US 3269478 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Aug. 30, 1966 D, E, JQSLYN 3,269,478
STAIR CLIMBING WHEEL CHAIR Flled Dec. 6, 1965 2 Sheets-Sheet l INVENTOR DONALD E. Josu/N M Arme/ve vs.
Aug. 30, 1966 D. E. JosLYN 3,26%47@ STAIR CLIMBING WHEEL CHAIR Filed Dec. 6, 1965 2 Sheets-Sheet 2 mvNToR DONA/.o E. las/.vw
M ATTORNEYS- United States Patent O M 3,269,478 STAIR CLIMBING WHEEL CHAIR Donald E. Joslyn, 252 Skiil' St., Hamden, Conn. Filed nee. 6, 196s, sa. No. 511,741 9 Claims. (Cl. MiG- 8) This invention relates to wheel chairs for invalids, and it relates more particularly to wheel chairs which enable the occupant tto travel safely up or down stairs and over curbs, as well as on the level, the present application being a continuation-impart of my copending Iapplication Ser. No. 350,263 filed March 9, 1964, and now abandoned.
A primary object of my invention is to provide la wheel chair which is equipped with a mechanical means for climbing up and down stairs and over curbs, while at the same time has all the features of a conventional hand-propelled wheel chair so that the occupant can maneuver the chair in the usual manner. Conventional wheel chai-rs, including those having power for driving the wheels can not negotiate stairs, steps, or in some cases street curbs, without the assistance of an attendant. Even then, it is difficult if not impossible to do, and it may be extremely dangerous, especially when an attempt is made to lift the chair and its occupant manually up a stairway of any length. In many cases the occupant does not have suficient strength in his arms or hands even to manipulate a chair over la curb.
There are accordingly many situations where an invalid could get around in a wheel chair if the chair were provided with an easily operated power-driven climbing mechanism, so that it can be positively maneuvered up `and down stairs or over curbs.
Another object of the invention is to provide a climbing mechanism which can be incorporated in the wheel chair of the collapsible type, so that the chair can t easily into an automobile. Other important requirements of such wheel chair are that it operate with absolute reliability, in Aorder to give 4the occupant a sense of confidence and assurance; that it be of strong construction, yet light in weight land compact; and that it have a suitable source of power for self-propulsion in situations where manual power is not suiicient.
These and other objects are attained by the present invention, wherein `a wheel chair is provided with front and rear rests on which it can be supported in a substantial-ly normal position when climbing a stairway or the like, while the wheels which are normally used are retracted. The chair is also provided with a pair of front legs and a pair of rear legs, which are pivoted so that they swing fore-and-aft of the chair. Each of the legs is extendible lengthwise of itself by means of a power device, so that the chair can be raised olf it-s supporting rests for fore-'and-aft movement on its legs. ln addition, another `power device is connected between the chair and at least one of the legs for pivota'lly driving the legs so that the chair can be moved forward or back while it is supported by the legs. Control means are likewise provided `for operating the lifting and driving power devices, so that the occupant of the chair can raise the chair up on its legs, move it forward or back over a stair lor stairs and set it down on its rests on the stairs. The legs are then retracted, swung into position on the next set of steps and extended to raise the chair again, so that it can be moved into a new position, either up or down the stairs, or even on the level `or other walking surface.
As will become apparent from the description of one embodiment of the invention which is shown in the accompanying drawings, each lifting leg may consist of a power cylinder, `one end of which is pivoted to the 3,269,478 Patented August 30, 1966 ICC chair, the piston rod of each power cylinder being directed downward for engagement with the surface along which the chair i-s traveling. The power' means for moving the chair fore-and-aft may also be power cylinders, which are preferably connected to the legs at the front of the chair. In order to position the rear legs at the desired point on the stair when the legs are retracted and while the chair `rests on its said support means, connecting rods may be provided between the front and rear legs so that both front and rear legs `are swung into position simultaneously. This eliminates the need :for shifting the front or rear legs independently of the other when they are raised off the floor. The piston rods of the lifting cylinders are extendable down into engagement with the floor or with the stairs, as the case may be, and the chair lifted vertically on said lifting legs from its support into a position so that it can be shifted forward or back onto the next step by means lof the driving cylinders. While the chair is thus supported on its legs, the connecting rods between the legs are inoperative and must be provided with means which permit them to elongate or shorten so that the chair can be swung into position onto the next step. Consequently,` las will be appreciated hereinafter, the connecting rods function lonly as a means of positioning the second pair of legs whi-le said legs are retracted. However, instead of using the connecting rods between the legs, it may be desirable in some cases to provide driving cylinders for both the front and back legs, thereby making it possible to position each pair of legs completely independently of the other.
The stair climbing mechanism of the present invention makes it possible for a person confined to the chair to negotiate stairs or steep slopes which conventional wheel chairs can not handle. Moreover, .the climbing mechanism can be controlled positively so that the chair does not tilt or tumble, endangering the occupant thereof. These and other advantages of the invention will become more apparent from @the specific description hereinafter of one particular embodiment of the invention shown more or less diagrammatically in the accompanying drawings, wherein FIG. l is a side elevational view of a stair climbing wheel chair in accordance with my invention, the chair being shown in the starting position as it is about to climb a set of stairs;
FIG. 2 is a view similar to FIG. 1, but showing the chair as it approaches the top of the stairs, and with the right driving wheel and mounting channel therefor `removed for purposes of clarity;
FIG. 3 is a longitudinal section through the length adjusting device for a connecting rod for the climbing mechanism;
FIG. 4 is a rear view of a modified form of wheel chair embodying the invention,
FIG. 5 is a vertical section taken on the line 5 5 of FIG. 4 and looking in the direction of the arrows;
FIG. 6 is a detail View in section taken on the line 6-5 of FIG. 5, showing a spring latch device for positioning the driving wheels for the chair; and
FIG. 7 is a diagram of the pneumatic system for operating the chair climbing mechanism.
Referring more particularly to FIGS. il and 2 of the drawings the chair 10, which is desirably constructed of light, rigid side frames 12, each having a hack portion 14, horizontal arm rest 16, and foot rest 18. Side frames 12 are spaced laterally of each other and are connected by a collapsible structure, which forms the seat and back rest for the chair as in conventional wheel chairs. A pair of swivel wheels 20 are provided just to the rear of the foot rest i8, and two large driving wheels 22, having hand 3 rims for manually propelling the chair, are provided, one on either side of the chair.
As will be more apparent hereinafter, driving wheels 22 are mounted so that they can be raised from their normal position for operation on level terrain, to a stair climbing position, as shown in broken lines in FIG. l, where they do not interfere with the movements of the chair as it is climbing the stairs. Thus, the hubs 24 for the rear driving wheels 22, are slidably mounted in a channel track 26, which is fixed to the side frames 12 of the chair and inclined upwardly and forwardly, as shown in FIG. l. When the driving wheels 22 are located in their normal position for use in traveling on level ground, they are locked in place by means of a spring plunger .25, such as that shown in FIG. 6 and more fully described hereinafter. On the other hand, when the chair is supported on the stair climbing mechanism, driving wheels 22 are moved up to the upper end of tracks 26 by disengaging the spring plunger and lifting the wlheels 22 into their inoperative position shown in FIG. 1 where they are again locked in position while the stair-climbing mechanism is in use.
The base of each side frame 12 of the chair is provided with xed rear and front rests 28 and 30, respectively, when it is resting on two adjacent steps, as shown in FIG. 2. To this end, rear rests 28 are disposed approximately one stair-riser distance above front rests 30. Moreover, each rest 30 is provided with a vertical adjustment within easy reach of the occupant, in order to accommodate steps of different height. When the driving wheels 22 are in the normal position, as shown in solid lines in FIG. l, for traveling on level ground, rests `28 and 30 are well above the ground so that they do not interfere with the normal operation of the ohair.
Chair 10 is designed in this instance to go up and down stairs with the occupant facing down the stairs, and to this end is provided with two pairs of lifting legs, one pair being pivotally mounted on the chair near the front, and the other at the back of the chair. The rear legs consist of a pair of power cylinders 32, each pivotally connected at one end 32 to the upper end of the back 14 on opposite sides of the chair. In like manner, the front legs consist of a pair of power cylinders 34, each pivoted at one end 35 to the front end of arrn rest 16 on each side of the chair. Cylinders 32 and 34 are so mounted that they swing in planes parallel to the side frames 12 of the chair on opposite sides thereof. It is desirable, moreover, that the pivot points of cylinders 32 and 34 be located one above the other on a line which is more or less parallel with the line defined by rests 28 and 30. In the particular embodiment of the invention here shown, power cylinders 32 and 34 are pneumatically operated and are supplied compressed air from a container or tank T (FIG. 7) suitably mounted on the chair. For this purpose a conventional pressure tank, reducing and regulating valves, such as those used in skin diving, may be employed. Alternatively, hydraulic cylinders may be used with power furnished by a battery-operated electric pump.
Each of cylinders 32 .and 34 has a downwardly extending piston rod 36 and 38, respectively, having a shoe or pad 40 and 42, respectively, at its free end. In this particular instance cylinders 32 and 34 are single-acting, air being supplied at their upper ends above their pistons so that the chair can be raised bodily off its rests 28 and 30. `In addition each cylinder is provided with a return spring for retracting shoes 40, 42 oft' the ground, so that they can be moved onto another step, as will be more apparent hereinafter. The rear cylinders 32 have a stroke which is at least twice as long as the height of the tallest step to be encountered, so that the back of the chair can be lifted a distance equal to twice the height of each stair. The stroke of the piston rods of the front cylinder 34, on the other hand, need only be long enough to lift the chair a distance equal to the height of one stair. This difference in cylinder strokes is due to the fact that when the chair is leaving or entering the top of a stairway, the rear cylinders must extend two stair-riser lengths down from its fully retracted position into engagement with the floor, as indicated in the broken-line position C in FIG. 2. However, in the arrangement here shown where the chair faces outward, the front cylinders need to extend only one stairriser length. The foregoing will become more apparent from the description of the operation of the chair hereinafter.
In order to move the chair in a horizontal direction when it is carried on lifting cylinders 32, 34, another pneumatic cylinder 44 (herein referred to as the driving cylinder) is pivotally mounted at 46 on each side frame 12 of the chair. The piston rod 48 of each driving cylinder 44 is pivotally connected at 49 to the corresponding front elevating cylinder 34 and swings it back and forth, in order to move the chair in a horizontal direction. Driving cylinders 44 are double-acting for positive control of the pivotal movement of elevating cylinders 34. Thus, when the Weight of the chair is taken on elevating cylinders 32, 34, extension of piston rods 48 of driving cylinders 44 causes front lifting cylinders 34 to swing counterclockwise, as viewed in FIGS. l and 2, relative to the frame of the chair. This causes the chair to move backward, or to the left as shown in the drawings. Retraction of the piston rods 48 of cylinders 44 shifts the chair forward.
It will be apparent from the foregoing that driving cylinders 44 may be connected to either the front or rear pair of legs, since pivotal movement of any of the legs causes the chair to move horizontally. Moreover, pivotal movement of any of the legs, causes all of them to pivot together. When the chair is supported on the stairs on its rests 28 and 30, fthe piston rods 36 and 38 of both sets of lifting cylinders are retracted so that they can be swung to a new position. Driving cylinders 44 are used in this instance to swing both the front lifting cylinders 34 and the rear lifting cylinders 32 into position simultaneously. However, in'order to do this it is necessary to provide a connection rod 50 between the front and rear legs at each side of the chair, each connecting rod being pivotally connected to the lower ends of lifting cylinders 32 and 34 at pivot points 52 and 54, respectively. Connecting rods 50 transmit the swinging movement of front elevating cylinders 34 to the rear cylinders 32 only when the shoes 40, 42 of the elevating cylinders are retracted off the floor, so that both elevating cylinders can be swung into position simultaneously in preparation for the next step.
The pivot points 52 and 54 at which connecting rods 50 are pivoted to adjacent front and rear lifting cylinders are located equidistant from the respective pivot points 33 and 35 at which lifting cylinders 32 and 34, respectively, are pivoted to the chair. Consequently, when the shoes 40, 42 are raised from the oor upon retraction of piston rods 36, 38, cylinders 32, 34 can be freely swung in unison on pivot points 33, 35 by means of cylinders 44. However when the chair 10 is moved in a horizontal direction as it is climbing the stairs, and especially as it enters or leaves the stairway, either at the top or bottom thereof, the length of the front and rear legs (ie. the distance from the pivot points 33 and 35 to the shoes 40 and 42, respectively) will not be equal. Under the circumstances lifting cylinders 32 and 34 will not swing through the same amount of rotation relative to each other, assuming of course that the shoes 40 and 42 on elevating cylinders 32 and 34 remain at the same place on the floor as the chair is shifted forward or back on its climbing legs. Accordingly, the distance between the pivot points 52 and 54 at which connecting rod 50 is fastened to cylinders 32 and 34 will increase or decrease slightly, depending on which way the chair is moved on its legs. Rod 50 therefore can not be of xed length without interfering with the action of the climbing legs of the chair while they are actually moving the chair in a horizontal direction.
In order to allow for such increase or decrease in the distance between pivot points 52 and 54, each connecting rod 5) is made in two sections connected by a compen- 'sating coupling 56, which permits rod 50 to increase or decrease in length, while at the same time transmits the motion of the front legs to the rear legs in order to position the shoes 40, 42 at the desired points on the stairs while they are suspended above the licor. As may be seen in FIG. 3, each compensating coupling 56, consists of an outer cylindrical housing 58, to one end of which is xed the lower section of connecting rod 50. The upper section of connecting rod 50 tits through an opening in the top of housing 58 and has a plunger 60 attached to its inner end. Plunger 60 is normally held mid-way between the ends of housing 58 by opposing coil springs 62 and 64, which are compressed between opposite ends of housing 58 and plunger 60. Springs 62 and 64 are of sufficient strength to transmit the unloaded push or pull of front elevating cylinder 34 on rear cylinder 32 when their shoes 40, 42 are lifted olf the ground. However, when the chair is shifted up or down the stairs on its lifting cylinders 32, 34, plunger 60 inside compensating coupling 56 can move in either direction longitudinally of housing 58 so that connecting rod 50 will be elongated or shortened in order to compensate for the change in distance between the points 52 and 54 at which it is connected to cylinders 32 and 34. Moreover, springs 62, 64 should be light enough so that there is no danger of the connecting rods forcing the shoes 40, 42 to slide on the steps or floor when they carry the weight of the chair.
It is of course apparent that connecting rods 50 can be replaced by suitable means for positioning the front and rear legs independently of each other. For example, each rear-leg cylinder 32 could be operated by another power cylinder similar to the cylinders 44 for the front legs and could be arranged to function in synchronism with cylinders 44 so that both the front 'and back legs swing in unison with each other, but with separate driving cylinders.
The lifting and driving cylinders of the stair-climbing mechanism may be operated by means of conventional pneumatic control valves and air supply lines shown by way of example in FIG. 7. Separate three-way control valves 70 and 72 are provided for elevating the chair on its stair-climbing mechanism. Control valves 70 and 72 can be manipulated individually to direct air from a main pressure line 74 to the rear lifting cylinders 32, 32 through supply line 76, and through supply line 73 to the front lifting cylinders 34, 34, respectively. Main pressure line 74 is supplied by pressure tank T and is provided with the usual cut-off and reducing valves. When valves 70 and 72 are in the position at which valve 70 is shown in the drawing, air pressure is supplied to the lifting cylinders in order to raise the chair to the desired level. By rotating these valves to an intermediate position illustrated by valve 72, cylinders 32 and 34 are cut-off from the air supply, but the pressure in the cylinders is maintained. When it is desired to lower the chair valves 70 and 72 are rotated until the supply lines 76 and 78 to cylinders 32 and 34 are connected with the vent lines to each valve, releasing the air in said cylinders.
By using separate con-trol valves for operating the front and rear lifting cylinders, the level of the chair fore-andaft can be controlled by .the occupant so that he will be more comfortable. lf desired, the chair can be provided with suitable stops .to prevent it from tilting too far in either direction when one or the other set of lifting cylinder-s is extended too far relative to the other. Furthermore, a self-leveling device can be readily installed in order to automatically keep the chair level.
A single ifour-lway valve 80 controls the fore-and-aft movement of the chair when it is supported on its legs. Valve 80 has connections to the main air supply line 74, supply-and-return lines S2 and 84 to `driving cylinders 44, 44, and a vent line. When valve 80 is rotated 45 to the right from the position shown in FIG. 7, line `82 to the rear end of cyl-inders 44 is connected with the air supply while line 84 is vented, causing the pisto-n rods 48 to extend. This moves the chlair baclcward, if it is elevated on its legs or, if the chair is resting on its rests 28 and 30 with its shoes raised, extension orf cylinders 44, 44 pivots lifting cylinders 32, 34 forward. By returning valve 80 co-unterclcckwise to the position shown, movement of the chair horizontally on its climbing legs is stopped. Continued counterclocklwise rotation of valve 80 through an additional reverses the flow of air to cylinders 44, causing the piston rods 48 to retract, Ithus reversing t-he pivotal movement of `the cylinders 32 and 34.
In climbing a set of stairs, the chair is backed up to the bottom of the stairs until the large driving wheels 22 engage the edge of the rst step as shown in the full-line position of .the chair in FIG. l. The lifting cylinders 32, 34 are t-hen swung reanwardly and their piston rods 36, 38 extended until the rear shoes 40 corne in contact with the top of the first step and the front shoes 4t2f touch the floor. The weight of the chair is then removed from its driving wheels 22 and swivel wheels 20 by extending cylinders 32 and 34 a little more. With the weight removed `driving wheels 22 can be slid up on their tracks 26 to their inoperative position indicated by .the brokenline in FIG. l and the solid-line in FIG.. 2, so that the chair can tbe moved closer to .the stairs.
Valve 80 is then shifted so as to extend the piston rods of cylinders 44, which pivot lifting cylinders 34 counterclockwise, as viewed in FIG. 1. Since at this point the weight of the chair is carried by the lifting cylinders, counterclock-wise rotation of cylinders 34 albo-ut their pivot points 35 causes the chair to move back toward the stairs to the broken-line position shown in FIG. 1. As part of the weight of the chair and its occupant is also carried by the rear lifting cylinders 32, these cylinders likewise pivot about the pivot points 33 simult-aneously with cylinders 34. Any elongation or contraction required of connecting rods during this movement is taken care of by their compensating :couplings 56, Which permit cylinders 32 and 34 to pivot freely without interference by connecting rods 56. When the chlair reaches its broken-line position in FIG. l its rear rests 28 are located above the first step. The lifting cylinders 32 and 34 are then vented by operating control valves and 72. This lowers the rear rests 28 of the chair onto the first step and the front rests 30 onto the floor. Continued .venting of Vlifting cylinders 32 and 34 causes their piston rods to fully retract by the return springs in said cylinders, lifting shoes 40 and 42 off the ground. At this point lifting cylinders 312 and 34 are swung as far forward as they will go with respect to the chair to a position designated by the letter A. Suitable sto-ps (not shown) are provided on the chair in order to positively prevent cylinders 32 and 34 from swinging so far in this direction that the chair is in danger of toppling over backward.
With the shoes 40, 452 lifted off the ground, valve is reversed causing cylinders 44 to retract, thus pivoting front lifting cylinders 34 in a clockwise direction, which in turn pivot rear cylinders 32 a like amount through connecting rods 5t). When cylinders 32, 34 reach the broken-line positions designated B, the rear shoes 40 are located above the second step, so that they can be lowered iuto engagement therewith, and the front shoes 42 will engage the floor rearward of their initial position. Again positive stops (not shown) are provided on the ch-air for preventing cylinders 32, `34 `from pivoting too far in a clockwise direction, which would cause the center of gravity of the chair to be located too far forward with respect to .the s-hoes 40, 42, so that when it is elevated by cylinders 32, 34, it would be in danger of toppling forward.
By Amanipulating lift control valves 70 and 72 the lift cylinders 32 and 34 are extended elevati-ng chair 13 until its rear rests 28 are level with the next step. Control valve 86 is then shifted so as -to supply air to the top of driving cylinders 44 while venting their opposite sides, causing the chair to move back. When rear rests 28 of the chair are located over the second step and the front rests 30 over 'the first, the lifting cylinders are vented so that the chair is brought to rest on these two steps. With retraction of the shoes 40, 42, the lifting cylinders are again swung rearwardly from their A positions to their B positions, as indicated in broken-lines in FIG. 2 and the stepJby-step climbing operation repeated. In order to facilitate manipulation of the chair so that -it can be simultaneously raised and moved horizontally on its climbing legs, a `single elevating control valve may be employed, which will operate both front and back lift cylinders together and at the s-ame time provide control for leveling the chair. The occupant o-f the chair can then have one hand on the elevating control and t-he other on the foreiandeaft control so that they can be operated together.
FIG. 2 illustrates the situation arising when the chair reaches the top of a ight of stairs. It will be noted that in this situation, the rear lifting cylinders 32 are already extended a riser-height when their shoes 40 engage the landing in their B positions. Consequently, as the chair is raised so as to bring the forward rests 30 up to the height of the landing, and then swung back to the position indicated in FIG. 2 as C, the rear lifting cylinder 32 must extend two riser-heights of the stairs. The front lifting cylinders 34, however, still need extend only one riserheight. When the chair has reached the top of the stairway and while its lifting cylinders are fully extended, the large driving wheels 22 are lowered into their normal operating positions and locked in place. The lifting cylinders 32, 34 are then retracted, bringing the weight of the Chair onto its wheels 22, and the chair moved back from the stairs in the usual manner.
It will be noted that when lifting, cylinders 32, 34 are retracted and pivoted forward into their A positions, they are out of the way and take up very little space. Furthermore, since the climbing mechanism at each side of the chair is mechanically distinct from the other, the chair can be made collapsible for storage or transportation purposes. High-pressure exible hose connections between the controls and the power cylinders are also used for the same reason.
Referring now more particularly to FIGS. 4 and 5, it may be desirable for some purposes to provide the chair shown in FIGS. 1 and 2 with a set of auxiliary casters 90 at the back of each side frame 12, in order to facilitate use of the climbing mechanism in various situations Without the necessity of lowering the driving wheels 22. For example, if the stairway to be negotiated by the chair has a landing in the middle of it from which the stairs run in ditferent directions, it is necessary upon reaching the landing to change the direction of travel. In order to do this without auxiliary casters 90, the driving wheels 22 must be lowered. Furthermore, if the landing is small, there may -be insufficient room on it to turn the wheel chair with the large wheels 22 in place. By using the small auxiliary casters 90, however, the wheel chair can be turned in a much smaller space, as indicated in full lines in FIG. 5, as opposed to the substantially larger space required (broken-line showing), if the driving wheels 22 are lowered. Except for the auxiliary casters 90, the chair shown in FIGS. 4 and 5 is in all respects the same as that of FIGS. 1 and 2, and the same reference characters are used to designate like parts.
Casters 90 are each mounted on a vertically slidable post 92, which is held in a guide sleeve 94 mounted on the inner side of each side frame 12 of the chair. Post 92 slides freely up and down in guide sleeve 94 so that caster 90 can be moved into and out of operative relation with the floor as shown in full lines in FIG. 5. The upper end of post 92 is provided with a handle 96 which extends laterally from both sides of the post. When the caster 90 is lowered to the operative position, one end of handle 96 is aligned with a locking slot 98 in the mounting bracket for guide sleeve 94. By grasping handle 96 and turning post 92 about its longitudinal axis, one end of handle 96 can be readily engaged in locking slot 98, thus locking the auxiliary caster in its operating position.
To store auxiliary :caster 90 in its inoperative position, handle 96 is disengaged from locking slot 98 and raised to the broken-line position shown in FIG. 5 where handle 96 is simply latched over a peg 100 projected inwardly from the side wall 12 of the chair. Casters 90 t through an opening in a bracket 102 xed to the inside of the side frame of the chair and forming a part of the rear rest 28, on which the chair is supported when climbing stairs.
In addition to making it possible to negotiate tighter places, auxiliary casters 90 can be employed in leaving or approaching the top of a set of stairs where it would be more convenient for some people to use the auxiliary casters 90 near the edge of the top step rather than to raise or lower the large driving wheels 22 at this point.
It will be noted that FIG. 4 illustrates how the air pressure tank T may be suitably carried under the seat of the chair. The spring plungers 2S for latching the driving wheels 22 in place are also shown in FIG. 4. FIG. 6 shows the wheel latching'device in greater detail. Thus, a plunger 104 extends through the hub 24 of each driving wheel, represented in FIG. 6 by the -spokes 108. The inner end of plunger 104 is urged into engagement with locating holes in track 26 and side frame 12 -by a coil spring 112. The outer end of plunger 104 is pivotally connected to a lever 114, which is pivoted at one end to a nut 116 at the Outer end of hub 24. When it is desired to shift the position of driving wheel 22, the occupant pulls the free end of lever 114 out, in order to withdraw plunger 104 from the locating hole 110. The wheel 22 can then be moved on a slide plate 118 up or down track 26 to its other position, where plunger 104 automatically re-engages in a second locating hole 110 and holds the wheel securely in place.
What is claimed is:
1. A wheel chair comprising in combination,
(A) a pair of wheels rotatably and retract-ably mounted on the chair for supporting the same when traveling on substantially level ground,
(B) front and rear rests on said chair for supporting said chair in a substantially normal position on a walking surface, such as stairs, when said wheels are retracted,
(C) a pair of front legs pivotally mounted adjacent the front of said chair,
(D) a pair of rear legs pivotally mounted adjacent the rear of said chair,
(E.) each of said legs being mounted to swing fore-andaft of the chair and being extendible lengthwise for engagement of its free end with said walking surface,
(F) drive means connected between said chair and at least one of said legs for pivoting the same,
(G) power means for extending said legs and for actuating said drive means such that said chair can be raised off said front and rear rests and moved forward or back, and
(H) means for controlling said power means such that the occupant of the chair can sequentially raise the chair on said legs, move it forward or back while supported on said legs, and lower the chair onto said rests.
2. A wheel chair as dened in claim 1, wherein said drive means is drivingly connected to at least one of said legs on each side of the chair.
3. A wheel chair as defined in claim 1, wherein said legs are provided with means for retr-acting their free ends from engagement with said walking surface, and which further includes a connecting rod between said front and rear legs at each side of the chair for pivoting said legs simultaneously when said chair is supported on its said rests and when the free ends of said legs are retracted from said walking surface.
4. A wheel chair as defined in claim 3, wherein said connecting rod is provided with a compensating coupling which permits it to be elongated or shortened in order to compensate for any non-parallelism between the free ends of said legs at each side of the chair when resting on said walking surface and the pivot points of said legs when said chair is moved forward or back on said legs.
5. A wheel chair as dened in claim 1, wherein each of said legs comprises a power cylinder pivoted at one end to said chair and having a piston rod by which its other end is extended into engagement with said walking surface.
6. A wheel chair as dened in claim 5, wherein -said drive means comprises a pair of double-acting power cylinders, each operatively connected t-o one of said front legs.
7. A wheel chair as defined in claim 6, wherein said power cylinders for extending and pivoting said legs are pneumatically operated and said power means comprises a tank of compressed air connected to said power cylinders.
8. A wheel chair as defined in claim 1, wherein said wheels comprise a pair of large drive wheels having means for locking them in an operative position for normal travel of the wheel chair on substantially level ground and for moving and for locking them in an inoperative position where they do not interfere with said front and rear rests when climbing stairs or the like, said chair being further provided with a pair of small auxiliary wheels retractably mounted adjacent said rear rests for use in place of said large drive wheels.
9. A wheel chair as defined in claim 8, wherein said auxiliary wheels each comprise a caster mounted on a substantially vertically disposed post, and which further includes a guide sleeve mounted on said chair and receiving said post for slidably supporting the same, and means for latching `said post in a lowered position at which its caster can support said chair and in a raised position at which said caster is inoperative..
References Cited by the Examiner UNITED STATES PATENTS 468,022 2/1892 Bray 280-528 2,701,005 2/1955 Bennett et al 280-5.3 3,150,733 9/1964 Goebel 180-8 LEO FRIAGLIA, Primary Examiner.