US3820478A

US3820478A - Article support stand

Info

Publication number: US3820478A
Application number: US00270819A
Authority: US
Inventors: E Bergenthal
Original assignee: Caddy Corp
Current assignee: Caddy Corp
Priority date: 1972-07-11
Filing date: 1972-07-11
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28
Also published as: JPS4956370A; DE2335231A1; GB1404907A; FR2192682A5

Abstract

An article support platform is resiliently mounted in the frame of an article support stand for reciprocal vertical movement in the stand in order to support a stack of articles, such as trays, dishes and the like, with the uppermost article in the stack located at a predetermined level at all times. The resilient support mechanism for the platform includes a lever which is pivotally mounted in the frame at a fixed pivot point and operatively connected to the platform by at least one flexible cable so that the lever is caused to pivot about its fixed pivot point during vertical movement of the platform. A resilient spring or the like is operatively connected between the lever and the frame to resist downward vertical movement of the platform while biasing the lever in a predetermined direction to urge the platform towards its uppermost position.

Description

United States Patent 91 Bergenthal ARTICLE SUPPORT STAND [75] Inventor: Eckhard J. Bergenthal, Glassboro,

[73] Assignee: Caddy Corporation of America,

Pitman, NJ.

22 Filed: July 11, 1972 211 Appl. No.: 270,819

[ June 28, 1974 Primary Examiner-Bobby R. Gay Assistant Examiner-Darrell Marquette Attorney, Agent, or Firm-Curtis, Morris & Safford ABSTRACT An article support platform is resiliently mounted in the frame of an article support stand for reciprocal vertical movement in the stand in order to support a stack of articles, such as trays, dishes and the like, with the uppermost article in the stack located at a predetermined level at all times. The resilient support mechanism for the platform includes a lever which is pivotally mounted in the frame at a fixed pivot point and operatively connected to the platform by at least one flexible cable so that the lever is caused to pivot about its fixed pivot point during vertical movement of the platform. A resilient spring or the like is operatively connected between the lever and the frame to resist downward vertical movement of the platform while biasing the lever in a predetermined direction to urge the platform towards its uppermost position.

15 Claims, 8 Drawing Figures PAH-m Imam SHEET 1 UP 3 PATENIEBJUN 9 3820.478

SHEET 3 [IF 3 ARTICLE SUPPORT STAND The present invention relates to article support stands and more particularly to support stands which will support a stack of individual articles with the uppermost article of the stack in a predetermined positlon.

Support stands of the above type have been previously proposed which will support a stack of articles, such as for example, serving trays, dishes or the like, on a resiliently mounted platform so that the uppermost article in the stack will always be located at a predetermined level on the stand. Such support stands are often used in cafeterias or other establishments, i.e., hospitals, schools and the like, wherein a continuous supply of individual trays or dishes must be present for people to use. Preferably, such support stands will hold a relatively tall stack of such articles and will keep the uppermost article at a predetermined height, e.g. the level of an adjacent countertop, so that the article is easily located and removed from the stack. After an article is removed, the support mechanism in the stand causes the entire stack to move upwardly slightly so that the next article in the stack is presented at the desired location or level.

One problem which exists with previously proposed devices of this type is that the force which is applied to the article support platform will vary over the path of travel of the platform. Thus, the platform will move downwardly, under a given weight, a smaller distance at the top of its path of travel, i.e., adjacent the countertop level, than it will under the same additional weight at a lower level in its path of travel. For example, if the platform moves downwardly one inch under the load of five trays when it is near the countertop level, it often occurs that the platform will move down more than 1 inch when an additional five pans are added to the stack as the platform approaches its lowermost position in the stand. This problem is undesirable in article support stands of this type since the number of articles which can be supported on the stand will be reduced and the stand will not keep the uppermost article in the stack at'the same level at all times, irrespective of the height of the stack. The problem arises because of the fact that the torque which resists the downward movement of the platfonn under the load of the stack of articles or trays generally varies as the platform moves downwardly.

Moreover, with this type of article support stand it is often necessary to adjust the force with which downward movement of the support platform is resisted. This force must be adjusted since the articles to be supported on the stand at different times may have different weights. Thus, if the force resisting downward movement of the platform is such that the platform moves downwardly one inch under the weight of five trays, then, when a stack of articles or trays having a greater weight are placed on the stand, five of the heavier articles will move the platform downwardly more than one inch. Accordingly, over a given path of platform travel, less of the heavier articles can be sup ported on the platfonn. Obviously, it therefore becomes desirable to be able to increase the resistance force on the support platform to accommodate more of the heavier articles. However, this has not always been completely or satisfactorily possible with previously proposed support stands.

Accordingly, it is an object of the present invention to readily support a stack of articles on a support stand wherein the uppermost article of the stack will be maintained at a predetermined level, with the force resisting downward movement of the stack being constant over the entire path of travel of the platform.

Another object of the present invention is to resiliently support a stack of articles on a vertically movable platform which is biased towards its upward position with a constant force gradient.

Yet another object of the present invention is to provide an article support stand of the described type which is relatively simple and durable in construction and inexpensive to manufacture.

In accordance with an aspect of the present invention an article support stand is provided having a generally vertically extending frame in which an article support platform is mounted for reciprocal vertical movement between upper positions. The support platform extends horizontally outwardly of the frame, in the manner of a cantilever, and is resiliently supported on the platform by a resilient or spring type mechanism which biases the platform towards its uppermost position and which resists downward movement of the platfonn. This mechanism includes a lever which is pivotally mounted in the base of the frame for pivotal movement about a fixed pivot point in a vertical plane. A first pair of flexible cables, respectively connected at one end to a common point on the frame and connected at their opposite ends to opposite sides of the platform are guided over a plurality of guide rollers mounted in the frame and a pair of rollers mounted on the lever. The latter rollers respectively engage and reverse the direction of the cables between their ends so that vertical movement of the platform between its upper and lower positions, in response to articles or stacks of articles placed thereon, causes the lever to pivot about its pivot point.

A spring is operatively connected to the lever to apply a biasing force to the lever and create therewith a moment force about the levers pivot point which resists downward movement of the platform and normally urges the platfonn towards its upper position. The biasing spring force is applied to the lever through a first carriage which is mounted for selective movement along the lever in order to vary the point at which the biasing force is applied thereto. In addition, a second carriage member, which is vertically movably mounted in the frame, is operatively connected to the first carriage on the lever in order to vary the location of the carriage along the lever in response to adjustment of the vertical position of the second carriage. As a result, the point of application of the biasing force to the lever is varied-so that the moment force resisting the vertical movement of the platform is simultaneously adjusted.

The above, and other objects, features and advantages of thepresent invention will be described in detail with reference to the accompanying drawings, wherein:

movement of the actuating mechanism of the invention, and in dotted lines a second position of a portion of the lever biasing mechanism;

FIG. 3 is a sectional view taken along line 33 of FIG. 2;

FIG. 4 is a sectional view taken alone line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2;

FIGS. 6 and 7 are partial elevational views, similar to In order to support articles on stand 10, a horizontally extending support platform 14 is mounted at one end 16 thereof in frame 12. This platform is mounted for vertical movement between upper and lower positions, illustrated respectively in solid and phantom lines in FIG. 1, and is adapted to support a plurality of articles 18 on its upper surface 20. The articles 18 may be of any desired form and, in the illustrative embodiment of the invention are shown as a stack of individual trays such as may be utilized in a cafteteria. Of course, it is to be understood that the articles supported on surface 20 may take any desired form as may be required for the particular use to which the stand is placed. In any case, stand 10 is constructed so as to maintain the uppermost article or tray in stack 18 at a predetermined level, such as for example, at the level of the top 22 of stand frame 12. Thus, platform 14 is supported, as described hereinafter, so as to move downwardly as additional articles are placed on stack 18 and to move upwardly as articles are removed from the stack, thereby maintaining the uppermost article at the desired predetermined level. i

To accomplish this result, platform 14 is supported in frame 12 by a pair of arms 24 which extend through vertical slots 26 in the front face 28 of stand 10. As seen in FIGS. 3, 6 and 7, arms 24 each are secured to separate support plates 29 at their free ends 30 within frame 12. Two pairs of spaced rollers 31 are mounted on each of the support plates 29 and respectively receive between them generally rectangular guide tracks or tubes 32 on which the pairs of rollers 30 move during the vertical movement of platform 14. By this arrangement, the platform is maintained at all times in its generally horizontal position, supported generally asa cantilever.

Platform 14 is supported in frame 12 by a resilient support mechanism 34, most clearly illustrated in FIGS. 2 and 6-8 of the drawings. This support mechanism biases platform 14 towards it uppermost position and resists the movement of the platform towards the base of frame 12. The support mechanism is constructed so that a constant or linear force gradient is applied to platform 14 at all times. That is, platform 14 will move downwardly at substantially equal distances under a given weight of trays at any point in its vertical movement. For example, if the platform moves downwardly one inch, under the weight of five trays added to the platform when it is in its uppermost position, then the platform will also move downwardly one inch when an additional five trays are added to a stack of trays when the platform is near its lowermost position. This constant gradient is achieved because, by the construction of the invention, the moment arm which is used to produce the torque that resists movement of platform 14 is constant at all times, thus there is no variation in the distance traveled by platform 14 upon removal or addition of a given number of trays or other articles from the stack.

Support mechanism 34 includes an elongated actuating lever 36 which is mounted on support block 38, secured in the base 40 of frame 12, for rotation about a fixed pivot point 42. Thus, at all times during the use and actuation of the apparatus lever 36 will rotate, as described hereinafter, about the same pivot axis. This is an important feature of the present invention since, as a result of this construction, the moment arm which is used to produce the torque that resists downward movement of platform 14 is the same and will remain the same irrespective of what position platform 14 occupies at a given moment in time.

Platform 14 is supported by lever 36 through a pair of

cables

44, 46, more clearly illustrated in FIGS. 6 and 7. Cable 44 is rigidly secured at one end 48 thereof to the left arm 24 of platform 14, and extends over a roller or pulley 50 rotatably mounted in the top of frame 12. From pulley 50 cable 44 extends to and over a roller 52 which is rotatably mounted on the free end 54 of lever 36. Roller 52 is one of a bank of three rollers (see FIG. 3) rotatably mounted on the end of the lever 36 to form a portion of the completed actuating mechanism 34. From roller 52 the direction of cable 44 is reversed so that the cable extends back towards the arm 24 at the left of platform 14 and the free end 56 of the cable is rigidly connected to a support block 58 or the like secured to frame 12.

Cable 46 on the other hand, is secured at its free end 59 to the arm 24 on the right side of platform 14. From this point the cable extends over a roller or pulley 60, also rotatably mounted on frame 12, towards a roller 62 which is rotatably mounted on a common axis with roller 50 (see FIG. 3). From roller 62, the direction of cable 46 is reversed and the cable extends to a roller 64 which is mounted on the free end 54 of lever 36 on a common axis with roller 52. Roller 64 again reverses the direction of cable 46, so that the cable now extends in the same direction as cable 44, with its free end 66 rigidly secured with the end 56 of cable 44 to support block 58.

It will be appreciated that since

cables

44 and 46 extend in the same direction about

rollers

52, 64, they will act simultaneously on or in response to lever 36. Thus, for example, when platform 24 moves downwardly, the ends 48, 59, respectively of

cables

44, 46 will move down together and in an equal amount. Simultaneously, because

cables

44 and 46 extend in the same direction about

rollers

52, 64 on lever 36, the lever 36 will be caused to pivot about axis 42 in a counterclockwise direction under the influence of both of the cables. Further, when lever 36 moves in a clockwise direction, under the biasing force applied to it, as more fully described hereinafter, the lever will draw

cables

44 and 46 simultaneously therewith, to cause the cables to lift platform 14 towards its uppermost position. Further, because of the arrangement of

cables

44 and 46, the free end 54 of lever 36, and in particular, the axis of rotation of

rollers

52 and 64, will move laterally a distance which is equal to one half of the distance which platform 14 moves vertically. Thus, if platform 14 moves downwardly one inch, it will be seen that the one inch of extra cable which must be drawn from

cables

44 and 46 to permit this movement will be supplied from the two lengths of cables which extend from

rollers

52 and 64 respectively. Each of these lengths will supply one half of the needed cable length for the vertical movement. Thus, platform 14 can move vertically twice the distance that lever 36 moves laterally.

Actuating mechanism 34 further includes a spring 70 which is operatively connected to lever 36 in order to apply the desired biasing force thereto. This spring may comprise one or more individual springs mounted in frame 12. In the illustrative embodiment of the invention a pair of springs 70 (see FIG. 3) are mounted with their ends 72 secured to support member 58 on a common axis with the

ends

56, 66 of

cables

44, 46. The free end 74 of springs 70 are commonly connected to an elongated flexible cable 76 which is in turn operatively connected to lever 36, on the right side thereof, as seen in FIG. 2, in order to apply the biasing force to lever 36.

Cable 76 is guided over a pair of rollers 78 mounted in the base 40 of frame 12, and passes over a roller 80 rotatably mounted in a carriage 82 on an axis which is in generally vertical alignment with the axis of one of the rollers 78. Carriage 82 is vertically movably mounted in frame 12, to permit adjustment of the point of application of the biasing force to lever 36, as more fully described hereinafter. From roller 80, cable 76 extends .toward lever 36 and over a roller 84 which reverses the direction of the cable. The free end 86 of cable 76 is then secured to the carriage 82.

Roller 84 is rotatably mounted on a carriage 88 which is, in turn, slidably mounted on lever 36 so that its position along the lever may be adjusted. In this manner, it is seen that the spring force provided by spring 70 is applied to lever 36 through cable 76 and roller 84. This force produces a moment force about pivot point 42 which normally biases lever 36 in a clockwise position, i.e., into the solid line position illustrated in FIG. 2. When any weight, or a stack of trays 18, is placed on platform 14, the platform tends to move downwardly against the resistance of this force. The weight on platform 14

causes cables

44, 46 to urge the free end 54 of lever 36 in a counterclockwise direction against the bias force of spring 70. On the other hand, when articles are removed from platform 14, the bias force of spring 70 will urge the lever arm 36 towards the right, in a clockwise direction, to raise platform 14 in order to maintain the uppermost tray or article in the stack at the desired predetermined level. It should be noted that because of the pivotal mounting of lever 36 about the fixed pivot point 42, the torque produced by arm 36 varies linearly since the moment arm produced by lever 36 is constant throughout the entire movement of lever 36 between its extreme positions, illustrated in solid and phantom lines in FIG. 2, because the point of application of the spring force to the lever is fixed. Accordingly, there is a constantly linear force gradient applied to platform 14 throughout its path of travel so that a given weight applied or removed from platform 14 will cause the platform to move a fixed distance, irrespective of the location of the platform when the weight is added or removed therefrom.

Carriage 88 comprises a pair of spaced plates 94 (FIG. 5) which receive therebetween the lever 36. Plates 94 are interconnected by a pair of rollers 96, which are mounted thereon in spaced relation to each other (FIGS. 2 and 5) and are held in relatively fixed position with respect to each other and to rollers 96 by the nuts 98 which are secured to the free ends of the roller shafts 100. Roller 84 is rotatably mounted between plates 94 on the side of lever 36 opposite rollers 96, so that as a result of this arrangement, the bias force applied to carriage 88 by spring 70, through cable 76, holds rollers 96 against the back surface 102 of lever 36 and permits the carriage 88 to move along the lever. The position of carriage 88, along lever 36, is adjusted by means of a reference cable which is operatively connected between carriage 88 and the vertically movable carriage 82. Cable 90 extends from its end 92 secured to carriage 88, along the rear side 102 of lever 36 and its direction is reversed by the passage of the cable over a roller 104 (FIG. 3) which is rotatably mounted on a common axis with

roller

52, 64 at the free end of lever 36. Cable 90 then extends along the front, or right, surface of lever 36 between plates 94 of carriage 88 and over an additional roller 106 rotatably mounted in any convenient manner on the pivot axis 42 with lever 36. From this point the direction of the cable is again changed by passage over roller 106 and it is guided to a roller 108 rotatably mounted in the base 40 of frame 12 and thence to carriage 82 where its end 110 is rigidly secured on the same axis 112 as the end 86 of cable 76.

By this arrangement, it will be appreciated that vertical movement of carriage 82 will cause movement of carriage 88 along lever 36. This movement will be in a one to one relationship because of the mounting arrangement' of cable 90, so that if carriage 82 moves upwardly one inch from its solid line position, carriage 88 will move along lever 36 one inch. This movement is shown in dotted lines in FIG. 2. As can be seen therein, when carriage 88 is moved upwardly along lever 36, the roller 84 moves closer to carriage 82. This lateral movement of roller 84 does not effect spring 70, because of the arrangement of cable 76 about

rollers

80 and 84 on the respective carriages. As will be appreciated from a careful consideration of the drawing, when roller 84 moves to the right, the excess cable which is present because of this movement is accommodated by the upward movement of roller 80 in carriage 82 so that the excess cable permits roller 80 to move upwardly without pulling on spring 70. As a result of this construction, the location of the application of the bias force applied by spring 70 to lever 36 may be adjusted. Therefore, the moment force applied by lever 36 to

rollers

52, 64 and thus

cables

44, 46 can be varied as desired in order to accommodate articles on platform 14 of varying weights.

In the operation of the device, the tension in cable 76 is initially adjusted by a conventional threaded adjustment connection 114 in order to exactly counterbalance the weight of platform 14 when it is empty. In this manner spring 70 is initially preloaded. By the construction of

carriages

88 and 82, this preloaded condition is not effected when carriage 88 is adjusted along lever 36 since the position of connection 114 with spring 70 is not effected by the movement of the carriages or of

rollers

84 and 80.

The construction of carriage 82 is illustrated most clearly in FIG. 4 of the drawing. As seen therein, this carriage comprises a pair of side plate members 116 between which roller 80 is rotatably mounted in any convenient manner. Two pairs of guide rollers 118 are mounted on plates 116 in spaced parallel relation to each other. These rollers are positioned to engage a pair of vertically extending rigid frame members 120 and to ride thereon during vertical movement of the carriage. Because spring 70 creates a tension in cable 76 which, at point 86 pulls carriage 82 towards the left in the drawing, rollers 118 are constantly maintained in engagement with frame members 120.

Vertical adjustment of carriage 82 is achieved by the use of hollow sleeve 122 rigidly secured to the upper end 124 of plates 116. Sleeve 124 includes a threaded nut or the like 126 rigidly secured to the upper end thereof which threadedly receives an elongated rod 128 extending between frame members 120 and through a support block 130 rigidly connected to these frame members. The upper end 132 of rod 128 is rigidly secured to a circular bearing block 134 which is seated on bearings 136 to permit rod 128 to be rotated but to prevent it from moving downwardly in the frame 12.

The free end 132 of rod 128 can be provided with any convenient engaging mechanism which will permit rotation of the rod in nut 126. In the illustrative embodiment of the invention end 132 is provided with a slot 138 which extends through the top surface 22 of frame 12 and which can be engaged by a screw driver or the like to rotate rod 128. Upon rotation of this rod, sleeve 122 is moved upwardly or downwardly along the rod depending upon the direction of rotation thereof. This movement of sleeve 122 in turn causes carriage 82 to move upwardly or downwardly along the track provided by frame members 120. As described above, this movement of carriage 82 causes, through reference cable 90, simultaneous movement of carriage 88 along lever 36 in order to adjust the moment force applied by the lever.

Accordingly, it is seen that a relatively simple and inexpensively constructed article supporting stand is provided which will movably support a stack of articles in order to maintain the uppermost article in the stack at a predetermined level. Initially, the apparatus is set by the adjustment of cable 76 through connecting member 114 on spring 70 in order to preload the spring to exactly counterbalance the weight of platform 14. Thereafter, carriage 82, and thus carriage 88, is adjusted in order to provide a predetermined moment force on rol-,

lers

52, 64 and thus

cables

44, 46, in order to permit the platform 14 to move downwardly a predetermined distance for a predetermined weight. For example, if it is desired that the platform move down 1 inch under the load or weight of five trays, the carriage 82 is moved to a position which will permit this deflection of platform 14 under that weight. Once this adjustment is made, that deflection or weight to distance gradient will be constant throughout the entire range of movement of platform 14 and lever 36 because of the fact that the lever am is pivoted about the fixed pivot point 42 so as to have a constant moment arm. Of course, in accordance with Hookes law, the bias force applied by spring 70 to the carriage 88 is constantly linear through the intire arc of movement of lever 36. Since the spring is expanded along a straight. line. Since this distance and the force provided by spring are constant, the moment force produced by the lever is also constant.

Should it be desired at a later time to vary the force gradient to permit greater or lesser deflection under a given load, the position carriage 82 and thus carriage 88 can again be adjusted in order to achieve the desired gradient. This adjustment of the carriage in no way effects the preload on spring 70, since the roller 84 moves towards carriage 82 to permit the carriage to move upwardly without effecting the deflection of spring 70. This is also an important feature of the invention since, as a result, the platform 14 will be exactly counterbalanced at any setting of carriage 82 so that it will always return to its uppermost position when no articles are placed on its upper surface.

Although an illustrative embodiment of the present invention has been described herein with reference to the accompanying drawings, it is to be understood that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of this invention.

What is claimed is:

1. An article support stand comprising, a frame, a generally horizontal article support platform mounted on said frame for reciprocal vertical movement, said means including a lever pivotally mounted in said frame at a fixed pivot point, means operatively connected between said lever, frame and platform, for causing said lever to pivot about said fixed pivot point during vertical movement of said platform and resilient means mounted in said frame for extension is a straight line path in the direction of its axis only and being oper-' atively connected between said frame and a predetermined point on said lever for applying a linearly varying force to said lever at a fixed point and at a fixed angle to the lever during movement of said platform, thereby to resiliently resist vertical movement of said platform in a first direction with a linearly varying torque and a constant weight to distance gradient; said resilient means applying a linearly varying bias to said lever to create-therewith a moment force about said pivot point toresist said vertical movement of the article support platform in said first direction and said stand including means for selectively varying the point of application of said bias force to said lever, without varying the preload force of said spring, whereby the moment force resisting said vertical movement of said platform and the force gradient applied to said platform are selectively varied.

2. The article supporting stand as defined in claim 1 wherein said means for selectively varying the point of application of said bias force to said lever includes a first'ca'rriage mounted for movement along said lever and being operatively connected to said resilient means.

3. The article supporting stand as defined in claim 2 wherein said means for selectively varying the point of application of said bias force to said lever further includes means for selectively varying the location of said first carriage on said lever.

4. The article supporting stand as defined in claim 3 wherein said means for varying the location of said first carriage on said lever comprises a second carriage mounted in said frame for selective vertical movement and means operatively interconnecting said first and second carriages for moving said first carriage along said lever in response to vertical movement of said second carriage, said last mentioned means permitting pivotal movement of said lever in response to vertical movement of said platform and holding said first carriage in a relatively fixed position, during said pivotal movement whereby the point of application of said bias force to said lever remains substantially constant during pivotal movement of said lever.

5. The article supporting stand as defined in claim 4 wherein said resilient means includes a spring, a flexible cable connected at one end to said spring and at its opposite end to said second carriage and a plurality of rollers defining a path of travel for said last mentioned cable, including a first roller mounted on said first carriage and a second roller mounted on said second carriage, said last mentioned cable being guided from its point of connection with said second carriage over said roller and then over said second roller to its point of connection with said spring whereby the initial load on said spring is uneffected by the position of said second carriage.

6. The article supporting stand as defined in claim 5 wherein said means for operatively interconnecting said first and second carriages includes a flexible reference cable operatively connected at its opposite ends to said first and second carriages and at least two rollers defining a path of travel for said reference cable and including a first roller mounted for rotation about said pivot point and a second roller mounted on said lever, at a position wherein said first carriage is between it and said second pivot point, said reference cable being guided from its point of connection with said first carriage over said second roller and thence over said first roller to said second carriage, whereby said first carriage moves along said lever in response to vertical movement of said second carriage, a distance equal to the distance moved by said second carriage.

7. The article supporting stand as defined in claim 6 wherein said means for causing said lever to pivot comprises at least one cable operatively associated with said lever and connected at one end to said platform and at its other to said frame.

8. The article supporting stand as defined in claim 7 wherein said means for causing said lever to pivot comprises at least two. flexible cables respectively connected at one end to a common point on said frame and connected at their opposite ends to opposite sides of said platform and a plurality of guide rollers including a pair of rollers mounted on said lever for respectively engaging and reversing the direction of said last mentioned cables between their ends whereby, for every two inches of vertical movement of said platform, said rollers move with said lever at most only'one inch, as said lever pivots about its pivot point.

9. The article supporting stand as defined in claim 8 wherein said platform is mounted in said frame adjacent only one edge thereof and extends from said frame as a cantilever and said lever is mounted in said frame for pivotal movement in a vertical plane located beyondsaid one edge of said platform to permit said platform to move vertically with respect thereto.

10. An article support stand comprising a generally vertically extending frame, an article support platform mounted at one end in said frame for reciprocal vertical movement between upper and lower positions on said frame and extending horizontally outward of each frame as a cantilever, and means for resiliently supporting said platform on said frame and for biasing said platform towards its uppermost position, and means including a lever pivotally mounted in said frame at a fixed pivot point for pivotal movement in a vertical plane, a first pair of flexible cables respectively connected at one end to a common point on said frame and connected at their opposite ends to opposite sides of said platform adjacent said one end thereof, a plurality of guide rollers mounted in said frame over which said first pair of cables are guided between their ends including a pair of rollers mounted on said lever for respectively engaging and reversing the direction of said cables between their ends whereby vertical movement of said platform between its upper and lowermost positions causes said lever to pivot about its pivot point; means for applying a biasing force to said lever to create therewith a moment force about said pivot point which resists downward movement of said platform and normally urges said platform towards its upper position, said biasing means including a first carriage mounted for movement along said lever, and a spring operatively connected to said carriage for applying said bias force to said lever in a predetermined direction to resist downward movement of said platform; and means, for selectively varying the location of said first carriage along said lever, thereby to vary selectively the point of application of said biasing force to said lever; said means for varying the location of said first carriage on said lever comprising a second carriage mounted in said frame for selective vertical movement, a flexible reference cable operatively connected at its opposite ends to said first and second carriages, a first roller mountedin said frame below said second carriage, a second roller mounted for rotation about said pivot point and a third roller mounted on said lever at a position wherein said first carriage is between said pivot point and said third roller, said reference cable being guided from its point of connection with said second carriage sequentially over said first through third rollers to its point of connection with said first carriage whereby said first carriage moves along said lever, in response to vertical movement of said second carriage, a distance equal to the distance moved by said second carriage.

11. The article supporting stand as defined in claim 10 including a flexible cable operatively connected at its opposite ends to said spring and said second carriage, a first guide roller mounted on said first carriage, a second guide roller mounted on said second carriage, and a third guide roller mounted in said frame, below said second carriage, in vertical alignment with said second guide roller, said last mentioned flexible cable being guided from its point of connection with said second carriage over said guide roller on said first carriage,'thence over the guide'on said second carriage and the third guide roller on said frame to its point of connection with said spring, whereby said spring is operatively connected to said first carriage to apply said bias force to said lever and said bias force is substantially uneffected by the position of said first and second carriages.

12. The article support stand as defined in claim 11 including a threaded actuating rod mounted in said frame and threadedly engaged with said second carriage, whereby rotation of said rod selectively varies the vertical position of said second carriage in said frame, thereby to vary the location of said first carriage on said lever.

13. An article support stand comprising, a frame, a generally horizontal article support platform mounted on said frame for reciprocal movement between upper and lower positions on said frame, and means for resiliently supporting said platform on said frame and for biasing said platform towards its uppermost position, said means including a lever pivotally mounted in said frame, means operatively connected between said lever, frame and platform for causing said lever to pivot, means for applying a biasing force to said lever to create therewith a moment force which resists downward movement of said platform and normally urges said platform towards its upper position, said biasing means including a first carriage mounted for movement along said lever and a spring operatively connected between said frame and said first carriage to apply said biasing force to said lever in a predetermined direction to resist downward movement of said platform; a second carriage mounted in said frame for selective vertical movement with respect thereto, and means, operatively interconnecting said first and second carriages and said spring, for varying the location of said first carriage on said lever in response to vertical movement of said second carriage and for holding said first carriage in a fixed position on the lever during pivotal movement thereof, without effecting the bias force applied to said lever, whereby the moment force resisting vertical movement of said platform may be selectively varied by selected movement of said second carriage.

14. The article support stand as defined in claim 13 wherein said means for varying the location of said first carriage on said lever includes a flexible reference cable operatively connected at its opposite ends to said first and second carriages, a first roller mounted in said frame below said second carriage, a second roller mounted for rotation about the pivotal axis of said lever and a third roller mounted on said lever at a position wherein said first carriage is between said pivot point and said third roller, said reference cable being guided from its point of connection with said second carriage sequentially over said first through third rollers to its point of connection with said first carriage whereby said first carriage moves along said lever, in response to vertical movement of said second carriage, a distance equal to the distance moved by said second carriage; and a second flexible cable operatively con nected at its opposite ends to said spring and said second carriage, a first guide roller mounted on said first carriage, a second guide roller mounted on said second carriage, and a third guide roller mounted in said frame below said second carriage in vertical alignment with said second guide roller, said last mentioned flexible cable being guided from its point of connection with said second carriage over said guide roller on said first carriage and thence over the guide roller on said second carriage and the third guide roller on said frame to its point of connection with said spring, whereby said spring is operatively connected to said first carriage to apply said bias force to said lever and said bias force is substantially uneffected by the position of said first and second carriages.

15. The article support stand as defined in claim 14 including a threaded actuating rod mounted in said frame and threadedly engaged with said second carriage, whereby rotation of said rod selectively varies the vertical position of said second carriage in'said frame, thereby to vary the location of said first carriage

Claims

1. An article support stand comprising, a frame, a generally horizontal article support platform mounted on said frame for reciprocal vertical movement, said means including a lever pivotally mounted in said frame at a fixed pivot point, means operatively connected between said lever, frame and platform, for causing said lever to pivot about said fixed pivot point during vertical movement of said platform and resilient means mounted in said frame for extension is a straight line path in the direction of its axis only and being operatively connected between said frame and a predetermined point on said lever for applying a linearly varying force to said lever at a fixed point and at a fixed angle to the lever during movement of said platform, thereby to resiliently resist vertical movement of said platform in a first direction with a linearly varying torque and a constant weight to distance gradient; said resilient means applying a linearly varying bias to said lever to create therewith a moment force about said pivot point to resist said vertical movement of the article support platform in said first direction and said stand including means for selectively varying the point of application of said bias force to said lever, without varying the preload force of said spring, whereby the moment force resisting said vertical movement of said platform and the force gradient applied to said platform are selectively varied.

2. The article supporting stand as defined in claim 1 wherein said means for selectively varying the point of application of said bias force to said lever includes a first carriage mounted for movement along said lever and being operatively connected to said resilient means.

8. The article supporting stand as defined in claim 7 wherein said means for causing said lever to pivot comprises at least two flexible cables respectively connected at one end to a common point on said frame and connected at their opposite ends to opposite sides of said platform and a plurality of guide rollers including a pair of rollers mounted on said lever for respectively engaging and reversing the direction of said last mentioned cables between their ends whereby, for every two inches of vertical movement of said platform, said rollers move with said lever at most only one inch, as said lever pivots about its pivot point.

9. The arTicle supporting stand as defined in claim 8 wherein said platform is mounted in said frame adjacent only one edge thereof and extends from said frame as a cantilever and said lever is mounted in said frame for pivotal movement in a vertical plane located beyond said one edge of said platform to permit said platform to move vertically with respect thereto.

10. An article support stand comprising a generally vertically extending frame, an article support platform mounted at one end in said frame for reciprocal vertical movement between upper and lower positions on said frame and extending horizontally outward of each frame as a cantilever, and means for resiliently supporting said platform on said frame and for biasing said platform towards its uppermost position, and means including a lever pivotally mounted in said frame at a fixed pivot point for pivotal movement in a vertical plane, a first pair of flexible cables respectively connected at one end to a common point on said frame and connected at their opposite ends to opposite sides of said platform adjacent said one end thereof, a plurality of guide rollers mounted in said frame over which said first pair of cables are guided between their ends including a pair of rollers mounted on said lever for respectively engaging and reversing the direction of said cables between their ends whereby vertical movement of said platform between its upper and lowermost positions causes said lever to pivot about its pivot point; means for applying a biasing force to said lever to create therewith a moment force about said pivot point which resists downward movement of said platform and normally urges said platform towards its upper position, said biasing means including a first carriage mounted for movement along said lever, and a spring operatively connected to said carriage for applying said bias force to said lever in a predetermined direction to resist downward movement of said platform; and means for selectively varying the location of said first carriage along said lever, thereby to vary selectively the point of application of said biasing force to said lever; said means for varying the location of said first carriage on said lever comprising a second carriage mounted in said frame for selective vertical movement, a flexible reference cable operatively connected at its opposite ends to said first and second carriages, a first roller mounted in said frame below said second carriage, a second roller mounted for rotation about said pivot point and a third roller mounted on said lever at a position wherein said first carriage is between said pivot point and said third roller, said reference cable being guided from its point of connection with said second carriage sequentially over said first through third rollers to its point of connection with said first carriage whereby said first carriage moves along said lever, in response to vertical movement of said second carriage, a distance equal to the distance moved by said second carriage.

11. The article supporting stand as defined in claim 10 including a flexible cable operatively connected at its opposite ends to said spring and said second carriage, a first guide roller mounted on said first carriage, a second guide roller mounted on said second carriage, and a third guide roller mounted in said frame, below said second carriage, in vertical alignment with said second guide roller, said last mentioned flexible cable being guided from its point of connection with said second carriage over said guide roller on said first carriage, thence over the guide on said second carriage and the third guide roller on said frame to its point of connection with said spring, whereby said spring is operatively connected to said first carriage to apply said bias force to said lever and said bias force is substantially uneffected by the position of said first and second carriages.

14. The article support stand as defined in claim 13 wherein said means for varying the location of said first carriage on said lever includes a flexible reference cable operatively connected at its opposite ends to said first and second carriages, a first roller mounted in said frame below said second carriage, a second roller mounted for rotation about the pivotal axis of said lever and a third roller mounted on said lever at a position wherein said first carriage is between said pivot point and said third roller, said reference cable being guided from its point of connection with said second carriage sequentially over said first through third rollers to its point of connection with said first carriage whereby said first carriage moves along said lever, in response to vertical movement of said second carriage, a distance equal to the distance moved by said second carriage; and a second flexible cable operatively connected at its opposite ends to said spring and said second carriage, a first guide roller mounted on said first carriage, a second guide roller mounted on said second carriage, and a third guide roller mounted in said frame below said second carriage in vertical alignment with said second guide roller, said last mentioned flexible cable being guided from its point of connection with said second carriage over said guide roller on said first carriage and thence over the guide roller on said second carriage and the third guide roller on said frame to its point of connection with said spring, whereby said spring is operatively connected to said first carriage to apply said bias force to said lever and said bias force is substantially uneffected by the position of said first and second carriages.

15. The article support stand as defined in claim 14 including a threaded actuating rod mounted in said frame and threadedly engaged with said second carriage, whereby rotation of said rod selectively varies the vertical position of said second carriage in said frame, thereby to vary the location of said first carriage on said lever.