WHEELCHAIR PROPULSION KIT

Abstract: A manual propulsion kit for a wheelchair (10) when the wheelchair includes a frame with two large wheels (18, 20) on either side of the frame (12) journaled to axles on the frame, each of the large wheels (18, 20) mounting a circular handrail (26, 226). The kit including a pair of manual propulsion assemblies (30, 230, 330) wherein each assembly includes a lever (236, 336) adapted to be journaled to one of the axles (214, 314) for rotational movement within a predetermined angular sector determined by a substantially vertical neutral position and a position forward of the frame (12). A crank handle (248, 348) having a crank web member (251, 351) is pivoted for rotation, at the end of the lever arm (236, 336) adjacent the handrail (226, 326) when the lever arm (236, 336) is mounted to the axle (214, 314), such that the crank member (248, 348) defines an arc and moves between a neutral position disengaged from the handrail (226, 326) and a forward position at a tangent to the handrail (226, 326). A crank handle grip (268, 368) is mounted to the crank web member (251, 351). Friction means (258, 260, 358, 360) are associated with the crank web member adapted to engage the handrail (226, 326) when pressure is applied to the crank handle to move the web member to a forward position whereby the manual propulsion assembly can be utilized to propel the wheelchair forwardly or rearwardly.

Description: "WHEELCHAIR PROPULSION KIT" Technical Field The present invention relates to wheelchairs and more particularly to hand or manual propulsion accessories to enable a wheelchair occupant to more readily propel the wheelchair in forward or rearward directions. Background Art Although several hand propulsion devices have been developed for conventional wheelchairs, most wheelchairs are still propelled by the occupant driving the circular handrail attached to the side of each wheel. The reason appears to be the complexity of operating most such prior art devices. Devices such as shown in U.S. Patents 3,189,368 Petersen 1965; 3,869,146 Bulmer 1975 and 5,263,729 Watwood 1993 are all representative of devices that must engage the periphery of the respective wheel. It is evident that the wheels of a wheelchairs are subject to wear, thereby creating adjustment problems for most of these prior art devices, as well as the fact that the periphery of the wheels collect dirt as well as road salt causing further problems in the operation of these mechanisms. U.S. Patent 3,877,725 Barroza 1975 and 4,354,691 Saunders et al 1982, describe hand propulsion devices that at least in part engage the handrail attached to the respective wheels on the wheelchair. Saunders et al includes a complicated structure requiring a specially designed handrail with a series of openings provided therein to cooperate with a lever arm having a bracket with a lug that must engage the openings in the handrail when the lever is pressed outwardly and then drives the wheelchair when the lever is pushed forwardly. The Barroza device is somewhat simpler and includes upper and lower pads that jam against the handrail to push forward or rearward the wheelchair. A brake pad engages the periphery of the wheel. Many older people develop physical handicaps at a late stage in their lives requiring that they adapt themselves to the confines of a wheelchair and learn how to propel and navigate the wheelchair. Although hand propulsion devices according to the prior art can increase the mechanical advantage and thereby reduce the force that such occupants must exert to propel a wheelchair equipped with such devices, the relatively complicated manipulations required to operate the prior art devices, deters from their use. In practically all prior art hand propulsion devices, the installation of such devices requires alterations to the wheelchair. In many cases, such as Saunders et al, a special handrail is necessary. Few if any prior art devices can be easily retrofitted to existing wheelchairs. Disclosure of the Invention It is an aim of the present invention to provide an improved hand propulsion apparatus that can be mounted to existing conventional wheelchairs without modifications to the wheelchair. It is a further aim of the present invention to provide an improved hand propulsion apparatus for a wheelchair that is simpler to operate by the occupant than the devices suggested by the prior art. It is a still further aim of the present invention to provide a manual propulsion kit that is simpler in construction and requires fewer parts than the known hand propulsion devices. A construction in accordance with the present invention comprises a manual propulsion kit for a wheelchair wherein the wheelchair includes a frame with two large wheels on either side of the frame and journaled to axles on the frame, each of the large wheels mounting a circular handrail, the kit including a pair of manual propulsion assemblies wherein each assembly includes a lever arm adapted to be journaled to the axle for rotational movement within a predetermined angular sector determined by a substantially vertical position and a position forward of the frame, a crank handle having a crank web member pivoted for rotation, at the end of the lever arm adjacent the handrail when the lever arm is mounted to the axle, about an axis coincident with the lever arm such that the crank member defines an arc and moves between a forward position forward of the lever arm, at a tangent to the handrail, and a reverse position extending rearward of the lever arm and at a tangent to the handrail, a crank handle grip mounted to the crank web member, friction means associated with the crank web member adapted to engage the handrail when pressure is applied to the crank handle grip, when the crank handle is in one of the forward and reverse positions whereby the manual propulsion assembly can be utilized to propel the wheelchair forwardly or rearwardly. In an embodiment of the present invention the friction means includes a bracket that is pivotally mounted to the lever arm adjacent and below the crank handle and the bracket includes a forward component extending forward of the lever arm and a rearward component extending rearwardly thereof and both components extend in a plane tangential to the handrail, and friction pads are mounted to the bracket components adapted to engage the handrail when pressure is applied to the crank handle in one of the forward and reverse positions. Brief Description of the Drawings Fig. 1 is a perspective view of a wheelchair incorporating the present invention; Fig. 2 is a perspective view of another embodiment of the manual propulsion assembly, in accordance with the present invention; Fig. 3 is a front elevation thereof; Fig. 4 is a side elevation of the assembly in accordance with Fig. 2; Fig. 5 is a rear elevation thereof; Fig. 6 is a top plan view of the embodiment shown in Fig. 2 while Fig. 7 is a fragmentary exploded view of a detail of the embodiment shown in Fig. 2; Fig. 8 is a rear elevation of the manual propulsion assembly mounted in relation to a handrail of the wheelchair shown in fragment; Fig. 9 is a front elevation of a still further embodiment of the manual propulsion assembly of the present invention; Fig. 10 is a side elevation thereof; Fig. 11 is a rear elevation of the embodiment shown in fig. 9; Fig. 12 is a top plan view thereof; Fig. 13 is a fragmentary exploded side elevation showing the embodiment of Fig. 9 assembled to the hub of a wheel; Fig. 14 is a side elevation, partly in cross-section, similar to Fig. 13 but showing the parts assembled; and Fig. 15 is a fragmentary front elevation of the embodiment shown in Figs. 9 to 14. Mode For Carrying Out The Invention Referring now to Fig. 1 there is shown a wheelchair 10 having a frame 12, and axles 14 extending on the either side of the frame to mount large wheels 18 and 20. As on conventional wheelchairs small caster wheels 22 and 24 are located on the front of the frame 12. The large wheels 18 and 20 both mount a circular handrail 26. Since both sides of the wheelchair are mirror images, only wheel 18 will be described. Thus, wheel 18 has a peripheral rubber tire 28. Referring now to Figs. 2 through 7 a second embodiment is shown. The reference numerals used for the various elements in this second embodiment correspond to the reference numerals utilized in the earlier embodiment but have been raised by 200. Thus, a lever 236 may be made of a flat metal bar such as stainless steel and is journaled to the axle 214, between a pair of washers 240 and 242 as shown in Fig. 4. In this case the axle 214 is in the form of a bolt with a head 214a. A spring bracket 232 is mounted between the hexagonal head 214a and washer 242 as shown more clearly in Fig. 7. A pair of side wings are provided on the bracket 232 to engage a flat edge of the hexagonal head 214a to prevent the rotation of the bracket 232. An elongated spring steel rod 234 is fixed to the bracket 232 and is threaded through the lever 236 at slots 238a and 238b as shown in Figs. 16 through 19. The end of the spring rod 234 is fixed through an opening 238c in the web 251 of rocker member 248. Rocker member 248 is pivotally mounted by means of pivot pin 246 to the end of the lever 236. The rocker member 248 includes a platform 249 having a wing 250 extending rearwardly thereof and a forward wing 252. A handle grip 268 extends upwardly from the platform 249 at the forward wing portion 252. A pad 258 made of resilient elastomeric material is as an L- shaped and is placed in the wing portion 250 on the underside of the platform 249 against the web 251 as shown in Fig. 5. Likewise an L-shaped elastomeric pad 260 is located in the forward wing portion 252 of the rocker member 248 as shown in fig. 19. Apertures 276, in the platform 249, and 276a, in the web 251 , may be provided to receive a projection from the respective pads 258 and 260 in order to better retain the pads to the rocker 248. Fig. 8 illustrates the relationship of the rocker 248 with a handrail 226 of a typical wheelchair. The rocker 248 is shown as being pivoted to pin 246 in a manner which is offset. In fact, radius r 2 of wing 250 defines arc B which is twice the dimension of r 1 corresponding to the wing 252 defining arc A. Thus, the relative distance that the rocker 248 will travel in arc A, so that the pad 260 engages the handrail 260, is represented by distance X which is smaller than the corresponding distance Y between the pad 258 on wing 250 to the handrail 226. Thus, in operation, when a person sitting in the wheelchair wishes to advance the wheelchair, that person merely applies forward pressure on the handle grip 268 causing the rocker 248 to rotate counter clockwise, as shown in Fig. 8, in a forward direction, so that the pad 260 engages the handrail and the handrail and thus the respective wheel of the wheelchair advances a corre- sponding distance. The forward pressure on the handle grip 268 is against the urging of the spring 234. However, the spring resistance of spring 234 is only great enough to return the lever 236 and corresponding rocker 248 back to its vertical neutral position, once pressure is released from the handgrip 268. If the person wishes to reverse the wheelchair that person must apply a pressure in the opposite direction on the handle grip 268, thereby rotating the rocker 248 counter clockwise through the greater distance Y so that the pad 258 comes into contact with the handrail 226 and the force is thus applied rearwardly. The distance Y is designed to be greater than the distance X in terms of travel so that the person does not accidentally engage the pad 258 against the handrail 226 when the lever 236 and the rocker 248 is returned to its neutral position after a forward stroke. The person would normally have a tendency of pulling back on the handgrip, slightly, with the spring 234 urging the assembly to return to its neutral position. This would sometimes cause the rocker 248 to rotate in a slight clockwise direction but not enough for the pad 258 to engage the handrail 226. The embodiment shown in Figs. 9 to 15 represent a further embodiment, based on the embodiment shown in Figs. 2 to 8. The reference numerals in the embodiment of Figs. 9 to 15 have been raised by 300 but otherwise correspond to the elements in the earlier embodiments. The purpose of the embodiments of Figs. 9 to 15, is to provide a manual propulsion assembly which can be adapted to a quick release wheel axle (which is coming more and more popular on lighter wheelchairs). In this embodiment, the hub H of a typical wheel is provided with a recess 335. A cylindrical mounting bracket 332 is provided to fit within the recess 335 and mounts the lever 336. Washers 340 and 342 provide the contact with the cylindrical bracket 332 as shown in Figs. 13 and 14. In the case of a quick release of wheel, the axle includes a detent 314b and the head of the axle is a nut 314a which is housed within the cylindrical bracket 332. The construction of the rocker 348 and lever 336 are essentially the same as in the embodiment of Figs. 2 to 8. However, it is not possible to mount a spring to the axle 314 which is no longer fixed but rotates freely in the hub H. Thus, a short spring 334 may be provided between the end of lever 336 and the rocker 348 to permit the rocker 348 to return to its neutral position. A bungie-cord or other device may be provided to return the lever back to its upright, neutral position after it has been extended by a force provided on the handle grip 368.

Claims: CLAIMS: 1. A manual propulsion kit for a wheelchair when the wheelchair includes a frame with two large wheels on either side of the frame journaled to axles on the frame, each of the large wheels mounting a circular handrail, the kit including a pair of manual propulsion assemblies wherein each assembly includes a lever adapted to be journaled to one of the axles for rotational movement within a predetermined angular sector determined by a substantially vertical neutral position and a position forward of the frame, a crank handle having a crank web member pivoted for rotation, at the end of the lever arm adjacent the handrail when the lever arm is mounted to the axle, such that the crank web member defines an arc and moves between a neutral position disengaged from the handrail and a forward position engaging the handrail, a handle grip mounted to the crank web member, friction means associated with the crank web member adapted to engage the handrail when pressure is applied to the crank handle to move the web member to a rotary forward position whereby the manual propulsion assembly can be utilized to propel the wheelchair forwardly, characterized in that the crank web member includes a rocker having a web portion in a plane parallel to the lever and pivoted to the end of the lever, and a platform at right angles to the web portion, the platform having a front wing and a rear wing wherein the rear wing extends rearwardly a greater distance from a longitudinal axis of the lever member than the forward extent of the forward wing portion and the crank handle grip is mounted in the forward wing portion. 2. The manual propulsion kit as defined in claim 1 , wherein the friction means includes L-shaped elastomeric pads provided underneath the platform and adjacent the web portion of the crank web member corresponding to the forward and rearward wings so as to frictionally engage the handrail. 3. The manual propulsion kit as defined in claim 1 , wherein a spring bracket is mounted to the axle and is connected to the lever member in order to define the predetermined angular section of movement of the lever. 4. The manual propulsion kit as defined in claim 1 , wherein the lever arm rotates on the axle and the axle is a quick release axle. 5. The manual propulsion kit as defined in claim 3, wherein a spring member is connected between the top of the lever member and the crank web member in order to urge the crank web member to a neutral position relative to the lever member. 6. The manual propulsion kit as defined in claim 5, wherein the spring member extending from the spring bracket and connected to the lever is the same spring member that connects the lever member to the crank web member. 7. The manual propulsion kit as defined in claim 2, wherein the extent of the rear wing from the axis through the lever is twice the extend of the forward wing. 8. The manual propulsion kit as defined in claim 4, wherein the lever is fixedly mounted to a cylindrical bracket which is mounted for rotation on the axle and spring means extend between the wheelchair and the lever for providing the predetermined angular sector.

Inventors: MITCHELL RAYMOND L, MITCHELL, RAYMOND, L.
Applicants: MITCHELL RAYMOND L, MITCHELL, RAYMOND, L.
Application year: 2000
Main classification: A61G5
IPC codes: A61G5