Wheelchair drive mechanism
OwnerBrian M. Watwood, Duane DeJong +1inventors
InventorsBrian M. Watwood, Duane DeJong, Errol C. Armstrong
Life of this patent
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Abstract
A wheelchair which shifts between forward and reverse by virtue of a roller mechanism which grabs in one direction and slips an opposite direction, thereby preventing binding. The shift mechanism is initiated by rotation of a shift paddle which is located on a extremity of a lever arm remote from the roller mechanism.
Claims16
1- A wheelchair drive mechanism comprising in combination:
- a lever arm having a hand grip end and a drive end,
- a wheel, and
- a transmission interposed between said lever arm and said wheel including means to bias said transmission into either a forward direction or a reverse direction, said biasing means attached at said lever arm hand grip end.
2- The mechanism of claim 1 wherein said biasing means includes a shift paddle projecting radially from said hand grip end, said paddle operatively coupled to a cable having an end terminating in said transmission.
3- The mechanism of claim 2 wherein said transmission includes a shift cage having a plurality of gear teeth disposed on an outer peripheral arc of said shift cage, and a bevel gear meshes with said shift cage gear teeth through an arc of a circle to select forward, reverse and neutral, said bevel gear operatively coupled to said cable.
4- The mechanism of claim 3 wherein shift cage is supported on an axle which supports a drive link coupled to said lever arm to impart motion there from, and plural cam points separated from each other by cam pockets associated with said shift cage, rollers supported in said cam pockets to migrate to said cam points to provide drive force either in forward or reverse.
5- The mechanism of claim 4 including a gear train formed in clusters to provide mechanical advantage interposed between said rollers and said wheel.
6- The mechanism of claim 5 wherein said gear train includes an output gear coupled to a spoked wheel which nests within a inner rim which is operatively coupled to said wheel.
7- The mechanism of claim 6 wherein said drive link includes a notch which receives a lever stop, said lever stop dimensioned to hold said lever in one position defined by said notch when said transmission is in neutral.
8- A wheelchair, comprising in combination:
- a frame having non-driven wheel means,
- a seat area supported by said frame,
- a lever means,
- driving wheels coupled to said frame and said lever means, and
- shift means located on said lever means and biasing means on said driving wheels to induce forward and reverse motion.
9- The wheelchair of claim 8 wherein said biasing means includes a shift paddle projecting radially from said hand grip end, said paddle operatively coupled to a cable having an end terminating in said transmission.
10- The wheelchair of claim 9 wherein said transmission includes a shift cage having a plurality of gear teeth disposed on an outer peripheral arc of said shift cage, and a bevel gear meshes with said shift cage gear teeth through an arc of a circle to select forward, reverse and neutral, said bevel gear operatively coupled to said cable.
11- The wheelchair of claim 10 wherein shift cage is supported on an axle which supports a drive link coupled to said lever arm to impart motion there from, and plural cam points separated from each other by cam pockets associated with said shift cage, rollers supported in said cam pockets to migrate to said cam points to provide drive force either in forward or reverse.
12- The wheelchair of claim 11 including a gear train formed in clusters to provide mechanical advantage interposed between said rollers and said wheel.
13- The wheelchair of claim 12 wherein said gear train includes an output gear coupled to a spoked wheel which nests within a inner rim which is operatively coupled to said wheel.
14- The wheelchair of claim 13 wherein said drive link includes a notch which receives a lever stop, said lever stop dimensioned to hold said lever in one position defined by said notch when said transmission is in neutral.
15- A wheelchair method, the steps including:
- providing a transmission between a rotation input and a wheel on at least one side of a wheelchair;
- including providing forward, neutral and reverse.
16- The method of claim 15 including providing two transmissions, one for each wheelchair side.