CA1215907A - Elevator device for wheelchair and wheelchair incorporating same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The invention relates to an elevator device for a wheelchair of the type comprising, on the one hand, an articulated structure comprising a seat, a footrest and a back, adapted on the frame of such a wheelchair and constituted by two symmetrical lateral systems each comprising a first deformable quadrilateral contributing to the support of the seat and articulated on the front part of the frame, a second deformable quadrilateral contributing to the support of the foot-rest, articulated on the front part of the first and a back reinforcement articulated on the first quadri-lateral opposite the second, and, on the other hand, at least one elastic compensating member, each lateral system comprises:
- a second deformable quadrilateral articu-lated on the front part of the frame, - a back reinforcement constituted by a tri-lateral articulated on the first quadrilateral, - an elastic member interposed between the first quadrilateral and the frame, - and a manoeuvring assembly interposed between the first quadrilateral and the frame and per-forming a function of control of the relative pivoting of the system and a function of geometrical locking of the system in position of lowering or of elevation of the structure with respect to the frame.

Description

- ~Zl~;9(~7 , ~LEVATOR DEVICE FOR WHE~LCHAIR AND ~HEELC~LAIR INCORPORATING SA~.

The i vention rclates to ~he~lcilairs llsed by handicapp~d persons and invalids and is equally well applicabJe to folding or non-folding wheeJchair~.
It is an incontestablc fact that whcelchairs have given handicapped persons and invalids the possibility of rnobility. HoweYer~ these whee~chairs 5 pres~nt several drawbacks due to the users being able ~o occupy only one sitting position in ~hich they generally remain ~or relatively long periods of Time.
Firstly the solc sitting position ~ hich r~lay be adopted does not allow readap~ation to norn-al living conditions and do~s not laciJita~e social con~acts.
Sccondly this sitting position mainTained fo. long periods of timc is responsible lor physical degradation such as loss of an~ular amplitude of the louer limbs poor blood circulation slo~ing down of the diges~ive and intes~inal functions. fragiJity of the bones etc In an at~en~pt to overcome the above drawbacks different propcsitions have already been put forward.
A first proposition has been to provide the irame of a wheeJchair with an articulated struct-;re comprising a back a seat and a footres~. Such a structure is mounted to pivot by the s~at on a fronl horizontaJ axis perpendi-cular tc the vertical plane of symmctry o~ the Irame. In such an embc-dir.qent a jack incorporating an electric motor is interposed bet heen the IralTIe and the structurc and more general~!. tl e seat so as to be ab~e to contro~ the raising or lo~ering o~ tl~e articulat~d structure.
Such a solution invo3ves a sourc~ of energy borne by the wh~elchair and poses problems of safety reliabili~y price and weight by reason of the use o~ electrical encrgy. These different problems render practical application difficult if not impossiblc.
Another proposition has been to mount on the frame of a wheelchair a seat plvoting on a iront horizontal axis. A hydraulic pump controlled manual-ly suppli~s a hydraulic jack interposed between 5uch a seat and the ~ramc.
Such a solution is in fact of intcrest onl~ hen a handicapped person usin~ a supporting appliance o~ the orthosis Iype is to be transferred from a sit~inK position lto a standing position and vice versa. Such a solution thcrefore cannot solve the problem raised that of o~fcring the possibility for a handi-cappcd person to occupy a sittin~ position or a stable pseudo-vertical position in complete safety.

l~S~1~7 A third known solution has been to propose the adaptation on the two Jateral sides of a wheelchair oI two articulated systems fixed to the pivoting armre~ts. A1eans are provided ~or maintainin~ the two systems laterallyand to the rear when the ~-~heelchair is used normally. The means provkled 5 are also ~esi~ned so as to allow the two ar~iculated systems to be ~olded down forwardJy, in which case they may be connected by a front bar on ~hich the patient may exert a traction b~ his arms to find assistance ~or rising.
The tw.o articulaoed s!sterrls are ~enerally designed ~o ~orm a sort of cage, in association with the front bar, such a cage bein~ compJeted by 10 the existance oI pivoting stops which may represent a back or bottom support ~or the pa~ien~ occupying the slanding position.
Such a soJution seems to respond to the general problem posed, but leads to a device which is long to piace in position or possibly to retract after use. In addition, such a device is little used in practice as it does not 15 offer the pati~nt the possibility o~ making frequent transitions ~rom sittin~position to standing position, and vice versa, rapidly, easily and without ~reatfatigue.
Fur~herm~re, ~he ~echnica1 means retained form a cumbersorne assem-bly rendering the wheelchair unusable in nurnerous practical cases, whenever 20 the ground surface s3r the volume of aecess is reduced.
Moreover, such a system can really be used only by a handicapped person or invalid capa~le of developing considerable muscular work and o~
finding a possibili~y of blocking the joints whcn the standing posision has been at~ained.
It is an objec~ oJ ~he invention to provide a real, practical solution ~o the problem se~ ~orth abovc, by proposin~ a simpJe~ robust, adjustable deviceoffering certain security and reliability, even when subjected to intensive use.
The objec~ of the inven~ion is designed so as to ~limina~e any auxiliary 30 or additional energy supply and to be 2ble to be used vir~ualJy by any handi-capped person, whatcver his age and the physical power that he can develop.
It is another c~hject of the invcntion to offer means of small dimensions which rnay be provided at rnanu~acture on wheelchairs especially designed to this end or adapted to equip whcelchairs of conventional design, whether 35 such whcelchairs are of rigid or foldable structure.

15.~'7 lt is a further object of the invention IO propose a novel device for adjusting, with precision, the different parameters having to be considered to effect transition from the sitting position to the standing position, taking into account the mor'phology, si~e and weight of each patient.
To attain the objectives set forth her'einabove, the object of the invention is characteri7ed in that it is in the form of an articulated structureconstituted b~ two articulated s)~stems symmetrical with respect to a vertical plane of symmetry, intcncled to be adapted laterally on tl-e frame o~ a wheel-chair and connected together by a back, a seat and a footrest, each articulated system comprising:
- a first deformable quadrilateral ;ntended to be mounted pivotally on the substantiallv front part of a wheelchair frame corresponding to the seat in order to contribute IO the support of a seat, - a second deformable quadrilateral articulated part!y on the first and partly on the frame in order to contribute to the support of a footrest, - a trilateral articulated on the first quadrilateral opposite the second in order to contribute to the support o~ a back, - an elastic member adapted to be interposed between the first quadri-Iateral and the frame, - and a manoeuvring assembly adapted to be disposed between the first quadrilateral and the frame in order to perform a function of manual control and monitoring of the relative pivoting of said system with respect to the frame and a function of stop and locking of said system in a lowered or elevated position of the structure.
The invention also relates to a wheelchair comprising an elevator device according to the invention.
The invention will be more readily understood on reading Ihe fol!owing description with reference to the accompanying drawings, in which:
Fig. I is a side elevation schematically showing a wheelchair for 30 a handicapped person or invalid, equipped with a device accorciing to the inven-tion.
Fig. 2 is a front view, on a different scale, taken along Jine 11-11 of ~ig. 1.
Fig. 3 is a schematic view, similar to FiK. 1, but illustrating a second 35 position characteristic of a wheelchair incorporating the device of the invention.

Fig. 4 is a schernatic view showing a variant embodiment of one of the elements constituting the object of the invention.
Referring no ~ to the drawin~s, Figs. I and 2 schematicalJy show a wheelchair I comprisin~ a frame 2 constituted by front uprights 3 and rear 5 uprights 4 connected together by sills 5 and crosspieces 6. These different constituent elements define a seat bearin~ reinforcement 7 and a back bearing reinforcement 8 in the upper part of which handles 9 may be provided to facilitate displacement of the wheelchair for a person assistin~ the handicappedperson.
The frame 2 is provided, in manr:er known per se, with bearing and driving wheels 10 and with swivelling guidin~ wheels 11.
The above frame 2 corresponds to a wheelchair of rigid design, but it is obvious that a substantially similar form is retained for a foldable wheel-chair. In Iact, in such a case~ the rigid elements forming the crosspieces 15 6 are replaced by folding elements of design known per se.
The above-described frarne 2 is equipped, accordin~ to the invention, with an elevator de ice in the form of an articulated structure 12 borne by the frame 2. The articulated structure is constituted by two articulated systems13 symmetrical with respec~ to a vertical plane of symmetry P of the wheel-20 chair or the bearing frame 2. Each articulated system 13 is intended to beadapted laterally on the frame 2 and is connected to the homologous system 13 by a back element 14, seat elementl5 and.footrest element 16. These differentelements are, in the example illustrated, formed by rigid structures, but it is obvious that a different embodiment may be adopted in the event of such 25 elements also having to comply with the imperalive of folding in concomitance with such possibility offered by the bearin ~ frame 2.
Each articulated s)stem 13 comprises a first deformable t1uad ilateral 17 constituted by t~!o bars 18 and 19 joined at their ends located near the back reinforcement ~, by a spacer bar 20. The quadrilateral 17 is adapted 30 to be disposed laterally, for example outside the corresponding lateral side of the frame 2, so that the bars 18 and 19 are substantially superposed.
The quadrilateral 17 is mounted on the seat reinforcement 7 by a first point of articulation 21 provided between the front free end of the lower bar 19 and, for example, the upper sill 5. A second point of articulation 22 35 is provided between the upper bar 18 and the seat reinforcement 7, so that ~s~0~

the geometrical axis of this point is substantially located in upper front position of said reinforcement 7. In the example illustrated the point of articulation 22 is borne by an ex~ension 23 formed by the corresponding front upright 3. In the case illustrated the distance separating tl-e points of articulation 21 and Z2 and that between the points 24 and 25 joining the bar 20 to the bars 1~ and 19 are equal and giv~ ~he quadrilateral 17 a privileged form of parallelogram.
A desired deforrnation of such a quadrilatera) may be envisaged with a view to adapting its characteristics as a function of the morphology of the patients. 1n this respect it may be provided to render the point of articula-tion 21 adjustable forwardly or rearwardly in the horizontal plane of the bearing Irame 2.
Each articulated system 13 further cornprises a second deformable quadrilateral 26 which is disposed on the frame 2 substantially in front of the seat reinforcement 7. Quadrilateral 26 comprises a jamb 27 connected by a point of articulation 2S to an e~tension 29 of the bar 18 be~ond the point of articulation 22. The extension 29 constitutes one of the sides of the quadri-lateral 26. The jamb 27 is joined to the corresponding front upright 3 by a spacer bar 30 articulated on points 31 and 32. The spacer bar 30 represents the third side of quadrilateral 26 of which the fourth is formed by that part of the upright 3 included bet een points of articulation 22 and 32.
The jamb 27 extends substantially belov the point of articulation 31 and supports a footrest 33 in cooperation ~ ith the jamb 27 of the homologousarticulated system. Although this has not been sho vn the means for connection between the footrest 33 and the jamb 27 are provided to allow adjustment in height and re ative orienlation.
The point of articulation 2~ is preferably adjustable so ~hat the practi-cal length of the extension Z9 can be modified and the inclination Gf the jamb 27 can be adapted as a function of the patient s morphology.
Each articulated system 13 further comprises an articulated trilateral 34 constituted by an upright 35 mounted pi~otally on pin 24. Trilateral 34 is composed of upright 35 the spacer bar 20 and a triangulation bar 36 articula-ted on the one hand on pin 25 and on the other hand on a pin 27 borne by the upright 35. The position of pin 37 on the upright 35 is preferably adjustable so as to allow possible adiustment o~ the angle formed by the upright with - \
~2~LS~9 -b-respect to the bar 18.
Each articulated systern 13 also comprises an elastic member 38 interposed between the deIormable quadrilateral 17 and the Irame 2. The elastic member 38 is interposed between the upper bar 1~ and the lower sill 5 5, being adapted on these elernents by points of articulation 39 and 40 which are preferably adjustable in position forwardly or rearwardly of the frame

2~ The elastic member 38 is designed to perform a function of compensation of ueight and energv absorption. as well as a function of restitution, as ~
appear hereinafter. The elastic member 38 may be constituted by a compensa-lO ting spring or, preferably according to the invention, bv a jack of the gasactuated type, advantageously provided with a valve for adjusting the transler of its fluid. Fig. 2 shows that the elastic member 38 is preferably placed inside the seat reinforcement 7 of the frame 2.
Each ar~iculated system 13 further comprises a manoeuvring member 15 41 intended to perform a function of manual controJ of the relative pivoting of the articulated system 13 with respect to the frame and a function of stop and locking of said system in a position of maximum lowering correspon-ding to the sitting position, as shown in Fig. 1, or in a position of elevation as will follow from the following. To this end, the manoeuvring assembly 20 41 comprises a lever 42 mounted pivotally by a point 43 on the first quadrilate-ral 17 and preferably on the upper bar 18. The lever 42 is extended by an angle arm 44 extending towards the front part of the frame 2 and joined by an articulation 45 to a connecting rod 46 mounted by a point oi articulation 47 on the frame 2. The elements constituting the assembly 41 are disposed 25 laterally and externally with respect to the articulatcd system 13, as shoun in Fig. 2.
~ ig. I shows that the assembly 41 is designed so that, in a position of ma~imum lowering corresponding substar)tially to tl-e sitting position, the pivot pin 43 is disposed below the fic~itious line passing through the points 30 of articulation 45 and 47. This results in a geometrical locking which opposes any untimely pivoting of the lever 42 in the direction of arrow fl. The functionof locking is completed by a function of stop determining the sitting position.
This stop function is for example performed by a catch 48 or the like borne by the arm 44 and under which the connecting rod 46 abuts in the position 35 illustrated in the drawing. This stop rnay be principal or preferably secondary, intervening in combination with a damper placecl between the quadrilateral 17 and the seat reinforcement 7.
As stated previously, the two articulated systems 13 ;~re connected by back, seat and footrest elements which are designed to establish a conjuga-5 tion of their relative displacement and form therewith the articulated structure12.
In the state illustrated in Fig. 1, the structure 12 occupies a position of maximum lowering with stop and locking and the wheelchair then performs the function of seat for a patient occupying the seat, back and footrest. In ' this position, the elastic members 38 are compressed.
When the patient wishes to be transferred from sitting position to a pseudo-vertica! position, he acts on levers 42, pivoting them in the directionof arrow fl, so as to pass the points of articulation 43 beyond the alignment of points 45 and 47 and thus to break the lateral geometrical lockings esta-15 blished by the assemblies 41. The levers 42 rnay thus pivot on points 43, abuttingby points 45 on the connectin~ rods 46. This results in the combined elevation of points 43 which controls pivoting of the quadrilaterals 17 in the direction of arrow f2 on points 21-22. This pivoting, once started by action on levers 42, is taken over, assisted or maintained, depending on the adjustments made, 20 by the elastic members 38 which restitute the energy previously stored.
In this way, the patient is progressively raised by the pivoting of the quadrilaterals 17 of the articulated systems 13, whilst having the possibility of controlling this pivoting movement by a retaining action on the levers 42, insofar as the action of restitution of the elastic members 35 is sufficient25 to take over pivoting of the structure 12 after unlocking by manual action on the levers 42.
By the pivoting of the deformable quadrilaterals J7, the trilaterals 34 are raised and maintain the uprights 35 substantially in their initial orienta-tion. This results in a pro~ressive opening of the angle formed between thc 30 seat and back planes.
Simultaneously, the downward pivoting of the extensions 29 subjects the quadrilaterals 26 to a corresponding deformation tencling to lower the ~s~

footrese 33. The jambs 27 are of such iength that, as a function of the adjust-men~ made to point 28, they abut on the ~round when the structure 12 occupies the position of maximum eJevation shown in Fig. 3. This position is attained, determined and locked via the two assemblies 41. In fact, the relative pivoting 5 in the direction of arrow fl of the levers 42 and the corresponding relative pivoting of the two quadrilaterals 17 have for their effect to bring points 45 beyond the alignment of the points of articulation 43.
This results in a geometrical locking in a stable position of elevation, determined by the abutment of arms 44 against stops 49 borne for example 10 by the lower bars 19 of the deformable quadrilaterals 17.
The above means consequently make it possible to maintain the struc-ture 12 in a position of elevation, as illustrated in Fig. 3, in which it represents a continuous plane of support and hold for a patient maintained in a virtually s~anding posture, bearing by his feet on the footrest 33.
IS Stable restraint of the patient may be ensured if necessary by straps passing around the legs and the torso.
When the patient wishes to control the reverse transition towards ~he stable sitting position, he acts on levers 42 in the direction of arrow f3 so as to break the geometrical lock allowing rotation of the levers on the 20 points of articulation 43. By effect of traction exerted on the connecting rods 469 the rotation of levers 42 is translated by a pivoting of the two defor-mable parallelograms 17 in the direction of arrow f4 and by a concomitant displacement of the quadrilaterals 26 and the trilaterals 34.
When this movement is started, the weigh~ of the reinforcerr,er t 25 12 and of the patient is responsible for the compression of the springs 3~
which store the restitution energy as the articulated structure 12 pivots in return towards its lower position.
The elastic membcrs 38 are provided to offer a certain resistance to such a cornpression, so as to effect a compensation of the weights supported 30 and to avoid a rapid return to the stable position of rnaximum lowering. As before, levers 42 make it possible to control, if necessary, the pivoting of structure 12 towards this position of maximum lowering.
Adjustment of the relative position and of the reaction of compression opposed by the elastic members 38 are in practice determined so as to obtain, 35 for a patient of given weight, a slow, progressive return from the position .

L$~
g of ma~imum elevation to the position of maximum iowering. In such a case of adjustment, the reverse pivoting involves a weak but constant ac~ion on ~he levers 42 so as to apply an additional force capable of overcorning the frictions created by the pivoting of the different elements constit~lting the 5 articulated structure 12 and of being added to the work of the elastic members 38.
As is seen from the foregoing, the means according to the invention are simple, inexpensive, reliable and robust and make it possible, withou-t additional outside energy, to control a transfer from a position of maximum 10 lowering to a position of maximum elevation, and vice versa, of the articulated structure i2 ensuring either the support of a patient in sitting position, or the maintenance of the patient In a virtually standin~ posture.
The means of the invention offer noteworthy stability in the position of maximum elevation, since the articulated structure 12, in extended position, 15 finds additional support on the ground via the jambs 27 which increase the bearin~ surface determined by the points of contact between the ground S
and the wheels 10 and 11.
It should be noted that the particular form of the manoeuvring assem-blies 41 is also chosen so ~hat the levers 42 represent, in the position of maxi-20 mum elevation, as illustrated in Fig. 3, lateral elements capable of contributingto a transverse wed~ing of the patient's body, if necessary.
In cer~ain cases, each manoeuvring assembly 41 may be provided with means for multiplying the amplitude of displacement, so as to reduce the amplitude of pivoting of lever 42. In that case, each assembly 41 comprises,25 as illustrated in Fi~. 49 a lever 42a articulated directly by point 43a on the deformable quadrilateral 17. Lever 42a is associated by a point of articulation 50 with an arm 51 which is articulated by a point 52 on a crank 53 itself articulated on a point 54 borne by the deformable quadrilateral 17. The end o~ crank 53, opposite the point of articulation 54, is joined by an articulation30 55 ~o connecting rod 46a.
Assemblies 41a function in similar manner to what is described above and perform the same functions for a lower amplitude of angular pivoting of the levers 42a.
The means of the invention make it possible to effect a rapid transfer 35 of position~ without using a great deal of physical energy, and may thus be - \
~2~
--lo-used relatively frequently by a patient wishing to adopt ~n upright position to facilitate his general activity and for carrying out ordinary tasks, or wishing to change his position so as to favour maintaining more suitable physical conditions.
S Another advantage of the object of the invention lies in the fact that the means used are of particularly small dimensions and are included within the maximum volume of an ordinary wheelchair.
Another important advantage of the object of the invention lies in the fact tha~ the technical means recommended make it possible to consti-10 tute an elevator device representing a structure easily adapted on a wheelchair of ordinary type, on the frame of which the necessary points of articulation are added.
It thus becomes possible to envisage marketin~ the elevator device alone and to fit it on wheelchairs of conventional design, or to envisage produ-~5 cing wheelchairs fitted at manufacture with a device according to the inven~ion.
In ~his respect, the invention therefore relates to an elevator deviceIn the genera3 sense and to a wheelchair, of any design, comprising such a device.
Another important advanta~e of the invention resides in that the 20 physical energy spent by the action of the arms on the levers 42 may be re-duced by using to advanta~e the action of the body and, more particular~y, of the torso on the back part of the structure 12. In fact, insofar as a strap connects the patient's torso to the back, a thrust action in the direction of arrow fS (Fig. I) has for its effect to stress the trilaterals 34 which then 25 tend to provoke pivoting of the quadrilaterals 17 in the direction o~ arrow f2. Such an action therefore contributes to reducin~ the force exerted on the levers 42~
A traction exerted in the direction of arrow f6, from the position according to Fig. 3, produces a similar aid for returnin~ the structure 12 into 30 sitting positionO
The invention is not limited to the examples described and shown, as various modifications may be made thereto without departin~ from the scope thereof.

Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An elevator device for a chair structure having a frame, and a seat, a backrest, and a footrest, movable between a first, sitting position and a second, standing position, the elevator device comprising:
(A) a first quadrilateral link mechanism attached to each side of the seat and pivotally atta-ched to the frame;
(B) a second quadrilateral link mechanism attached to each side of the footrest and attached to the first quadrilateral link mechanism and pivotally attached to the frame;
(C) a trilateral link mechanism attached to each side of the backrest and pivotally attached to the first quadrilateral link mechanism;
(D) manually operable maneuvering linkages located on each side of the chair structure, each com-prising:
(i) a lever pivotally attached to the first quadrilateral link mechanism at a first pivot point;
(ii) a rod; and, (iii) first means pivotally connecting the rod to the lever at a second pivot point and second means pivotally connecting the rod to the frame at a third pivot point, such that in the first, sitting po-sition, the first pivot point is below a line passing through the second and third pivot points and, in the second, standing position, the second pivot point is above a line passing through the first and third pivot points so as to form an overcenter locking mechanism in each position; and (E) an elastic member interposed between the first quadrilateral link mechanism and the frame to counterbalance the weight of the user during movement between the sitting and standing positions.

2. The elevator device according to claim 1 further comprising a stop catch attached to the lever so as to contact the rod to limit the lowering motion of the device and define the first, sitting position.

3. The elevator device according to claim 1 wherein the lever comprises first and second lever arms, the first pivot point located at the juncture of the lever arms and the second pivot point being located adjacent the distal end of the second lever arm.

4. The elevator device according to claim 3 wherein the first and second lever arms are disposed at approximately 90° from each other.

5. The elevator device according to claim 3 fur-ther comprising a first stop catch attached to the se-cond lever arm so as to contact the rod to limit the lowering motion of the device and define the first, sitting position.

6. The elevator device according to claim 5 fur-ther comprising a second stop catch attached to the first quadrilateral link mechanism so as to contact the second lever arm to limit the raising motion of the de-vice and define the second, standing position.

7. The elevator device according to claim 1 wherein the elastic member comprises a gas actuated jack.

8. The elevator device according to claim 1 wherein the first means connecting the rod to the lever multiplies the amplitude of displacement of first qua-drilateral link mechanism.

9. A wheelchair for an invalid or handicapped person comprising:
(A) a frame;
(B) a plurality of wheels rotatably attached to the frame;
(C) a seat;
(D) a backrest;
(E) a footrest;
(F) a first quadrilateral link mechanism attached to each side of the seat and pivotally atta-ched to the frame;
(G) a second quadrilateral link mechanism attached to each side of the footrest and attached to the first quadrilateral link mechanism and pivotally attached to the frame;
(H) a trilateral link mechanism attached to each side of the backrest and pivotally attached to the first quadrilateral link mechanism;
(I) manually operable maneuvering linkages located on each side of the wheelchair, each compri-sing:
(i) a lever pivotally attached to the first quadrilateral link mechanism at a first pivot point;
(ii) a rod; and, (iii) first means pivotally connecting the rod to the lever at a second pivot point and second means pivotally connecting the rod to the frame at a third pivot point, such that in the first, sitting po-sition, the first pivot point is below a line passing through the second and third pivot points and, in the second, standing position, the second pivot point is above the line passing through the first and third pi-vot points so as to form an overcenter locking mecha-nism in each position; and, (J) an elastic member interposed between the first quadrilateral link mechanism and the frame to counterbalance the weight of the user during movement between the sitting and standing positions.

10. The wheelchair according to claim 9 further comprising a stop catch attached to the lever so as to contact the rod to limit the lowering motion of the de-vice and define the first, sitting position.

11. The wheelchair according to claim 9 wherein the lever comprises first and second lever arms, the first pivot point located at the juncture of the lever arms and the second pivot point being located adjacent the distal end of the second lever arm.

12. The wheelchair according to claim 11 wherein the first and second lever arms are disposed at appro-ximately 90° from each other.

13. The wheelchair according to claim 11 further comprising a first stop catch attached to the second lever arm so as to contact the rod to limit the lowe-ring motion of the device and define the first, sitting position.

14. The wheelchair according to claim 13 further comprising a second stop catch attached to the first quadrilateral link mechanism so as to contact the se-cond lever arm to limit the raising motion of the devi-ce and define the second, standing position.

15. The wheelchair according to claim 9 wherein the elastic member comprises a gas actuated jack.

16. The elevator device according to claim 9 wherein the first means connecting the rod to the lever multiplies the amplitude of displacement of first qua-drilateral link mechanism.