar, once released, is resiliently biased so as to return towards the locking bar to thereby releasably lock the locking pin in the mating aperture, thereby mating the locking bar in a locked position relative to the stile extension member and thereby releasably locking the stile extension member onto the corresponding stile of the ladder. 
   In one embodiment, the aperture in the mating bar is a key slot, and the mating aperture in the latch bar is positioned over a narrow end of the key slot. The narrow end of the key slot engages the locking grooves in the locking pin. 
   A handle may be formed on the free end of the latch bar adjacent the mating aperture, for grasping by a user so as to bias the free end of the latch bar away from the locking bar. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is, in front perspective view, an exploded assembly for the ladder leveller in alignment of the ladder ports used to attach to the ladder body. 
       FIG. 2  is, in front perspective view, and exploded assembly of the ladder leveller without a ladder present. 
       FIG. 3  is, in front perspective view, a partially exploded assembly of the ladder leveller without a ladder present. 
       FIG. 4  is, in perspective view, the locking components of the ladder leveller. 
       FIG. 5  is, in side cut-away view, the mounting interface between ladder stile, rung port and ladder leveller. 
       FIG. 5   a  is, in top cut-away view, the mounting interface between ladder stile, rung port and ladder leveller. 
       FIG. 6  is, in perspective view, a ladder with a ladder leveller attached to one stile in a extended position with the locking bar engaged. 
       FIG. 7  is, in perspective view, a ladder with a ladder leveller attached to one stile in a retracted or stowed position with the locking bar engaged. 
       FIG. 8 , is in perspective view, a ladder with a ladder leveller installed and extended to support the ladder on a set of stairs. 
       FIG. 9 , is in top cross sectional view, the ladder locking bar guides. 
       FIG. 10  is, in perspective view, an alternative embodiment of the channel and locking bar according to the present invention. 
       FIG. 10   a  is, in exploded view, the channel and locking bar of  FIG. 10 . 
       FIG. 11  is an enlarged view of a portion of  FIG. 10 . 
       FIG. 12  is an enlarged view of a portion of  FIG. 10 . 
   

   DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
   The present invention is a ladder leveling device that attaches to various stile designs of hollow rung ladders and is described with reference to the accompanying drawings wherein similar characters of reference denote corresponding parts in each view. One embodiment of the present invention as seen in  FIGS. 1–9  is attached to a ladder  12  by first passing threaded rods  6  centrally through the hollow rungs  13  and securing them in place using insulated ladder collar  5  which has locking pin  11  press fit into it, and together are retained on rod  6  by hand threading the collar and locking pin assembly onto rod  6 , and seated by locating ring  19  in the ladder port  10  against the ladder stile  20 , with the locking grooves  21  on the collar being positioned normal to the longitudinal axis of the ladder stile  20 . 
   The leg assembly as shown in  FIG. 2 , complete with channel  2 , and locking bar guides  4  secured by rivets  16 , and locking bar  1  is attached to the ladder by bringing the assembly of  FIG. 2  to a ladder stile as shown in  FIG. 1  so that the locking pins  11  pass through the channel slots  3  and the locking bar slots  8  and  9  until the grooves  17  in the channel engage with the grooves  21  in the collars. The locking bar  1  is then moved towards the foot of the ladder engaging the locking bar slots  8  and  9  in the locking pin  11  slots  18 . Similarly a second ladder leveling device may be optionally attached to the opposite stile. 
   To adjust the ladder leveling device one lifts the locking bar  1  until the locking bar slots  8  and  9  disengage the locking pin grooves  18  allowing the leg assembly to move away from the ladder stile  20  enough for the channel grooves  17  and the collar grooves  21  to clear. The leg assembly is then moved towards or away from the foot of the ladder to the desired position, the leg assembly is moved towards the ladder style  20  until the channel grooves  17  and collar grooves  21  are once again engaged. The locking bar  1  is then moved towards the foot of the ladder stile  20  engaging the locking pin  11  in groove  18  by the locking bar slots  8  and  9 . Once the locking bar  1  is fully engaged in the locking pin grooves  18 , the ladder can be positioned and used as shown for example in  FIG. 8 . 
   The combination of the cylindrical grooves  25  on the locking bar guides as shown in  FIG. 9 , and the key hole slot  8  and  9  on the locking bar enables the key hole slots  8  and  9  to engage the groove  18  of the locking pin  11 . The locking bar  1  is pushed down through the locking bar guides  4  until the top end of the key hole slot  8  and  9  slide until the bar fully engages the top half circumference of pin slot  18 . The locking bar  1  will not engage the collar pin  11  if the grooves between the collar  21  and the channel  17  are misaligned, signaling to the user that the ladder leveller is not locked in position and is not safe to use. 
   The ladder collar  5  may be made of insulating material so as to provide an extra measure of protection against unintentional grounding of the ladder when used in servicing electrical devices, which may be energized at the time. The combination of the insulated collar and centrally locating this steel threaded rod inhibits an electrical charge passing through the attachment to the ladder body. The locking pin  11  is shown as a separate component from the collar  5 , and can be metallic in nature adding strength to the locking mechanism. An alternative embodiment may have the collar  5  and locking pin  11  combined as a single component that could be made of a high strength electrically insulating material such as plastic, or it could be made of a metallic material which may simplify the design while possibly forgoing the electrical insulating properties of the collar  5 . 
     FIGS. 5 and 5   a  show the ladder collar  5  securely engaging the ladder port  10  and stile  20  by means of the protrusion or locating ring  19  on the collar  5  seating within the ladder port  10 , while the shoulder portion of the collar engages the surface of the stile  20 , and is held in contact with the stile  20  by the pressure resulting from two such collars  5  being turned onto the threaded rod  6  until they both actively engage the opposing rung ports  10  with the collar locating ring  19 , and the stile  20  with the shoulder portion of the collar. 
     FIGS. 5 and 5   a  also show by top view cutaway section the channel  2  grooves  17  and  21  engaged, and the locking bar  1  slot  8  engaged with the locking pin  11  groove  18 . The locking bar  1  is also shown entrapped by the locking bar guides  4  which are riveted  16  to the channel  2 . 
   Non-slip rubber pads on the swivel feet  22  are typically installed at the foot of the ladder levellers by bolting through hole  7  on the channel  2 , providing the ladder leveller additional safety through both non-slip and electrical insulation properties of the feet. The rotational degree of freedom in the mounting of the feet  22  enhances the ladder safety when used on different ladder slopes. 
   The u-shaped channel  2  is used for legs in the present invention due to its improved strength and weight characteristics when compared with much of the prior art. The present invention may be installed onto a conventional hollow rung ladder without the use of tools, modification of the ladder, or interference with the ladder operation. It is may be adjusted without tools by simply lifting and lowering the locking bar  1 . The ladder leveller may be moved from one side of the ladder frame to the other side with out the use of tools, and is not restricted to specific ladder widths making it a flexible add on to most existing ladder designs. 
   The insulated ladder collar separates the ladder leveller from the main ladder frame and is non-conductive, adding a measure of safety when used around energized electrical circuits. The ladder leveller has two connecting points to the ladder, spreading the stress over a greater area than some of the prior art. There is no contact between the ladder frame and the ladder leveller leg, other than through the insulated collar, which distributes the load through the rung port. The grooves on the insulated collar and the grooves on the ladder leveller channel positively lock into each other to provide very secure support. The locking bar prevents unintended unlocking as it has to be lifted up in a vertical direction and is generally held in place through friction and gravity. The ladder leveller does not interfere with the clear operation of the ladder at any time. No tools are required for installation or removal of the ladder leveller, making it easy to move from one ladder to another. 
   The tightening and the precise alignment of the two insulated collar grooves on the ladder to engage the locking bar  1  is done without tools using the following method. The ladder attachments lower slot and grooves are engaged on the lower collar and the locking bar in slid into place. The attachment is rotated around in a circular arc securing the insulated collar against the face of the ladder style. The attachment is rotated again till the upper insulated pin aligns with the upper corresponding slot and passes through. The process is followed for the upper insulated collar and when complete the ladder grooves are now aligned exactly and the locking bar and corresponding grooves can be engaged properly. 
   In an alternative embodiment seen in  FIGS. 10–12 , the lower end of locking bar  1  is planar and slides along channel  2  under an opposed facing pair of channel rails  2   a  so that locking bar  1  is held snugly flush against the web  2   b  of channel  2  as the locking bar is slid along channel  2  in direction A. Locking bar  1  has key slot  8  so as to engage a locking pin  11  extending from collar  5  through channel slots  3  in channel web  2   b . The narrowed slot  8   b  of key slot  8  engages corresponding slots  18  in locking pins  11 . 
   A flexible latch bar  1  a is mounted by fastener  1   b  to channel web  2   b  at one end of the latch bar so as to flexibly dispose the free end of the latch bar over the lower of the key slots  8 . Latch bar  1   a  has an aperture  1   c  in the free end thereof sized to fit snugly over the exposed end of locking pin  11 . Thus, once the exposed end of locking pin  11  is inserted through the large opening  8   a  in key slot  8 , and with the free end of latch bar  1   a  elevated away from locking bar  1  in direction B, locking pin  11  may be slid along the narrow slot  8   b  of key slot  8  until aligned with aperture  1   c  in latch bar  1   a . Latch bar  1   a  may then be lowered so as to journal the exposed end of locking pin  11  through aperture  1   c . This locks locking pin  11  into key slot  8  until such time as it is desired to remove locking bar  1  from engagement with locking pin  11 . When it is desired to remove locking bar  1 , the free end of latch bar  1   a  is elevated in direction B to allow locking pin  11  to be removed from aperture  1   c , thereby allowing locking pin  11  to be slid along locking bar  1  into the opening  8   a  of key slot  8  for removal of locking pin  11  through opening  8   a . This allows disengaging of locking bar  1  from locking pin  11  thereby allowing the removal of channel  2  from engagement with the corresponding stile  20  of ladder  12 . 
   As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.