Abstract: A backrest adjusting device for office chairs comprising: a seat portion having a seat cushion and a stand for supporting the seat cushion; a back having a frame, a back cushion fixed on the surface of the frame, a connecting member for connecting the bottom of the back to a rear side of the seat portion, a hollow containing space formed at the middle section of the back, an n-shaped member being disposed in the containing space and extended backward; and a first attaching device installed on the n-shaped member of the containing space, thereby achieving the adjustment of the three-dimensional space of position, longitudinal buffer and angular rotation. Moreover, the back further includes a support member disposed at the top of the back, and a second attaching device installed on the support member and having a structure identical to the first attaching device. Meanwhile, the first attaching device has an attaching body made in compliance with the shape of a human waist to form a backrest bump.

Abstract: Structure for anatomical support for the back, headrest and seat components of chairs in general and especially seats in motor vehicles comprising a frame, a convex cushioned plate fitted with sliding means in relation to the frame and pull-push cables, the first end of which is fixed to one or other end of the cushioned plate, freely sliding inside a sheath whose first end is fixed, on the frame, to one or other of the ends of the cushioned plate, while the second end of said push-pull cable and of said sheath is fixed to control devices for adjusting the position of the cushioned plate if the first end of the sheath is fixed to the frame, or for adjusting convexity of the cushioned plate if the first end of the sheath is fixed to said plate.

Abstract: A seat assembly includes a seat cushion, an adjuster mechanism and a seat back. The seat cushion has opposite front and rear ends. The adjuster mechanism is operatively coupled between the floor of the motor vehicle and the seat cushion. The adjuster mechanism allows selective adjustment of the seat cushion relative to the floor among a plurality of vertical positions. The seat back has an outer frame. The outer frame has spaced apart side members. The seat back has an inner frame slidably engaged with the side members for movement along a path defined by the side members. The inner frame of seat back is connected to the rear end of the seat cushion for movement of the inner frame relative to the outer frame along the path in response to corresponding adjustment of the seat cushion among the plurality of vertical positions.

Abstract: A back and internal organ supportive belt that can be installed in a chair or a seat, including the driver's seat of a vehicle or the operator's seat of a piece of equipment, to provide support to internal organs, and to the musculoskeletal system of the driver or operator. The back and internal organ supportive belt includes an inelastic support structure with upper and lower sections; belts and straps for fastening the belt to a seat, and for strapping the driver/operator into the supportive belt; vertically extendable foam lordotic support pads; an inflatable bladder for applying vertical extension and lumbar vertebrae distraction; and a pad for providing heat and/or vibration for the driver's or operator's further comfort.

Abstract: A motor vehicle seat system, control arrangement, actuating arrangement, and process are used to control a lumbar support device of a motor vehicle seat. The lumbar adjustment device has a first drive for adjustment in a first adjustment direction and a second drive for adjustment in a second adjustment direction. The adjustment directions differ from each other. A first adjustment position is ascertained in the first adjustment direction and the drive movement of the second drive is controlled as a function of at least one of the first adjustment position and the temporal change in the first adjustment position.

Abstract: The present invention relates to a portable seating device (e.g., portable stadium seat) that includes a seat and a backrest movably interconnected with the seat, and that is generally positionable in both stowed and deployed positions. The backrest also may be selectively movable toward and/or away from the seat, at least when the device is in the deployed position. One embodiment of the device may include a base that is interfacable with a supporting surface on which the device is to be supported, and a mechanism for rotatably interconnecting the seat with the base. Accordingly, the seat may be rotatable relative to the base. Another embodiment of the device may include a stand having a first end that is detachably interconnectable with the seat and/or base, and a second end that may be spaced from the base and interfacable with the supporting surface on which the device is to be supported.

Abstract: A lumbar support cushion consists of a seat portion and a back portion, foldably joined along a crease positioned therebetween. An opening extends in a continuous manner upward into the back portion, and downward into the seat portion. The opening may have an oval shape. In one embodiment, a support member is provided, and is positioned across the front of the back portion. The position of the support member along the back portion may be made adjustable, for example by the use of mating hook and loop material on the support member and a rear portion of the back portion.

Abstract: A chair back includes a waist support, a board-shaped part, and a mesh member; the board-shaped part has guide grooves on a front side; the mesh member includes a frame, and a mesh secured over a space encompassed by the frame; the mesh member is secured right in front of the board-shaped part; the waist support is sandwiched between the mesh member and the board-shaped part with such a tightness that it can be moved up and down for adjusting position; the waist support has guide protrusions on a rear side thereof, which are fitted in the guide grooves of the board-shaped part; the waist support has two grip portions extending from two ends thereof and sticking out from two lateral edges of the chair back such that the sitter is allowed to adjust the waist support by means of exerting force on the grip portions.

Abstract: A seating unit includes a back support with a perimeter frame defining an opening, and a plurality of resilient members spanning the opening. An upholstery cover extends over and covers the resilient members and a front of the perimeter frame. A bow-tie-shaped lumbar device is positioned between the cover and sides of the perimeter frame for vertical adjustment. The lumbar device includes a body with end sections defining a greater dimension than a middle of the body. Upper and lower edges of the end sections are thin and serve to wedgingly slip between the cover and the resilient members in a manner leading the middle over irregular surfaces between the resilient members. A thick area between the upper and lower edges causes a change in lumbar support force and shape as the lumbar device is adjusted. Handles are attached to the body by stretchable fabric.

Abstract: An adjustable lumbar support (100) adapted to be easily integrated into new or existing seat structures. Adjustable lumbar support (100) includes a lower floating plate (115) that is adapted to have a second, or upper, plate (130) hinged relative to the lower plate (115). The upper and lower plates have independently actuated support linkages (120 and 140) that are selectively actuated by first and second actuating mechanisms. In this manner, selective actuation actuator mechanisms associated with the lower and upper support plates (115 and 130) provides adjustment of a vertical dimension of the adjustable floating plate lumbar support. The degree of support provided by floating plates (115 and 130) is adjusted by adjusting the effective length of the support linkages.

Abstract: An ergonomic weight support device for a seat comprising a housing having a channel defined by at least one guide boss, an extending element having an unanchored weight supporting end and an engaged end slidingly disposed within the channel of said housing and an actuator fixedly attached to said housing and in moving communication with said extending element whereby said actuator mediates the weight supporting end of said extending element between a substantially retracted position and an extended position.

Abstract: A back for a chair includes fabric panel with a flexible carrier attached to the panel around its periphery. The carrier is configured to be secured along a bottom edge to a bottom portion of a chair back frame member. The carrier is also secured to two vertical frame supports at its two upper corners. Preferably, the upper carrier and frame connections are ball and socket joints. A lumbar support is provided that is easily height adjustable, by providing tension to the back frame and requires no screws or adjustment knobs in its adjustment mechanism.

Abstract: A sliding assembly of a dynamic mechanism of a massage chair is used in a massage chair. The massage chair has a dynamic mechanism and a sliding unit. The sliding unit is movable between two tracks; each track having a first lateral plate and a second lateral plate. At least one of wheel units installed at a periphery of the sliding unit. Each wheel unit includes a first wheel, a second wheel and one elastic element. The elastic element resists one wheel outwards so that the first wheel and second wheel resist against inner sides of the two lateral plates of one respective track. Thus, since the sliding unit has wheels which are tightly resist against the lateral plates of moving tracks, no noise is generated as the dynamic mechanism of the massage chair moves.

Abstract: The actuator has a housing with a longitudinal passage between a first end and an opening at a second end. A spindle, supported and moveable in the passage, has oppositely handed, first and second threaded portions each nearer a respective end of the housing. A first nut fixed relative to the housing is engaged with the first threaded portion. The spindle is rotated and moved relative to the first nut by a handle at the housing first end. A second nut fixed against rotation relative to the housing and engaged with the second threaded portion moves relative to and in the same direction as the spindle as the spindle rotates. The second nut is connectable through the opening to a device, and the spindle is rotatable by the handle for adjusting the device by movement of the spindle and the second nut.

Abstract: A lumbar support apparatus includes a guide rail on a seat frame, and a bendable occupant support structure mounted for sliding movement on the guide rail. The bendable structure, which is preferably configured as a grid, includes a spring that imparts increasingly bowed contours to the grid upon increasingly arched deflection of the spring relative to the seat frame and the guide rail. The apparatus further includes an actuator, a cable, and a fastener. A first section of the cable extends from the actuator into engagement with the grid so as to apply a bending force to the grid under the influence of the actuator. A second section of the cable extends from the first section to an end portion of the cable that is anchored to the seat frame.

Abstract: A device for supporting a seated person, comprising a seat and a support for the lumbar-thoracic transition region, which is connected to the seat, and characterized by an adjustable lumbar-sacral support, which is mounted at a location of a lower side of the support for the lumbar-thoracic transition region. Preferably, an adjustable support is furthermore provided for the thoracic-cervical transition region, which support is mounted at the location of the upper side of the support for the lumbar-thoracic transition region.

Abstract: A dual drive actuation system includes a driver gear, a pair of actuators with driven gears, and a transmission for switching the driver gear between the pair of actuators. The transmission can be controlled by a solenoid, and the driver gear can be powered by a motor. The dual drive actuation system can be used with different actuators that are changed based on their required usage, sizing and range of motion.

Abstract: A chair or other seating unit comprises a seat, a backrest, and an adjustable lumbar support, the adjustable lumbar support comprising a lumbar pad and a position adjustment means. The position adjustment means comprises a vertical adjustment means for mounting the lumbar support pad to the back rest, a substantially stationary support means that receives the vertical adjustment means, and a tension adjustment means, that releases the tension between the vertical adjustment means and the substantially stationary support means to allow the lumbar support to be positioned, and that increases the tension to hold the lumbar support means in a preferred selected position. The stationary support means is fixedly secured to the backrest.

Abstract: A mesh chair back includes a loop-shaped frame, an elastic mesh part, a waist support unit, and a smooth separating plate; the loop-shaped frame has left and right upright portions; the elastic mesh part is positioned over and secured on the loop-shaped frame; the waist support unit is arranged behind the elastic mesh part, and connected to the left and the right upright portions of the loop-shaped frame at two ends in an up and down displaceable manner; the smooth separating plate is positioned between the mesh part and the waist support unit for preventing the waist support unit from rubbing and causing wear to the mesh part while the waist support unit is being adjusted in height; the waist support unit props the separating plate and the mesh part forwards such that the separating plate and the mesh part each has a forwards protruding portion.

Abstract: Chair backrest, comprising a support structure (12), an upper backrest member (30) connected in oscillating fashion to said support structure (12), a lower backrest member (32), and a connecting element (80) which is fixed relative to one of said backrest members (32) and able to slide telescopically inside the other backrest member (30), the connecting element (80) having at least one elastically deformable zone (82) and being able to apply an elastic force to said backrest members (30, 32) as a result of a variation in the relative angular position of said backrest members (30, 32).

Abstract: A powered lumbar support mechanism includes a lumbar plate having a power mechanism having connecting links connected to opposite ends of the plate. One of the connecting links is longitudinally movable to change the convexity of the outer surface of the plate to adjust the lumbar support. The power mechanism includes a housing which retains a threaded rod threaded into a worm gear mechanism held within the housing. The housing also retains a motor having a worm which drives the threaded worm gear. The housing can also incorporate a second threaded rod, threaded to a second threaded worm gear also fixed within the housing such that the end of the second threaded rod is connected to a seat support so as to allow for the adjustability of the vertical position of the lumbar mechanism.

Abstract: A new and improved portable ergonomic cushion for relieving pressure on the coccyx (tailbone) and on the ischial tuberosities, for promoting correct positioning of the sacroiliac joint and for supporting the lower back of the user is described. The portable ergonomic cushion includes a narrow ridge back support allowing the cushion to be used with numerous styles of chairs and seats, and a lumbar support cushion that is removably attached to the back support. The portable ergonomic cushion may also make use of inflatable cushions for increasing the flexibility of the sitting cushion by allowing users to adjust the cushions to their desired support by varying the amount the cushions are inflated. The portable ergonomic cushion is also foldable into a compact non-use position for easy transportation and storage, and futher does not require the use of straps for retaining the cushion while in use.

Abstract: A chair includes a base having a control assembly operably supporting a seat assembly and also a back assembly for movement about a seat tilt axis and a back tilt axis, respectively. The back assembly includes a flexible sheet supported at upper/outer corners by a back support structure and hanging downwardly. The flexible sheet includes a lower portion coupled to the back support structure by a tensioner for holding the lower portion rearwardly. A vertically-adjustable lumbar mechanism is adjustably supported on the back support structure and operably engages the flexible sheet for flexing a lumbar area of the flexible sheet forwardly to provide an optimal ergonomic horizontal and vertical convex shape for postural lumbar support.

Abstract: A lumbar support system includes a fixed mounting bracket having a first traction cable sleeve support, a second sleeve support and a slider guide. A traction cable having a wire disposed to slide axially through a first sleeve and second sleeve, is attached to the first sleeve support of the fixed mounting bracket and to an actuator operatively engaged with the traction cable wire. A slider is also attached to the traction cable wire, is operatively engaged with the slider guide and adjusts the position of a flexible support element as it slides along the slider guide.

Abstract: A lumbar support for a seat includes an archable pressure surface having an upper region and a lower region and a force actuator such as an electric motor. The force actuator is held in a housing. The actuator housing is fixedly attached to said archable pressure surface in a compact design. A force transmission element such as a cable is connected to at least one of the upper and lower regions of the pressure surface and the force transmission element is also connected to the actuator. When force is applied by the force actuator to the cable, the pressure surface arches from a substantially flat position to an arched position.

Abstract: A back portion (16) for a chair (10) includes a peripheral frame (34) defining an opening therein. A lumbar support portion (36) is disposed in the opening. The lumbar support portion (36) comprises a substantially rigid panel (207). Two hinge devices (214) are hingedly mounted on opposite sides of the peripheral frame (34). The lumbar support portion (207) is mounted on the peripheral frame by the two hinge devices (214). Each hinge device has a biasing device (226) associated with it to bias the hinge devices (214) forwardly relative to the peripheral frame (34). A cushion (540) may be mounted atop the lumbar support portion (207). The cushion has a first substantially planar sheet (542) of resiliently flexible material and a second substantially planar sheet (544) of resiliently flexible material. The first and second sheets are separated by a plurality of spaced webs (546) of resiliently flexible material.

Abstract: A chair back comprises a back frame, a movable back support, and a contouring assembly. The back frame includes a portion rearward of the back support. The contouring assembly is coupled to the back support and the portion of the back frame. The contouring assembly pulls the back support toward the portion of the back frame. The present invention is also directed to a chair including such a chair back.

Abstract: An ergonomic weight support device for a seat comprising a housing having a channel defined by at least one guide boss, an extending element having an unanchored weight supporting end and an engaged end slidingly disposed within the channel of said housing and an actuator fixedly attached to said housing and in moving communication with said extending element whereby said actuator mediates the weight supporting end of said extending element between a substantially retracted position and an extended position.

Abstract: A chair equipped with a lumbar support unit is disclosed. The lumbar support unit includes a lumbar plate attached to a lower portion of a tiltable backrest part, and an actuating connector comprising a connecting wire which is connected at one end to an upper end of the lumbar plate and is connected at the other end to a chair frame supporting the seat and back parts, and a connecting tube surrounding the connecting wire, which is positioned at one end at a location downwardly spaced from the one end of the connecting wire, and is connected at the other end to a movable frame. The lumbar plate is automatically protruded forward to snugly support a lumbar region of a user when the back part is tilted rearwardly. The chair can afford convenient operation and protection of a lumbar region of a user.

Abstract: An ergonomic weight support device for a seat has a weight distribution surface attached to a traction arching lumbar support. The weight distribution surface is only attached at the apex of the arch of the arching pressure surface. The upper and lower ends of the weight distribution surface are free to flex between a passenger's spine and the arch, distributing the passenger's weight for greater comfort.

Abstract: A powered lumbar support mechanism includes a lumbar plate having a power mechanism having connecting links connected to opposite ends of the plate. One of the connecting links is longitudinally movable to change the convexity of the outer surface of the plate to adjust the lumbar support. The power mechanism includes a housing which retains a threaded rod threaded into a worm gear mechanism held within the housing. The housing also retains a motor having a worm which drives the threaded worm gear. The housing can also incorporate a second threaded rod, threaded to a second threaded worm gear also fixed within the housing such that the end of the second threaded rod is connected to a seat support so as to allow for the adjustability of the vertical position of the lumbar mechanism.

Abstract: A chair includes a base having a control assembly operably supporting a seat assembly and also a back assembly for movement about a seat tilt axis and a back tilt axis, respectively. The back assembly includes a flexible sheet supported at upper/outer corners by a back support structure and hanging downwardly. The flexible sheet includes a lower portion coupled to the back support structure by a tensioner for holding the lower portion rearwardly. A vertically-adjustable lumbar mechanism is adjustably supported on the back support structure and operably engages the flexible sheet for biasing an intermediate portion of the flexible sheet forwardly to both form the intermediate portion into a forwardly convex shape for postural lumbar support and also to tension the flexible sheet.

Abstract: A chair includes a seat, a backrest mounted to the seat, the backrest including a rear face having two sides, a chassis fixed to an underside of the seat, a leg assembly attached to the chassis, two stays respectively attached to the sides of the rear face of the backrest, and a connecting frame. Each stay has an upper end fixed to an associated side of the rear face of the backrest. The connecting frame has two ends and an extension extending from the connecting frame. The extension is securely connected to a rear end of the chassis. Each end of the connecting frame is fixed to a lower end of an associated stay.

Abstract: The invention relates to a support with adjustable arch, especially a lumbar support for seats, in particular motor vehicle seats and chair back rests as well as for any type of bed, the structure of which comprises an arching element and an adjustment device for setting and readjusting the arching of the arching element.

Abstract: A unitized back plate and lumbar support device for a seat including a back plate, a housing with a channel, which housing is fixedly attached to the back plate, and an extending paddle. The extending paddle has a free end with a pressure surface, the surface being a load bearing element proximal to a seat occupant, and the extending paddle has an encapsulated end in extendible communication with the channel in the housing. An actuator mediates travel of the extending paddle between a substantially retracted position and an extended position.

Abstract: Disclosed is a chair and a method using the chair, which can be not only used easily and comfortably but also utilized in treating an improper alignment of spinal vertebrae. The chair has a seat assembly for seating the user on the seat assembly, the seat assembly being operated by the user in such a manner as that the user can adjust a height of the seat assembly; a backrest assembly for supporting a back of the user, the backrest assembly being operated separately from the seat assembly by the user in such a manner that the user can adjust a height of the backrest assembly; a headrest assembly for resting a head of the user on the headrest assembly, the headrest assembly being assembled with the backrest assembly; and a backrest frame for supporting the backrest assembly and the headrest assembly, the backrest frame being fixed to the seat assembly, the backrest assembly moving along the backrest frame when the height of the backrest assembly is adjusted.

Abstract: An ergonomic weight support device for a seat comprising a housing having a channel defined by at least one guide boss, an extending element having an unanchored weight supporting end and an engaged end slidingly disposed within the channel of said housing and an actuator fixedly attached to said housing and in moving communication with said extending element whereby said actuator mediates the weight supporting end of said extending element between a substantially retracted position and an extended position.

Abstract: An ergonomic weight support device for a seat comprising a housing having a channel defined by at least one guide boss, an extending element having an unanchored weight supporting end and an engaged end slidingly disposed within the channel of said housing and an actuator fixedly attached to said housing and in moving communication with said extending element whereby said actuator mediates the weight supporting end of said extending element between a substantially retracted position and an extended position.

Abstract: An adjustable backrest for a seating structure includes an upright having a rack. The backrest is moveably mounted on the upright. A pawl is pivotally mounted to the backrest about a pivot axis and is pivotable between an engaged position, wherein the pawl is engaged with the rack, and a disengaged position, wherein the pawl is disengaged from the rack. The pawl is further translatably mounted to the backrest, wherein the pawl is translatable relative to the backrest between at least a disabled position and an operative position. A spring biases the pawl into the engaged position when the pawl is in the operative position. A method of adjusting the height of the backrest is also provided.

Abstract: A back pain reliever has a linear alignment support with at least two bi-pad supports mounted thereon. The linear alignment support runs along the spine of a person with least two bi-pad supports mounted thereon, so each of the two pads of the bi-pad support are on opposite sides of the spine of a person.

Abstract: The invention relates to a device for supporting a seated person, comprising a seat and a support for the lumbar-thoracic transition region, which is connected to the seat, and characterized by an adjustable lumbar-sacral support, which is mounted at the location of the lower side of the support for the lumbar-thoracic transition region. Preferably, an adjustable support is furthermore provided for the thoracic-cervical transition region, which support is mounted at the location of the upper side of the support for the lumbar-thoracic transition region.

Abstract: A device for lumbar support for an office chair having a seatback including a seatback frame and a membrane stretched over the seatback frame. The device can be arranged behind the membrane and can be housed in the seatback frame to provide vertical and horizontal adjustment independent of the membrane. Preferably, the device includes a central part having two comparably rigid carrier elements connected to each other via an elastic element arranged therebetween, the rigid carrier elements each including a guide track that can be arranged in the seatback frame to provide the vertical adjustment. A front part includes a cushion attached to an upholstery plate, the upholstery plate facing the membrane. A rear part includes a plastic plate. The cushion and the plastic plate are connected via a clip connection, and the clip connection is guided in slots of the carrier elements.

Abstract: A lumbar support for a chair having a flexible back, includes at least one generally vertical support member disposed to the rear of the chair back. A transverse member engages the vertical support and has opposed ends provided with grippers for gripping opposed edges of the flexible back. The transverse member is configured to force the opposed edges of the flexible back forwardly of the chair back in the lumbar region of the user to provide support therefor. The transverse member may also be configured to slide on the vertical support to provide for height adjustability of the lumbar support of the fabric.

Abstract: An upright space-dividing panel which mounts thereon a cushion usable as a back rest. The cushion is secured to the panel by at least one strap which is secured to the panel and overlies a side face thereof in a generally vertical orientation. The cushion includes a mounting arrangement on the rear side thereof which cooperatively engages with the strap to permit vertical sliding movement of the cushion relative to the panel so as to define a back rest which is usable in conjunction with a furniture component disposed adjacent the panel and defining a seating surface thereon.

Abstract: An adjustable pillow system is provided for use with a juvenile vehicle seat. The pillow system includes a vertical slide strap adapted to be coupled to the juvenile vehicle seat and a pillow coupled to the vertical slide strap to slide up and down on the strap.

Abstract: A lumbar support for a chair having a flexible back, includes at least one generally vertical support member disposed to the rear of the chair back. A transverse member engages the vertical support and has opposed ends provided with grippers for gripping opposed edges of the flexible back. The transverse member is configured to force the opposed edges of the flexible back forwardly of the chair back in the lumbar region of the user to provide support therefor. The transverse member may also be configured to slide on the vertical support to provide for height adjustability of the lumbar support of the fabric.

Abstract: A chair includes a flexible back shell, a back covering that covers at least a portion of a front surface of the back shell, and an adjustable lumbar device positioned between the back shell and the back covering. The adjustable lumbar device is flexible so that the lumbar device will flex to conform to a horizontal shape of the chair back shell, but is relatively stiff in a direction perpendicular to a front surface of the back shell, such that the lumbar device provides good lumbar support. The lumbar device is positioned between the back shell and the back covering for vertical height adjustment, and frictionally engages the same to retain its adjusted position. Further, the adjustable lumbar device includes rearwardly-extending protrusions that engage slots in the back shell to form a detent-like feature for holding a selected position, and further includes forwardly protruding tabs that act as handles for grasping the lumbar device for adjustment.

Abstract: A chair equipped with a lumbar support unit is disclosed. The lumbar support unit includes a lumbar plate attached to a lower portion of a tiltable backrest part, and an actuating connector comprising a connecting wire which is connected at one end to an upper end of the lumbar plate and is connected at the other end to a chair frame supporting the seat and back parts, and a connecting tube surrounding the connecting wire, which is positioned at one end at a location downwardly spaced from the one end of the connecting wire, and is connected at the other end to a movable frame. The lumbar plate is automatically protruded forward to snugly support a lumbar region of a user when the back part is tilted rearwardly. The chair can afford convenient operation and protection of a lumbar region of a user.

Abstract: An adjustable backrest of a motor vehicle seat is provided. The backrest includes two vertical, laterally undivided stationary supportive areas, and a central supportive area arranged between them. The central supportive area includes an upper section, as a guided headrest, the height of which may be adjusted. The central supportive area, that is provided beneath the headrest, is embodied in such a way as to be divided horizontally into a lower and a central section. The lower section is arranged to be stationary and the central section is arranged such that its height may be adjusted.

Abstract: An ergonomic weight support device for a seat comprising a housing having a channel defined by at least one guide boss, an extending element having an unanchored weight supporting end and an engaged end slidingly disposed within the channel of said housing and an actuator fixedly attached to said housing and in moving communication with said extending element whereby said actuator mediates the weight supporting end of said extending element between a substantially retracted position and an extended position.