GB2122141A

GB2122141A - Transmission for one arm driven wheelchairs

Info

Publication number: GB2122141A
Application number: GB08217467A
Authority: GB
Inventors: Martin PRITCHARD
Original assignee: Vessa Ltd
Current assignee: Vessa Ltd
Priority date: 1982-06-16
Filing date: 1982-06-16
Publication date: 1984-01-11
Also published as: DE3314416A1

Abstract

A transmission for a wheelchair in which propulsive force is transmitted across the wheelchair from a drive shaft through the axis of one wheel to a driven shaft passing through the axle of the opposite wheel comprises first and second members 31, 32 of non-circular cross-section biased apart by spring 33 or other resilient means and having at their outer ends formations 34 that in use locate with corresponding formations on the inner ends of the drive shafts. <IMAGE>

Description

SPECIFICATION Improvements in one arm drive units for wheelchairs The present invention relates to an improved transmission for a one arm drive unit for a wheelchair.

Broadly stated the invention provides a wheelchair having first and second main wheels on opposite sides, a first handwheel directly connected to the first main wheel and a second handwheelon the same side of the wheelchair as the first handwheel connected to a drive shaft that passes through the axle of the first mainwheel and is linked to a drive shaft that passes through the axle of the second majnwheel so that propelling force on the second handwheel is transmitted across the wheelchair to the second mainwheel, wherein said linkage comprises first and second tubular members of non-circular cross section resiliently biassed apart and having at their outer ends formations that locate in driving engagement with corresponding formations on the inner ends of the drive shafts.

The invention also provides a linkage for transferring propelling force across a wheelchair from a drive shaft through the axle of one wheel to a drive shaft passing through the axle of another opposite wheel comprising first and second tubular members of non-circular cross-section resiliently biassed apart and having at their outer ends formations that in use locate in driving engagement with corresponding formations on the inner ends of the drive shafts.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a general assembly view of a conventional one arm drive unit for a wheelchair; Figure 2 is a general assembly view of a one arm drive unit according to the invention; and Figure 3 is a view of a drive tube assembly according to the invention.

In Figure 1 a wheelchair has a left hand main wheel 10 and a right hand main wheel 11. The wheel 11 is directly driven by a handwheel 12 directly connected thereto and the wheel 10 is driven by a smaller left hand handwheel 13. The hub of the wheel 11 is supported on a hollow cylindrical stub axle 1 4 with outer ball bearings 15, 1 6. The handwheel 13 is fixed to a shaft 17 that passes through stub axle 14 and is supported therein by inner ball bearings 18, 1 9. At its inner end the shaft 17 is pinned at 20 to a lazy tongs collapsible linkage 21 which extends across the wheelchair and is pinned 22 at its other end to a shaft 23 of a similar wheel hub unit to that for the wheel 10.The outer end of shaft 23 is connected to drive flange 24 that is drivingly secured to the wheel 10 by means of bolts 25. By this means drive from handwheel 1 3 is transmitted across the wheelchair to the wheel 10 but the linkage 21 can also collapse to permit folding of the wheelchair frame.

In the arrangement of Figure 2 the hub units 25, 26 of wheels 10, 11 are as previously described except that the inner ends of shafts 17, 23 are hexagonal in form. Transmission of drive between the two shafts is by means of a removable telescopic drive tube 27 whose internal construction is shown in Figure 3. It comprises a pair of telescoping tubes 31, 32 of square or other non-circular cross-section biassed apart by coil spring 33, and each terminating at its outer end in a hexagonal socket 34 that fits onto the end of the drive shafts 1 7, 23. Over-extension of the drive tube 27 when removed from the wheelchair is prevented by means of a retaining cord 35. This arrangement has a number of advantages not possessed by the lazy tongs linkage of Figure 1.It is inexpensive to produce and it is simple to fit and remove from the wheelchair, allowing its frame to fold fully. A single length of drive tube can be used over a wide range of wheelchairs of different widths. The radius of rotation of the tube 27 is less than that of the lazy tongs linkage 21 so that a single-arm drive can be fitted to wheelchairs provided with rear cross-brace members or rear shopping bags. Backlash on the handwheel 1 3 is less than with a lazy tongs linkage. Furthermore the drive tube 32 is superior to the lazy tongs linkage from the standpoint of styling, and does not present traps for fingers.

It will be appreciated that modifications may be made to the embodiment described above without departing from the invention, the scope of which is defined in the appended claims. For example the telescoping tubes could be of oval cross-section instead of square. And the sockets could be provided on the drive tubes, the ends of the telescoping members being provided with hexagonal studs.

1. A wheelchair having first and second main wheels on opposite sides, a first handwheel directly connected to the first main wheel and a second handwheel on the same side of the wheelchair as the first handwheel connected to a drive shaft that passes through the axle of the first mainwheel and is linked to a drive shaft that passes through the axle of the second mainwheel so that propelling force on the second handwheel is transmitted across the wheelchair to the second mainwheel, wherein said linkage comprises first and second tubular members of non-circular cross section resiliently biassed apart and having at their outer ends formations that locate in driving engagement with corresponding formations on the inner ends of the drive shafts.

2. A wheelchair according to Claim 1 wherein the tubular members are of square cross-section.

3. A wheelchair according to Claim 1 wherein an internal coil spring resiliently biases the tubular member apart and a retaining cord spanning the ends of the first and second members prevents over-extension thereof when removed from the wheelchair.

4. A wheelchair according to any preceding claim wherein the formations at the outer ends of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in one arm drive units for wheelchairs The present invention relates to an improved transmission for a one arm drive unit for a wheelchair. Broadly stated the invention provides a wheelchair having first and second main wheels on opposite sides, a first handwheel directly connected to the first main wheel and a second handwheelon the same side of the wheelchair as the first handwheel connected to a drive shaft that passes through the axle of the first mainwheel and is linked to a drive shaft that passes through the axle of the second majnwheel so that propelling force on the second handwheel is transmitted across the wheelchair to the second mainwheel, wherein said linkage comprises first and second tubular members of non-circular cross section resiliently biassed apart and having at their outer ends formations that locate in driving engagement with corresponding formations on the inner ends of the drive shafts. The invention also provides a linkage for transferring propelling force across a wheelchair from a drive shaft through the axle of one wheel to a drive shaft passing through the axle of another opposite wheel comprising first and second tubular members of non-circular cross-section resiliently biassed apart and having at their outer ends formations that in use locate in driving engagement with corresponding formations on the inner ends of the drive shafts. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a general assembly view of a conventional one arm drive unit for a wheelchair; Figure 2 is a general assembly view of a one arm drive unit according to the invention; and Figure 3 is a view of a drive tube assembly according to the invention. In Figure 1 a wheelchair has a left hand main wheel 10 and a right hand main wheel 11. The wheel 11 is directly driven by a handwheel 12 directly connected thereto and the wheel 10 is driven by a smaller left hand handwheel 13. The hub of the wheel 11 is supported on a hollow cylindrical stub axle 1 4 with outer ball bearings 15, 1 6. The handwheel 13 is fixed to a shaft 17 that passes through stub axle 14 and is supported therein by inner ball bearings 18, 1 9. At its inner end the shaft 17 is pinned at 20 to a lazy tongs collapsible linkage 21 which extends across the wheelchair and is pinned 22 at its other end to a shaft 23 of a similar wheel hub unit to that for the wheel 10.The outer end of shaft 23 is connected to drive flange 24 that is drivingly secured to the wheel 10 by means of bolts 25. By this means drive from handwheel 1 3 is transmitted across the wheelchair to the wheel 10 but the linkage 21 can also collapse to permit folding of the wheelchair frame. In the arrangement of Figure 2 the hub units 25, 26 of wheels 10, 11 are as previously described except that the inner ends of shafts 17, 23 are hexagonal in form. Transmission of drive between the two shafts is by means of a removable telescopic drive tube 27 whose internal construction is shown in Figure 3. It comprises a pair of telescoping tubes 31, 32 of square or other non-circular cross-section biassed apart by coil spring 33, and each terminating at its outer end in a hexagonal socket 34 that fits onto the end of the drive shafts 1 7, 23. Over-extension of the drive tube 27 when removed from the wheelchair is prevented by means of a retaining cord 35. This arrangement has a number of advantages not possessed by the lazy tongs linkage of Figure 1.It is inexpensive to produce and it is simple to fit and remove from the wheelchair, allowing its frame to fold fully. A single length of drive tube can be used over a wide range of wheelchairs of different widths. The radius of rotation of the tube 27 is less than that of the lazy tongs linkage 21 so that a single-arm drive can be fitted to wheelchairs provided with rear cross-brace members or rear shopping bags. Backlash on the handwheel 1 3 is less than with a lazy tongs linkage. Furthermore the drive tube 32 is superior to the lazy tongs linkage from the standpoint of styling, and does not present traps for fingers. It will be appreciated that modifications may be made to the embodiment described above without departing from the invention, the scope of which is defined in the appended claims. For example the telescoping tubes could be of oval cross-section instead of square. And the sockets could be provided on the drive tubes, the ends of the telescoping members being provided with hexagonal studs. CLAIMS

4. A wheelchair according to any preceding claim wherein the formations at the outer ends of the tubular members are hexagonal sockets that fit onto hexagonal inner end formations on the drive shafts.

5. A wheelchair arranged to be driven by first and second handwheels on the same side thereof and having a telescopic transmission member that serves to transfer the propelling force across the chair to the opposite wheel substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. A linkage for transferring propelling force across a wheelchair from a drive shaft through the axle of one wheel to a drive shaft passing through the axle of another opposite wheel comprising first and second tubular members of non-circular cross-section resiliently biassed apart and have at their outer ends formations that in use locate in driving engagement with corresponding formations on the inner ends of the drive shafts.

New claims or amendments to claims filed on 21 March 1983 New claim:- 7

7. A connector for connecting spaced devices so that the said devices rotate together, said connector comprising first and second telescopic tubular members of non-circular cross-section resiliently biassed apart, and at opposed ends of said members formations that locate by push fit with mating formations on the devices so that rotation of one device is transmitted through the connector to the other device.