US3259396A

US3259396A - Wheel chair

Info

Publication number: US3259396A
Application number: US323328A
Authority: US
Inventors: Rodvinon I Zamotin
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-11-13
Filing date: 1963-11-13
Publication date: 1966-07-05
Anticipated expiration: 1983-07-05

Description

July 5, 1966 R. 1. ZAMOTIN 3,

WHEEL CHAIR Filed Nov. 13, 1965 7 Sheets-Sheet 1 INVEN'IOR RODVINON I. ZAMOTIN BY Jaw Q y ATTORNEYS R. l. ZAMOTIN WHEEL CHAIR July 5, 1966 7 Sheets-Sheet 2 Filed NOV. 13, 1963 FIG. 3

ATTORNEYS R. l. ZAMOTIN WHEEL CHAIR July 5, 1966 7 Sheets-Shed 3 Filed Nov. 13, 1963 INVENTOR RODVINON I. ZAMOTIN BY Jf QQ 1 4 ATTORNEY S July 5, 1966 R. 1. ZAMOTIN 3,259,396

WHEEL can: Filed Nov. 13, 1963 '7 Sheets-Sheet 5 IIID INVENTOR RODVINON I. ZAMOTIN BY $saq hr ATTORNEY 5' July 5, 1966 R. 1. ZAMOTIN 3,259,396

WHEEL CHAIR Filed Nov. 1.3, 1963- 7 Sheets-Sheet 6 45 A In! INVENTOR RODVINON I. ZAMOTIN BY ciaseq w ATTORNEYS July 5, 1966 R. 1. ZAMOTIN 3,

WHEEL CHAIR Filed NOV. 13, 1963 7 Sheets-Sheet 7 II/II;

INVENTOR RGDVINON I. ZAMOTIN 251 fir IIII 25 BY F/Gu l9 ATTORNEYS United States Patent 3,259,396 WHEEL CHAIR Rodvinon I. Znmotin, 600 Curtiss Parkway, Miami, Fla. Filed Nov. 13, 1963, Ser. No. 323,328 8 tClaims. (Cl. 280--5.22)

This invention relates to wheel chairs. More particularly, this invention relates to a self-propelled wheel chair capable of ascending and descending inclined surfaces such as steps, curbstones etc. as well as travelling on flat, or substantially flat surfaces.

There are many individuals who must spend considerable time without the use of their legs while recuperating from physical injury and many more individuals who are permanently unable to walk. The wheel chair provided a relatively inexpensive device to aid such people to travel about by themselves and thereby regain a measure of normal mobility. Thus the invalid was enabled, by using his arms and hands, to travel about on smooth level surfaces and on smooth gentle slopes. In order to traverse steep slopes, it is necessary, with the ordinary wheel chair, to enlist the aid of a helper to either push the chair from behind or restain the chair from rapidly descending a steep slope. To obviate the need of a helper, specialized expensive motorized vehicles have been developed whereby motor power can be applied to the wheels to drive the chair. As it is necessary, to enter and leave most homes and buildings, that the wheel chair traverse steps, it has been necessary to provide ramps for the use of people confined to wheel chairs. It is now common to observe such ramps provided in private homes and public buildings and a great many new well-planned public buildings include such ramps in their original design. There remain, however, a large majority of buildings with no such provision and in addition, there are many obstacles such as curbstones which are all but impossible to traverse, unaided, in an ordinary wheel chair. And it is further impossible to traverse an ordinary flight of steps, even with aid. In such situations the whole chair must be lifted and carried by two persons.

It is an object of the present invention to provide a wheel chair that will overcome the aforementioned disadvantages.

It is a further object of the present invention to provide a self-propelled wheel chair capable of traversing level surfaces and inclined irregular surfaces such as curbstones and stairs, by a minimum of effort expended by a person confined to said chair and without outside help.

It is still a further object of the present invention to provide a wheel chair of the type just described which is light in weight, inexpensive and which maintains a person sitting in said chair in an upright, stable position while said chair is traversing either level or inclined surfaces.

These and other objects are achieved according to the present invention by providing a wheel chair with a frame having an endless belt disposed below an inclined surface thereof and retractable rear wheels securable in an extended position to maintain the chair upright for travel on a level surface and retract-able to permit engagement of said belt with an inclined surface to maintain the chair upright for travel on an inclined surface.

Such devices which achieve the aforementioned objects and further objects which will become apparent, are more fully described in the following detailed description of a preferred embodiment of the invention taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a wheel chair according to the present invention showing the general relationship of the operable components of the chair;

'ice

FIGURE 2 is a front view of the chair of FIGURE 1, omitting some of the detailed features of FIGURE 1 to clearly show structure permitting the chair to be folded;

FIGURE 3 is a front view of the chair depicted in FIG- URE 2 in a folded position;

FIGURE 4 is a side view of a side frame of the chair of FIGURE 1 including significant structural and operational features;

FIGURE 5 is a cross sectional view along the lines 55 of FIG. 4.

FIGURE 6 is a detailed view of a belt used in conjunction with the chair shown in FIGURE 1;

FIGURES 7 and 8 are side elevation and cross sectional views along the lines 8-8 of FIG. 7 respectively of structure whereby the main wheels of the chair are secured to the frame;

FIGURE 9 is a side view of a ratchet mechanism for controlling the movement of rear legs of the wheel chair of FIG. 1.

FIGURE 10 is a cross sectional view along the lines lit-I0 of FIGURE 9.

FIGURE 11 is a perspective view showing detail of neutral locking device for the ratchet mechanism of FIGS. 9 and 10.

FIGURE 12 is an exploded perspective view of a brake for the chair depicted in FIG. 1.

FIGURES 13 and 14 are rear and side views respectively of the rear leg structure of the chair of FIG. 1.

FIGURE 15 is a perspective and exploded detailed view of the rear wheel and lock assembly of the chair of FIG- URE 1.

FIGURE 16 is a perspective view of the lock mechanism of FIG. 15 in a raised, unlocked, position.

FIGURE 17 is a cross sectional elevation of a pin for locking the rear wheel in position.

FIGURE 18 is a side view of a portion of a side frame member of the wheel chair of FIG. 1 showing the detail of a belt guiding arrangement.

FIGURE 19 is a cross sectional view taken along the lines 19-ll9 of FIG. 18.

In the drawings, wherein like numerals refer to like parts, a wheel chair is shown which comprises a central seat portion 1, side frames 2, drive wheels 3, rear leg and wheel assembly 4, rotatable disc and chain drive 5 for raising and lowering the rear leg and wheel assembly, endless belt 6 and chain drive 9 for driving said endless belt, these general features being best shown in FIGS.

As can be seen most clearly from FIGS. 2 and 3 side frame members 2 are substantially identical in shape and each serves as a frame for supporting one main drive wheel and endless belt assembly, one rear leg assembly, and a disc assembly 5 for raising and lowering each rear leg assembly. Thus, in order to describe the wheel chair in detail, it is only necessary to describe the structure of one side frame member, it being understood that the other side frame member is identical thereto in structure and function except of course that each is of opposite hand.

It will be readily understood from FIGS. 2 and 3 that the wheel chair may :be fioldab'le. Any suitable structure 8 which permits :the side frame members to be secured in an extended open position as shown in FIGURE 2 and also permits the chair .to be folded into the position shown in FIGURE 3 may be used. The structure 8 depicted is known in wheel chair construction per se. It is to be understood that this feature is not necessary to the present invention, but does serve to admit of easier handling and storage. This feature, when combined with the other features ihereinaf-te-r disclosed discloses an advantageous and preferred embodiment of the present invention as heretofore no practical wheel chair has been all available which combines foldability and stair-traversing ability.

Seat portion 1 comprises a fabric seat 11 and \a fabric back 12. Fabric construction admits of folding. Any suitable fabric may be employed and may include an integral pillow sewn therein to serve as a head rest. The fabric may be attached to the

appropriate frame portions

21 and 22 in any convenient manner such as sewing, riveting, etc. Seat portion 1 also comprises foot rests 13 folda-ble upwards (see FIGS. 2 and 3) and may be of any .type Well known per se in the wheel chair art. The type illustrated are moveable downward into a fixed rest position and rotatably mounted on a shaft portion 23 of frame 2. A horizontally disposed portion 2 1 of frame 2 may be covered with wood or any suitable arm rest material 14 to serve as an arm rest in association with seat portion 1. FIGURE 11 best shows this feature. Arm rest material 14 may be secured to frame portion 24 by any convenient manner such vas fastening devices or suitable adhesive.

Each frame member 12 constitutes an important part of the present invention. With particular reference to FIG- URE 4, it will be seen that the frame has a general appearance somewhat like a hockey stick. The frame is tubular and preferably square aluminum alloy tubing 1" on a side and having a wall thickness of .094". Various portions of the side frame may be assembled and secured by Welding, bolting or other suitable means. Each side frame 2 forms .an outer surface .25 for guiding end-less belt 6. By a suitable arrangement of pulley-s and guiding surfaces the belt 6 is caused to conform to the outer guiding surface 25 of each side frame member. This feature is most clearly shown in FIGURES 18 and 19 wherein strips 251 are disposed on opposite sides of frame 2 thereby forming a guide to align belt 6 on surface 25. Each side frame member comprises a .lower port-ion 2d and an upper portion 27 each of which forms contiguous outer belt guiding surface 25 together with

pulley assemblies

28 and 29 located at respectively front and rear ends of each side frame member. A pair of plates -27-a is disposed between

pulley assemblies

28 and 29 on each side frame and joins upper portion 27 to lower portion 26 by means of welding or other fastening means to provide added strength to the frame. An idler pulley 27-1) is journaled in each pair of plates 27a to hold belt 6 to the configuration of the frame.

In order that the significance of the structure of the side frame members be readily understood, brief reference will herein be made to operation of the wheel chair depicted. The rear leg assemblies 4 are retractable. When extended, as shown in FIGURE 1, the seat 11 is substantially horizontal and the chair upright. If it is desired to ascend stairs, the operator backs up to the bottom of .the stairs and retracts the rear legs. The rear wheels are thus caused to rise and the chair begins to tip backwards. Eventually, the rear whels will rise as high as the lower portion of the frame and the chair will thus be tipped back .to the point where the rear portion of the frame is in contact with the ground. The wheels are then retracted further and the frame, or more precisely the belt in contact with the frame, is solely in contact with the ground. The operator causes the belt to move by rotating the main wheels. The belt contacts the stairs and the chair thus starts in ascent. After the first few steps are traversed, the belt will contact the lips of several steps thus providing a firm gripping surface. As the stairs are inclined and as the frame is inclined at a suitable angle, it can readily be seen that as the chair ascends the stairs, the seat is maintained in a substantially horizontal position. The center of gravity of the device when occupied is well back and low thus ensuring stability. Further, the angle of inclination is such that when traversing the steepest stairs in ordinary use (35 /2 the seat is inclined at 9 /2 to the horizontal to further ensure stability. It has been found that stairs in homes average 34 /2, those in ofiice buildings average 34, and a courthouse had stairs at 27. At the top of the stairs, once the rear portion of the chair has overre-ached the top, the belt and chassis (section 26 of frame 2) makes full contact with the floor. The operator is comfortable although low as on a lounge chair. His visibility is good due to a bead-rest and the .angle of backrest in relation to frame portion 26. He then raises chair to normal by use of disc whee-l 5. To descend stairs, the reverse of the above procedure is followed. The wheel chair may be equipped with a brake device such that during either ascent or descent the operator may remove both hands from the device to rest if necessary. Very little energy is required to perform the foregoing operation. A man weighing 200 pounds can ascend stairs having an angle of 35 by exerting a force of 12 pounds to the rim of each drive wheel of a chair made in accordance with the present invention, depending on the mechanical advantage of the belt drive.

In view of the above discussion, it can be readily understood that the lower portion 26 of frame 2 comprises a rear inclined portion 261 for contacting the edges of a flight of stairs. An examination of stairs in public buildings and homes has revealed that in no instance (except where space is at a premium such as in lighthouses, etc.) does the angle of inclination of a flight of stairs exceed 37. Thus, rear frame portion 261 must be inclined at this angle to assure that the chair is upright during ascent and descent. To provide a safety factor, rear portion 261 is preferably inclined at 45 to the horizontal such that the center of gravity of an occupied chair will be well backwards. Thus, during ascent or descent, the occupant will be securely braced within the chair.

The lower portion 26 of each side frame member 2 further includes forward portion 263 inclined conveniently at an angle of 45 which permits belt 6 to contact a raised surface such as a curbstone. Thus the chair may traverse a single step in a forward direction without the necessity of retracting the rear legs. An intermediate, substantially horizontal portion 262 lies between

inclined portions

261 and 263.

Each rear wheel assembly 8 is fitted with a rotatable skid 81 which can be secured in a forwardly extended or back- Wardly extended position or may be permitted to swivel. Details of the assembly are shown in FIGURES 15, 16, and 17. The assembly comprises a caster having a square shaft 82 for insertion into a square recess in rear leg 41. The caster comprises an upper race 83 integral with shaft 82 and a lower race (not shown) integral with skid 81. Wheel 84 is rotatable on shaft 85 mounted in skid 81. A large washer 86 is mounted on the periphery of the lower race. The washer 86 includes two holes 87 (see FIG. 15) one of which is aligned with the extended portion 811 of skid 81 and the other of which is spaced therefrom by A locking mechanism 88 provides means to secure the skid in the two aforementioned positions by introducing a pin into a hole 87 or, by raising the pin 881, permits skit 81 to swivel freely.

To ascend a curb as above described, skid 81 is first secured such that portion 811 is disposed forward. The sloped lower surface of skid 81 thus will contact a curb edge and the chair will thus be lifted thereover. It can be seen that extremity 811 should be high enough off the ground to admit ascent of high curbs. A height of 8 inches has been proven adequate to handle all but the exceptionally high curbs occasionally found. A study of hundreds of city curbs disclosed an average high of 6 /2" and a low of 4 /2".

To ascend or descend stairs, the skid is secured such that portion 811 extends backwards as shown in FIGS. 1 and 4. This keeps the skid in a fixed position and thus prevents it from jamming against the frame when the rear legs are raised.

For travel on level surfaces, pin 881 is secured in a raised position by means of cable 882. Pin 881 is biased towards washer 86 by means of spring 882 but can be pulled upwards by pulling on handle 883 which is secured to cable 884. A bolt $85 is slideable under handle 833 to maintain the handle, and thus the pin, in an upright position away from holes 87. Thus, skid 81 is free to rotate in the usual manner. These skid-caster assemblies are well known per se and are self aligning. That is, portion 881 always tends to align itself away from the direction of wheel chair motion. Thus, to secure skid 81 such that portion 881 is rearwardly extended, the operator, while going forward, pulls bolt 885 rearward thus permitting spring 882 to bias pin 881 towards a hole 87. When the pin and hole are in engagement, handle 883 will drop indicating insertion of the pin into the hole.

Front wheels 3 serve to propel the wheel chair in the usual manner and also to transmit motion to belt 6. Each wheel 3 may be of the type usually employed in wheel chairs which include an external rim for grasping by the operator. For purposes of the present invention, it has been found preferable to mount front wheels to the frame such that they can be raised and lowered to a slight eX- tent. When the chair is used to mount thresholds or curbs, especially the latter, it is helpful if the belt disposed along the intermediate portion 262 of frame memher 2 is in contact with the ground, as this gives the chair more traction. But where the chair is used for travel on a level surface, the wheels only should touch the ground. Thus, front wheels 3 are mounted such that they can be secured in a downward position such that the lower portion thereof is disposed lower than the lower edge of belt 6. This is accomplished by mounting the front wheels as shown most clearly in FIGURES 4, 7 and 8. By mounting the wheels as shown in the preferred manner, each weel can move substantially in a vertical direction a distance of approximately inch. When in the raised position, the lowermost portion of the wheels will be raised off the ground and will lie approximately A above the lowest portion of belt 6. When in the lowered portion, the lowermost portion of the wheels will contact the ground and will lie approximately A" below the lowest portion of belt 6.

Vertical frame members

273 and 274 are welded to forward portions of

frame members

26 and 27. Each

frame member

273 and 274 is welded at the top thereof to arm rest frame member 24 and to a plate 275 to form a rigid frame for supporting the drive wheels. A further plate 276 is rotatably secured to member 273 by bolt 277a. A lever 277 is integral with plate 276. A hollow axle 360 is integral with plate 276. As plate 276 is pivotally mounted to frame member 273, it can be readily seen that motion of lever 277 causes axle 300 to move in a substantially vertical direction over short dis tances although the axle, when moved, actually describes a circular path about bolt 277. Axle 300 supports each wheel 3 and thus, the aforedescribed vertical motion of each wheel is provided. Each wheel rotates, by means of a standard needle bearing, on hollow aXle 300. Wheel motion is transmitted to chain 9 through sprocket 101 which is secured to the hub of wheel 3 and, like wheel 3, is free to rotate about axle 360. To provide directional control of wheels 3, a drive shaft 31 is disposed rotably' within hollow axle 36d and secured at one end to the hub of wheel 3. This may be accomplished by providing shaft 31 with a square end to mate with a square hole in hub 301 of wheel 3 or by other suitable means such as a weld. As hub 301 is integral with wheel 3, wheel motion is transmitted directly to shaft 31. Shaft 31 is attached at its other end to a ratchet 162 by means of a square recess 56 which mates with a square shaft 57 of a rachet. The ratchet, which is similar in construction to the ratchet shown in FIGURE 9 for controlling rear leg motion, has three operative positions: forward, reverse, and neutral. These positions and results, in terms of wheel motion, are achieved in a manner well known, per se,

by providing a spring biased pawl actuated by rods 103 which terminate in control knobs on the arm rests.

Lever 277 is long enough so that a top portion thereof is engageable with the foremost portion of armrest 24 as shown in FIGURES l and 4. Lever 277 is secured to plate 276 such that when the lever is positioned forward of armrest 24, wheels 3 are in contact with the ground and slightly below the lowermost portion of belt 6. This is clearly shown in FIGURES 2 and 3. It will be readily understood that motion applied to the wheels when in this position will be transmitted to the ground to cause horizontal motion of the chair in the same manner as an ordinary wheel chair. With reference to FIGURES 1 and 4, it can be seen that if the operator moved levers 277 inwards, they would move rearwards when they passed inboard of armrest 24. The weight of the chair would thus cause the chair to settle relative to the wheels and thereby bring belt 6 into contact with the ground at frame portion 262. In this position, belt movement is transmitted to the ground thus making for easy forward assent of a curb or similar rise. While low curbs can be ascended without this feature, it has been found to be diflicult to ascend some higher curbs which are prevelent enough to justify incorporation of this feature into the preferred embodiment of the present invention.

By mounting the wheels in the aforedescribed manner, at least the following objects are achieved:

(1) The chair, while ratchet 102 is set in neutral, is capable of performing as an ordinary wheel chair with customary maneuverability.

(2) Each wheel may be set for either forward or reverse motion only. This prevents the chair from inadvertently descending while ascending an incline, regardless of whether the incline is smooth or is a flight of stairs or curb.

(3) As each wheel may be independently set, the wheels can be driven in opposite directions making very tight turns possible.

(4) As the wheels are moveable vertically, great f-rictional contact can be obtained between the belt and a stair or curb lip.

As has been mentioned previously, the present wheel chair is caused to transverse inclined surfaces by contact of endless belt 6 therewith. Wheels 3 provide the means whereby power is applied to belt 6. As has been stated, side frame 2 is constructed to provide a flat guiding surface for belt 6. A suitable belt 6 is shown in FIGURE 6. The belt is of multi-characteristic construction and comprises a hard, slippery toothed portion 61 and a relatively soft gripping portion 62 bonded at 63. Portion 61 is disposed inwardly towards side frame 2 and contains teeth 64 engageable with teeth in driving

pulleys

28 and 29. Thus, motion of

pulleys

28 and 29 causes endless belt 6 to travel about guiding surface 25 of each side frame 2. The portion 61 is similar to commercial Timing Belts. A suitable material comprises a nylon-neoprene belt and includes integral cord or wire bracing 65 for strength. The nylon-neoprene portion 61 is quite slippery and does not have the usual gripping property of rubber and thus slides freely on the flat surface of the square frame supporting it. The outer, gripping surface is a resilient nibber belt 62. A synthetic non-marking rubber having a give of approximately 33 durometer has been found to be excellent. This belt, with a flat surface, not polished, does the grabbing. It gives in at the stair lip and forms a perfectly contoured fit to this stair lip. The same weight which causes this belt to indent itself keeps it from slipping. The tendency for it to move or bunch up is completely arrested by its bond to a non-stretch belt like the Timing Belt. Moreover, at the beginning of the chairs journey up, there is a greater indentation in the belt due to the fact that it begins by grabbing only one or two stair noses. This compensation makes it efficient right from the beginning.

Pulley assemblies

28, 29 which drive belt 6, are caused to rotate by a chain 9 which is moved by rotation of wheels 3. As shown in FIGURES 1 and 4, chain 9 is disposed about drive mechanism 100, idler wheel 91 and

pulleys

28 and 25. Each

pulley assembly

28, 29 is mounted on frame 2 in an identical fashion and is identical in construction. The manner of mounting and construction are shown in detail in FIGURE 5 for pulley assembly 21 Each assembly comprises a toothed wheel 291 journaled for rotation about shaft 293 in plates 292 secured to frame 2. Plates 292 may be Welded or secured to the frame in any convenient manner. Plates 292 extend beyond limits of frame 2 and pulleys 291 so as to act as retaining guides for the belt 6. Strips 251 (FIGURES 18 and 19) also extend below frame 2 to guide and retain belt 6. In a preferred embodiment, an extension of has been found satisfactory. A sprocket wheel 294 is bolted to wheel 291 parallel and spaced slightly therefrom. An internal plate 295, together with the outer of plates 292, serve as side guides for belt 6. Chain 9 is fitted in contact with the teeth of sprocket 294. Thus, through sprocket 294, pulleys 28, 29, and thereby belt 6, are caused to move by motion of chain 9.

Chain 9 is caused to move by drive mechanism 100 most clearly shown in FIGURE 8. This mechanism consists essentially of a sprocket wheel 1111 secured to the hub 32 of wheel 3. It should be remembered that a shaft 31 passes through axle 300 and drives ratchet 102. Wheel 3 is provided with bearings 33 to provide free motion of the wheels about axle 300. Wheels customarily used in wheel chairs contain a bearing and shaft assembly suitable for the present invention. However, it is necessary to secure a sprocket wheel 161 to the hub of the wheel. As shown most clearly in FIGURE 4, chain 9 is arranged for maximum contact with

sprockets

101 and 294. It can be seen that chain 9 contacts approximately 55% of the circumference of each of these sprockets by the selected position of idler 91. It should be readily apparent that other chain arrangements, including dual sprockets 1131 together with a chain connected to each of sprockets 294 associated with

pulleys

29, 28, would be suitable. It should also be apparent that a dual drive necessitates a wider chair and it is desirable to keep the chair to a certain maximum width so that the chair can pass through normal doorways. The drive mechanism 100 further comprises the aforementioned ratchet mechanism 102 operable by links 103 and which is identical to a ratchet mechanism 102 depicted in FIGURES 9 and used in conjunction with means for raising and lowering rear legs 41 and will be fully explained hereinafter with reference to raising and lowering the rear legs. However, it should be understood that this ratchet mechanism 102 admits of main wheel motion in one direction only and can be also set in neutral. As belt 6 is driven by the main wheels, it should be apparent that the belt is moveable only in one direction at a time. Thus, when links 102 are in a first position, the wheels and belts can be moved in only a first direction. When the links 103 are in a second position, the wheels and belt are moveable in the opposite direction. In this manner, when ascending stairs (noting that the chair ascends stairs backwards) the links are set to permit rearward motion only. Thus, the operator may let go of wheels 3 and ratchet mechanism 1112 will prevent descent. The ratchet 102 should of course be of rugged construction. Suitable ratchets are readily available and involve construction found in socket wrenches. A lock mechanism 103B is provided to secure links 103 in neutral position.

As a safety device, and as an aid in descending stairs, a brake mechanism 110 shown in detail in FIGURE 12, is provided to restrain forward motion of belt 6 along top portion 211 of frame 2. This restrains forward motion of the wheel chair. Brake 110 comprises a flat shoe 111 having a curved forward portion 112 and pivoted in housing 113 secured to frame 271. Rod 114 is connected at one end to the rear end of shoe 111 by means of spring 115 and at the other end to handle 116 rotably secured to armrest 24 by bolt 117. By pushing handle 116 forward, portion 112 of shoe 111 is raised above belt 6. By pulling handle 116 rearwards, spring 115 puts a lifting force on the rear of shoe 111 thus forcing the forward portion 112 of shoe 111 downward against the belt. In this manner, forward motion of the belt can be restrained to any desired limit, depending on the tension of spring 115. Handle 116 comprises a pin 119 protruding therefrom thus forming a rest against which rod 114 bears when the handle is pulled rearwardly. Link 1 18 becomes positioned rearward of hinge pin 117 thus securing the brake shoe in the downward, applied, position. This brake mechanism is very useful for descending stairs. For such use, the chair moves forwardly down the stairs. As ratchet mechanism 102 must be set for forward motion, it follows that a chair would be free to descend stairs of its own accord. It the chair were occupied, this might result in harm if the occupant fainted. By means of a suitable brake spring tension, the chair can be restrained from descent of its own accord. Thus, the operator would merely apply slight force to the wheels and gently push himself down the stairs. When both brakes are set, the ratchet controlling wheel motion direction can be set in neutral and the brake will prevent the chair from descending the stairs. This enables each wheel to be driven in either direction and thus it is possible to drive the belts in opposite directions much like tank treads. This feature provides great maneuverability on stairs and permits the operator to climb stairs having landings and tight turns. While ordinarily a paraplegic occupies a first fioor dwelling, the present invention provides additionally for the unusual case.

In order for the wheel chair to be able to ascend or descend stairs, it is necessary that rear legs 41 be raised such that rear wheels 8 are raised up above the lower frame portions. Each rear leg 41 has rack gear 43 at the rear thereof. Teeth 42 are engaged by teeth in gear 43. A rectangular tubular frame member 44 is secured to each of side frame members 2. Gear 43 is journalled to member 44 for rotation such that leg 41 can be raised up into hollow member 44 as shown most clearly in FIGURES 13 and 14.

Stops

45 and 46 present inadvertent overextension of leg 41, while the wheel caster limits upward movement thereof. Stop 46 also prevents leg 41 from wobbling in tube 44. To replace a rear leg, the rear wheel assembly is removed and legs 41 drawn upwards. Shaft 47 supports gear 43 and a sprocket 48. A chain 51, driven by disc 52, is secured to sprocket 48. Movement of disc 52 moves chain 51 which rotates shaft 47 and gear 43 thus raising or lowering leg 41. With reference now to FIGURES 9 and 10, disc 52 is journaled. via shaft 53 and bearing 54, for rotation in frame 2. Conveniently, as shown in FIGURE 9, bearing 54 may be journaled to a pillow block secured beneath armrest 24. A sprocket 55 is also secured to shaft 53 and chain 51 is attached thereto. Thus, motion of discs 52 is transmitted to rear legs 41. It has been found that a 7 pound force applied by hand to the peripheral portion of disc 52 will lower rear legs 41 and thus raise the chair when occupied by a 200 pound man. In order to prevent inadvertent motion of rear legs 41, a ratchet device 1112 identical or similar to that used to limit motion of main wheels 3 is provided as shown in FIGURES 9 and 10. Shaft 53 has an inward facing square recess 56. Into recess 56 is secured a square shaft 57 of a ratchet head 58. A pawl 59 is pivotally secured below the ratchet head. Conveniently, the ratchet and pawl mechanism is encased in a housing such that only arms 71 extend therefrom. Ratchet head 58 is rotable on shaft 72 in housing 71 which is secured to frame member 2 and conveniently to plate 275. Links 1113 actuate pawl 59 through connections to arms 71. The structure depicted is common to socket wrenches and includes spring 74 and ball 75 which permit oscillation of pawl 58. Each link 103 extends upwards through armrest 24 and is provided with a handle 1103A. A lock mechanism 103B may be provided to secure the pawl 58 in the neutral disengaged position shown in FIGURE 11. This lock mechanism permits motion of ratchet device 1102 in either direction and is conveniently utilized in conjunction with the ratchet associated with the main drive wheels (see FIGURE 8). Thus, in the neutral position, the wheels are free to move as in an ordinary wheelchair. 'Io ascend or descend stairs, lock mechanism 1103B is disengaged and links 106 actuated to set the ratchet and pawl for motion in the desired direction. Once set, the pressure of ball 75 and spring 74 retains the pawl in position. Opposing pressure, as when the chair is on an incline, further sets the pawl and ratchet as in any ratchet wrench. No mechanism to lock mechanism 102 in neutral is necessary or desirable for the rear legs lowering and raising mechanism.

Operable components, such as ratchets, sprockets, gears etc. should be of robust construction to provide a wide margin of safety.

With reference to the above description of the belt drive mechanism, it should be noted that whenever the drive wheels are turned, the belt turns also. This is because the belt is driven by a sprocket directly secured to the main drive wheel shaft. By raising the main wheels, the chair runs on its belt and trailing rear legs. It assumes a powerful, low gear drive. This can be used to go up smooth inclined ramps and slopes. For going downhill, the brake may be applied and the chair gently pushed down the incline.

Due to the fact that the aforedescribed structure is inexpensive, it represents a preferred embodiment of the present invention as it is the prime object of the present invention to provide a wheel chair capable of wide mobility and yet within the economic reach of persons who have already probably incurred great medical expense. However, it would be a simple matter to drive chain 9 through a clutch actuated sprocket disengageable from the drive shaft. Any suitable known clutch arrangement could be utilized for this purpose.

In addition, there is no necessity of providing a foldable wheel chair. If expense were of no object, it would be quite easy to provide a non-foldable wheel chair of the type described but fitted with a motor for accomplishing what can be accomplished by hand power. Due to the unique construct-ion of the present device, a man weighing 200 pounds can ascend stairs having an angle of 35 by exerting a force of 12 pounds to the rim of each drive wheel of a chair made in accordance with the present invention. Further, the chair as described weighs less than 68 pounds.

In detail, the chair drive ratios are as follows:

For the main wheel drive, sprocket 101 has 14 teeth and each

pulley assembly

28, 29 has 24 teeth.

For the rear wheel lowering drive, disc is 11 /2" diameter and has teeth on its sprocket while the rear wheel sprocket has 14 teeth.

I claim:

El. A wheel chair cap-able of travelling on inclined irregular surfaces comprising a frame having side frame members defining a seat therebetween, each of said side frame members having a portion inclined to the horizontal, endless belt means on each side frame member and disposed along said inclined portion, a driveable wheel rotatably secured to each side frame member, retractable wheels located on said frame, said retractable wheels being secureable in an extended position to maintain said vehicle in an upright position such that said driveable wheels and said retractable wheels simultaneously contact a fiat horizontal surface thereby permitting horizontal motion of the vehicle over said flat surface, and said retractable wheels being secureable in a retracted position located above the lowermost edge of said inclined portions of said side frame members, means located 10 on the wheel chair and controllable by an occupant of the wheel chair to linearly extend and retract said retractable wheels, and means to transmit motion from said driveable wheels to said endless belt means to enable said vehicle to travel over inclined surfaces.

2. A wheel chair as claimed in claim 1 wherein each of said side frame members comprises a first section having a lower edge raised at an angle to the horizontal and at least partially disposed forward of said driveable wheel, a second section having a lower edge raised at an angle to the horizontal and at least partially disposed rearward of said driveable wheel, and a third section intermediate said first and second sections having a lower edge contiguous with the lower ends of said first and second sections thus forming a continuous belt guiding surface at the lower edge of said side frame member for guiding an endless belt.

3. A foldable wheel chair capable of travelling over inclined surfaces comprising two vertically disposed side frame members; a seat portion between said side frame members; foldable frame means disposed between and interconnecting said side frame members to secure said side frame members in a first spaced apart position and permit said side frame members to move into a second position wherein said side frame members are in close adjacency; a driveable wheel vertically disposed and rotatable in a plane parallel to and outside of each of said side frame members; each of said side frame members having a first forward section wherein the lowermost portion is a first belt-guiding surface inclined at an angle to the horizontal, a second rear section wherein the lowermost portion is a second belt guiding surface inclined at .an angle to the horizontal, and a third section intermediate said first and second sections and having a lowermost portion forming a belt-guiding surface contiguous with said first and second belt guiding surfaces; belt-guiding means disposed at the front end of said first frame section forward of said driveable wheel and at the rear end of said second section abaft said driveable wheel; an endless belt forming a loop over said belt guiding means and having a lower portion disposed adjacent the belt guiding surfaces of each side frame member; a retractable member movable vertically relative to said frame and disposed on each of said side frame members rearwardly of said driveable wheels; a rear wheel vertically disposed on the lower end of each of said retractable members and rotatable on longitudinal and transverse axes of said retractable member; means for moving each of said retractable members in a vertical direction to secure said rear wheels in an extended position wherein said seat portion is substantially horizontal when said driveable wheels and said rear wheels are in contact with a horizontal surface and in a retracted position disposed above said second belt-guiding surface of the rear section of each of said side frame members wherein said seat portion is substantially horizontal when the portion of the endless belt disposed along said second belt-guiding surface is in contact with an inclined surface; each of said driveable wheels rotatably mounted on a shaft disposed on a member connected to each side frame member to permit the lowermost portion of each of said driveable wheels to move to a first raised position above the third intermediate guiding surface of each side frame member and to a second lowered position below said third guiding surface; means to move said member to secure said driveable wheels in said lowered position; and means to transmit rotating motion of each of said driveable wheels to the endless belt disposed on the side frame member to which a driveable wheel is secured.

4. A wheel chair as claimed in claim 3 further including spring biased brake means for applying pressure to said endless belt to prevent said Wheel chair from inadvertently descending an inclined surface.

5. A wheel chair as claimed in claim 3 wherein said means to transmit rotating motion of the driveable wheels comprises a chain drive controlled by ratchet means permitting selective motion in one of two opposite directions to thereby prevent inadvertent motion of said wheel chair.

6. A wheel chair as claimed in claim wherein said means to move said retractable members comprises chain drive means.

7. A wheel chair as claimed in claim 6 wherein said retractable member comprises a toothed shaft fitted Within a hollow frame member and engageable with a gear wheel secured to said hollow frame member; and said means for moving said retractable member comprises a ratchet chain drive for selectively turning said gear wheel in one of two opposite directions; and said rear wheel includes a skid rotatable on a longitudinal axis of said toothed shaft and means to secure said skid in a fixed position to prevent rotation thereof.

8. A wheel chair capable of travelling on inclined irregular surfaces comprising a frame having side frame members defining a seat therebetween, each of said side frame members having a portion inclined to the horizontal, endless belt means on each side frame member and disposed along said inclined portion, a driveable Wheel rotatably secured to each side frame member, retractable wheels mounted on said frame, said retractable Wheels being secureable in an extended position to maintain said vehicle in an upright position such that said driveable wheels and said retractable wheels simultaneously contact a fiat horizontal surface thereby permitting horizontal motion of the vehicle over said flat surface, and said retractable wheels being secureable in a retracted position located References Cited by the Examiner UNITED STATES PATENTS 2,751,027 6/1956 McLaughlin 2805 .22 X 3,111,331 11/1963 Locke 2 -5.22 3,127,188 3/1964 Greub 280-522 3,142,351 7/1964 Green -8 3,146,841 9/1964 Locke 28()5.22

FOREIGN PATENTS 693,983 7/1953 Great Britain.

OTHER REFERENCES Brochure, Wanted a Stair-Climbing Wheel Chair, Natl Inventors Council, January 1962, Washington, D.C.

BENJAMIN HERSH, Primary Examiner.

ARTHUR L. LA POINT, Examiner.

R. I. JOHNSON, Assistant Examiner.

Claims

1. A WHEEL CHAIR CAPABLE OF TRAVELLING ON INCLINED IRREGULAR SURFACES COMPRISING A FRAME HAVING SIDE FRAME MEMBERS DEFINING A SEAT THEREBETWEEN, EACH OF SAID SIDE FRAME MEMBERS HAVING A PORTION INCLINED TO THE HORIZONTAL, ENDLESS BELT MEANS ON EACH SIDE FRAME MEMBER AND DISPOSED ALONG SAID INCLINED PORTION, A DRIVEABLE WHEEL ROTATABLY SECURED TO EACH SIDE FRAME MEMBER, RETRACTABLE WHEELS LOCATED ON SAID FRAME, SAID RETRACTABLE WHEELS BEING SECUREABLE IN AN EXTENDED POSITION TO MAINTAIN SAID VEHICLE IN AN UPRIGHT POSITION SUCH THAT SAID DRIVEABLE WHEELS AND SAID RETRACTABLE WHEELS SIMULTANEOUSLY CONTACT A FLAT HORIZONTAL SURFACE THEREBY PERMITTING HORIZONTAL MOTION OF THE VEHICLE OVER SAID FLAT SURFACE, AND SAID RETRACTABLE WHEELS BEING SECUREABLE POSITION LOCATED ABOVE THE LOWERMOST EDGE OF SAID INCLINED PORTIONS OF SAID SIDE FRAME MEMBERS, MEANS LOCATED ON THE WHEEL CHAIR AND CONTROLLABLE BY AN OCCUPANT OF THE WHEEL CHAIR TO LINEARLY EXTEND AND RETRACT SAID RETRACTABLE WHEELS, AND MEANS TO TRANSMIT MOTION FROM SAID DRIVEABLE WHEELS TO SAID ENDLESS BELT MEANS TO ENABLE SAID VEHICLE TO TRAVEL OVER INCLINED SURFACES.