Supporting Stand

Abstract

A lock mechanism for controlling the height adjustment of a supporting stand tray or the like in which the actuation of a release button sets the lock for release upon taking the additional step of relieving the lock from its load; the lock also acting as a one-way automatic lock, holding the tray in successively higher positions in response merely to incremental raising of the tray.

Description

The supporting stand, commonly called a Mayo Stand, is a well known article of hospital or operating room furniture, similar to an over-bed table, with a base, a post or pedestal and a tray, the post being generally so designed as to permit the tray to be supported at different adjusted heights.

According to the present invention, the post comprises outer (upper) and inner (lower) sections, the outer section being telescoped over the inner section; wedge-type locking means associated with the upper end of the inner section; and release means extending from the locking means to a foot operated release pedal. The release means includes a lost motion connection such that actuation of the release pedal biases the release means toward a lock unlocking position, while the locking means will stay locked until it is relieved of the load imposed by the tray and outer post section. Thus, the tray cannot be accidentally lowered by unintentional actuation of the pedal.

As a further convenience, the lock will automatically release and re-lock as the tray is lifted to successively higher positions, requiring no actuation of the pedal.

Pedal controlled vertically adjustable pedestals are shown in such prior U.S. Pat. Nos. as Taplinger, 1,022,608, Burk, 1,772,240, and Stevenson, 1,859,223, each relating to a stand for dress or garment forms, but none having the lost motion connection of the present invention, and each being of materially different mechanical construction. Manually adjustable vertical stands or supports with wedge-type locking elements are shown also by Luetke, U.S. Pat. No. 439,411, Beilmann, U.S. Pat. No. 449,028 and Cox et al. U.S. Pat. No. 461,238.

A practical embodiment of the invention is shown in the accompanying drawings, wherein:

FIG. 1 represents a perspective view of the stand;

FIG. 2 represents a detail vertical section through the post and adjoining portions of the base and tray frame, parts being broken away;

FIG. 3 represents an exploded perspective view of certain parts constituting the locking means and lock releasing means, other adjacent parts being omitted or broken away for clarity of illustration, and

FIG. 4 represents a detail bottom perspective view of the base plate with the release pedal removed.

FIG. 5 represents a detail vertical section showing a modified form of post and wedge.

Referring to the drawings, the stand comprises a base assembly 10, legs 11, a post assembly 12 and a tray 13, each having such reinforcements as may be necessary and/or desirable, together with locking and adjusting mechanism.

The base assembly 10 comprises the elongated base plate 15 having stiffeners 16 welded thereto along at least half the length of the plate and leg guides 17 welded across the width of the plate at short distances from either end. The base plate is provided with a central opening 18 to receive the lower end of the inner post section and a hole 19 to receive the release button. Approximately midway between the opening 18 and hole 19 is a threaded stud 20 welded to the base plate and projecting downward therefrom.

The base plate is enclosed, upwardly and laterally, by means of a boxlike cover 21 of sheet metal or the like (FIG. 1 only) having a flat upper surface 22 and downwardly turned sides and ends 23, 24, the upper surface having holes matching the opening 18 and hole 19 of the base plate.

Each leg comprises a solid bar 25 strongly affixed in a suitable manner to the base plate 15 adjacent to a leg guide 17, the legs projecting from points near the ends of the base plate, in a direction perpendicular thereto, and the projecting portions of the legs being encased in smooth tubular leg covers 26.

The post assembly 12 comprises an inner post 27 and an outer post 28, each being rectangular (e.g. square) in cross-section, the inner post having a bevel cut lower end 29 and being welded in the opening 18 of the base plate. At its upper end, two opposite sides of the inner post are slanted inward to form wedging surfaces 30, each provided with a vertically extending medial slot 31. The outer post 28 fits telescopically on the inner post with a free sliding fit, the upper end of the outer post being securely welded (or otherwise secured) to the tray frame 32, in a position to support the tray 13 at one end, projecting in a cantilevered manner laterally above the legs 25.

The locking and adjusting mechanism includes a pair of metal straps 35 fixed within the outer post 28, having their ends 36 bent around the lower edge 37 of said post and firmly secured by a collar 38 that clamps the strap ends to the post, the straps being looped at their mid-points over a pin 39 extending across the interior of the post 28 near its upper end. The straps are spaced laterally by a distance at least as great as the width of the slots 31 and are designed to lie against or adjacent to the wedging surfaces 30 in any adjusted relative vertical positions of the posts. Locking wedges 40 (inverted L-shaped in vertical section) are so proportioned that they can be disposed between the straps and adjacent inner wall surfaces of the outer post; when the upper out-turned corners 41 and lower outer corners 42 of the wedges rest against the post wall the inner surfaces 43 of the wedges lie parallel to the surfaces 30, spaced therefrom by the respective pairs of straps. Each wedge has a hole 44, slightly above center, and the wedges are interconnected by a cross-pin 45 in the upper end of the actuating rod 46, the ends of the cross-pin passing freely through the slots 31 and fitting loosely in the holes 44.

The actuating rod 46 extends from a point near the upper end of the inner post 27 to a point below the base plate. A release lever 47 in the form of a flat bar is pivotally supported on the stud by means of a lock nut 48, one end of the lever 47 having a hole 49 through which passes the lower end of rod 46 and the other end of lever 47 being located beneath the release button 50 in the hole 19. At a short distance above its bottom end the actuating rod 46 is provided with a washer-like collar 51 (welded to the rod) and a compression spring 52 surrounds the rod and bears against said collar and the release lever 47. The bottom end of the rod 46 is provided with a retaining washer 53 and screw 54. The inner post is shown as having a bevel cut lower end 29, for ease in welding to base plate 15 and stiffeners 16, providing extra rigidity and minimizing distortion by welds situated in different planes instead of only around opening 18.

The force of the spring 52 and its adjustment, as by moving the lock nut 48 on the stud 20, are so calculated that, in the rest (locking) position of FIG. 2, some of the weight of the actuating rod is carried, through crosspin 45, by the wedges 40. This holds the wedges in locking position between the straps 35 and the adjacent inner wall surfaces of the outer post, so that the post (and tray) cannot move downward. A heavier load on the tray only increases the locking force of the wedges, whereas lifting the tray moves the wedges slightly upward to unlocked positions until a new height has been established. When the lifting force is terminated the wedges immediately lock in the new position.

In order to lower the tray two motions are required: the release button 50 must be depressed to apply, through lever 47, additional compressive force to the spring 52, and a slight lifting force must be applied to the tray and/or outer post. The release lever 47 and spring 52 provide a lost motion feature to the lowering operation, because the spring, when compressed, overcomes the weight vector of the actuating rod, biasing it and the wedges upward toward unlocking position, but this bias can only cause movement when the wedges have been relieved of the weight of the tray and outer post.

Locking and unlocking forces are communicated to the wedges not only by line contact with the post walls but also by surface contact with the respective straps 35 which move with the outer post. As a result, the locking action is instant and reliable, while unlocking is assured with no possibility of jamming.

In the modified form of FIG. 5 the inner post 55 is formed with a single inwardly slanted wedging surface 56 provided with a vertical slot 57, similar to the slots 31. A single locking wedge 58 is proportioned to fit in the space between the surface 56 and the inner wall surface of the outer post 59 and straps 60 (corresponding to straps 35) have their ends fixed in the outer post at points near the lower and upper ends of said post and are designed to lie against or adjacent the wedging surface 56. The actuating rod 61 is operatively connected to the wedge 58 by a pin 62, passing through the slot 57 and a hole 63 in the wedge, the mechanism for biasing and moving the rod 61 and wedge 58 being the same as described above in connection with FIGS. 1 to 4, and the operation being the same.

It may be noted that the tray 13 is preferably separable from the frame 32 in order to facilitate thorough cleaning and sterilizing of these parts, as frequently required, e.g., in operating room procedure.

While the post-height adjusting mechanism has been described in connection with a supporting stand, it is evidently adaptable to other supports for devices requiring vertical adjustment.

It will be understood that various changes may be made in the form, construction and arrangement of the several parts without departing from the spirit and scope of the invention and hence I do not intend to be limited to the details shown or described herein except as the same are included in the claims or may be required by disclosures of the prior art.

Claims

What I claim is:

1. A stand comprising a base assembly, a work-supporting surface, a post extending between the base assembly and the work-supporting surface and means for controlling the height adjustment of said surface, said means including inner and outer post sections, the inner section being mounted on the base, the outer section being telescopically fitted over the inner section, the inner section having at least one upper side surface slanted away from an adjacent surface of the outer section to form a wedging space, a vertically movable locking wedge in said space, an actuating rod connected to said wedge and extending downwardly therefrom to a point adjacent the base, a release means in the base, a compression spring effectively interposed between the release means and the actuating rod, the spring being compressible by operation of the release means to bias the actuating rod and wedge toward unlocking position with a force insufficient to move the wedge until the outer section is lifted.

2. A stand according to claim 1 wherein the inner section has two opposite side surfaces slanted away from adjacent surfaces of the outer section to form two wedging spaces, and which includes a locking wedge in each said space, the actuating rod being connected to both said wedges.

3. A stand according to claim 2 wherein said slanted surfaces are provided with vertical slots and the actuating rod is connected to said wedges by a pin passing through said slots.

4. A stand according to claim 1 which includes a metal strap fixed within the outer section at upper and lower points therein, said strap passing between the wedge and the slanted surface adjacent thereto.

5. A stand according to claim 2 which includes metal straps fixed within the outer section at upper and lower points therein, each said strap passing between a respective wedge and the slanted surface adjacent thereto.

6. A stand according to claim 5 wherein said slanted surfaces are provided with vertical slots and the actuating rod is connected to said wedges by a pin passing through said slots, there being two metal straps between each wedge and the adjacent slanted surface.

7. A stand according to claim 1 wherein the lower portion of the actuating rod passes through the spring, the rod being provided with a collar spaced from its lower end and the release means being a lever extending into proximity with the lower end of the rod and engaging the lower end of the spring to compress the spring, when the lever is operated, between said lever and said collar.

8. A stand according to claim 7 which includes a release button mounted in the base in operative association with one end of the release lever.

9. Locking means for interposition between inner and outer telescopically engaged members comprising at least one side surface portion of the inner member slanted away from an adjacent surface of the outer member to form a wedging space, a locking wedge movable in said space in engagement with said adjacent surface, and a flexible strap having its end fixed at spaced points within said outer member and passing between said wedge and the adjacent slanted surface, whereby opposite wedge surfaces bear only against surfaces which are movable with the outer member.