Abstract:
A device for allowing a user to selectively extend and retract wheels at the feet of an A-frame stepladder thereby enabling the user to move the ladder from point “A” to point “B” without physically moving, lifting or dragging the ladder. The apparatus includes a gear assembly at the foot of each ladder siderail having an attached caster-style wheel. Each gear assembly is mechanically associated with a handgrip trigger mechanism located along the ladder siderail in a position convenient for the user to operate with each handgrip trigger mechanism controlling the two gear assemblies on the same side of the stepladder.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to ladders and, more specifically, to an extendable/retractable device for moving A-frame type stepladders. The device consists of four mechanisms providing means for extending/retracting wheel elements, one mechanism for each leg of the ladder and two control mechanism, each attached to a pair of leg mechanisms. When the handles of the control mechanisms are squeezed, the wheels are extracted until engaging the ground whereupon continued pressure applied to the control mechanism raises the ladder, enabling the user to move the ladder from point “A” to point “B” without physically lifting, closing or dragging the ladder. 
     The design consists of four retractable wheels positioned within a housing, one on each leg of the ladder and two grip handles attached to the wheels by a length of line. When the handles are squeezed the line contracts pulling the wheels along a gear face until they extend below the housing and raising the ladder enabling the user to move the ladder from point “A” to point “B” without lifting the ladder, closing the ladder or dragging the ladder. 
     A guide rack assembly is provided and includes; a rack, pulley, pinion, swivel wheel, pin, cable adjustment and rack guide. The rack gear is driven by the pinion gear which is a part of the pulley. When the handle is activated, the pulley and pinion gear move the rack gear and wheels in a downward motion. When the handle is released, a spiral spring located on the opposite side of the pulley releases the tension built on it when the cable was activated, causing the pinion gear to move the rack gear into its stored position. 
     2. Description of the Prior Art 
     There are other ladder devices designed for moving ladders. Typical of these is U.S. Pat. No. 1,293,066 issued to Faulkner on Feb. 4, 1919. 
     Another patent was issued to Mayberry on Apr. 11, 1950 as U.S. Pat. No. 2,503,626. A patent was issued to Fredericks et al. on Dec. 14, 1976 as U.S. Pat. No. 3,997,024. Yet another U.S. Pat. No. 4,063,616 was issued to Gutierrez on Dec. 20, 1977 and still yet another was issued on May 15, 1984 to Giezendanner as U.S. Pat. No. 4,448,282. 
     Another patent was issued to Kuperman on Mar. 27, 1990 as U.S. Pat. No. 4,911,263. Yet another U.S. Pat. No. 5,464,071 was issued to Rice et al. on Nov. 7, 1995. Another was issued to Gugel et al. on Dec. 17, 1996 as U.S. Pat. No. 5,584,357 and still yet another was issued on Jan. 7, 1997 to High et al. as U.S. Pat. No. 5,590,739. 
     Another patent was issued to Bendickson et al. on Aug. 5, 1997 as U.S. Pat. No. 5,653,306. Yet another U.S. Pat. No. 6,039,147 was issued to Gillis et al. on Mar. 21, 2000. Another was issued to Bieszczad on Oct. 23, 2001 as U.S. Pat. No. 6,305,496. 
     U.S. Pat. No. 1,293,066 
     Inventor: Albert N. Faulkner 
     Issued: Feb. 4, 1919 
     This invention relates to improvements in and relating to ladder feet, and has for its object to provide a device that attaches to a ladder as a non-slipping device. 
     U.S. Pat. No. 2,503,626 
     Inventor: Robert Mayberry 
     Issued: Apr. 11, 1950 
     The present invention relates to ladders and more particularly, to improve means for adjustably connecting ground engaging legs to the stiles of the ladder. 
     U.S. Pat. No. 4,063,616 
     Inventor: Ernest F. Gutierrez 
     Issued: Dec. 20, 1977 
     A safety ladder assembly having a plurality of steps and at least three support feet for supporting the ladder on a horizontal surface. A caster assembly having at least three casters for providing for rollingly transporting the ladder from one location to another. The casters are positively and conjointly moveable between a retracted storage position in which the support feet stably support the ladder on a horizontal surface and a second transporting position in which the casters stably support the ladder assembly on the horizontal surface with the support feet elevated thereabove so that the ladder assembly may be rollingly transported along the surface. A linkage interconnects the casters so that they may be raised and lowered via actuating and retracting pedals. 
     U.S. Pat. No. 4,448,282 
     Inventor: Ruedi Giezendanner 
     Issued: May 15, 1984 
     The ladder includes two separate ladder elements, which are pivotable and slidable relative to each other and can also be completely separated from each other. It can be used as a step-ladder and as a leaning type ladder. The ladder element is equipped with wheels, in order to simplify the transport of the collapsed ladder. In addition, an outwardly pivotable support plate is arranged between the wheels, so that the ladder element can serve as a hand truck, whereby the bent ends of the side beams serve as hand grips. The ladder has a simple construction and can be used in many ways in household use and in commercial operations. 
     U.S. Pat. No. 4,911,263 
     Inventor: Aryeh Kuperman 
     Issued: Mar. 27, 1990 
     Ambulatory ladder apparatus constructed as a stepladder frame supported on a set of four base wheels. A user-powered drive is mounted under the lowermost step of the ladder, and is mechanically connected with a pair of the base wheels. A drive arm extending from the drive is accessible to a user while aboard the stepladder. By pumping action of the drive arm, the user-powered drive causes rotation of the base wheels, moving the ladder forward. A steering mechanism provided on the drive arm allows the user to direct the motion of the ladder during the pumping action. Thus, without requiring the user to dismount, the ladder may be easily repositioned by operation of the drive, allowing greater work efficiency in many repair, remodeling, painting and construction projects, by eliminating the additional time normally required for dismounting and repositioning the ladder. 
     U.S. Pat. No. 4,911,263 
     Inventor: Aryeh Kuperman 
     Issued: Mar. 27, 1990 
     A portable collapsible scaffold ladder has a pair of upright caster-mounted end members joined together by a horizontal platform member. A pull-out ladder for scending to the platform is connectable at its upper end and sliable along its connected end member for movement between a nested position within that end member and a diagonally extending operative position. The platform member is joined to the two end members by T-shaped glide members pivoted to each of the four corners of the platform member. Each glide member has a glide portion slidable along one side of a connected end member and a pivot portion pivoted to an adjacent side portion of the platform member. Each glide member has a resilient leaf-type spring which carries two locking pins, one for interlocking with the platform and the other for interlocking with one of a series of pin-receiving openings in the upright. When the pins are engaged, the glide members rigidly interlock the platform member and two end members at right angles for use, or in parallel collapsed relationship for transport. When one pin of each pair of glide members is disengaged, the platform can be moved along the adjacent end member. When the opposite pin of each pair of glide members is disengaged, the platform and end members can be freely pivoted with respect to one another. 
     U.S. Pat. No. 5,464,071 
     Inventor: Crispin J. Rice et al. 
     Issued: Nov. 7, 1995 
     A new and improved ladder leveling device comprising a gear box having a plurality of gears coupled to an interior of the gear box on shafts. The shaft of a lowest gear extends outwardly of the gear box. A crank couples with the outwardly extending shaft of the lowest gear. The crank serves to rotate the lowest gear thereby collectively rotating the plurality of gears. A pin selectively couples with an uppermost gear and extends outwardly of the left wall. The pin serves to selectively engage or disengage the three gears. A plate is secured to a lower portion of the gear box. The plate serves to support the ladder&#39;s leg. Included in the device is a vertical rack having a plurality of teeth thereon. The vertical rack is secured within the gear box. The plurality of teeth engage the plurality of gears and are optionally raised or lowered by the rotation of the gears when the pin is disengaged. A foot pad is pivotally coupled with the vertical rack. The foot pad serves to lie flat on the ground and stabilize the device. An adjustable clamp is secured to the wall of the gear box upwardly of the plate. The clamp serves to secure the ladder&#39;s leg against the gear box. 
     U.S. Pat. No. 5,584,357 
     Inventor: Leslie H. Gugel et al. 
     Issued: U.S. Pat. No. 5,584,357 
     The instant invention is directed to increasing the safety of ladders and includes an accessory holder for the top of ladders forming a tray which expands in size allowing placement of working materials in the tray. The tray collapses into a size assimilating a conventional ladder top for compact storage. The tray can be raised to various heights and allows the operator to remove the tray in its entirety to carry items to the ladder providing for convenience and safety. An alternative embodiment provides for the use of solid portions in place of a tray allowing smaller ladders such as to be used as saw horses yet provide a means for forming a smaller tray for sacrament of miscellaneous working materials. The improved ladder employs handles that couple to each side limb of the ladder allowing an operator to grasp the handles while climbing. An electrical socket mounted in a limb provides for a prewired extension along the length of the limb providing an electrical connection near the top portion of the ladder. Biased wheels allow the ladder to be moved without lifting. 
     U.S. Pat. No. 5,590,739 
     Inventor: DeWayne High et al. 
     Issued: Jan. 7, 1997 
     A motorized utility extension ladder having a main and upper riser section extendable by a motor. The ladder further comprising a telescopic prop so that the ladder may be free standing, side wing legs for stabilizing the ladder, wheels for transporting the ladder, and a removable shelf. 
     U.S. Pat. No. 5,653,306 
     Inventor: Roy Bendickson et al. 
     Issued: Aug. 5, 1997 
     A ladder system comprising a ladder having side rails and a plurality of steps disposed between the side rails. The ladder system also is comprised of at least one corner brace for supporting a bottom step of the ladder. The corner brace is attached to a side rail of the ladder and the bottom step. Additionally, the ladder system is comprised of at least one caster assembly integrally attached to the corner brace for allowing the ladder to roll. Preferably, the caster assembly and corner brace are disposed on the ladder such that a predetermined weight placed on the ladder prevents the ladder from rolling. The corner brace is preferably comprised of a first portion, a second portion connected to the first portion and a third portion connected to the second portion. The first portion is attached to a bottom of the ladder. The second portion is attached to the caster assembly. Additionally, the third portion is attached to a rail of the ladder. A caster apparatus comprises a corner brace for supporting a bottom step of a ladder. The caster apparatus is also comprised of a caster assembly integrally attached to the corner brace for allowing the ladder to roll. A method for forming a ladder system. The method comprises the steps of attaching a caster assembly to a corner brace for a ladder such that the caster assembly is in biased sliding relationship with the corner brace. Then, there is the step of fixing the corner brace having the caster assembly to a bottom step of the ladder and to a side rail of the ladder such that the rail is maintained off of ground by the caster assembly when there is essentially no weight on the ladder. Preferably, after the fixing step, there is the step of rolling the ladder on the caster assembly to a desired location. 
     U.S. Pat. No. 6,039,147 
     Inventor: Donald Gillis et al. 
     Issued: Mar. 21, 2000 
     A safety ladder stand comprising a generally rectangular base having a front and rear and a center beam, a plurality of stair treads extending upward from the front of said base and means for supporting said stair treads secured to said base, front wheels mounted at the front of said base and beneath the top of said stair treads; center wheels mounted on said center beam of said base, and rear wheels mounted at the rear of said base, and a set of feet mounted on the front of said base; wherein said ladder stand has an activated position wherein said front and center wheel sets are in contact with the ground to enable said ladder stand to roll and said rear wheels and front support feet are not in contact with the ground, as well as a deactivated position wherein the front and center wheel sets are not in contact with the ground and said rear wheels and front support feet are in contact with the ground to prevent said ladder stand from being rolled; and means for moving said ladder stand from said deactivated position to said activated position. 
     U.S. Pat. No. 6,305,496 
     Inventor: Todd Bieszczad 
     Issued: Oct. 23, 2001 
     The ladder stand employs a pair of swivable caster wheels at the front and a pair at the rear which are used in cooperation with a pair of closely located non-swivable caster wheels, thereby providing a structure which has three modes of operation, one mode for climbing, a second mode which permits the stand to be pushed in a straight line with wide turns and a third mode of operation which permits the stand to be first pushed laterally and to provide sharp turns. A front wheel support is mounted on the front end and a retractable first pair of swivable caster wheels is mounted on the front support. A rear wheel support is mounted on the rear end, with a retractable second pair of swivable caster wheels mounted on the rear support. A third pair of non-swivable rigid caster wheels are mounted at the rear end. 
     While these ladder devices may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention, as hereinafter described. The device consists of four mechanisms for extending/retracting wheels, one on each leg of the ladder and control mechanisms attaching to the siderails of the stepladder. When the control mechanisms are squeezed, the wheel elements are extracted and touch the ground raising the ladder, enabling the user to move the ladder from point “A” to point “B” without lifting the ladder, closing the ladder or dragging the ladder. 
     SUMMARY OF THE PRESENT INVENTION 
     A primary object of the present invention is to provide an extendable retractable device for moving stepladders that consists of four retractable wheels with continued pressure lifting the ladder, one on each leg of the ladder and two grip handles attaching to the wheel or guide rack. 
     Another object of the present invention is to provide a grip and wheel device that when the handles are squeezed, the wheels are extracted and touch the ground, enabling the user to move the ladder from point “A” to point “B” without physically lifting, closing or dragging the ladder. 
     Another object of the present invention is to provide a guide rack assembly that includes; the rack, pulley, pinion, swivel wheel, pin, cable adjustment and rack guide. 
     Yet another object of the present invention is to provide a device that allows the user to move a ladder without the risk of injury to their back. 
     Additional objects of the present invention will appear as the description proceeds. 
     The present invention overcomes the shortcomings of the prior art by providing an extendable/retractable device for moving stepladders that consists of wheel extension/retraction mechanisms, one on each leg of the ladder and control mechanisms attaching to the siderails of the ladder. Also, a device that when the handles are squeezed, the wheels are extracted and touch the ground, enabling the user to move the ladder from point “A” to point “B” without physically lifting the ladder, closing the ladder or dragging the ladder. 
     The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying drawing, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawing, like reference characters designate the same or similar parts throughout the several views. 
     The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     In order that the invention may be more fully understood, it will now be described, by way of example, with reference to the accompanying drawing in which: 
     FIG. 1 is an illustrative view of prior art in use; 
     FIG. 2 is an illustrative view of the present invention in use; 
     FIG. 3 is a perspective view of the present invention; 
     FIG. 4 is an exploded view of the rack guide unit of the present invention; 
     FIG. 5 is a right perspective view of the rack guide unit of the present invention; 
     FIG. 6 is a left view of the rack guide unit of the present invention; 
     FIG. 7 is a sectional view of the rack guide unit of the present invention; 
     FIG. 8 is a perspective view of the handle grip unit of the present invention; 
     FIG. 9 is a side view of the rack gear with wheel of the present invention; 
     FIG. 10 is a view of the connection between the hand grip and the rack guide assembly of the present invention; 
     FIG. 11 is a perspective view of the functioning components of the present invention; and 
     FIG. 12 is a sectional view of the rack guide assembly of the present invention in use. 
     DESCRIPTION OF THE REFERENCED NUMERALS 
     Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the Figures illustrate the locator device of the present invention. With regard to the reference numerals used, the following numbering is used throughout the various drawing figures. 
       10  retractable wheel and lift device for ladders 
       12  ladder 
       14  siderail of  12   
     operator engagement means 
       20  hand grip trigger mechanism 
       22  cable 
       24  wheel member 
       26  wheel extension and retraction means 
       28  rack and pinion gear assembly 
       30  gear assembly housing 
       32  rack gear 
       36  bottom end of  32   
       38  rack guide 
       40  pinion assembly 
       41  pinion gear 
       42  pulley 
       44  first side of  42   
       46  second side of  42   
       48  post member of  42   
     spring retaining channel 
     spring retaining pin 
       54  operator 
       56  cable adjustment means 
       58  cable retaining recess 
       60  cable stop 
       62  first end of cable 
       64  second end of cable 
       66  flat spiral spring element 
       68  access cover of  30   
       70  axle pin 
     first end of  66   
       74  second end of  66   
       76  axle recess 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following discussion describes in detail one embodiment of the invention. This discussion should not be construed, however, as limiting the invention to those particular embodiments, practitioners skilled in the art will recognize numerous other embodiments as well. For definition of the complete scope of the invention, the reader is directed to appended claims. 
     FIG. 1 is an illustrative view of prior art. Conventional ladders  12  tend to be difficult and cumbersome to move about a work area. Lifting a ladder  12  from point “A” to point “B” tends to be a time consuming project and a back breaking effort, also, every time a user  54  must move a ladder  12  about a work area, the arms are extended forward while in movement, leaving a good chance for a back or shoulder injury to occur. 
     FIG. 2 is an illustrative view of the present invention  10  in use. The present invention  10  is designed for A-frame type ladders but may also be adapted for use with extension ladders or other appropriate applications. The design consists of four retractable pivoting wheel members  24 , one on each siderail  14  of the ladder  12  and two hand grip trigger mechanisms  20  attaching to the wheel  24  or guide rack. When the hand grip trigger mechanisms  20  are squeezed, the wheel members  24  are extracted and touch the ground and continued applied pressure raises the ladder thus enabling the user  54  to move the ladder  12  from point “A” to point “B” without physically lifting, closing or dragging the ladder  12 . 
     FIG. 3 is a perspective view of the present invention  10  integral with an A-frame ladder  12 . The wheel extension and lift device for ladders  10  may be manufactured into new ladders  12  or retrofit to existing ladders. The present invention  10  consists of an operator engagement means  18  comprising hand grip trigger mechanisms  20  and related cables  22  that communicate with a rack and pinion gear assembly  28  that includes pulleys  42  and wheel members  24 . 
     FIG. 4 is an exploded view of the rack and pinion gear assembly  28  of the present invention  10  showing the rack guide  38  within the gear assembly housing  30  and the cable  22  passing through the cable adjustment means  56  and into the gear assembly housing  30  where the cable stop  60  on the second end  64  of the cable  22  is to be placed within the cable retaining recess  58  of the pulley  42  for engagement therewith. The pulley  42  has a post member  48  extending therefrom with a spring retaining channel  50  traversing therethrough for receiving and retaining the first end  72  of the flat spiral spring element  66 . The second end  74  of the spring element  66  is maintained by spring retaining pin  52  that is shown in the removable access cover  68  of the gear assembly housing  30 . An axle pin  70  is also shown in the access cover  68  and is to be inserted into the axle recess  76  in the end of the post member  48 . The gear rack  32  travels reciprocatively through the rack guide  38  during extension and retraction of the wheel member  24 . 
     FIG. 5 is a detail view of the rack and pinion gear assembly  28  showing the pinion gear  41  engaged with the rack gear  32 . The pinion assembly  40  comprises the pinion gear  41  and the attached pulley  42  and the rotation thereof results in the rack gear  32  traveling accordingly through the rack guide  38 . 
     FIG. 6 is a detail view of the rack and pinion assembly  28  showing the spring element  66  adjacent the pulley  42  and the spring retaining pin  52  and the axle pin  70  installed in the access cover  68  of the gear assembly housing  30 . 
     FIG. 7 is a sectional front view of the rack and pinion gear assembly  28  of the present invention  10 . The pinion assembly  40  is axially maintained by the axle pin  70  as it passes centrally through the access cover  68 , the spring element  66 , the pulley  42 , the pinion gear  41 , and the gear assembly housing  30 . The first side of the pulley  44  is fixedly attached to the pinion gear  41  establishing the pinion assembly  40  which, when rotated by the pulling of the cable  22 , drives the gear rack  32  downward until the attached wheel member  24  makes contact with the ground, at which point the applied pressure initiates the lifting of the ladder  12  upward. The rotation of the pinion assembly  40  winds the spring element  66  to create a torque potential until the hand grip trigger mechanism  20  is released and the torque is applied to rotating the pinion assembly  40  in the opposite direction thereby effectively driving the gear rack  32  upward and retracting the wheel member  24  into the stored position where it is maintained by the applied bias of the spring element  66 . 
     FIG. 8 is a perspective view of the operator engagement means  18  wherein the first end  62  of the cable  22  is attached to the hand grip trigger mechanism  20  which, when pulled by the operator  54 , engages the wheel extension and retraction means  26 . 
     FIG. 9 is a side view of the rack gear  32  with a pivoting caster type wheel member  24  attached to the bottom  36  thereof. The pivoting action of the wheel member  24  provides for easy maneuverability of the ladder  12  when the rack and pinion gear assembly  28  is engaged. 
     FIG. 10 is a view demonstrating the set-up permitting a single operator engagement means  18  to act upon a plurality of wheel extension and retraction means  26 . When the operator  54  pulls the hand grip trigger mechanism  20  the two connected cables  22  simultaneously engage their respective rack and pinion gear assemblies  28 . 
     FIG. 11 is a perspective view demonstrating the basic configuration of the components of the present invention  10  for it&#39;s typical application with an A-frame ladder  12 . Two individual hand grip trigger mechanisms  20  each operate two gear assembly housings  30  thereby enabling the operator  54  to simultaneously lift all four legs off of the ground simply by squeezing the two hand grip trigger mechanisms  20  and to set the ladder  12  by releasing them. 
     FIG. 12 is a sectional side view of the rack and pinion gear assembly  28  and ladder sidewall  14  demonstrating the lifting ability of the present invention  10 . 
     It will be understood that each of the elements above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claims, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.