Wheelchair suspension
Wheeled vehicles, such as wheelchairs, that are adapted to traverse obstacles are provided. The wheeled vehicles include a frame, drive wheels, front anti-tip wheels positioned in front of the drive wheels and rear anti-tip wheels positioned behind the drive wheels. One exemplary vehicle includes front anti-tip wheels supported by rigid arms that are fixed to the frame and drive assemblies that are independently suspended from the frame. Another exemplary vehicle includes a linkage that links the front and rear anti-tip wheels, such that movement of one of the front or rear anti-tip wheel relative to the frame causes movement of the other wheel relative to the frame.
1. A power wheelchair comprising:
a frame;
a suspension assembly having:
a rear arm having a pivot connection to a lower portion of the frame and a body extending rearward and upward from the pivot connection and extending rearward of the frame;
a drive assembly mounting arm having a pivot mount and a body extending forward of the pivot mount, the pivot mount located forward of the rear arm pivot connection;
a link having a body connecting the rear arm to the drive assembly mounting arm;
a first biasing member in contact with the frame and the rear arm;
a second biasing member in contact with the frame and the drive assembly mounting arm; and
a rear wheel connected to the rear arm.
2. The power wheelchair of claim 1 further comprising a front anti-tip assembly having:
a front arm pivotably connected to a lower front portion of the frame and extending forward of the frame; and
an anti-tip wheel connected to the front arm, the front arm maintaining the anti-tip wheel above a horizontal supporting surface of the wheelchair.
3. The power wheelchair of claim 1 wherein the first biasing member contacts a central portion of the rear arm.
4. The power wheelchair of claim 1 wherein the first biasing member comprising a spring.
5. The power wheelchair of claim 1 wherein the first biasing member comprises a spring and shock absorber.
6. The power wheelchair of claim 1 wherein the drive assembly mounting arm independently pivots with respect to the rear arm.
7. The power wheelchair of claim 1 wherein the link transfers motion from the rear arm to the drive assembly mounting arm.
8. The power wheelchair of claim 1 wherein the link allows the drive assembly mounting arm to independently move with respect to the rear arm.
9. The power wheelchair of claim 1 wherein the link comprises a rigid link.
10. The power wheelchair of claim 1 wherein the link comprises a flexible link.
11. The power wheelchair of claim 1 wherein the link comprises an extendable link.
12. The power wheelchair of claim 1 wherein the link comprises a spring and shock absorber.
13. The power wheelchair of claim 1 wherein the rear arm pivot connection and the drive assembly mounting arm pivot mount are proximate a central lower portion of the frame.
14. A power wheelchair comprising:
a frame;
a suspension system having a plurality links; the plurality of links comprising:
a first link pivotably connected to a lower central portion of the frame and extending upwardly and rearwardly therefrom;
a second link pivotably connected with respect to a lower portion of the frame and forward of the first link;
a third link connected to the first and second links;
wherein the first link movement is transferred to the second link by the third link;
a drive wheel connected to the second link to provide a front wheel drive configuration; and
a rear wheel connected to the first link.
15. The power wheelchair of claim 14 further comprising:
a fourth link pivotably connected to a lower front portion of the frame and extending forward of the frame; and
an anti-tip wheel connected to the fourth link, the fourth link maintaining the anti-tip wheel above a horizontal supporting surface of the wheelchair.
16. A power wheelchair comprising:
a frame;
a first pivot connection disposed proximate a lower central portion of the frame and on the frame;
a second pivot connection disposed proximate a lower central portion of the frame and forward of the first pivotal connection;
a first arm extending rearward and upward from the first pivot connection and extending rearwardly of the frame;
a second arm connected to the second pivot connection and extending forward from the second pivot connection;
a link connected to the first and second pivot connections;
a drive wheel connected to the second arm and wherein the drive wheel axis is forward and above the second pivot connection; and
a front wheel connected to the frame and wherein the front wheel is maintained above a horizontal supporting surface of the wheelchair.