US 2728621 A
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1955 J; c. KEMPTER VERTICALLY ADJUSTABLE BOOKKEEPING STAND 2 Sheets-Sheet 1 Filed Feb. 1, 1955 m r mwflv ATTORNEY Dec. 27, 1955 J. c. KEMPTER VERTICALLY ADJUSTABLE BOOKKEEPING STAND 2 Sheets-Sheet 2 Filed Feb. 1, 1955 INVENTOR. JOfiEPH C. KEMPTER nite 1 VERTICALLY ADJUSTABLE EGGKKEEPING STAND Application February 1, 1955, Serial No. 485,519
3 Claims. (Cl. BIL-39) This invention relates to bookkeeping stands and has particular relation to a stand for trays, ledges and the like which may be raised and lowered to any desired height for most convenient use and is counterbalanced for such movement throughout the range thereof.
Various devices of this type havebeen devised and marketed, particularly those employing a counterbalance mechanism. However, some difiiculty has developed in finding a counterbalance mechanism which is really suitable throughout its entire range of operation.
Frequently such devices as have been heretofore provided are uneven in operation. The leverages involved are such that the counterbalance springs are frequently stretched beyond their effective range. The initial movement will be extremely stiif, but as the tray is elevated, the resistance of the springs lessens to a point. where considerable force is required to bring the stand to its full effective height, the dead weight of the file drawers and the like becoming too great for the springs.
Also one difiiculty often encountered is that of adjusting the stand to varying weights of different file drawers or the same file drawer as the contents are removedor added to. An easy method of compensating for these changes in weight is desirable.
It is therefore the primary object of my inventionto provide a device in which the counterbalance mechanism, including the counterbalance springs, are required to move only through a relatively short distance and therefore may be short and of substantial size.
It is a further object of my invention to provide a device in which the counterbalance springs may be easily positioned at dilierent points to compensate for varying loads.
It is still another object of my invention to provide a device which involves a minimum of friction in its operating portions and one in which the load is distributed over a wide area to prevent binding.
It is a still further object of my invention to provide a device which is easy and simple to manufacture and not readily subject to damage by reason of overloads.
Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specifications, wherein is disclosed a single exemplary embodiment of the invention, with the understanding, however, that such changes may be made therein as fall within the scope of the appended claims, without departing from the spirit of the invention.
In said drawings:
Figure 1 is a view in perspective of a bookkeeping stand constructed according to my invention, the device being positioned in a partially raised position.
Figure 2 is a view in perspective of the device shown in Figure 1, except that the stand is shown in the lowered position.
Figure 3 is a detailed view of the counterbalance spring adjusting means, and
Figure 4 is a side view of the stand with the lower file States Patent cabinet removed to show the relative position of the two elevating arms.
Referring now to the drawings, and particularly to Figure 1; the structure generally comprises a rectangular base 10 which has four upwardly extending corner angles 11, 12, 13 and 14. Slidably positionedin these upwardly extending angles are legs 15, 16, 17 and 13 which are adapted to telescope into the lower angles. These members serve to carry a table top 19 which in turn will hold file drawers or the like. The entire mechanism is supported on casters on all four corners, such as shown at 20, 21 and 22. Mounted on the base of the stand is a cabinet type file drawer 23 which may be used for the storage of the ledger trays or such other equipment as may be desired.
I will now describe in some detail the elevating and counterbalance mechanism which serves to move the table top in relation to the base member. A pair of tie rods, such as is shown at 24, are mounted on the upwardly extending angles of the base on both sides of the stand. Pivotally mounted on these tie rods are two elevating arms 25 and 26. The upper ends of the arms are provided with rollers such as shown at 27 which roll on the bottom side of the table top, preferably in a channel provided for that purpose.
Connected to the lower ends of these lever arms are relatively heavy spring members 28 and 29, their opposite ends being attached to the base of the stand by clips 30 and 40.
To distribute the load at the upper end of the lever arms over the table top, a secondary lever arm, such as is shown at 31, is provided. This is also pivotally mounted on the primary lever arm and has a roller 41 at its upper end. The spring 33 operatively connects the opposite end of the secondary lever arm to the primary arm. The primary and secondary lever arms with their four rollers serve to distribute the force over the entire table top more easily and prevent binding.
To secure a range of adjustment. between the spring 28 and the lever arm 25, I have provided an adjusting mechanism such as I will now describe.
Fastened to the lower end of the lever arm are two brackets 34 and 35 which serve to hold a bolt member 36 which is positioned substantially parallel to the lever arm itself. This bolt contains a series of slots 37 which extend in an angular direction in relation to the bolt and are less than one-half the diameter of the bolt in depth. These slots are provided to receive the loop of the spring 28. At the lower end of the bolt member is a right angle lever 38.
The operation of the foregoing mechanism will be at once apparent. The spring may be engaged in any one of the plurality of slots. The closer the spring is positioned towards the pivotal point of lever arm 25, the
less force it will exert on that arm and, conversely, the
further it is positioned from that pivotal point, the greater will be the force applied. It will also be apparent that, in any event, the spring will customarily be under some tension and it would ordinarily be diflicult to move from one slot to another. However, by turning the lever mechanism 38, the smooth surface of the bolt member can be brought into position against the outer portions of tr e loop of the spring 28. The spring may then he slipped along the length of the bolt, and when the desired notch is reached, the bolt may then again be turned to bring that notch again into engagement with the spring loop.
From the foregoing description, it will be seen that powerful counterbalancing force can be exerted on the elevating arms by substantially heavy springs. Since the mounting point of these arms is on a tie rod on the lower portion of the stand, the actual range of movement of these counterbalancing springs need not be too great, and
to the upper righthand corner, the opposite arm will ex 7 tend from the lower righthand corner to the upper lefthand corner, thereby distributing the lifting force relatively evenly across the table top. The secondary lever arms 31 and 32 further serve to diffuse this force over the entire area of the table top.
It is also desirable to lock the table in a fixed position as a safety precaution. To accomplish this purpose, I have provided a plunger mechanism 39 which is mounted on one of the upwardly extending anglesv A series of openings 4% are positioned in the corresponding telescoping legs and adapted to receive the inner end of the plunger 39. It might be noted that this mechanism is not substantial in nature and that a heavier locking mechanism is not required, since the range of adjustment of the counterbalance portion of the device is wide enough to bear most of the load and permit the table to be positioned in elevation and remain there by virtue of its evenly balanced counterforces.
Although I have described a specific embodiment of my invention, it is apparent that modifications thereof may be made by those skilled in the art. Such modifications may be made Without departing from the spirit and scope of my invention as set forth in the appended claims.
I claim as my invention:
l. In a bookkeeping stand, a base member having upwardly extending angles, a table member having downwardly extending legs adapted to telescope in said angles, a counterbalance mechanism disposed between said base member and said table, said counterbalancing mechanism comprising a pair of lever arms pivotally mounted on a portion of said base member, spring biasing means mounted on said base member and adapted to engage the lower end of said elevating arms, means for adjusting the relationship between the springs in said lever arms, a secondary lever arm pivotally mounted on the first mentioned lever arm and adapted to engage the table top, and spring 4 means interconnecting said primary lever arm and said secondary lever arm.
2. In a device of the type described, a base member and a table member adapted to telescope in relation to each other, a plurality of lever arms pivotally mounted on said base member and adapted to engage said table member, a counterbalance spring operatively connecting said lever arm to said base member, means for adjustably positioning said spring and said lever in relation to each other, said means comprising a slotted bolt member pivotally mounted parallel to said lever arm and adapted to receive the end loop of said spring, a plurality of slots angularly disposed in said bolt member and projecting less than one-half the diameter thereof in depth, and means for turning said bolt member so that the slotted portion or the smooth portion of said bolt may be selectively engaged to the loop of the spring member, thus permitting the easy movement of said spring throughout the length of the bolt or locking said spring in relation thereto.
3. In a device of the type described, a base member having a plurality of upwardly extending angles, a table top having downwardly extending legs adapted to slidably engage said angles, opposed tie rods interconnecting said angles a short distance above the bottom of the base member, a pair of elevating levers pivotally mounted on said tie rods in opposed angular relation to each other and having rollers on the upper end thereof, secondary arms pivotally mounted on said first named levers and adapted to contact said table top, spring actuated counterbalancing means operatively connecting said base members at the lower ends thereof, said levers, tie rods, and said counterbalance springs being positioned to permit a relatively limited range of movement thereof, and means for adjusting the point of connection between said spring and said lever at will, a portion of said last named means comprising a pivotally mounted slotted bolt member.
References Cited in the file of this patent UNITED STATES PATENTS 2,158,020 Huska et al. May 9, 1939 2,560,928 Bockius July 17, 1951 2,645,538 Segal July 14, 1953 2,672,385 Segal Mar. 16, 1954 2,672,386 Segal Mar. 16, 1954