US3072437A

US3072437A - Telescopic adjustable leg rest

Info

Publication number: US3072437A
Application number: US57240A
Authority: US
Inventors: William C Shea; William J Pivacek
Original assignee: MOBILAID Inc
Current assignee: MOBILAID Inc
Priority date: 1960-09-20
Filing date: 1960-09-20
Publication date: 1963-01-08
Anticipated expiration: 1980-01-08

Description

Jan. 8, 1963 w. c. SHEA ErAL TELESCOPIC ADJUSTABLE LEG REST 2 Sheets-Sheet 1 Filed Sept. 20, 1960 INVENTOR. W/L LIA/Y C! S'Hf?! W/lL/A/Y-Z' F/I/fiCf/T ader-g f I Jan. 8, 1963 w. c. SHEA EIAL 5 2,

' TELESCOPIC ADJUSTABLE LEG REST Filed Sept. 20, 1960 2 Sheets-Sheet 2 INVENT OR. WILL lA/Y 6.3715141 United States Patent 3,072,437 TELESCOPIC ADJUSTABLE LEG REST William C. Shea and William J. Pivacek, Elyria, Ohio, as-

signors to Mobilaid, Inc., Elyria, Ohio Filed Sept. 20, 1960, Ser. No. 57,240 9 Claims. (Cl. 297-435) This invention relates to an adjustable foot and leg rest for use with a chair and is designed especially for use with a collapsible wheel chair.

In the use of invalid wheel chairs, it is frequently necessary to be able to adjustably support the lower leg and foot of a person occupying the chair in any position between a normal sitting position with the lower leg extending downwardly and an extended position with the lower leg extending substantially horizontally approximately at the level of the seat of the chair.

In leg and foot rests of the type with which our invention is generally concerned, it is conventional to employ a leg rest panel for supporting the calf of the lower leg and a foot rest panel for supporting the sole of the foot. The distance between the midpoint, for example, of the calf and the sole of the foot of a particular person remains constant for all positions of the leg and, therefore, the distance between the midpoint, for example, of the leg support panel and the surface of the foot support panel ideally remains constant throughout all possible angular positions of adjustment of the leg and foot rest. Additionally, in order to provide adequate support, the supporting sunfiace of the foot rest panel ideally should remain at a substantially constant distance from the pivotal axis of the knee throughout all positions of swinging movement of the persons lower leg and foot regardless of his particular fore and aft location on the chair seat and without requiring shifting of the persons thighs and body in the seat of the chair upon angular adjustment of the leg support. It is, therefore, among the objects of our invention to provide an adjustable leg rest or foot support for an invalid chair, for example, which fulfills these requirements and thereby assures adequate and comtortablesupport for the leg of the user in all adjusted positions.

Another object of our invention is to provide a leg and foot rest which acts automatically to maintain the proper dimensional relationships between the support and the leg of the user mentioned above so that the lower leg and foot of the user are supported naturally and evenly in all adjusted positions and during movement therebetween.

It is another of our objects to provide self-energizing means for locking the adjustable leg and foot rest of my 7 invention in any of its angular positions of adjustment.

It is also our object to provide means which can be conveniently and easily operated by the occupant of a chair for unlocking the foot and legrest of our invention from any locked position of angular adjustment even whilet-he rest is supporting substantially the entire weight of the lower leg and foot of the occupant.

Another object is to provide such adjustable leg and foot support means that can be quickly and conveniently mounted and dernounted on a wide variety of chairs and which does not interfere with the normal functioning of the chair.

The means and manner for accomplishing these and other objects will become apparent from the following detailed description and appended claims together with the accompanying drawings of a particular embodiment of our invention in which:

FIGURE 1 is a top plan view of a conventional wheel chair equipped with a leg and foot support of our invention 'andshown in its extended or horizontal position of adjustment;

Fatented Jan. 8, 1963 "ice FIGURE 2 is a side elevation of the wheel chair and leg and foot support shown in FIGURE 1;

FIGURE 3 shows in perspective and in enlarged scale the adjustable leg and foot support shown in FIGURE 2 and a small portion of the wheel chair to which it is attached;

FIGURE 4, also in perspective and in larger scale than that of FIGURES 1 and 2, shows the leg and foot support in a lowered position together with parts of the wheel chair to which it is attached;

FIGURE 5 shows in substantially tull scale and with portions broken away the means for locking and unlocking the adjustable leg and foot support of my invention in and from various adjusted positions; and

FIGURE 6, also substantially full scale and with a portion broken away, is a view taken in plane 66 of FIGURE 3 showing in detail one of the adjusting means of the leg and foot support of our invention.

Briefly, our invention comprises a leg rest panel and a foot rest panel maintained in fixed adjusted relationship with respect to each other and related to and mounted on a chair such as an invalid wheel chair by means per-mitting both swinging movement in a vertical plane of the panels in their fixed adjusted relationship about a pivot point and forward and rearward movement of the pivot point with respect to the seat of the chair in the same vertical plane. The swinging movement is cont-rolled by a bracing rod and coacting lever operated and controlled eccentric cam mechanism. The complementary and cooperating swinging and translatory movements of which the support is capable permit the leg rest panel and foot rest panel to assume and to follow the natural positions and motion of the lower leg and foot of an occupant fixedly seated in the chair in any position from lowered vertical to extended horizontal and at all times permit the leg support panel and foot support panel to evenly and uniformly support the leg and foot of the occupant.

In the drawings, we have shown the adjustable foot and leg rest of our invention adapted for use with a conventional wheel chair indicated generally at W in FIG- URES l and 2. Wheel chair W has two spaced apart side frames 10, each having a front leg 11 and a lower rear leg 12 terminating in a handle 14. The front and rear legs 11 and 12 of each of the side frames 10 are connected by an arm rail 15 forming a support for arm rest 16, a seat rail 17 and a lower rail 18. Extending between the upper portion of rear legs 12 is a back panel 19 and between the seat rails 17 of each of side frames 10, a seat panel 20. Side panels 21 extend between and are fastened to front and rear legs 11 and 12 above seat rails 17 and below arm rests 16. The chair is provided with a pair of conventional large rear wheels 22 attached to rear legs 12 and caster wheels 23 pivotally mounted at the lower end of front legs 11.

As shown in FIGURES l and 2, wheel chair W is equipped with a fixed, downwardly extending leg and foot support of conventional construction indicated generally at 24 and mounted on the right-hand front leg 11. An adjustable leg and foot rest embodying our invention is shown generally at 26 in its position of extended adjustment for supporting the right leg of an occupant of the chair W in a generally horizontal position and mounted on front and rear legs 11 and 12 of the left-hand side frame 10. It is understood, of course, that the chair may be equipped with a pair of adjustable leg and foot rests embodying our invention or any combination of right-hand and left-hand adjustable and fixed leg and foot rest.

Referring now especially to FIGURES 3 and 4 of the drawings, our adjustable'leg and foot rest is made up of a swingable support 28 pivotally connected to a stub leg 29 at 30 for swinging movement substantially in the plane of stub leg 29. The support 28 is preferably comprised of an upper straight portion 31 and a lower L-shaped portion 32 telescopically fitting within upper portion 31 in order to provide for longitudinal adjustment of swingable support 28. The two

tubes

31 and 32 can be locked in any of the various positions of telescopic adjustment by means of a band clamp 33 fixedly attached to the outer tube 31 and adapted to constrict the wall of outer tube 31 against the wall of inner tube 32. In order to facilitate and promote the constriction of the wall of outer tube 31, we prefer to provide a T-shaped slot in the wall of the lower end of outer tube 31 comprising an axial portion 34 extending inwardly from the end of outer tube 31 and a circumferential portion 35 crossing the inward end of axial portion 34 as illustrated in FIGURE 6 of the drawings.

Upper tube 31 carries a leg support panel 36 swingable through a limited are about the axis of upper tube 31 and mounted thereon by means of U bolts 37. The lower portion 38 of inner tube 32 extending substantially at a right angle to that portion of tube sliding within outer tube 31 carries a foot support panel 39 swingably mounted thereon so that it may be folded and lie along support 28 when used in conjunction with a collapsible wheel chair.

The angular relationship between swingable support 28 and stub leg 29 is determined and maintained by brace rod 41 pivotally connected at 42 to the under or back side of upper tube 31 of swingable support 28. The other end of brace rod 41 acts through an eccentric cam adjustment and locking mechanism 43 mounted on the forward side of stub leg 29 below the pivotal connection 30 of stub leg '29 and swingable support 28.

The structure of locking mechanism 43 is shown to best advantage in FIGURE 5. The mechanism consists of a small diameter shaft or pin 44 journaled to the side of stub leg 29 at a point somewhat below pivotal connection 30 of swingable support 28 and stub leg 29. In FIGURE 5, we have shown in phantom only a portion of stub leg 29 in order to reveal more clearly the parts of locking mechanism 43. The relationship of pin 44 and pivot connection 30 on stub leg 29 can be seen clearly in FIGURES 3 and 4. The free ends of a U-shaped strap 45 are journaled on pin 44 permitting the closed end 46 of strap 45 to travel in a circular arc of fixed radius from pin 44. A cam 47 of approximately semi-circular shape is eccentrically mounted on and keyed to pin 44 at a point thereon between the two free ends of strap 45 so that the peripheral surface of cam 47 moves toward and away from closed end 46 of strap 45 as it is rotated relative thereto clockwise and counterclockwise, respectively, as seen in FIGURE 5. A spring 48 is also mounted on pin 44 and acts between strap 45 and cam 47, urging the latter to rotate clockwise with respect to the former. An unlocking lever 49 is also keyed to pin 43 permitting rotation of cam 47 in opposition to spring 48.

The free end of brace rod 41 passes through locking mechanism 43 between the periphery of cam 47 and closed end 46 of strap 45. The end of brace rod 41 may be provided with means such as acorn nut 50 to prevent the rod from sliding free of locking mechanism 43. Upon engagement with U-shaped strap 45, acorn nut 50 also acts to limit the upward swinging travel of support member 28.

Locking mechanism 43 acts automatically to resist motion of brace rod 41 therethrough in a generally downward and rearward direction as when lowering swingable support 28 while freely permitting travel of brace rod 41 in the. opposite direction therethrough as when swingable support 28 is raised. When it is desired to lower swingable support 28, cam 47 is rotated counterclockwise by means of unlocking lever 49 to release brace rod 41 from its wedged engagement between the cam and closed end 46 of strap 45, permitting brace 41 to slide through locking mechanism 43 in a downward and rearward direction. We prefer that the engaging surfaces of cam 47, brace rod 41 and strap 45 be made irregular or roughened to promote the frictional engagement between these surfaces when spring-urged cam 47 is acting to wedgingly engage brace rod 41 between itself and closed end 46 of strap 45. We have found that serrations or ridges extending transversely of the line of travel of brace rod 41 through locking mechanism 43 on the engaging surfaces accomplishes this purpose.

Pivotally connected swingable support 28 and stub leg 29 are mounted on the chair by means of a telescopic structure indicated generally at 52. Structure 52 consists of a pair of tubes 53 held in a fixed parallel relationship to each other by transverse members 54 extending between and attached to adjacent ends of tubes 53. Members 54 are of a generally semi-circular cross section adapted to receive and be attached to the front and rear tubular legs 11 and 12 of side frame 10 of the chair by any suitable means such as bolts 55. A pair of extension tubes 56 are slidably and telescopically received within tubes 53 and carry at their forward ends stub leg 29 fixedly attached to them as by welding.

Swingable support 28 and stub leg 29 carrying pivot connection 30 are thus mounted on chair W and at the same time are provided with a translatory motion along a generally horizontal path toward and away from the front of the chair. Tubes 53 may, of course, be attached to chairs of different configuration than the one we have shown in a suitable manner. Regardless of the manner or means of attaching tubes 53 in their approximately horizotnal parallel relationship to a chair, the leg and foot support of this invention is easily and conveniently mounted on or demounted from a chair so equipped merely by inserting or withdrawing extension tubes 56 from tubes 53. When demounted, the chair is capable of all its normal functions without interference from any structure connected with the adjustable leg and foot support.

In operation, the combined swinging and translatory motion capability of swingable L-shaped support 28 carrying leg support panel 36 and foot support 39 permits the leg and foot support of our invention to support and to follow effectively and comfortably the lower leg and foot of an occupant of a chair throughout the natural motion of the leg upon bending at the knee without requiring any special relationship between the pivotal axis of the knee and the chair or leg and foot support.

When the leg and foot support is utilized to support the lower leg and foot of the occupant of the chair in a normal sitting position, tubes 56 are retracted telescopically within tubes 53 mounted on the side frame of the chair so that stub leg 29 is adjacent front leg 11. Swingable support 28 is lowered to a position of acute angular relationship with stub leg 29 by a forward unlocking motion of lever 49 permitting almost all of brace rod 41 to pass through locking mechanism 43. Leg support panel 36 and foot support panel 39 are swung into their supporting positions so that they lie in planes substantially perpendicular to each other and with the leg support panel 36 behind the calf of the lower leg and foot support panel 39 beneath the sole of the foot. L-shaped lower support tube 32 is telescopically adjusted within upper support tube 31 so that the foot is comfortably and evenly supported by foot support panel 39. This adjustment of foot support panel 39 with respect to leg support panel 36 is maintained throughout all adjusted angular positions of the support by tightening band clamp 33.

In order to raise and support the lower leg and foot, the outer end of swingable support 28 is lifted by an attendant or by the occupant hooking or pressing his heel on foot support panel 39 and lifting his lower leg. This motion requires no manipulation of the locking mechdirection which automatically rotates cam 47 out of wedging engagement with rod 41.

Simultaneously and automatically with the upwardswinging movement of support member 28, there occurs a translatory motion of support member 28 together with stub leg 29 provided byv telescopic structure 52. Thistranslatory motion permits foot support panel 39 to follow the natural path of the foot supported thereby as it swings upwardly regardless of the particular fore and aft location of the occupant on the seat and without requiring any shifting of the lower legs and body of the occupant of the chair. It is apparentthat if the leg and foot support were not capable of the translatory as well as swinging motion, foot support panel 39 would not and could not follow the sole of the supported foot throughout its natural arc of swinging motion about the pivotal axis of the knee unless the knee were in the one and unlikely position with its pivotal axis coincident with the axis of pivotal connection 30. It will be noted that while the translatory motion provided by the telescopic structure 52 permits foot support panel 39 to be translated forwardly away from chair W as the leg support is being raised, the distancebetweentthe support panel 39 and leg support panel 36 remains fixed so that once this relationship is adjusted to comfortably support a particular occupant of the chair this same support is maintained throughout all adjusted positions of the swingable support.

When the swingable support 28 is raised to the desired position and released, cam 47 will automatically rotate in a rearward direction and wedgingly engage brace rod 41 between itself and closed end 46 of strap 45 in locking mechanism 43. v The ridges we prefer to provide on the camming surface of cam 47 and brace rod 41 act to in: sure the prompt and automatic locking without slipping of swingable support 28 in any particular raised position and prevents the slipping and inadvertent lowering of swingable support 28 even .when it is supporting substan tial weight such as might be present were the lower leg of the occupant of the chair encased in a large, heavy cast.

The leg and foot support may be lowered .or returned to the normal sitting position by forward rotation of unlocking lever 49 which rotates cam 47 out of wedging engagement with brace rod 41 and the closed end 46 of strap 45. As swingable L-shaped support 28 of the leg and foot rest is lowered, theventire support. is translated rearwardly by retraction of extension tubes 56' within tubes 53 mounted on the side frames of the chair. This translatory motion occurs automatically and only to the extent necessary to maintain even support of the foot and is instituted by the horizontally rearward acting component of the weight resting on leg-support panel 36. Aslong as unlocking lever 49 is held forward against the pressure exerted by: spring 48 on cam 47, swingable support 28 will-swingdownwardly about its pivotal connection 30 with stub "leg'29' and, at the same time, be translated rearwardly toward the forward edge of the seat of the chair. When unlocking lever 49 is released, cam 47 will engage brace rod 41 in weding engagement with strap 45 locking and maintaining the position swingable support 28 was in when unlocking lever 49 was released. In summary, we have provided an adjustable leg and foot support adapted for use with a chair and particularly wheel chairs. The support is especially convenient for use with conventional wheel chairs having tubular front and rear legs and may easily and conveniently be attached and detached as required by theuser of the chair. The structure of the support does not interfere with the ordinary functions of even a collapsible wheel chair. The support provides positive and comfortable support for all positions of the supported leg without requiring the user to be seated in a particular location on the seat of the chair or to shift position in the chair upon changing the position of. the supported leg. In addition, the support of our invention includes mechanism operable by its user for providing easy and positive locking and unlocking of the support in an from any of its possible positions of adjustment.

Changes, modifications and improvements'may be made to the above-described preferred form of our invention without departing from the precepts and principles of the invention. Therefore, we do not wish our patent to be limited to the particular form of our invention specifically illustrated and described nor in any manner inconsistent with theextent to which our invention has promoted the art.

We claim: a v

1. A foot and leg rest for use with a chain comprising suspending means mounted on said chair capable of translatory motion toward and away from the forward edge of the seat of said chair in a fore and aft direction with respect thereto, supporting means having lower leg and foot panels mounted thereon in planes substantially normal to and adjustably spaced from each other and adapted to engage and support the back of the calf and the sole of the foot respectively of an occupant oftsaid chair, said supporting means being pivotally connected to said suspending means for fore and aft swinging motion at approximately seat level, and locking means comprising a brace rod acting between said pivotally connected supporting means and said suspending means and having one end pivotally connected to one of said means and the other end slidably releasably engaged between a bearing member and a spring-biased eccentric cam mounted on said other means.

2. A foot and leg rest for use with a chair having side frames and a seat therebetween comprising horizontally aligned tubular mounting means disposed on a side frame of said chair, suspending means telescopically engaging said mounting means and capable of sliding translatory motion relative thereto, supporting means having lower leg and foot panels mounted thereon in planes substantially normal to and adjustably spaced form each other and adapted to engage and support the back of the calf and'the sole of the foot respectively ofan occupant of said chair, said supporting means being pivotally connected to said suspending means for fore and aft swinging motion at a point substantially at seat level and locking means for releasably holding said supporting means in adjusted positions of angular relationshipwith the seat of said chair.

: 3. A foot and leg rest for use with a chair having side frames and a seat therebetween comprising horizontally aligned tubular mounting means disposed on a side frame of said chair, suspending means telescopically engaging said mounting means and capable of translatory motion, supporting means having lower leg and foot .panels mounted thereon in planes substantially normal to and adjustably spaced froth -each other and adapted to engage the back of the calf and the sole of the foot respectively of an occupant of said chair, said supporting means being pivotally connected to said suspending means for fore and aft swinging motion at approximately seat level, said locking means comprising a brace rod acting between said pivotally connected supporting means and said suspending means and having one end pivotally connected to one of said means and the other end slidably releasably engaged between a bearing member and a spring-biased eccentric cam mounted on said other means.

4. A foot and leg rest for use with a chair having side frames including front and rear legs and a seat and back extending therebetween comprising a pair of parallel tubular mounting members removably mounted on one of said side frames and extending substantially horizontally between said front and rear legs thereof, suspending means comprising a pair of parallel tubular exension members adapted to be telescopically received by said pair of tubular mounting members and a stub leg extending vertically between and connected to the adjacent ends of said extension members projecting from the forward ends of said mounting members, supporting means having'lower leg and foot supporting portions and pivotally connected to said suspending means for fore and aft swinging motion at a point substantially at seat level and locking means for releasably holding said supporting means in adjusted positions of angular relationship with the seat of said chair.

5. A foot and leg rest for use with a chair having substantially vertical side frames including front and rear legs and a seat and back extending therebetween comprising a pair of parallel tubular mounting members mounted on one of said side frames and extending substantially horizontally between said front and rear legs thereof, suspending means comprising a pair of parallel tubular extension members adapted to be telescopically received by said pair of tubular mounting members and a stub leg extending vertically between and connected to the adjacent ends of said extension members projecting from the forward ends of said mounting members, supporting means having lower leg and foot panels mounted thereon in planes substantially normal to and adjustably spaced from each other and adapted to engage the back of the calf and the sole of the foot respectively of an occupant of said chair, said supporting means being pivotally connected to said stub leg of said suspending means for fore and aft swinging motion at approximately seat level and locking means for releasably holding said supporting means in adjusted positions of angular relationship With the seat of said chair.

6. A foot and leg rest for use with a chair having substantially vertical side frames including front and rear legs and a seat and back extending therebetween comprising a pair of parallel tubular mounting members removably mounted on one of aid side frames and extending substantially horizontally between said front and rear legs thereof, suspending means comprising a pair of parallel tubular extension members adapted to be telescopically received by said pair of tubular mounting members and a stub leg extending vertically between and connected to the adjacent ends of said extension members projecting from the forward ends of said mounting members, supporting means having a lower leg and foot panels mounted thereon in planes substantially normal to and adjustably spaced from each other and adapted to engage the back of the calf and the sole of the foot respectively of an occupant of said chair, said supporting means being pivotally connected to said stub leg of said suspending means for fore and aft swinging motion at approximately seat level, and looking means comprising a brace rod acting between said pivotally connected supporting means and said suspending mean and having one end pivotally connected to said supporting means and the other end slidably releasably engaged between a bearing member and aspring-biased and lever-released eccentric cam mounted on said suspending means.

7. A foot and leg rest assembly for a folding wheel chair having a side frame and a foldable seat, comprising that said side frame have horizontally extending guide means, foot and leg supporting means slidably engaging said guide means and having a part disposed toward the front of said chair, a foot and leg rest having panels for supporting the calf and the foot respectively of an occupant of the chair and being pivotally connected to said part of said supporting means for swinging motion about an axis normal to said frame near the level of said seat, means for holding said foot and leg rest in selected angular positions realtive to said supporting means, said supporting means slidably carrying said axis horizontally to maintain comfortably spaced support of the said foot and calf of said occupant when said foot and leg rest is moved about said axis.

8. A foot and leg rest assembly in a chair having a side frame and a seat, comprising that said side frame have spaced, horizontal tubes opening toward the front of the chair, means telescopically engaging and slidably movable in said tubes and having a forward part disposed toward the front of said chair, a foot and leg rest adapted to have panels for supporting the calf and the foot respectively of an occupant of the chair and having one end adjacent the foot of the occupant and having its opposite end pivotally connected to said forward part of said means for swinging motion about an axis normal to the plane of said frame, means for adjustably holding said foot and leg rest angularly about said axis, said first named means slidably carrying said axis horizontally to maintain comfortably spaced support of the said foot and calf of said ocupant when said foot and leg rest is moved about said axis.

9. A foot and leg rest assembly in a chair having a side frame and a seat, comprising that said side frame have spaced, horizontal tubes opening toward the front of the chair, means telescopically engaging and slidably movable in said tubes and having a forward part disposed toward the front of said chair, a foot and leg rest having panels for supporting the calf and the foot respectively of an occupant of the chair and having a portion between said panels and the chair, said portion of said foot and leg rest being pivotally connected to said forward part of said means for swinging motion about an axis normal to the plane of said frame, means for adjustably holding said foot and leg rest angularly about said axis, said first named means slidably carrying said axis horizontally to maintain comfortably spaced support of the said foot and calf of said occupant when said foot and leg rest is moved about said axis.

References Cited in the file of this patent UNITED STATES PATENTS 1,936,942 Koenigkramer et a1 Nov. 28, 1933 2,598,985 Everest et a1 June 3, 1952 2,601,889 Everest et a1. July 1, 1952 2,793,682 Duke May 28, 1957 2,960,150 Bauer et al. Nov. 15, 1960 Disclaimer 3,072,437.William U. Shea and William J. Pivacek, Elyria, Ohio. TELE- SCOPIC ADJUSTABLE LEG REST. Patent dated J an. 8, 1963. Disclaimer filed July 9, 1965, by the assignee, M o bilaid Inc. Hereby enters this disclaimer to claim 1 of said patent.

[Ofiicz'al Gazette Octobw- 1Q, 1965.]

Claims

1. A FOOT AND LEG REST FOR USE WITH A CHAIN COMPRISING SUSPENDING MEANS MOUNTED ON SAID CHAIR CAPABLE OF TRANSLATORY MOTION TOWARD AND AWAY FROM THE FORWARD EDGE OF THE SEAT OF SAID CHAIR IN A FORE AND AFT DIRECTION WITH RESPECT THERETO, SUPPORTING MEANS HAVING LOWER LEG AND FOOT PANELS MOUNTED THEREON IN PLANES SUBSTANTIALLY NORMAL TO AND ADJUSTABLY SPACED FROM EACH OTHER AND ADAPTED TO ENGAGE AND SUPPORT THE BACK OF THE CALF AND THE SOLE OF THE FOOT RESPECTIVELY OF AN OCCUPANT OF SAID CHAIR, SAID SUPPORTING MEANS BEING PIVOTALLY CONNECTED TO SAID SUSPENDING MEANS FOR FORE AND AFT SWINGING MOTION AT APPROXIMATELY SEAT LEVEL, AND LOCKING MEANS COMPRISING A BRACE ROD ACTING BETWEEN SAID PIVOTALLY CONNECTED SUPPORTING MEANS AND SAID SUSPENDING MEANS AND HAVING ONE END PIVOTALLY CONNECTED TO ONE OF SAID MEANS AND THE OTHER END SLIDABLY RELEASABLY ENGAGED BETWEEN A BEARING MEMBER AND A SPRING-BIASED ECCENTRIC CAM MOUNTED ON SAID OTHER MEANS.