Abstract: An office chair comprises a seat element (3) mounted movably on a fixed support element (1) and a back support element (2). The arrangement simultaneously allows the seat element (3) to move and tilt backwards when the user leans backwards. The seat element (3) carries the chair seating panel (4) in such a way that when the user leans to a side, said chair seating panel (4) tilts to the same side according to the user's movement and independently of the chair's back element (2).

Abstract: A chair having a first frame portion with a backrest support and a rear leg portion at least part of the backrest support and the leg portion being formed from a single piece. A second frame portion has a seat support and a front leg portion extending in a direction transverse to the seat support, the seat support in a fixed position relative to the backrest support. The backrest support molded thereover in foam, the backrest support being substantially peripherally located around the foam of the backrest and the backrest being provided free from rigid supports extending across a middle portion of the backrest. The seat support molded thereover in foam, the seat support being substantially peripherally located around the foam of the seat and the seat being provided free from rigid supports extending across a middle portion of the seat.

Abstract: A vehicle seat attachment includes a riser bracket of a vehicle frame. A pin is biased through the riser bracket to a securing position. A seat bracket has an angled channel that extends to a securing aperture, wherein slidable engagement of the angled channel with the pin is configured to bias the pin away from the securing position until the pin reaches the securing aperture wherein the pin returns to the securing position.

Abstract: It is described an incineration toilet especially suitable for caravans and camping cars. The toilet comprises a toilet chair with a pouch bowl (3). In the pouch bowl (3), a waste pouch can be arranged. Below the pouch bowl, there is a hatch mechanism over a combustion chamber (4). The hatch mechanism comprises a spring-loaded flap (21) in the back part of the pouch bowl, as well as a hatch (11) abutting an opening in the upper part of the combustion chamber (4). The hatch (11) is coupled to a motor (13) via a stay transmission (14, 15). The motor is arranged to lift the hatch (11) and revolve it up behind the flap (21), so that the flap is released and the pouch can fall down into the combustion chamber (4).

Abstract: A chair adjustment mechanism for adjusting a position of a chair component. The mechanism comprises a first adjustment shaft, a second support shaft, as well as a set of friction plates, each friction plate comprising an elongated slot and the friction plates being fixedly mounted on the second support shaft while being slideably mounted on the first adjustment shaft. A guiding structure directs movement of the second support shaft along a direction of travel of the chair component. An adjustment handle is provided to reversibly compress the friction plates together in a locked position for fixing position of the component of the chair through braking displacement of the second support shaft along the guiding structure. The plurality of friction plates provides greater braking pressure for locking the mechanism.

Abstract: An angle adjusting device for a bicycle saddle is disclosed. The device includes a frame coupling block, which is coupled at a lower end thereof to an upper portion of a height adjustment unit. A saddle coupling post is coupled at a lower end thereof to an upper end of the frame coupling block and is coupled at an upper end thereof to the saddle, with a through hole formed in the upper portion of the saddle coupling post. An angle fixing unit includes a pair of fan-shaped plates attached to left and right sides of the frame coupling block, and a pair of rectangular plates coupling front and rear edges of the fan-shaped plates to each other. An angle adjusting unit is coupled to the saddle coupling post, and is detachable from holes in the angle fixing unit to control the rotation of the saddle coupling post.

Abstract: This invention is directed to a two-position, at rest, seat angle adjustment assembly that locks the seat in two distinct positions. In a first position, the seat is generally horizontal, while in a second position, the seat is inclined at an angle relative to horizontal. The assembly includes left and right adjustment mechanisms, a rod, and a lever. The left and right adjustment mechanisms are mounted to the seat and the back assembly on each side thereof. Each of the mechanisms includes a housing, and a cam. The cam is received in the housing and the rod is fixably received within the cam. The lever is attached to the rod proximate the right adjustment mechanism. The lever is utilized to rotate the cams within their respective housings thereby moving the seat with respect to the back assembly.

Abstract: A highchair includes a seat frame, a first fixing socket disposed on the seat frame, and a seat pivotally connected to the first fixing socket. The first fixing socket has a sliding groove and a first engaging groove. The sliding groove communicates with the first engaging groove. The highchair includes a pivoting member, a restraining member, a connecting member, an adjusting member and a fixing member. The adjusting member is movably disposed on the seat. The fixing member is rotatably disposed on the seat and capable of selectively locking or releasing the adjusting member. The pivoting member is pivotally connected to one side of the seat. One end of the connecting member is connected to the pivoting member and the other end is connected to the adjusting member. The restraining member is disposed at one end of the pivoting member and movably engaged with the first engaging groove.

Abstract: A seat assembly for improving posture of a user comprises a substantially firm seat portion angled downwardly from rear to front, a back support extending upwardly in a rear area of the seat portion, a pad positioned on the back support and, the back support positionable at at least two locations for varying seat depth.

Abstract: A tilting fitting device enables a chair seat to be tiltable forwards and backwards against spring force of tilt-resisting springs, the tilting fitting having an upper part that is fastenable to the chair seat and a lower part that is fastenable to a chair base and tiltably connected to the upper part, wherein the tilting resistance is adjustable by adjusting spacing between the tilt-resisting springs and distance of each spring from a respective side of a tilting axis for the upper part. An actuating element is arranged for simultaneous engagement with two support members, an actuating element, along a part of each of its two sides in the element's direction of motion. On movement of the actuating element in the longitudinal direction of the tilting axis, it is adapted to cause rotation of the support members and springs mounted thereon, thereby changing the spacing of the springs.

Abstract: A seat assembly for improving posture of a user comprises a substantially firm seat portion angled downwardly from rear to front, a back support extending upwardly in a rear area of the seat portion, a pad positioned on the back support and, the back support positionable at least two locations for varying seat depth.

Abstract: A chair, in particular an office chair, has: a chair column, a seat holder secured to said chair column, and a backrest, wherein an adjusting mechanism is provided with which the backrest can be inclined relative to the vertical, wherein the adjusting mechanism includes an upward-arching curved guide, which is rigidly joined to the seat holder and on which a holder element that supports the backrest is movable along an upward-arching curved path for adjusting an inclination of the backrest, wherein the seat holder is inclined to a horizontal via an adjusting device secured to the chair column, and wherein the adjusting device includes a supporting arm, secured to the chair column, on which arm the seat holder is mounted pivotably via a joint with a horizontal pivot axis.

Abstract: An apparatus comprising a cantilever having a distal end and a proximate end, a frame portion coupled to the distal end, a base portion coupled to the proximate end, and a locking apparatus coupled to the frame portion, the base portion, or the cantilever, wherein the locking apparatus has a locked position and an unlocked position, and wherein the locking apparatus prevents the frame portion from tilting relative to the base portion when the locking apparatus is in the locked position.

Abstract: A chair designed for outdoor use, in particular various hunting applications. The chair is independently adjustable in the seat platform, the legs and the seatback to meet the different requirements for hunting various types of game, such as reclining for fowl flying above, or upright for land animals. It is also mounted on a swivel for quickly pivoting to follow the movement of game. The invention can be used in conjunction with blinds, or can include a pop up tarp for partially concealing the hunter. The seat is not just useful for hunters, but other outdoor enthusiast that want to view wildlife easily and in comfort.

Abstract: A highchair includes a seat frame, a first fixing socket disposed on the seat frame, and a seat pivotally connected to the first fixing socket. The first fixing socket has a sliding groove and a first engaging groove. The sliding groove communicates with the first engaging groove. The highchair includes a pivoting member, a restraining member, a connecting member, an adjusting member and a fixing member. The adjusting member is movably disposed on the seat. The fixing member is rotatably disposed on the seat and capable of selectively locking or releasing the adjusting member. The pivoting member is pivotally connected to one side of the seat. One end of the connecting member is connected to the pivoting member and the other end is connected to the adjusting member. The restraining member is disposed at one end of the pivoting member and movably engaged with the first engaging groove.

Abstract: An article of seating furniture includes a base, a seat and a back. The back includes a reclining mechanism. The seat is interconnected with the reclining mechanism such that reclining movement of the back moves the seat forwardly and upwardly. When the back is fully reclined and the seat is fully raised, an upper surface of the seat is coplanar with an upper surface of the back. A footrest is movable between a retracted position and an extended position. When extended, the footrest is generally coplanar with the seat. The back includes a spine having a lower end pivotably interconnected with the base. The spine includes a seat mounting extension to which the seat is pivotably mounted. Mounting links between the seat and the base provide movement of the seat when the back is reclined.

Abstract: A seat (11) having a seat cushion (12) and a squab (16), the seat (11) being adjustable between a first configuration adapted to provide seating accommodation for a user and a second configuration adapted to provide leaning accommodation for a user, wherein in the second configuration, the squab (16) is positioned forwardly of its position in the first configuration and substantially above the forward most position of the seat cushion (12).

Abstract: A collapsible high chair for children comprises a frame, a seat portion, a backrest and an adjusting mechanism, all of which are sequentially connected with. The adjusting mechanism further comprises a pivotal member connecting the seat portion and the frame, a first engaging unit, and a second engaging unit. A sliding piece of the first engaging unit cooperates with two rods and makes the rods be escaped from the restriction of the pivotal member while a button of the second engaging unit cooperates with a cam and makes the cam be escaped from the restriction of the rib. Only when the rods and the cam are simultaneously escaped from the restriction of the pivotal member, the seat portion can be pivotally rotated relative to the frame. Also, the backrest can be rotated relative to the seat portion, so that the volume of the collapsed high chair is very small.

Abstract: A seat (10) for a wheeled carriage or chair for children or disabled people, the seat having a multipart seat surface (11) and a pivotable backrest (12) connected to at least one part of the seat surface (11), such that with the pivoting of backrest (12) the position of at least one part of the seat surface is changed.

Abstract: An apparatus for reducing rattle in an automotive seat release mechanism includes a torsion spring applying both a rotational force and a linear force to a cross member operatively connecting a first release and a second release. The spring force biases the cross member toward the second release linearly, and biases the cross member in a first rotational direction to reduce rattle between the cross member and components connecting the cross member to the first and second releases.

Abstract: An adjustable chair, particularly for the use of attendees at meetings, is disclosed in which a gas cylinder is operatively connected between the underside of the chair seat and a lower cross-member to afford the user control of the lift and tilt of the chair over a range of positions.

Abstract: A chair includes a leg unit with left and right sides, and a generally L-shaped seat member connected pivotally to the leg unit and swingable about a horizontal axis. The seat member has left and right sides. A seat-tilting mechanism includes a pair of movable plates disposed respectively, vertically and movably on the left and right sides of the leg unit and connected fixedly to each other. Each of the movable plates has an upper edge which is formed with a row of pin notches that are arranged one behind another. An aligned pair of engaging pins is mounted respectively and fixedly to the left and right sides of the seat member. A biasing unit biases the movable plates upward so as to engage a selected one of the notches in each of the movable plates with a respective one of the pins, thereby positioning the seat member with respect to the leg unit.

Abstract: A reclining chair including a seat frame and a base is disclosed. The seat frame is suspended from pivot connectors that are connected between right and left side stand members and right and left sides of the seat frame by means of plates that include a arcuate slot. Locking members are received in the slots and are used to lock the seat frame relative to the base in a range of angular orientations as defined by arcuate slots formed in the plates. The seat frame is spring biased into an upright position when the locking members are released.

Abstract: An adjustable seat back and supporting rear rail for a specialty vehicle is disclosed. The rear rail is secured by a latches to a pair of pillars of the vehicle within a range of vertical locations. The seat back is selectively lockable within a range of angular orientations from horizontal to vertical. The seat back includes pivot pins that are held by locking fasteners in the desired angular orientation on the rear rail.

Abstract: A tilt control mechanism for an office chair includes a spring arrangement which permits forward and rearward tilting of the chair while also urging the chair to a normal upright position. The spring arrangement includes front and rear springs which act in combination such that the upward acting forces acting on the chair can be varied during use. The forces being applied by the front spring are adjusted by a side-actuated tension adjustment mechanism which incorporates a wedge block for adjusting the spring forces. Further, the rear springs provide a variable spring force such that the spring force is maximized when in the normal position but is decreased substantially once the chair is fully reclined. This reduction in spring force allows a user to maintain the chair in the fully reclined position with significantly less force than was required to tilt the chair rearwardly while a sufficient spring force continues to be applied by the front spring to urge the chair to the normal position.

Abstract: An adjustable highchair, comprising a seat which is associated with a frame by virtue of seat position adjustment elements, characterized in that the seat position adjustment elements comprise actuation elements which are arranged in an upward region of the seat which can be accessed easily.

Abstract: A recliner chair includes a seat assembly, a pair of spaced-apart side frames having armrests which extend along each side of the seat assembly, a pair of seat supports pivotally suspended from the armrests for supporting the seat assembly and allowing the seat assembly to pivot relative to the side frames, and a pair of locking bars pivotally connected to the armrests at their upper ends and slidably connected to the seat supports at lower portions of the locking bars. The slidable connections are defined by longitudinal slots formed through lower portions of the locking bars, and projecting members mounted on the seat supports and extending through the slots and being engaged by locking controls. The locking controls are actuatable to clamp against the locking bars to prevent relative movement between the locking bars and the seat supports, thus fixing the seat assembly in a selected position.

Abstract: A vehicle seat assembly includes a seat track member with a recliner pivot linkage pivotally connected thereto. A one-piece shell member is pivotally connected to the recliner pivot linkage and includes a back portion operative as a seat back frame and a lower seat support portion. At least one inflatable bladder supports the lower seat with respect to the lower seat support portion, and a linear actuator is positioned between the lower seat support portion and the seat track member for pivotally adjusting the shell member.

Abstract: A rocking apparatus has a supported member and a supporting member. The supported member rotatably supported on the supporting member at two distant points on a rotary shaft. The rotary shaft is provided with a reaction force imparting member, which is constantly pushed toward its initial position by a reaction force imparting mechanism, so as to be capable of oscillation. A strut is provided between the reaction force imparting member and the supported member, and the supported member is supported on the reaction force imparting member and the rotary shaft by the three-point support using the connecting members and the strut.

Abstract: A reclining chair having a base frame (1) supporting a reclining unit (2) by a mechanism having downwardly converging swing links (15 and 16) pivoted at their upper ends at (22 and 23) respectively to the frame, a rigid member (14) pivotally connected to the lower ends of the swing links (15 and 16 at 20 and 21). The rigid member (14) has a link (13) rigidly connected to it which in turn is rigidly connected to the reclining unit (2). The center of gravity of the reclining unit with its occupant is maintained in a substantially horizontal plane as the unit moves from upright to reclined positions.

Abstract: A seating unit comprises a support member; a seat member pivotally mounted on the support member; an arm rest member having an actuating button positioned in the arm rest member, the button being movable between a first position and a second position; a fluid pressure cylinder having actuating means and operatively connected to the seat member for adjustment of the inclination thereof; and, a flexible cable having a first end connected to the button and a second end operatively connected to the actuating member. When the button is moved from the first position to the second position, the actuation member is actuated so that the inclination of the back member or the seat member may be adjusted and when the button is moved from the second position to the first position, the inclination of the back member or the seat member is fixed.

Abstract: A front seat assembly having a seat bottom assembly and a seat back pivotally attached to the seat bottom assembly. The seat bottom assembly includes a pair of fixed rails extending fore and aft and being laterally spaced across a vehicle from one another. Brackets are attached to the fixed rails for attachment to the vehicle. A slide rail is supported by each of the fixed rails for fore and aft movement relative to the fixed rails. Front and rear cross beams interconnect the slide rails for supporting a number of components. A support sheet, having a pair of openings, extends between and is supported by the cross beams. A seat pan, having a front section and a rear section, is disposed above the support sheet for supporting an occupant. A pair of projections are pivotally connected to and extend from the seat pan for sliding engagement within the pair of openings in the support sheet.

Abstract: The chair is constructed with a seat frame which is pivotally mounted at a forward end on a support frame. The rear of the seat frame is interconnected by a linkage to the support frame. The linkage includes a transverse bar which is manually movable to rest against the support legs of the support frame with the seat frame in an upright position or a reclined position.

Abstract: A seating unit comprises a support member; a seat member pivotally mounted on the support member; an arm rest member having an actuating button positioned in the arm rest member, the button being movable between a first position and a second position; a fluid pressure cylinder having actuating means and operatively connected to the seat member for adjustment of the inclination thereof; and, a flexible cable having a first end connected to the button and a second end operatively connected to the actuating member. When the button is moved from the first position to the second position, the actuation member is actuated so that the inclination of the back member or the seat member may be adjusted and when the button is moved from the second position to the first position, the inclination of the back member or the seat member is fixed.

Abstract: Device for locking in a chair seat in a desired angular position, comprising several lamellae (1) connected with the seat, extending through a retainer (7) and between fixed lamellae (2) arranged in the retainer, whereby clamping shoes (3, 4) which are abutting against the outer fixed lamellae (2) may be clamped by bolts (5, 6) for locking the position of the seat and providing possibility for adjustment of the clamping points of the bolts, where lameellae (1) without holes are arranged abutting against fixed lamellae (2) across their width, the lamellae (1) being connected with the seat of the chair, the fixed lamellae (2) being captured by the retainer (7) and the bolts (5, 6), each provided with a clamping shoe (3, 4) and aligned axially.

Abstract: An office chair seat carrier includes a seat platform carrier and a back rest carrier pivotally connected about parallel rotatable axes to a carrier part. A stack of lamellar disks is pivotally connected between the carrier part, seat platform carrier, and back rest carrier for holding the carriers in place by frictional contact. The stack of lamellar disks is linked with a holding member rigidly attached to the carrier part. Frictional contact is established by activating an actuator lever which slides a clamping member against the stack of lamellar disks. The clamping member applies a lateral clamping force upon the stack of lamellar disks forcing the disks together. Frictional contact is broken only after the actuator lever releases the clamping force and a mechanical force is exerted on the seat platform carrier or back rest carrier.

Abstract: A chair tilt control mechanism for a pedestal base chair having a chair control housing mounted on the pedestal chair base and pivotally supporting a chair seat support member. A laterally movable front stop member retained within the chair control housing is movable and contacts the front flange of the chair seat support member and limits the pivotal movement of the chair seat support member to predetermined angular positions with respect to the chair control housing and the floor supporting the chair. Also disclosed is a lever member adapted to lock the chair seat support member in one or more predetermined angular positions. Also disclosed is a hollow plastic pivot pin for pivotally connecting a chair control housing to a chair seat support member.

Abstract: A seat for a vehicle with a scissor-like pivoting system and device for the adjustment of the inclination and/or height of the surface of the seat includes the feature that the device for the adjustment of the inclination and/or height must be space-saving and is not permitted to influence the pivoting system. Scissor-type sets of arms are proposed for the pivoting system whose upper arm-components are angularly adjustable and capable of being fixed relative to the remaining lower components of the same arm.

Abstract: A tiltable table has a pneumatic actuator and a locking system for establishing and maintaining a table position. The locking system is operated by an air cylinder that engages a dog with a ratchet plate secured to the table. The ratchet permits the table to be raised but not lowered while locked. The ratchet must be unlocked before the table can be lowered. The dog is spring-biased to locking position, and is air-operated for release against the action of the biasing spring. On lowering the table, air from the actuator can be used to unlock the ratchet. The air can be permitted to escape through a restriction orifice at a slow enough rate to maintain sufficient air pressure to keep the locking system disengaged, but sudden release of all the air pressure will again permit the spring to re-lock the system to prevent a downward slamming of the table surface.

Abstract: A chair tilt control mechanism for a pedestal base chair having a chair control housing mounted on the pedestal chair base and pivotally supporting a chair seat support member. A laterally movable front stop member retained within the chair control housing is movable and contacts the front flange of the chair seat support member and limits the pivotal movement of the chair seat support member to predetermined angular positions with respect to the chair control housing and the floor supporting the chair. Also disclosed is a lever member adapted to lock the chair seat support member in one or more predetermined angular positions. Also disclosed is a hollow plastic pivot pin for pivotally connecting a chair control housing to a chair seat support member.

Abstract: A tiltable table has a pneumatic actuator and a locking system for establishing and maintaining a table position. The locking system is operated by an air cylinder that engages a dog with a ratchet plate secured to the table. The dog is spring-biased to locking position, and is air-operated for release against the action of the biasing spring. On lowering the table, air is permitted to escape through a restriction orifice at a slow enough rate to maintain sufficient air pressure to keep the locking system disengaged, but sudden release of all the air pressure will again permit the spring to re-lock the system to prevent a downward slamming of the table surface.

Abstract: An adjustment mechanism (1) is disclosed which has a locking assembly (2) and an actuator (3). The locking assembly (2) is self-contained because it is biased by a spring (12) which acts between a housing (11) for the assembly and clutch leaves (5(a), 5(b)). The actuator (3) has a cam rod (15) which does not take any part in the clamping action on the leaves (5(a), 5(b)). There is a large mechanical advantage in the actuator (3) because the cam surface (17) is formed from a cut-out in the rod (15). A single actuator (45) may be used for two or more locking assemblies. Depending on configuration of the cam surfaces (48, 49), exclusive operation of one locking assembly may be achieved.

Abstract: Disclosed is a tilt control mechanism for a knee tilt chair that permits the chair to be locked in a number of intermediate tilt positions, as well as in a full upright and a fully reclined position. A portion of a pivotal chair seat support member is a curved flange that is provided with a plurality of spaced openings. The chair control housing contains a lock block slidably supported on guides. An actuator shaft attached to the chair control housing has a cam member attached to the shaft. A quarter turn of the actuator shaft causes the cam member to move the lock block to a forward position adjacent the curved flange. With the lock block in the forward position, one of a plurality of spring loaded pins in the lock block, is allowed to enter one of the openings in the curved flange thereby locking the chair support member of the chair into a predetermined tilt position.

Abstract: A device for supporting a saddle of a bicycle, a mountain bike, etc., which includes a support frame, a guide tube secured to the support frame, and a tubular support member upwardly biased by a spring means. The projecting end portion of the tubular support member is connected to a mounting member for the saddle so that the support member and the saddle mounting member are movable relative to each other in a direction transverse to the longitudinal axis of the support member. The saddle mounting member is swingably connected to the guide tube.

Abstract: In a chair having a seat which is adjustable in both height and tilt, there is provided a simplified adjustment mechanism over prior art document 2226756-A, in which a first adjustment mechanism is provided to tilt the seat of the chair to suit the physique of a particular user, which mechanism is compatible, and used in conjunction with a second adjustment mechanism which is used to vary both height and tilt of the seat cooperatively to suit the specific requirements of said particular user for being in a seated, or semi-standing position at various heights.

Abstract: A seat leveling apparatus for levelling the seat on a vehicle when the vehicle turns onto an inclined surface which includes upper and lower members that pivot relative to each other on a longitudinal axis parallel to the path of the vehicle. Apparatus is provided with a facility to latch the seat in a preselected tilted position as well as a facility to adjust the frictional restraint on the operation of the mechanism as a means of control.

Abstract: A shock absorbing seat is provided in a personal watercraft or boat. The seat has an elongated configuration and is mounted at the front end thereof to the hull or other structural member of the watercraft for limited pivoting motion relative to the hull or structural member. A shock absorber assembly which includes a fluid filled cylinder, a piston therein, and a coil spring externally mounted to the cylinder piston combination, or an elastic envelope filled with pressurized air, is mounted for limited motion relative to the hull or other structural member of the watercraft, and to the seat so as to support at least a substantial portion of the weight of the seat and occupant thereof, and to absorb forces generated between the hull and the seat while the watercraft is in motion.

Abstract: There is disclosed a unitary brake for a chair tilt mechanism. The chair tilt mechanism is of the type having a seat back support mechanism biased with respect to a seat tilt mechanism, the seat back support mechanism provided with a mounting bracket and the seat tilt mechanism has a housing attachable to the underside of a chair. The mounting bracket is pivotally attached to the housing adjacent to an end portion thereof. The unitary brake comprises a spindle bracket pivotally mounted in the housing for receiving therein a chair support spindle. The spindle bracket has a plurality of parallel slotted arms extending therefrom with the spindle bracket and the arms being of one piece unitary construction. The unitary brake includes a rear lammal pivotally mounted on the mounting bracket. The rear lammal includes arms interleaved with the spindle bracket arms. The rear lammal arms have slots extending therethrough which are in registration with the slots in the spindle bracket arms.

Abstract: A convertible child restrain seat is provided having a seat portion pivotally mounted to a base, the base including a spring biased slide bar having a post, the seat portion having an elongated member having a plurality of catches configured to mate with the post. Each catch corresponds with a different angle of inclination of the seat portion relative to the base. The post is thereby biased towards the catch to secure the seat portion at a selected angle of inclination. The angle can be adjusted by sliding the slide bar away from the catch and pivoting the seat portion between an upright position, a semi reclined position and an inclined position. An adjustable shield is also provided incorporating a cam actuated height adjustor to allow for shield position adjustment relative to the seat portion.

Abstract: The present assembly relates to a wheel chair having a base frame, a seat frame and a back frame, and a control device for rotating the back frame relative to the seat frame. The back frame includes a back support to receive a trunk portion of a user, the back support being displaceable by another control device relative to the back frame. A control unit communicates with the control devices for rotating and for displacing, the control unit being adjustable to vary the displacement of the back support according to the rotation of the back frame to minimize shear forces between the user's trunk and the back support.