A wheelchair includes at least one side frame connected to a front caster assembly, and a cross-brace assembly. The cross-brace assembly includes a cross-brace member; at least one rear caster assembly connected to the cross-brace member; at least one main drive wheel axle tube fitting connected to the cross-brace member; and at least one arm connected to the cross-brace member. The at least one arm is pivotally connected to the at least one side frame through a pivot joint.
1. A wheelchair comprising:
a first assembly that includes;
a seat frame;
a stop connected to the seat frame;
a front caster assembly fixed for movement with the seat frame;
a second assembly that includes;
an axle tube;
a pair of drive wheels connected at opposite ends of the axle tube;
a rear caster arm fixed to the center of the axle tube such that the axle tube and the rear caster arm form a “T ” shape;
a rear caster connected to the rear caster arm;
a pivot arm fixed to the axle tube and extends rearward from the axle tube;
a pivot joint that connects the pivot arm to the first assembly;
wherein the first assembly pivots with respect to the second assembly to raise the front caster from a supporting surface of the wheelchair; and
wherein the pivoting of the first assembly with respect to the second assembly is limited by engagement of the first assembly with the stop.
2. A wheelchair as set forth in claim 1 wherein the rear caster a single caster that is centrally located laterally on the wheelchair.
3. A wheelchair as set forth in claim 1 wherein the pivot joint comprises an arm that is fixed for movement with the axle tube and extends rearward from of the axle tube.
4. A wheelchair as set forth in 1 wherein the first assembly comprises a side frame that connects the seat frame to the front caster assembly, wherein the side frame includes at least one releasable link, the link when released allowing collapsing of the wheelchair after removal of main wheels of the wheelchair.
5. A wheelchair as set forth in claim 1 wherein the rear caster arm is pivotable upward relative to the at first assembly to a degree sufficient to enable pulling the wheelchair backward up a set of steps.
6. A wheelchair as set forth in claim 1 wherein the rear caster assembly includes a single tubular arm.
7. A wheelchair as set forth in claim 1 wherein the rear caster assembly includes a resilient member.
8. A wheelchair as set forth in claim 1 wherein the rear caster assembly has a non-linear geometry.
9. A wheelchair set forth in claim 1 wherein the stop comprises a bracket connected to seat frame.
10. A wheelchair comprising:
a first assembly that includes;
a left side seat frame;
a left front caster assembly fixed for movement with the left side seat frame;
a right side seat frame;
a right front caster assembly fixed for movement with the right side seat frame;
a seat fixed for movement with the left and right side seat frames and left and right front caster assemblies;
one or more stops connected to the side seat frames;
a second assembly that comprises:
an axle tube that includes left and right main wheel fittings;
left and right main wheels connected to the left and right main wheel fittings of the axle tube;
a left arm connected to and fixed for movement with the axle tube, the left arm extending rearward from the axle tube, the left arm being pivotally connected to the left side seat frame through a left pivot joint;
a right arm connected to and fixed for movement with the axle tube, the right arm extending rearward from the axle tube, the right arm being pivotally connected to the right side seat frame through a right pivot joint;
a rear caster arm fixed to the center of the axle tube such that the axle tube and the rear caster arm form a “T ” shape;
a rear caster connected to the rear caster arm;
wherein the first assembly pivots with respect to the second assembly to raise the left and right front caster assemblies from a supporting surface of the wheelchair; and
wherein the pivoting of the first assembly with respect to the second assembly is limited by engagement of the first assembly with the one or more stops.
11. A wheelchair set forth in claim 10 wherein to stop comprises a bracket connected to the seat frame.
12. A wheelchair as set forth in claim 10 wherein the rear caster arm is a single arm that is centrally located laterally on the wheelchair.
13. A wheelchair as set forth in claim 10 wherein the left and right pivot joints are located rearward of the axle tube.
14. A wheelchair as set forth in claim 13 wherein the rear caster arm is a single arm that is centrally located laterally on the wheelchair.
15. A wheelchair as set forth in claim 10 including a left releasable link in the left side frame and a right releasable link in the right side frame, the links when released allowing collapsing of the wheelchair after removal of the left and right main wheels of the wheelchair.
16. A wheelchair as set forth in claim 10 wherein the rear caster arm is pivotable upward relative to the left and right side frames to a degree sufficient to enable pulling the wheelchair backward up a set of steps.
17. A wheelchair as set forth in claim 10 wherein the rear caster assembly includes a single tubular arm.
18. A wheelchair as set forth in claim 10 wherein the rear caster assembly includes a resilient member.