Abstract:
The present invention is a wheelchair with a pair of levers on either side that actuate a reciprocating gear-ratchet assembly for moving the wheelchair when the levers are moved.

Description:
INDEX TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of PCT application PCT/IB2007/001342 filed Mar. 9, 2007, which claims the benefit of Colombian Patent Application No. 06-051587 filed May 30, 2006, the disclosures of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The traditional wheelchair had its origin from the necessity of providing mobility for persons unable to walk. Electrical and motor driven wheelchairs exist. However, a vast majority of wheelchairs in use today are operated without the benefit of drive motors. There is a need to increase the mechanical advantage from the force expended by a person in a wheelchair and to translate this force into a more efficient energy to move a wheelchair. 
       BRIEF SUMMARY OF THE INVENTION 
       [0003]    In one embodiment, the present invention is a wheelchair having: 
         [0004]    a. a gear plate attached to a pair of rear wheelchair wheels, with a plurality of gear teeth circumferally about the edge of said gear plate; 
         [0005]    b. a lever pivotably attached to the gear plate; and 
         [0006]    c. a ratchet mechanism attached to said lever. 
         [0007]    The gear plate is constructed and arranged to rotate on each of a pair of rear wheels on a wheelchair. The gear plate rotates freely as each wheel rotates when the chair is moved. When a user desires to move the chair, they push forward on a lever on either side of the wheelchair. The lever is connected to an actuating mechanism that causes a ratchet assembly releasably engage gear teeth on the gear plate. 
         [0008]    When the lever is retracted towards a person in said wheelchair and subsequently extended forward away from a person sitting in the wheelchair, ratchet mechanism engages the gear teeth on the gear plate and the motion of pushing the lever forward imparts forward force on the gear assembly, thus moving the wheelchair forward. 
         [0009]    The mechanism for actuating the ratchet mechanism is disengaged when the lever is retracted from an extended position and the lever is moved towards a person sitting in the wheelchair. 
         [0010]    The gear plate rotates with the rear wheels about an axel. In one embodiment, the gear plate shares the same axel as the rear wheels. In an alternative embodiment, the gear plate has a separate axel from the axel that is used in rotation of the rear wheels. 
         [0011]    The reciprocating process of repeatedly engaging and disengaging the ratchet mechanism on the gears results in rotation of the rear wheelchair wheels. 
         [0012]    In one embodiment, the wheelchair has at least two gear plates with a first gear plate constructed and arranged to move the wheelchair forward and a second gear plate constructed and arranged to move the wheelchair backward. 
         [0013]    In the embodiment with two gear plates, the lever is constructed and arranges with an actuator that is user changeable to impart either a forward or backward motion on the wheelchair. 
         [0014]    The present invention is also a method of moving a wheelchair having the steps of: 
         [0015]    a. providing a wheelchair according to the present invention; 
         [0016]    b. sitting a person in said wheelchair; 
         [0017]    c. moving said lever into a retracted position towards said user; 
         [0018]    d. extending said lever outward from said user; 
         [0019]    e. releasing said level from said extending of said level; 
         [0020]    f. allowing rear wheels to rotate. 
         [0021]    The method provides that repeating the steps of extending and retracting the lever impart a reciprocating ratchet gear engagement/disengagement that imparts motion on the gear plates and rear wheels of the wheelchair. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view of the wheelchair. 
           [0023]      FIG. 2  is a side view of the wheelchair with a person sitting thereon. 
           [0024]      FIG. 3  is a side view of the wheelchair. 
           [0025]      FIG. 4  is a perspective view of the wheelchair. 
           [0026]      FIG. 5  is a perspective view of the wheelchair. 
           [0027]      FIG. 6  is a close up of the handle region of one lever of the wheelchair with drive direction mechanism in a reverse position. 
           [0028]      FIG. 7  is a close up of the handle region of one lever of the wheelchair with drive direction mechanism in a neutral position. 
           [0029]      FIG. 8  is a close up of the handle region of one lever of the wheelchair with drive direction mechanism in a forward position. 
           [0030]      FIG. 9  is a perspective view of the wheelchair showing one drive direction mechanism in a forward position ( 28   a ) and a second drive mechanism in a neutral position ( 28   c ) arranged for driving one rear wheel and subsequently turning the wheelchair. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    The present invention is a wheelchair  10 , with a back portion  22 , a seat portion  23 , for supporting a person  24 . Wheelchair  10  has a pair of rear wheels  11  and a pair of front wheels  12 , as are commonly known in the art. Each of rear wheels  11  have identical assemblies as depicted in  FIGS. 2 and 3 . Gear plate  14  has gear teeth  13  positioned about the outer circumference of gear plate  14 . Gear teeth  13  are constructed and arranged to interact with a first ratchet  17  and a second ratchet  18  that are mounted on lever  19  near plate  14  at lower ratchet actuator  26 . Lever  19  is pivotably attached at axel  16  centrally positioned on plate bearing  15 . Lever  19  is moved by person  24  into either retracted position B or extended position A. Lever  19  has gear wires  20  that are mechanically actuated by lever bearing assembly  21 . 
         [0032]    In one embodiment, lever bearing assembly  21  is on handle  27  of lever  19 . Direction actuator  28  is identified in the Figs. with letter indications to indicate position, is movable and is moved in position  28   a  to impart forward motion,  28   c  to impart reverse motion, and  28   b  to disengage the drive-ratchet assembly into a neutral position in which no motion is imparted to rear wheels  11 . As shown in  FIG. 9 , each of direction actuators  28   a  and  28   b  may be in different positions. In this configuration, only the rear wheel  11  associated with direction actuator in  28  a will move forward. Rear wheel  11  associated with direction actuator  28   c  will not move when lever  19  is moved because  28   c  indicates a neutral position. Thus, when only one rear wheel moves, wheelchair  10  turns. Wheelchair  10  turns using only a single lever  19 , or turns using one lever  19  engaged in a drive position  28   a  or  28   b , and the opposite lever disengaged as in  28   c.    
         [0033]    Wheelchair  10  has a cover  25  that covers gear plate  14 . 
         [0034]    When a person  24  retracts lever  19  into position B, each of first ratchet  17  and second ratchet  18  disengage from gear teeth  13  and on gear plate  14 . When lever  19  is pushed forward such that lever  19  is in extended position A, lever bearing  21  imparts tension on gear wires  20 . The tension on gear wires  20  pulls each of first ratchet  17  and second ratchet  18  into position such that the end of each of first ratchet  17  and second ratchet  18  contact a position between gear teeth  13 . First ratchet  17  and second ratchet  18  become rigid about lower ratchet mechanism  26  by virtue of tension imparted by gear wire  20 . When lever  19  is pushed forward, the fixed position of first ratchet  17  in second ratchet  18  gear teeth  13  attached to wheel plate  14  rotates wheel plate  14  and subsequently rotate each of rear tires  11 . 
         [0035]    When person  24  releases lever  19 , first ratchet  17  in second ratchet  18  releases, or disengages from gear teeth  13  and each of rear tires  11  roll freely. 
         [0036]    In one embodiment, wheelchair  10  has two gear plates  14  and  14   a . The user can engage an actuator in lever  19  in order to impart rearward motion on wheelchair  10 . 
         [0037]    The ratchet and moving mechanism described herein is constructed and arranged to be affixed to a conventional wheelchair. 
         [0038]    While the invention has been described in its preferred form or embodiment with some degree of particularity, it is understood that this description has been given only by way of example and that numerous changes in the details of construction, fabrication, and use, including the combination and arrangement of parts, may be made without departing from the spirit and scope of the invention.