US3800342A

US3800342A - Body support cushioning system with sideboard positioning mechanism

Info

Publication number: US3800342A
Application number: US00245157A
Authority: US
Inventors: A Tenteris; B Wetzel
Original assignee: Jobst Institute Inc
Current assignee: BSN Jobst Inc
Priority date: 1972-04-18
Filing date: 1972-04-18
Publication date: 1974-04-02
Anticipated expiration: 1991-04-02
Also published as: BE798418A; DE2318961A1; IT980248B

Abstract

A cushion for uniformly distributing support of an invalid comprising a liquid container of flexible sheet material which is impervious to the liquid, and means to elevate side portions of the container to form a loose upper surface which can conform to the supported body portions of the invalid and support these portions as in flotation. For a constant volume of liquid in the container, the position of the side portions adjusts the depth to enable bodies of varying weight to be floated free of the underlying support surface. The means for varying the position of the sideboards applies maximum torque when the sideboards are in the horizontal position and maximum speed as the sideboards approach the vertical position.

Description

United States Patent [191 Tenteris et al.

[ 51 Apr. 2, 1974 BODY SUPPORT CUSHIONING SYSTEM WITH SIDEBOARD POSITIONING MECHANISM [75] Inventors: Ansis U. Tenteris, Toledo; Bruce W.

Wetzel, Millbury, both of Ohio [73] Assignee: Jobst Institute, Inc., Toledo, Ohio [22] Filed: Apr. 18, 1972 [21] Appl. No.: 245,157

[52] US. Cl 5/348 WB, 5/60 [51] Int. Cl A6lg 7/10, A47c 27/08 [58] Field of Search 5/18 R, 18 B, 61, 348,

[56] References Cited UNITED STATES PATENTS 3,585,660 6/197l Gottfried et al. 5/348 R 3/1894 Karp 5/18 B X Primary Examiner-Bobby R. Gay Assistant Examiner-Andrcw M. Calvert Attorney, Agent, or Firm-David H. Wilson [57] ABSTRACT A cushion for uniformly distributing support of an invalid comprising a liquid container of flexible sheet material which is impervious to the liquid, and means to elevate side portions of the container to form a loose upper surface which can conform to the supported body portions of the invalid and support these portions as in flotation. For a constant volume of liquid in the container, the position of the side portions adjusts the depth to enable bodies of varying weight to be floated free of the underlying support surface. The means for varying the position of the sideboards applies maximum torque when the sideboards are in the horizontal position and maximum speed as the sideboards approach the vertical position.

12 Claims, 3 Drawing Figures BODY SUPPORT CUSHIONING SYSTEM WITH SIDEBOARD POSITIONING MECHANISM SUMMARY OF THE INVENTION This invention relates to body supporting systems and particularly to cushioning means for supporting invalids and a support structure for the cushioning means with asideboard positioning mechanism.

A body support system of the type disclosed in U.S. Pat. No. 3,585,660 entitled Body Support Cushioning System by Max Gottfried,. Dennis G. Mosiniak and Ansis V. Tenteris is utilized to avoid the occurrence of bedsores or decubitus ulcers. Bedsores are usually attributed to the occulsion of the blood supply to areas of support of an invalid where high pressures are developed as in the region of bony protuberances upon which the body weight is concentrated. In these regions when the surface pressure exceeds the pressure distributing the lymph fluid, a starvation of the cells occurs. The above referenced patent teaches the utilization of the principal of flotation to support an invalid. The invalid is effectively floated in a pool of liquid which is isolated from the invalid by a flexible material such as neoprene impregnated nylon which presents a loose interface between the supporting liquid pool and the invalid. The material essentially conforms to the invalids body in a manner similar to that where the invalid is immersed directly in the liquid. Thusly the supporting force is evenly distributed over the surface of the invalids body.

In order to minister to the invalid the sideboardsof the supporting apparatus are lowered and the supporting fluid flows to these side portions thereby lowering the invalid to the underlying support. Manual positioning of the sideboards presents two obvious difficulties. First a single attendant can only operate one sideboard at a time. Since various positions are provided to adjust the depth of the pool the attendant may have to make several trips from one side of the bed to the other in order to achieve the proper adjustment. The second disadvantage is that it may be extremely hard for a relatively weak attendant to exert the force required to lift a sideboard from the horizontal position.

The present invention-solves these difficulties by utilizing a sideboard positioning mechanism. The positioning mechanism allows the attendant simultaneous control of the sideboards and provides an infinite number of intermediate positions between horizontal and vertical. The mechanical advantage of the mechanism greatly reduces the amount of force required to raise the'sideboards from the horizontal position.

An object of the invention is to improve body support cushions for invalids.

A second object is to facilitate the manipulation of a body support cushion utilizing liquid for the supporting medium and therefore involving a substantial weight of liquid.

A third object is to provide an infinite range of sideboard positions to enable adjustment in the depth of a liquid pool providing support for an invalid.

In accordance with the above objects a feature of this invention is mechanical means for positioning the pivoted side panels of a support for a liquid filled body support cushion with relation to a horizontal base such that a liquid impervious flexible envelope containing the supporting fluid can conveniently be shifted in posi- 2 tion to adjust the depth of the supporting pool of liquid.

Another feature resides in a positioning mechanism which has mechanical advantage which increases as the force required to control alteration of position increases. It is to be appreciated that the fluid nature, of the heavy liquid employed for displacement support of a body causes the weight of that liquid to follow the means which confines it. When side panels are lowered the liquid flows to the region of the panels imposing forces which must be overcome. In the case where the panels approach the horizontal and the envelope for the liquid is of sufficient lateral extent to extend beyond the outer limits of the panels a pendant reservoir is formed and in extreme circumstances is suspended at the outer edges of the panels. This imposes essentially all of the weight of the supporting liquid at the maximum moment arm around the pivotal mounting of the panels and requires a very substantial mechanical advantage in the positioning mechanism to maintain the driving forces at reasonable levels. Such advantage is achieved by the relationship of the length and location of pivoted linkages in the drive mechanism and the means to shift the location of those pivots and to shift the moment of force'around them as the loading is changed.

A further feature is the incorporation of a biasing means counterbalancing the liquid loading of the movable panels to facilitate the movement of the panels by the drive mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of a body support system according to this invention showing an invalid floating in a cushion;

FIG. 2 is a perspective of the system of FIG. 1 showing an invalid positioned for treatment with the flotation pool dispersed to expose the invalid; and

FIG. 3 is a front elevation of the sideboard positioning mechanism for one sideboard according to the invention with the linkage for the opposite sideboard brokenaway and omitted.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is illustrated as applied to a bed. FIG. 1 depicts a body support cushioning system such as the one shown in FIG. 1 of the above referenced Gottfried Patent. The bed 11 provides a cushioned support for the entire body of an invalid 12 by in effect floating the invalid in a pool of liquid, conveniently water. An envelope 13 for the liquid is made up of liquid impervious flexible sheet material such as neoprene coated nylon fabric fabricated into an upper and lower face 14 and 15 joined at their margins in a liquid tight joint 16 shown in FIG. 2. When arranged as a full cushion for a bed 11, the envelope 13 is of a length slightly exceeding the length of the bed and a width exceeding the width of the invalid by at least twice the depth of the pool of liquid required to float the invalid free of the underlying support surface. When the sides of the envelope 13 are raised and brought toward each other the lower face 15 defines a cupped container for the flotation liquid while the upper face 14 has excess material available to confonn to the invalids body. When the invalid is raised free of the underlying support as in FIG. 1 the free upper face 14 imposes the supporting force of the liquid displaced by the invalid uniformly over the supported region of the body of the invalid thereby effectively floating that region.

The present system is arranged so that the envelope can be contained in a region that can be varied between that defining a pool which is wide and shallow and narrow and deep. While the envelope should be of such dimensions as would minimize the volume of liquid required to separate the inner surfaces of the faces 14 and 15, a large range of sizes of invalids must be accommodated by a given envelope. A thin person can be floated in a shallower pool of liquid than that required to float afat person or a person having a thick body. The variation is accomplished by providing a range of positions in which the longitudinal edges of the envelope are maintained both as to-their lateral separation from each other and their height above the underlying major area of envelope support.

In order to expose the patient for treatment or examination as in FIG. 2 the upper face 14 of the envelope 13 which enfolds the patient must be lowered relative to the underlying support. This is accomplished by manipulating the pool of liquid so that the patient is gently lowered to the supporting surface 22 beneath the lower face 15 of the envelope 13. Since the supporting liquid exceeds the patients weight it is a significant load to be manipulated by nurses and attendants.

Manipulation of the liquid pool as between the conditions illustrated in FIGS. 1 and 2 is facilitated by the mounting for envelope 13. A headboard l7 and a footboard 18 to be described later are joined by side rails 19 secured thereto by brackets 21 to provide a rigid mounting for previously mentioned envelope support panel 22. Lateral restraint for the envelope 13 is supplied by sideboards 23 extending between headboard 17 and footboard 18. The parallel sideboards 23 are spaced at their lower edges 24 at the minimum width dimension of the cushion. This dimension is dependent upon the maximum body width which is to be accommodated for a maximum flotation pool depth.

The width and depth of the pool contained by envelope 13 may be regulated for a given volume of liquid by. the positioning of sideboards 23. The sideboards 23 are pivoted about their lower edge 24 at headboard l7 and footboard 18. This may be accomplished by providing pivot rod extending from each end of the sideboards. The protruding stub ends of rod 20 fit into sleeve bearings 30 in the headboard and footboard. Tangs 6 are secured to pivot rods 20 as by welding and can be secured to the sideboard 23 by screws or other fasteners. The width of the pool varies as the angular relationship of the sideboards 23 to the support panel 22. The cross-section of the pool therefore will vary from an inverted truncated triangle when the sideboards are between the vertical and horizontal to a rectangle when the sideboards are vertical. As the sideboards 23 vary from horizontal to vertical their longitudinal edges remote from the pivot rod 20 and coupled to the envelope 13 are elevated to increase the depth of the pool to its maximum depth when the sideboards 23 are perpendicular to the support panel 22.

In order to achieve and maintain a particular angular relationship between the sideboards 23 and the support panel 22 a mechanism for pivoting the sideboards is enclosed in footboard l8. Advantageously the mechanism can be as that shown in FIG. 3. The sideboards 23 pivot about pivot point 25 centered in bearing 30 in the footboard and headboard. Link arm 26 is firmly attached to sideboard 23 through pivot rod 20 at pivot point 25 and therefore moves through the same angle as does sideboard 23.

A threaded nut 27 is free to move along threaded shaft 28 journaled for rotation by means not shown in footborad 18. The advance ofnut 27 is dependent upon the direction the shaft is turned. Attached to the threaded nut 27 at pivot point 29 is link arm 31. At the top of threaded shaft 28 is a fixed pivot point 32 for link arm 33. Link arm 31 and link arm 33 are connected at pivot point 34 so that, for example, as threaded nut 27 moves up threaded shaft 28 it causes. pivot points 29 and 34 to move upward. Pivot point 34 is moved away from threaded shaft 28 since link arm 33 moves counter clockwise as viewed in FIG. 3 about pivot point 32 to move link arm 31 clockwise about pivot point 29.

As pivot point 34 moves away from threaded shaft 28 so does pivot point 35 at the upper end of link arm 31. Pivot point 35 is attached to link arm 36. Link arm 36 is connected to crank or link arm 26 at pivot point 37. Pivot point 37 is constrained to movement in an are around pivot point 25 so the outward movement of link arm 36 causes crank 26 and sideboard 23 to rotate about pivot point 25 in a clockwise direction. This rotates the sideboard 23 clockwise to lower its edge remote from pivot rod 20 and reduce the depth of the pool. Of course, when threaded nut 27 is moved down threaded shaft 28 the opposite motion occurs, sideboard 23 rotates in a counter clockwise direction, and the depth of the pool is increased. Advantageously, a torsion spring 38 may be attached to the footboard and sideboard in such a manner as to counterbalance a portion of the weight of the liquid in envelope 13, thereby decreasing the force required to lift the sideboard andthus facilitating operation of the mechanism.

Advantageously threaded shaft 28 may have a bevel gear 39 mounted at one end and meshed with another bevel gear 41 which is turned by hand crank 42 in FIGS. 1 and 2. In this manner a nurse or attendant may use the hand crank 42 to raise and lower sideboards 23 thereby controlling the depth of the liquid in envelope 13.

Let us assume that sideboard 23 is in the horizontal position where the weight of the liquid resting upon it is the greatest. This weight produces a moment M, about pivot point 25 in a clockwise direction. In order to balance the load a force must be applied at pivot point 37 in a counterclockwise direction to produce a moment on crank 26. If we designate this force as F, and apply in a direction parallel to the axis of link 36, then the force times the effective length L, of crank 26 equals the moment on sideboard 23 or F X L M The effective length of crank 26 is determined by projecting a line through pivot points 35 and 37 and measuring the perpendicular distance to pivot point 25.

The force F, is provided by a force applied on hand crank 42 and transmitted through

bevel gears

41 and 39, threaded shaft 28 and threaded nut 27 such that a component F of the applied force is perpendicular to link 31 at pivot point 29. If we designate the distance between pivot points 29 and 34 as L then there is a moment F X L about pivot point 34. The perpendicular distance between link 36 and pivot point 34 is the effective length L of the distance between pivot points 34 and 35. Therefore in order to balance the-moments about pivot point 34 a force F is produced at pivot point 35 parallel to link 36 in a counter clockwise direction and F L F X L;,.

Also produced by the force on the hand crank 42 is a force component at pivot point 29 parallel to link 31. This force component acts upon link 36 at pivot point 35 to produce a force component F parallel to link 36 and in the same direction as F Thus the combination of F and F produces F or'F P F As the sideboard 23 is rotated toward the vertical position the moment M, decreases since the weight of liquid decreases as it flows toward the longitudinal center of the cushion system and the effective length of the moment arm decreases. Since link 31 is rotating in a counter clockwise direction about pivot point 34 the force component F decreases therefore decreasing F and in turn F Thus a constant force at hand crank 42 produces maximum torque when sideboard 23 is in a horizontal position and decreasing torque as the sideboard is rotated to the vertical position. It is evident that if an increase in maximum torque is required it may be achieved by increasing the length of crank 26 or decreasing the distance between pivot points 34 and 35 or increasing the distance between pivot points 29 and 34 or any combination thereof.

The constant force input to the system is particularly advantageous where it is desired to drive the bevel gear with an electric moter. Each type of motor has a particular point on its performance curve where it is operating at maximum efficiency..Thus it would be desirous to operate at that point in order to be able to utilize the smaller and least expensive motor available. Looking at

links

31 and 33 it can be seen that as threaded nut 27 is moved down threaded shaft 28 in equal increments the distance between pivot point 34 and the shaft becomes smaller by increasing increments. These increasing increments of horizontal movement are reflected through link 36 to crank 26. There they are trans formed into increasing increment of rotational movement about pivot point 25. Thus as the threaded shaft 28 is turned at a constant speed the speed of rotation of sideboard 23 increases from the horizontal to the vertical position. Since the torque required to produce the movement is decreasing as the load decreases, the power required remains constant. Therefore the power input to the system remains constant and the motor operates at maximum efficiency.

While the overall dimensions of the system will depend upon the space available and the maximum load required to be lifted, certain relations must be maintained. In order to avoid locking up or over-center conditions the distance between pivot points 29 and 34 and pivot points 34 and 32 must be greater than the maximum distance desired between pivot points 29 and 32. Also the distance between pivot points 25 and 37 and pivot points 37 and 35 must be greater than the maximum straight line distance between pivot points 25 and 35 when the sideboard 23 is in its vertical position. Fi-

. nally the distance between pivot points 34 and 35 and pivot points 35 and 37 must be greater than the straight line distance between pivot points 34 and 37 when the sideboard is in its horizontal position.

Exemplary geometry of the drive linkage involves a load moment imposed on sideboard 23 around the fixed pivot 25 and a drive moment imposed through crank arm 26 at coupling point 37 which can move in a fixed arc of radius defined by link 26 about fixed pivot 25. A second fixed arc of motion is that of the fulcrum or pivoted coupling point 34 about fixed pivot 32, that arc having a radius defined by link 33. A broken link having a toggle-like action is made up of link 36 and link 31 pivotally coupled at 35. When the sideboard pivot is twelve inches from the axis of screw 28, the effective radius of the first arc (link 33) is six inches and the second arc (link 26) is four and one quarter inches, and when the effective length oflink 36 is eight and one quarter inches while the space between

pivots

29 and 34, along link 31 is three and three-eighths inches and between

pivots

34 and 35 is four and fiveeighths inches, link 26 pivots around 25.9 for a displacement of pivot 29 from a location six inches below pivot 32 to a position six and one half inches below pivot 32. Successive half-inch increments of displacement downward increase the arc of counter clockwise displacement of link 26 to approximately l0.5, 12, 14 and 21. In such an arrangement a three-inch displacement of pivot 29 toward a position in which links 33 and 31 approach a straight line'relationship results in a pivotal displacement of link 26 of about 76. It is advantageous to locate sideboard 23 about 30 clockwise from link 26 in such an arrangement so that with pivot 29 six inches below pivot 32 sideboard 23 is essentially horizontal.

If desired the lifting mechanism-enclosed in endboard 18 may be a hydraulic or electric motor. The linkages can be changed in length and their angular relationships to alter the mechanical advantage they offer. Ac-

cordingly, it is to be understood that the above embodiments are presented as illustrative and are not to be read as imposing limitations on the invention.

We claim:

- 1. A cushioning system for invalids comprising an envelope of a flexible, liquid impervious, sheet material closed upon itself to form a container for liquid, said container having a lateral extent greater than the portion of the invalid to be supported; a body of liquid within said envelope upon which a portion of the invalid is supported at least in part by displacement of said liquid; a support for said envelope including a horizontal region adapted to support a major face of said envelope; an endboard perpendicular to said horizontal region and having spaced generally parallel major faces; first and second opposed sideboards extending upwardly from said horizontal support; a pivotal mounting for at least one of said sideboards for pivotal motion around an axis adjacent and generally parallel to said horizontal support and perpendicular to said endboard, said envelope being coupled to portions of said sideboards remote from said pivotal mounting; lever arm means enclosed between said spaced major faces of said endboard and coupled to said pivotal mounting for pivotal motion around said axis; and means enclosed between said spaced major faces of said endboard to drive said lever arm means and thereby to drive said one sideboard about said pivotal mounting.

2. A combination according to claim 1 in which said drive means includes means to maintain said sideboard at any of a selected plurality of inclinations with respect to said horizontal support.

3. A combination according to claim 2 including a second pivotal mounting for said second sideboard along a second axis adjacent said horizontal support and generally parallel to said pivot axis ofsaid first sideboard; second lever arm means enclosed between said spaced major faces of said endboard and coupled to said second pivotal mounting for pivotal motion around said axis; and means to couple said drive means to said second lever arms means whereby said drive means drives said second sideboard about its respective pivot mounting simultaneously with the driving of said first sideboard.

4. A cushioning system for invalids comprising an envelope of a flexible liquid impervious, sheet material closed upon itself to form a container for liquid, said container having a lateral extent greater than the portion of the invalid to be supported; a body of liquid within'said envelope upon which a portion of the invalid is supported at least in part by displacement of said liquid; a support for said envelope including a horizontal region adapted to support a major face of said envelope; first and second opposed sideboards extending upwardly from said horizontal support; a pivotal mounting for at least one of said sideboards for pivotal motion around an axis adjacent and generally parallel to said horizontal support, said envelope being coupled to portions of said sideboards remote from said pivotal mounting; means to drive said one sideboard about said pivotal mounting; and counterbalancing means which aid said driving means when said portion of said sideboard remote from said pivotal mounting is being raised and which oppose said drive means when said portion of said sideboard remote from said pivotal mounting is being lowered.

5. A combination according to claim 4 in which said counterbalancing means is a torsion spring.

6. A cushioning system for invalids comprising an envelope of a flexible liquid impervious, sheet material closed upon itself to form a container for liquid, said container having a lateral extent greater than the portion of the invalid to be supported; a body of liquid within said envelope upon which a portion of the invalid is supported at least in part by displacement of said liquid; a support for said envelope including a horizontal region adapted to support a major face to said envelope; first and second opposed sideboards extending upwardly from said horizontal support; a pivotal mounting for at least one of said sideboards for pivotal motion around an axis adjacent and generally parallel to said horizontal support, said envelope being coupled to portions of said sideboards remote from said pivotal mounting; means to drive said one sideboard about said pivotal mounting; and means included in said drive means to decrease the torque applied to and increase the speed of said sideboard for a given applied power as it is pivoted from a position of maximum load to a position of minimum load.

7. A combination according to claim 1 in which said drive means is actuated by a manual crank.

8. A support for an envelope of a flexible, liquid impervious, sheet material closed upon itself to form a container for liquid, and providing cushioning for a body by displacement of said liquid comprising a primary panel adapted to be mounted with the plane of its major face'horizontal, an end panel mounted perpendicular to said primary panel, first and second side panels, pivotal mounting means for mounting a side panel for pivotal movement around a longitudinal edge adjacent the major face of said primary panel and for shifting the elevation of a second longitudinal edge relative to the plane of said primary panel, drive means arranged to decrease the torque applied to said side panel tending to pivot it around said mounting means and to increase the speed of arcuate motion of said sideboard for a given applied power as said side panel is pivoted from a generally horizontal position toward a vertical position, and means to apply operating power to said drive means.

9. A combination according to claim 8 wherein said drive means comprises a lead screw, a nut on said lead screw, a first drive link pivotally coupled at one end to said nut, a second drive link pivotally coupled to the first drive link at a point remote from said nut, a third link defining a fixed arc of motion at a point along its length and having a fixed pivot in proximity to the axis of said lead screw and spaced from said nut, a fulcrum from said fixed arc defined by said third link for said first drive link and coupled to said first drive link between said nut and the pivotal coupling to said second drive link, and a crank arm extending from said pivotally mounted side panel and pivotally coupled to said second drive link at a point spaced from the pivotal coupling between said first and second drive links.

10. A support for an envelope of a flexible, liquid impervious, sheet material closed upon itself to form a container for liquid, and providing cushioning for a body by displacement of said liquid comprising a primary panel adapted to be mounted with the plane of its major face horizontal, an end panel mounted perpendicular to said primary panel. first and second side panels, means mounting said side panels with a first longitudinal edge adjacent the major face of said primary panel and a second longitudinal edge adapted to be elevated from the plane of major face of said primary panel, and a system of levers enclosed in said end panel adapted to alter the elevation of said second longitudinal edge of at least one panel with respect to the plane of the major face of said primary panel.

11. A combination according to claim 10 wherein said first longitudinal edges are spaced and parallel on said major face of said primary panel and a pivotal mounting for said side panels at said first longitudinal edges.

12. A combination according to claim 9 wherein the effective length of said second drive link and said crank between their respective pivotal couplings approximates the spacing of said pivotal mounting means from the axis of said screw, the radius defined by said third link approximates one half the spacing of said pivotal mounting means from the axis of said screw, and the length of the first drive link exceeds the length of said third link.

Claims

1. A cushioning system for invalids comprising an envelope of a flexible, liquid impervious, sheet material closed upon itself to form a container for liquid, said container having a lateral extent greater than the portion of the invalid to be supported; a body of liquid within said envelope upon which a portion of the invalid is supported at least in part by displacement of said liquid; a support for said envelope including a horizontal region adapted to support a major face of said envelope; an endboard perpendicular to said horizontal region and having spaced generally parallel major faces; first and second opposed sideboards extending upwardly from said horizontal support; a pivotal mounting for at least one of said sideboards for pivotal motion around an axis adjacent and generally parallel to said horizontal support and perpendicular to said endboard, said envelope being coupled to portions of said sideboards remote from said pivotal mounting; lever arm means enclosed between said spaced major faces of said endboard and coupled to said pivotal mounting for pivotal motion around said axis; and means enclosed between said spaced major faces of said endboard to drive said lever arm means and thereby to drive said one sideboard about said pivotal mounting.

3. A combination according to claim 2 including a second pivotal mounting for said second sideboard along a second axis adjacent said horizontal support and generally parallel to said pivot axis of said first sideboard; second lever arm means enclosed between said spaced major faces of said endboard and coupled to said second pivotal mounting for pivotal motion around said axis; and means to couple said drive means to said second lever arms means whereby said drive means drives said second sideboard about its respective pivot mounting simultaneously with the driving of said first sideboard.

4. A cushioning system for invalids comprising an envelope of a flexible liquid impervious, sheet material closed upon itself to form a container for liquid, said container having a lateral extent greater than the portion of the invalid to be supported; a body of liquid within said envelope upon which a portion of the invalid is supported at least in part by displacement of said liquid; a support for said envelope including a horizontal region adapted to support a major face of said envelope; first and second opposed sideboards extending upwardly from said horizontal support; a pivotal mounting for at least one of said sideboards for pivotal motion around an axis adjacent and generally parallel to said horizontal support, said envelope being coupled to portions of said sideboards remote from said pivotal mounting; means to drive said one sideboard about said pivotal mounting; and counterbalancing means which aid said driving means when said portion of said sideboard remote from said pivotal mounting is being raised and which oppose said drive means when said portion of said sideboard remote from said pivotal mounting is being lowered.

8. A support for an envelope of a flexible, liquid impervious, sheet material closed upon itself to form a container for liquid, and providing cushioning for a body by displacement of said liquid comprising a primary panel adapted to be mounted with the plane of its major face horizontal, an end panel mounted perpendicular to said primary panel, first and second side panels, pivotal mounting means for mounting a side panel for pivotal movement around a longitudinal edge adjacent the major face of said primary panel and for shifting the elevation of a second longitudinal edge relative to the plane of said primary panel, drive means arranged to decrease the torque applied to said side panel tending to pivot it around said mounting means and to increase the speed of arcuate motion of said sideboard for a given applied power as said side panel is pivoted from a generally horizontal position toward a vertical position, and means to apply operating power to said drive means.