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Publication numberUS3191953 A
Publication typeGrant
Publication dateJun 29, 1965
Filing dateDec 28, 1962
Priority dateDec 28, 1962
Publication numberUS 3191953 A, US 3191953A, US-A-3191953, US3191953 A, US3191953A
InventorsEdward M Aysta
Original AssigneeEdward M Aysta
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Stair climbing wheel chair
US 3191953 A
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Description  (OCR text may contain errors)

E. M; AYSTA STAIR CLIMBING WHEEL CHAIR June 29, 1965 4 Sheets-Sheet 1 Filed Dec. '28; 1962 A i/[N702 fan/A20 M. Arsm 5% 4 flrraz/vfys June 29, 1965 E. M; AYSTA STAIR CLIMBING WHEEL CHAIR 4 Sheets-Sheet 4 Filed Dec. 2a, 1962 United States Patent 3,191,953 STAIR CLIMBING WHEEL CHAR Edward M. Aysta, 124 6th St. S., Virginia, Minn. Filed Dec. 28, 1962, Ser. No. 248,107 10 Claims. (Cl. 2805.22)

This invention relates to an invalid chair, Wheel chair, or similar conveyance, and in particular to vehicles of this type capable of traversing uneven terrain and obstructions and which are capable of passing over curbs and ascending and descending stairs.

There has been a long standing need for an invalid chair or wheel chair which would increase the range of mobility of a handicapped individual beyond that capable of being provided by conventional style chairs of this type. This need has been intensified of late by increased efforts to make handicapped individuals as selfsufiicient as possible and by efforts encouraging the employment of handicapped individuals. A great deal of effort has been expended and numerous types of wheel chairs have been devised in a search for a practical and workable wheel chair which would provide the range of mobility desired and which at the same time would retain the conventional Wheel chairs versatility and convenience and which would have maximum maneuverability, be safe and easy to operate and which would be capable of being constructed at a reasonable cost to enable purchase thereof by a maximum number of the handicapped. Despite the ingenuity and effort which has been directed up to now to the solution of this problem, no wheel chair has yet been developed which meets all of the desired requirements and which would'constitute a practical and workable design.

The type of wheel chair desired should enable the handicapped person to cope with the usual problems which he normally encounters in traveling to and from work or other places, and in moving about building interiors such as his own home or place of employment. One of the most important problems which must be met in this regards is to provide a chair capable of traversing street curbings and the like and capable of easily and safely ascending and descending any stairways with average height rise-rs and depth of tread as found in oflice buildings, homes and industrial plants and the ascent and descent thereof should be able to be performed without damaging the stair treads or the risers, and without requiring the assistance or presence of an attendant. Since the vehicle must perform the usual wheelchair functions most of the time, the chair provided with the aforementioned curb and stair traversing ability should alsohave the versatility and convenience of conventional wheel chairs. The wheel chair should be capable of being folded by active handicapped persons in order to enable them to readily put them in automobiles and provide the handicapped wit-h the independent mobility desired. The chair must be strong enough to safely support the weight of the user and be capable of withstanding the rigors of use, and at the same time be sufii-ciently light in weight to enable the chair to be easily folded, handled and lifted where necessary. The chair should also be as narrow as possible to provide proper freedom of movement in buildings and other structures for negotiating passage through narrow doorways and the like. The chair should also have maximum maneuverability and the turning radius thereof should be as small as possible. a

Any changes or adjustments required between normal travel and ascending or descending travel should be capable of being accomplished in a minimal amount of time to eliminate unnecessary delays at street crossings, crowded stairway-s, etc. Vehicles driven or propelled by 3,191,953 Patented June 29, 1965 ice the occupant should require a minimum amount of effort on the part of the occupant. Preferably, the vehicle should be capable of being conveniently propelled by an arm strength of ten pounds. The chair should also be so designed that the chair and the occupant are always in a proper state of balance and the chair should be fail safe to prevent uncontrolled descent thereof. The chair should also be of reasonably inexpensive construction and should not require the installation of special ramps, mechanical contrivances or electrical outlets in buildings.

One object of this invention is to provide an invalid chair or wheel chair which meets all of the foregoing requirements and is superior to devices of this type previously developed and which constitutes a practical and workable solution to the problems long associated with vehicles of this type.

Another object is to provide novel means for readily converting a conventional wheel chair into a vehicle capable of traversing curbs, stai-rways and the like while retaining all of the desirable features of said conventional chair and to provide a novel vehicle propulsion system for accomplishing same. 1

Another object is to provide a stair climbing wheel chair having traction wheels for normal travel and track or tread means for negotiating curbs and stairways, and wherein the relative positions of the wheels and tracks can be selectively changed for selective interchangeable engagement thereof with the chair supporting surface.

Another object is to provide a wheel chair of the type above described in which the wheels are operatively disengaged from the tracks during normal travel and serve as the means for powering said tracks when traversing stairways, and in which the seat structure automatically shifts between normal travel position and stair traversing position simultaneously with the change in relative posi- .tions of the wheels and tracks.

Still another object is to provide a novel wheel chair which embodies therein traction wheel means for normal travel and tread or track means for negotiating stair- Ways, curbing and the like, which wheels are retractable when the chair is to be used for stair climbing and descending purposes and which While so retracted are capable of functioning as the means for powering the tread or track means.

These and other objects and advantages of this invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views,'and in which:

FIG. 1 is a side elevational View of a wheel chair embodying the present invention shown in normal traveling position with the near drive wheel omitted for clarity;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view of the chair of FIG. 1 with the near drive wheel removed showing the relation of the several parts when said chair is ascending a stairy;

FIG. 4 is a vertical half-section taken along the line 4-4 of FIG. 1;

FIG. 5 is a front elevational view of the chair when folded;

FIG. 6 is a detail view of the brake mechanism;

FIG. 7 is a sectional view on an enlarged scale of the track tightening mechanism taken along the line 7-7 of FIG. 1;

FIG. 8 is a detailed elevational View on an enlarged scale of the ratchet and pawl mechanism as seen along the line 8-8 of FIG. 1;

FIG. 9 is a detailed elevational view in partial section and on an enlarged scale of the seat latching mechanism; and

FIG. is a top plan view on an enlaged scale of the front cross-bracing unit.

The illustrated embodiment comprises a collapsible wheel chair having substantially identical opposing traversely spaced apart side assemblies interconnected by collapsible bracing and a tiltable, collapsible seat assembly mounted between the two side assemblies whereby the entire wheel chair assembly can be laterally collapsed and folded into compact form. Each side assembly includes a basic or main frame structure on which endless traction belt means, tracks or treads are mounted in fixed position relative to their respective frames for supporting and propelling the vehicle when ascending and descending stairways. The side assemblies also include large manually operable traction drive wheels which are retractably mounted on the main frame structure whereby when lowered they engage the ground and maintain the endless tracks above and out of engagement with the ground and the raising of which causes lowering of the tracks to a position whereby the tracks can serve as the means for propelling the vehicle up and down the stairs. The side assemblies also include drive or transmission systems connected to their respective track for powering same, and additional drive means connected to, movable with and driven by the traction drive wheels, the additional drive means operatively and drivingly engaging said transmission systems when the wheels are raised and being disengaged from the transmission systems when the Wheels are in lowered ground engaging position. Thus, the drive wheels are drivingly connected to the tracks when the wheels are raised, and are disconnected therefrom when lowered. The tilting seat structure interposed between the side assemblies is linked to the traction drive wheels in such fashion that the seat structure automatically tilts to the desired position simultaneously with the raising or lowering of the wheels.

The illustrated embodiment also includes additional features, including brake mechanism for preventing uncontrolled descent of a stairway, releasable latch mechanism for maintaining the seat structure in fixed position during normal use, and ratchet and pawl mechanism for preventing slippage and reverse movement of the track drive and drive wheels while ascending a stairway, all of which are set forth in detail hereinafter.

Reference is now made to the accompanying drawings for a more detailed explanation and better understanding of this invention. Since the side assemblies are substantially identical in construction and arrangement, it is to be understood that a description of one applies to both, unless otherwise indicated.

Considering the invention in more detail, each side assembly includes basic integral frame structure which includes front and rear generally vertically disposed members 10 and 11 respectively, the upper end portions of which are interconnected by longitudinally extending members 12 which also serve as arm rests for the occupant. The lower end portions of the vertical members 10 and 11 are rigidly interconnected by elongate longitudinally extending lower frame members 13 which extend rearwardly of the rear vertical members 11 and the rear end portions of which are bent or curved upwardly to facilitate the engagement of the chair with a stairway preparatory to ascending same in a manner hereinafter described. Curved bracing members 14 extend between and interconnect the vertical members 11 and the rearwardly extending portions of the member 13. The frame members 10, 11, 12, 13 and 14 are preferably formed of tubular, strong light weight metal to achieve maximum strength with minimum weight. The side assemblies also include endless cleated tracks 15 capable of supporting the chair on a stairway and propelling it thereover, which tracks are trained about forwardly disposed drive pulleys 16 and a longitudinally arranged series of idler pulleys 17, 18, 19

and'20. The drive pulleys 16 are rotatably mounted on the lower end portions of the front vertical frame members 10 by means of stub shafts 16a. Idler pulleys 17 are connected to the frame structure by means of elongate pulley supporting members 21 which have the idler pulleys 17 rotatably mounted on the leading ends thereof by means of stub shafts 17a. The rear ends of said pulley supporting members 21 are connected to the lower frame members 13 by bolt fasteners 18a, which also serve as the axles for pulleys 18. The intermediate portions of the supporting members 21 are supported by vertically disposed brackets 22 which are fastened to the rear vertical members 11 by means of U-bolts 23, the lower ends of said brackets being fastened to the pulley supporting members 21 by means of bolt fasteners 24. The idler pulleys 19 and 20 are rotatably mounted on the lower frame members 13 by means of stub shafts 19a and 20a respectively.

To enable the tracks to be properly tensioned and tightened, the stub shafts 20a on which the rear idler pulleys 20 are mounted are slidably seated in elongate slots 25 provided in the rear end portions of the lower members 13 and connected to block members 26 which are slidably enclosed within the tubular members 13 (as best seen in FIG. 7). Adjusting bolts 26a are connected to said block members 26 and are housed within the member 13 and protrude from the rear end thereof. The bolts 26a are provided with nuts 27 which bear against the closed ends or caps 13a of the member 13 which provide seats for the nuts 27 whereby the tension on the tracks can be adjusted as desired by loosening or tightening said nuts 27.

0 power and drive the endless tracks 15, chain drive or transmission systems are provided as follows. Small sprockets 28 are rotatably mounted on the rear frame members 11 by means of stub shafts 28a and larger sprockets 29 are rotatably mounted on the front frame members 10 by means of stud shafts 2901, said sprockets 28 and 29 being drivingly interconnected by endless sprocket chains 30 trained thereabout. Sprockets 31 which are smaller than sprockets 29 are connected to sprockets 29 and driven thereby and therewith and similar sprockets 32 are connected to the drive pulleys 16 for driving same, said sprockets 31 and 32 being drivingly interconnected by means of endless sprocket chains 33. These chain drive systems are driven in a manner hereinafter to be described.

Large conventional bicycle type traction drive wheels 34 capable of being manually operated by the occupant of the wheel chair are provided on each side of the wheel chair as a part of each side assembly. Each drive wheel is retractably mounted on its respective frame by means of an arm or lever 35, one end of which is pivotally connected to the rear frame member 11 by its being journaled on shaft 28a. The other end of the arm 35 carries an axle 36 on which the hub 34a of the wheel is journaled. The hub has connected thereto an axle enclosing sleeve 37 which constitutes an extension of the hub and on which is mounted a drive sprocket 38 which is rotatable with the sleeve 37 and driven by the rotation of the drive wheel. The sprockets 38 are in planar alignment with their respective chains 30 so as to be operatively engageable with the lower course thereof for driving same when the drive wheels are retracted and raised to stair climbing position. When in normal lowered position, the drive wheels 34 engage the chair supporting surface and maintain the tracks 15 above and out of engagement with said surface to provide maximum mobility and maneuverability during normal use. However, the connection of the drive wheels to the frame by means of the arms 35 enables the drive wheels and arms to swing or pivot about the axis 28a to a raised stair climbing position in which the drive wheels are preferably raised above the lowermost course of the tracks to enable the tracks to properly engage the stairs and propel the chair thereover. When the drive wheels are in this raised stair climbing position, the drive sprockets 38 connected thereto are brought into driving engagement with the chains whereby turning of the drive wheels in this raised position effects powering of the tracks through the medium of the transmission system provided, and hereinbefore described. The gear ratio of the track drive mechanism may be varied as desired and is preferably such that a small amount of force (a minimum arm strength of ten pounds) applied to the drive wheels will provide the power necessary to propel the chair up a flight of stairs. The illustrated arrangement provides a preferred minimum ratio of 20 to 1 but it is apparent that this can be varied to meet any requirement.

The side assemblies are collapsibly interconnected by means of a pair of collapsible scissors type cross bracing units located forwardly and rearwardly of the chair. The front unit consists of a pair of elongate crossed bracing members 39 and the rear unit consists of a similar pair of crossed bracing members 40, each of said pairs being pivotally interconnected as at 41. The lower ends of the bracing members 39 and 40 are pivotally connected as at 42 to their respective front and rear vertical frame members 10 and 11. The upper ends of the front cross braces 39 are pivotally connected to link members 43 as at 44, said link members 43 being pivotally secured to the front vertical frame members 10 as at 43a.

The upper ends of rear cross braces 40 are pivotally connected at 45a to one end of dog leg shaped link members 45, the other ends of said links being secured to the rear vertical frame members 11 as at 45b. The link members 43 are offset as at 43b (as best seen in FIG. 10), said offset portions being adapted to engage the extreme upper end portions of the braces 39 located above the pivot connections 44 when the wheel chair is unfolded (as best seen in FIG. 2) to limit the unfolding movement of the cross braces and hold them in the position desired. It will be noted that the corresponding pivot connections 41 and 42 of the front and rear bracing units are co-axial as are the corresponding pivot connections 44-45a and 4351-451) of these same units to insure corresponding movement between said units.

The wheel chair assembly is additionally collapsibly supported and braced by means of a pair of elongate bracing members 46 and 46', the outer ends of which are also pivotally connected to their respective front frame members at 46b, the inner ends of which are pivotally interconnected as at 47, one member 46 carrying a stop element 4a; for engaging the other member 46 and holding said member in the desired horizontal aligned unfolded position illustrated.

Thus, the entire wheel chair assembly can be collapsed into a compact folded condition by simply raising members 46-46 out of alignment and pushing the side assemblies thereof towards each other and thereby folding the cross braces 39-39, 40--40, and 46-46 and the entire chair assembly to the folded collapsed condition of FIG. 5.

The tiltable laterally collapsible seat assembly is disposed between the side assemblies and is designed to tilt relative to the basic supporting frame structure hereinbefore described simultaneously with the raising or lowering of the drive wheels 34. This seat assembly includes a pair of generally vertically disposed transversely spaced back frame members 48, and a back panel 49 of collapsible material extending between and connected to said back members 48 to provide a back rest or support for the occupant. The seat assembly also includes a pair of longitudinally extending generally horizontal disposed laterally spaced apart elongate seat frame members 59, which are rigidly connected to their respective back frame members 48. A seat panel 51 of collapsible material extends between and is connected to the seat members 50 to provide a seat for the occupant. Said seat assembly also includes a pair of elongate depending leg members 52, the upper ends of which are rigidly connected to the seat frame members 50. The lower ends of the legs 52 have 6 caster wheels 53 swivelly mounted thereon, which caster wheels engage the ground or other supporting surface during normal use. These leg members have mounted thereon a forwardly extending foot rest supporting members 54 on which are pivotally mounted suitable foot rests 55 which are capable of being folded from a normal horizontal position to a raised vertical collapsed position.

The back frame members 46 have handle bars 56 mounted thereon provided with hand grips 57 to enable the wheel chair to be pushed and steered by an attendant where necessary or desirable. Thus, the seat assembly is capable of collapsing laterally in response to the movement of the side assemblies towards each other and folding of the wheel chair. The seat assembly is provided with braces 53 which rigidly interconnect the back and the seat frame members 48 and 50 respectively.

To tiltably connect the seat assembly to the basic frame structure, the forward end of the seat assembly is hinged to the main frame by means of links 59 which extend between and are pivotally connected to the leg members 52 and the front vertical frame members 10 at 5% and 5% respectively. The intermediate portion of the seat assembly is hinged to the frame by means of link members of? which extend between and are pivotally connected to the seat frame members 50 and the lower frame members 13 at ila and dill) respectively. The rear portion of the chair is hingedly linked to the supporting frame by means of link members 61, the upper ends of which are ivotally connected to the rear end portions of the seat frames 5%) at 61a, the lower ends of which are pivotally connected to the rear vertical frame member 11 at 61b. Side panels 62 are provided which extend between and are connected to each pair of frame members 10 and 11 to partially enclose the sides of the chair assembly.

In order to accomplish simultaneous movement of the drive wheels and the seat assembly, elongate actuating levers 63 are provided, the lower ends of which are rigidly secured to the wheel arms 35 so as to be integral therewith and constitute an extension thereof. The upper ends of the levers 63 are connected to the seat back by a sliding connection provided by mounting brackets 64 secured to the back frame members 48 and extending rearwardly thereof, said brackets having generally vertically disposed slots 65 formed therein, said brackets and levers 63 being slidably interconnected by means of bolts or pins 56 extending therebetween and slidably seated in the slots 65. The seat assembly and the drive wheels 34 are linked together through the medium of the arms 35 and levers 63 for simultaneous movement thereof relative to the supporting frame structure. When the seat assembly is tilted rearwardly, the drive wheels simultaneously rise, and vice versa. To properly position the component parts of the wheel chair for ascending and descending stairways, the occupant simply leans backward against the back of the seat assembly causing same to tilt rearwardly and may simultaneously pull upwardly on the drive wheels, all of which causes the seat assembly to tilt to the desired position to insure that the occupant will be properly seated and balanced while on the stairway and raises the drive wheel to a retracted position to enable the tracks to properly engage the stairs and places the drive wheels in driving engagement with the drive system for the tracks whereby turning of the drive wheels will propel the tracks in whichever direction desired.

The sprockets 38 are held in driving engagement with the chains 36 by the weight of the occupant against the back of the seat assembly, which engagement also limits the backward tilting of the seat assembly. The leg 52 and links 43 are also designed and arranged that the legs 52 will engage the links 43 and be frictionally held thereby to limit the backward tilting of the seat assembly past any undesirable position. The tilting of the seat assembly is so arranged and controlled that the occupant will be maintained in substantially the same position when traversing a stairway as when in normal use.

The illustrated wheel chair has several additional other features which improve the efficiency, ease of operation or safety thereof. For example, elongate helically coiled counterbalancing springs 67 are provided on each side which extend between and are connected at opposite ends to the links 60 and the front frame members 10 at oia and 67b respectively, which springs are tensioned by the tilting of the seat assembly and bias the seat assembly from tilted stair traversing position to normal travel position to facilitate the return movement thereof.

Shock absorbing means for cushioning the return movement of the seat from tilted to normal position is provided by pneumatic piston and cylinder assemblies d8 similar to the conventional door check, the cylinders of which are pivotally connected to the links 60 at 63a, the piston rods thereof being pivotally connectedto the front frame members 10 at 6%. To prevent uncontrolled descent and make the wheel chair fail safe, brake arms 69 are provided on each side as a safety feature. These brake arms are pivotally mounted on the lower frame members 13 by means of Crosby clips 70, carried by said members 13, one leg 79a of said clips serving as the pivot for the brake arms, the other leg 70b of said clips serving as a stop for retaining and holding the brake arms in the desired braking position, said other legs 70!) being adapted to be seated in recessed portions 69:: of the brake arms. The brake arms are yieldingly held in braking position against the stops 70b by means of elongate helically coiled springs 71, the lower ends of which are attached to the upper ends of their respective brake arms above the pivot point thereof at 71a, the upper ends of the springs being connected to the curved frame members 14 at 71b. When raised, the lower ends of the brake arms are disposed above the lower course of the track so as not to interfere with normal stair descent. When lowered, the lower end of the brake arms are positioned below the tracks so as to engage the stair tread and prevent further movement of the chair down the stairs.

When ascending a stairway, the brake arms are maintained in lowered braking position whereby if the wheel chair should start to slip downwardly, the lower ends of the brake arms would engage the stair treads and prevent further movement of the chair. However, as long as the chair is properly moving upwardly on the stairway, the brake arms will not interfere with nor obstruct the upward movement of the wheel chair since the lower end portions of the brake arms below their pivot points will be pushed upwardly against the action of the springs 71 when engaging the stairs in normal upward movement so as to pass freely thereover.

However, when descending the stairs, the brake arms must be maintained in a releasable raised position until such time as they may be needed to avoid interference with the normal downward movement of the wheel chair. To accomplish this, brake control levers 72 are provided, the lower ends of which are pivotally connected on the side panels 62 at 72a. Stop members 73 are mounted on the panels 63 forwardly of the pivot 72a for engaging the leading edges of the control levers and limiting the forward movement thereof and maintaining the levers in a forward position in which the brake arms are in a raised position in which they do not interfere with stair descending movement. Pulleys 74 are mounted on the control levers and cables 75 are trained thereabout, the lower ends of the cables being attached to the lower end portions of the brake arms below their pivots at 75a, the upper ends of the cables being anchored to the panels 62 at 75b. Rear stop members 76 are mounted on the panels 62 rearwardly of the pivot 72a of the brake control lever for engaging the control levers 72 and limiting the rearward movement of the control lever and holding same in a brake release position.

The aforedescribed arrangement provides an over-center action for the brake control levers 72. When the levers are pushed forwardly so as to engage and rest against the front stops 73, the lower ends of the cables are pulled upwardly and pull with them the lower end portions of the brake arms upwardly against the action of the springs 71 to a position where it will not engage the stairs when the chair is descending same. To release the brake arms for stair engagement, the control levers '72 are simply pulled or swung rearwardly so as to bring them into engagement with the rear stop members 76. This movement shortens the effective distance between the two ends of the cables and enables the brake arms to be pulled downwardly into stair engaging and braking position through the biasing action of the springs 71.

To prevent undesirable slippage, back-up or lost motion of the drive wheels when ascending and descending stairs and also to prevent uncontrolled movement of the track drive systems in the event that the operator should let go of or lose control of the drive wheels, ratchet wheels '77 are also rotatably mounted on the stub shafts 28a and fixedly connected to the sprockets 28. Pawl members or arms 78 are pivotally mounted on the frame members 11 at 78a and are adapted to continuously engage the ratchet wheels 77 and permit free rotation thereof and the track system in one direction and prevent movement thereof and the track system in the opposite direction in a manner well known when the wheel chair is ascending a stairway.

In the arrangement shown, it is apparent that to move the wheel chair up the stairs, the drive wheels must be pushed forwardly or rotated clockwise in FIGS. 1 and 3 to accomplish counter clockwise stair climbing movement of the endless tracks. The ratchet and pawl mechanisms in the illustrated embodiment are designed to permit the drive wheels to turn freely in a clockwise direction when the wheel chair is ascending a stairway, but prevents counter clockwise movement of the drive wheels. When the drive wheels are released, such as when the operator has reached the end of a forward pushing movement on the drive wheels and is moving his hands rearwardly so as to initiate another pushing movement on the drive wheel, the ratchet and pawl mechanism will hold the drive wheels against reverse counter clockwise movement and prevent slippage thereof until the operator has again firmly grasped the wheel to operate same.

For descending the stairs and for normal travel over level surfaces, the drive wheels must be free to rotate counter clockwise in the illustrated embodiment and for these purposes the pawls are simply swung upwardly out of engagement with the ratchet wheels to permit free turning of the drive wheels in either direction as desired. To hold the pawls out of engagement with the ratchet wheels, spring latches 79 are mounted on the panels 62 and have offsets 79a which engage and hold the pawls in raised position, the pawls being released for engagement with the ratchet wheels by pushing the latches 79 inwardly towards the panels 62.

Releasable latch mechanism is also provided to positively hold the seat assembly in a fixed forward position during normal use. In the illustrated embodiment, this latch mechanism comprises a latch member 80 slidably mounted on the right hand front frame member 10 (as best seen in FIG. 9) for movement transversely of the seat assembly. The inner end of the latch member 80 is adapted to overlie and engage the right seat frame member 59 and hold the seat assembly in fixed forward position for normal use. A helically coiled compression spring 81 is housed within the frame member 10 and encircles the reduced shank portion Stla of the latch, which spring bears against the inner wall of the frame member 10 and the shoulder 80b of the latch to continuously urge the latch member inwardly and hold it in engagement with the seat frame member 50. The outer end of the latch is provided with a shoulder 80c which engages the outer wall of the frame member 10 and limits the inward movement of the latch and a handle 82 for operating said latch. The inner end of the latch is beveled at 80d to permit the seat frame member 50 to bear thereagainst and push the latch outwardly to enable the frame member 50 to move therepast and therebelow, the latch spring inwardly under the action of the spring 81 when the frame member has passed therebelow to lock the seat assembly in forward position. To tilt the seat assembly backwards, the occupant simply pulls the latch outwardly by pulling on the handle 82 against the action of the spring 81 until the frame member 50 is unlocked and the seat assembly is free to tilt.

Thus, for normal travel over level ground, the wheel chair assembly appears as in FIG. 1, with the drive wheels 34 in lowered position and the tracks raised to an outof-the-way position in which they do not engage the chair supporting surface. In such condition, the sprocket 38 is disengaged from the chain 30, and there is no operative connection between the drive wheels and the endless tracks. The seat assembly is held in fixed forward position by the latch 80, and the pawls 78 are not engaged with the ratchet wheels 77, leaving the drive wheels free to turn in either direction whereby the wheel chair can be manually propelled and turned in the conventional manner by manipulation of the drive wheels. The brake arms 69 during normal use are preferably held in raised position, but if left in lowered position will not interfere with most normal usage, since when lowered they are above and out of engagement with a normal level supporting surface.

To ascend a flight of stairs, the chair is backed up to the lowermost stair so that the rear upwardly inclined portions of the tracks can rest against the lowermost stair. It will be noted that the tracks are normally inclined from front to rear, not only to facilitate initial engagement with the lowermost stair preparatory to ascending same, but also to have the tracks at an inclined attitude approximating the normal angle of inclination of the average stairway, thereby reducing the degree of tilting movement required for the seat assembly to place it in the properly balanced position desired for traversing a stairway. The latch mechanism between the seat assembly and the frame is then released and the drive wheels are free to retract and rise and the seat assembly is free to tilt rearwardly, said retracting and tilting movement being facilitated by the occupant leaning backward against the chair structure and simultaneously lifting upwardly on the drive wheels, the tilting movement and rising of the drive wheels continuing until the sprockets 38 are in positive driving engagement with the chains 30. The drive wheels rise sufificiently to enable the tracks to be lowered to stair engaging position whereby the tracks can serve as the means for propelling the wheel chair over the stairs, and the forward end of the tracks are lowered into engagement with the ground or floor surface immediately adjacent the lowermost stair whereby the entire wheel chair is supported by the tracks engagement with the ground surface and the lowermost stair immediately prior to beginning ascent thereof. The drive wheels are preferably raised (as illustrated) to a position where they are located entirely above the lowermost courses of the tracks whereby the drive wheels do not engage the stairs during travel thereover.

Also, it will be noted that as the seat assembly tilts rearwardly, the front casters are also raised sufficiently so that they too will be in a non-interfering position for travel over the stairway. To complete the preparation for stair ascent, the pawls are lowered into engagement with the ratchet wheels and the brake arms are lowered to braking position. When the foregoing has been accomplished, the ascent of the stairs can be take place by the occupants simply turning the drive Wheels, the turn ing thereof causing driving of the sprockets 38, which in turn power the track through the track chain drive system hereinbefore described. The wheel chair during the ascent of a stairway appears as shown in FIG. 2. Upon reaching the top or bottom of a stairway, the chair components are returned to their normal position as 1d illustrated in FIG. 1 by simply tilting the chair forwardly, lowering the drive wheels to ground engaging position and raising the tracks to inoperative position. It will be further appreciated that the rearward tilting of the chair for ascending and descending stairways enables the occupant to be in properly balanced state or condition at all times and thereby maintains the occupant in a safe and comfortable position at all times.

When ascending a stairway, the brake arms readily yield as they engage the stair (as seen in FIG. 3), the forward end of the brake arms swinging upwardly against the action of the springs 71 to enable the brake arms to freely pass over the stairs without interfering with the movement of the wheel chair thereover. However, should the wheel chair begin to slip downwardly on the stairs, the lower ends of the brake arms engage the stair treads (as best seen in FIG. 6) and hold the wheel chair against further downward movement.

To descend a stairway, the drive wheels are retracted and the tracks lowered at the top of the stairs, and the wheel chair is then moved forwardly and down the stairs by turning of the raised drive wheels in a direction opposite to that required for ascending movement. As the chair descends the stairway, it appears as seen in FIG. 3, with the exceptions that the pawls are disengaged from the ratchet wheels and the brake arms are in the raised non-braking position of FIG. 1, with the brake control levers 72 in forward position. If the wheel chair should slip or begin uncontrolled descent, the occupant simply pulls the brake control levers 72 rearwardly, thereby releasing the brake arms for engagement with the stair treads in the manner hereinbefore described.

For storage or carrying in an automobile, the wheel chair can be easily folded and collapsed to the compact condition illustrated in FIG. 5 by simply pushing the two side assemblies towards each other.

Although the embodiment of the invention herein illustrated and described is of the manually operable type, it will be recognized that the wheel chair of this invention can be readily modified so as to be power driven. It will also be apparent that presently available conventional wheel chairs can be readily modified to incorporate the novel aspects of this invention which enable the chair to be readily and interchangeably used for both conventional level travel and for travel up and down stairs, over curbing and the like.

It will further be appreciated from the foregoing description that the wheel chair of this invention incorporates all of the features therein considered desirable to give the handicapped the range of independent mobility desired, and yet retains all of the convenience and versatility of a conventional wheel chair. Thus, the wheel chair of this invention can be readily converted for travel up and down stairs and for normal level travel without undue delay or difficulty. It retains all of the high maneuverability of conventional wheel chairs and is capable of turning in a minimum radius and is capable of being readily folded and collapsed in the conventional manner into a compact package for storage and for carrying in automotive vehicles and the like. The chair is virtually fail safe particularly as applied to its travel up and down stairs, and can be operated with a minimum of effort on the part of the operator.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

and a raised position, said vehicle being supported and propelled by said wheel means when said wheel means are in said lowered position, said track means being maintained in raised position above the lowermost portion of said wheel means when said wheel means are in said lowered position, and disposed below the lowermost portion of said wheel means when said wheel means are in raised position whereby said vehicle is supported and capable of being propelled by said track means for travel over a stairway, means interconnecting said chair structure and wheel means for simultaneous movement thereof whereby movement of said wheel means between lowered and raised position effects simultaneous tilting movement of said chair structure between a forward normal travel position and a rearwardly tilted stair traveling position, first drive means drivingly connected to said track means for driving same, and second drive means for driving said first drive means, said second drive means being driven by said wheel means and swingable therewith whereby said second drive means drivingly engages said first drive means when said wheel means is in raised position and is disengaged therefrom when said wheel means is in lowered position.

2. A vehicle comprising a frame, endless track means mounted on said frame structure in fixed position relative thereto, traction wheels mounted on said frame structure for swinging movement relative thereto between a lowered ground engaging position and a raised position, said tracks being in engagement with the vehicle supporting surface when said wheel are in said raised position, first drive means drivingly connected to said track means for driving same, and second drive means for driving said first drive means, said second drive means being driven by said wheels and swingable therewith between said raised and lowered positions, said second drive means when in said raised position being drivingly engaged with said first drive means whereby said tracks can be driven by said wheels, said second drive means being moved out of driving engagement with said first drive means by the lowering of said wheels to said lowered position.

3. A vehicle comprising frame structure, track means mounted on said frame structure in fixed position, wheel means mounted on said frame structure and capable of movement between a lowered position in which said wheel means engage the vehicle supporting surface and a raised position in which said track means are in engagement with said supporting surface, and chair structure supported by said frame structure and movable relative thereto between first and second positions, and means interconnecting said chair structure and wheel means whereby said chair structure is moved between said first and second positions by the movement of said wheel means between said raised and lowered positions.

4. The vehicle of claim 3, including means for drivingly interconnecting said track and wheel means when said wheels are in raised position whereby said track means can be driven by said wheel means when said track means are in engagement with the vehicle supporting surface.

5. A stair climbing wheel chair comprising laterally spaced apart opposed side frame structure, chair structure including integrally connected back, seat and leg portions disposed between said side frame structure and pivotally mounted thereon for tilting movement relative thereto between a forward normal travel position and a rearwardly tilted stair climbing position, endless longitudinally extending track means mounted on each of said side frame structures in fixed position relative thereto, said track means being upwardly and rearwardly inclined when said wheel chair is in condition for normal travel over a substantially horizontal supporting surface, traction wheels pivotally mounted on each of said side frames for swinging movement relative thereto between a lowered vehicle supporting and propelling position and a raised position, said track means being maintained above the vehicle supporting surface when said wheel means are in lowered position and capable of supporting and propelling the vehicle when said wheels are in raised position, means interconnecting said chair structure and said wheels for simultaneous movement thereof whereby swinging movement of said wheels between lowered and raised position effects simultaneous tilting movement of said chair structure between said forward and rearwardly tilted positions, first drive means drivingly connected to each of said track means for driving same, and second drive means for driving said first drive means, said second drive means being connected to and driven by said wheels and swingable therewith whereby said second drive means drivingly engages said first drive means when said wheel means is in raised position whereby said track means can be driven by the turning movement of said wheels, said second drive means being disengaged from said first drive means when said wheels are in lowered position.

6. A stair climbing wheel chair comprising opposed laterally spaced apart side frames, chair structure including integrally connected back, seat and leg portions pivotally mounted on and between said side frames for tilting movement relative thereto about a horizontal transverse axis between a forward normal travel position and a rearwardly tilted stair climbing position, endless longitudinally extending track means mounted on said side frames in fixed position relative thereto, said track means being upwardly and rearwardly inclined, a pair of traction wheels, and means for mounting said wheels on said side frames for swinging movement relative thereto comprising an elongate arm, one end of which is pivotally mounted on said side frame, said wheel being rotatably mounted on the other end portion of said arm, said wheels being capable of swinging movement relative to said side frame between a lowered ground engaging and vehicle supporting and propelling position and a raised position, said tracks being maintained in raised position above the wheel supporting surface when said wheels are in lowered position, said tracks being lowered to ground engaging vehicle supporting and propelling position by the raising of said wheel to said raised position, said arm being connected to said chair structure for simultaneous movement of said wheels and aid chair structure whereby movement of said wheels between lowered and raised position effects simultaneous tilting movement of said chair structure between said forward and rearwardly tilted positions, endless drive chain means supported by said side frames and drivingly connected to said track means for driving same, and gear means carried by said arm and driven by said wheel, said gear means being adapted to drivingly engage said endless chain means when said Wheel is in raised position whereby said tracks can be driven by said wheels, said gear means being moved out of engagement with said endless chain means by the lowering of said wheels to said lowered position.

7. A stair climbing wheel chair comprising frame structure, track means mounted on said frame structure in fixed position relative thereto, wheel means mounted on said frame structure and movable relative thereto between a lowered ground engaging position and a raised position, said track means being maintained in spaced relationship to the ground when the wheel means are in said lowered position and adapted to support said wheel chair on a stairway and propel it thereover when the wheel means are in raised position, and chair structure mounted on said frame for tilting movement relative thereto between a forward normal travel position and a rearward stair traveling position and means interconnecting said chair structure and said wheel means for simultaneous movement thereof whereby movement of said wheel means between said lowered and raised positions effects simultaneous movement of said chair structure between said forward and rearward positions, the seat portion of said chair structure and said track means being in forwardly diverging relationship when said wheels are in lowered position and in raised position, the angle of divergence being greater when the wheel means are in raised position than when they are in lowered position.

8. A vehicle comprising a frame, chair structure mounted on said frame, endless track means and traction wheel means mounted on said frame, each of said means being adapted to independently support said vehicle on and propel it over a vehicle supporting surface, one of said means being movable relative to said frame and to said other means between two positions, the other of said means being mounted in fixed position relative to said frame, said vehicle being supported by said track means when said one means is in one of said positions, and supported by said wheel means when said one means is in the other of saidpositions, said chair structure being adapted for V movement relative to said frame between two positions,

and means for moving said chair structure between said positions simultaneously with and in response to the movements of said movable means.

9. A stair climbing wheel chair comprising laterally spaced apart opposed side frame structure, chair structure mounted between and supported by said side frame structures, endless longitudinally extending track means mounted on each of said side frame structures in fixed position relative thereto, said track means being upwardly and rearwardly inclined when said wheel chair is in condition for normal travel over the ground, traction wheels mounted on each of said side frames for free movement relative thereto between a lowered vehicle supporting and propelling position and a raised position, said track means being maintained spaced from the ground when said wheel means are in lowered position and capable of supporting and propelling the vehicle on a stairway when said wheels are in raised position, said chair structure being capable of tilting movement relative to its supporting side frame structure and said tracks, and means interconnecting said chair structure and wheel means for simultaneous movement thereof whereby movement of said wheel means between lowered and raised position effects simultaneous tilting movement of said chair structure between forward normal travel position and a rearwardly tilted stair traveling position.

10. A stair climbing wheel chair comprising laterally spaced apart opposed side frame structure, chair structure mounted between and supported by said side frame structures, endless longitudinally extending track means mounted on each of said side frame structures in fixed position relative thereto, said track means being upwardly and rearwardly inclined when said wheel chair is in condition for normal travel over the ground, traction wheels mounted on each of said side frames for free movement relative thereto between a lowered vehicle supporting and propelling position and a raised position, said track means being maintained spaced from the ground when said Wheel means are in lowered position and capable of supporting and propelling the vehicle on a stair way when said wheels are in raised position, said traction wheels being pivotally mounted on each of said side frames for swinging movement relative thereto between said raised and lowered positions, said chair structure being capable of tilting movement relative to its support ing side frame structure and said tracks, and means interconnecting said chair structure and wheel means for simultaneous movement thereof whereby movement of said wheel means between lowered and raised position effects simultaneous tilting movement of said chair structure between forward normal travel position and a rearwardly tilted stair traveling position.

References Cited by the Examiner UNITED STATES PATENTS 2,902,101 9/59 Cates 280-522 X 2,946,602 7/60 Lee 2802l1 3,111,331 11/63 Locke 280-522 FOREIGN PATENTS 693,983 7/53 Great Britain.

OTHER REFERENCES Brochure: Wanted-A Stair Climbing Wheel Chair, January 1962, National Inventors Council, US. Dept. of Commerce.

ARTHUR L. LA POINT, Primary Examiner.

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Classifications
U.S. Classification280/5.22, 280/DIG.100, 280/11, 280/250.1, 280/211
International ClassificationA61G5/06, B62D55/075
Cooperative ClassificationA61G5/066, A61G5/08, A61G2005/0825, A61G5/061, B62D55/075, Y10S280/10
European ClassificationB62D55/075, A61G5/06C, A61G5/06A, A61G5/08