GB1455241A - Wheelchairs - Google Patents

Abstract

1455241 Wheelchairs; hand propulsion C RAMSHAW 14 Aug 1973 [18 May 1972] 23344/72 Headings B7B and B7E A wheelchair including a frame has at least one endless belt 20 associated with each of a pair of drive wheels 2, a portion of the belt being located adjacent the seat 7 to be moved by the occupant lengthwise of the wheelchair. The belt is preferably moved by the hand of the occupant but may be moved, for example, by a pulley driven by a hand crank or by a reciprocating lever carrying a ratchet device. The belt may be a toothed belt, or a V-belt. In a preferred embodiment, Fig. 1, each side of the chair frame is of tubular construction and comprises two struts 5, 6, a seat member 7 with idler pulleys 17, 18, arm rest 8 and back member 9, the two side frames being linked by transverse tubular members. The base frame 1 has a pair of driving wheels 2 and a pair of castor wheels 3 mounted under subframe 4. An endless toothed belt 20 runs over pulleys 17, 18 and meshes with sprocket 19 formed integrally with each drive wheel 2. To fold the chair the frame is swung backwards about pivot 10 thus releasing bottoms of struts 6 from retaining members 11, and the seat member 7 is folded towards back member 9 so that the frame may lie flat upon base frame 1. In another embodiment, Fig. 2, the frame comprises a pair of vertical supports 21, 22 linked by seat members 23 and arm rest 24. A belt 34 passes round one channel of a double idler pulley 33 and sprocket wheel 19, and another belt 35 passes round pulley 17 and the other channel of double pulley 33. The double pulleys 33 may have channels of different diameters to provide an increased or decreased velocity ratio, and may be replaceable by pulleys of alternative ratios. A two part strut 27 is first disconnected at 28 before the frame is folded. Scissor struts, Fig. 3 (not shown) may be used to connect the two side frames of the wheel chair to allow transverse folding. Guards may be provided on the belts and pulleys and the latter may be spring loaded for belt tensioning. Provision can be made for the castor action of wheels 3 to be locked. The driving wheels may be either at the front or rear of the chain.