US2676077A

US2676077A - Typewriter lift mechanism

Info

Publication number: US2676077A
Application number: US212535A
Authority: US
Inventors: Mcmahan Walter Carl
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-02-24
Filing date: 1951-02-24
Publication date: 1954-04-20
Anticipated expiration: 1971-04-20

Description

April 20, 1954 w. c. MGMAHAN TYPEWRITER LIFT MECHANISM Filed Feb. 24, 1951 2 Sheets-Sheet 1 INVENTOR.

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April 20, 1954 w. c. MGMAHAN TYPEWRITER LIFT MECHANISM '2 Sheets-Sheet 2 Filed Feb. 24,v 1951 INVENTOR.

T TOE/VE ym, Hh 1%? I u Mc .m M A C. .w mm. Non Nw.. m R m. MM: c I u W W W @Y NN ,mh QN QM. .N .WI uw Sm? n. www. @is w1. m m Nm. Q mw A mm. Sw QQ Ww A :wwe m, w NN Sw mm www fm N R .ww wl- Patented Apr. 20, 1954 UNITED STATES ATENT OFFICE This invention relates to typewriter lift mechanisms especially adapted to be incorporated in desks.

Such lifts commonly employ a shelf that may he manually moved from an inactive position below the desk top to an active position projecting outwardly of the desk, and at a convenient height.

Various means, such as springs, may be used in such mechanisms, and which partly compensate for the weight of the typewriter supported on the shelf, to facilitate the manual lifting and lowering of the shelf.

It is one of the objects of this invention to provide a simplified mechanism ci this character, and particularly one in which the manual operation of raising and lowering the typewriter support or shelf is facilitated.

It is another object of this invention to provide a support which, when elevated, is positively restrained against inadvertent lowering or sidewise tilting of the shelf.

It is another object of this invention to provide a typewriter support that is rigid and that will not vibrate while the operator uses the typen writer.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration ci one embodiment of the invention.

For this purpose, there is shown a form in the drawings accompanying and forming part ci the present specification. The form will now be described in detail, illustrating the general principles of the invention; but it is to he understood that this detailed description is not to be taken in a limiting sense, since the scope of this Ainvention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a vertical section of a typewriter desk incorporating the invention, the typewriter support being in lowered position;

Fig. 2 is a fragmentary sectional view, taken along a plane corresponding to line 2 2. of Fig. l;

Fig. 3 is a view similar to Fig. 1, but illustrating the typewriter support in extended or raised position;

Fig. 4 is an enlarged sectional view, taken along a plane corresponding to line -d. of Fig. 3; and

Fig. 5 is an enlarged sectional view, showing the latch-releasing mechanism used in connection with the invention. l Y

A typewriter desk is shown having a top i, a back wall 2, wallsy 3, and legsv ft.

4 Claims. (Cl. S12- 27) To provide a space 5t for a typewriter at the right-hand side of the desk, a vertical partition 5 (Figs. 2 and 4) extends between a lower desk brace E and the top i.

A shelf-like support l is adapted to be disposed in the lowered position beneath the top l, as indicated in Figs. l and 2, or to extend forn wardly to a position near the top of the desk l, illustrated in Figs. 3 and 4. In Fig. 3, a typewriter 26 is shown as resting on support 7.

In order to suspend the support l in space 5t, use is made of four links, two at each edge of the support 7. Thus, links 8 and 9, shown in Fig. 1, are pivoted at their lower ends to one edge of the support At their upper ends these links are pvoted by

pivots

22 and 23 on a supporting cleat I0 that is attached to a clearJ il fastened to the partition 5. A similar supporting cleat I2 (Fig. 2) is attached to a cleat l 3 that is placed at the top of the inner side of the wall 3. From this support i3 there extend two links 8 andL il,

similarly arranged to the links shown in Fig. 1.

In the lowered position of Figs. l and 2 the cleats I0 and i2 are in juxtaposed relationship with respect to the support 1. The links 8 and Q are movable to a substantially coincident relations ship with respect to the cleats it and l2, thereby swinging the support 'l out o1" juxtaposed relationship with respect to the cleats l@ and i2 and the top l, as illustrated in Fig. 3.

In the loweredposition of Fig. 1, the support l is held against inadvertent forward movement. as by the aid oi a spring catch Ul fastened to the lower side of the support l, and adapted to engage a detent I5. This detent l5 is supported near the lower edge of the typewriter opening 5t. The catch it may be released from the detent l5 by manually raising this spring latch by the aid of the horizontal end l. When the support 'i is lowered, the catch I4 rides over the detent I5 until the parts reach the position of Fig. 1, when the catch snaps into latching position.

A pair of tension springs Il and It is provided Yfor urging the support 'i to the lowered position of Fig. l `or to the raised position of Fig. 3. When the support kl' is in the lowered position, the springs exert a force urging the links 8 and il in a counterclockwise direction, thereby main taining Vthe support .7 in the lowered position. When the latch iai is released and the support brought forward yto a deiinite point, the springs Ail and I8 then exert a force vassisting the raising operation. j A g Thus, the left-hand ends of the springs il and i8 are anchored on across bar i9 extending across the top of the typewriter space 50 and attached to the supports I and I2. The righthand ends of springs I1 and I8 are engaged in apertures formed in an anchor member 2D. This anchor member 2E has legs attached to links 9 (Fig. 2), as by the aid of the rivets 2|, In the lowered position of Fig. l, the force of the'springs I1 and I8 on links 9 is directed to the left, and above, the

pivots

22, 23 of the links 8 and 9. Accordingly, the force of the spring urges the links 8 and 9 in a direction to maintain the support 'i in the lowered position.

Now, when support 1 is moved forwardly, the anchor 20 moves downwardly and below the

pivots

22 and 23. When this downward movement reaches a position where the direction of the force of the springs is below these

pivots

22 and 23, the force of the springs is in a direction to move the links 8 and 9 in a clockwise direction. This clockwise direction is such as to raise the support 1 ultimately to the position ofsFig. 3. In this position, the typewriter 2li is supported at a convenient height for operation. Similarly, when it is desired to lower the support 1, it may be urged downwardly and inwardly from the position of Fig. 3 until the springs i1 and IB assume a position above the

pivots

22 and 23.

The space between the opposed supporting bars I3 and I2 is slightly less than the width of shelf 's' and links S. These links thus slightly diverge toward the shelf 1. When theY sheif is raised to the position of Fig. 3, the shelf and links are thus wedged firmly in place, and all vibration is eliminated.

When the support 1' is in the raised position of Fig. 3, it is securely latched in this position until it is desired to lower the support. For this purpose, hooks 25 are disposed on opposite sides of the support 1. These hooks may be formed on the ends of a bent strap 26 that extends across the bottom of support 1. These hooks 25 are intended to engage a latch bar 2?. This latch bar extends transversely across the top of the typewriter opening. It is guided, as by slots 2S located in the ends of the supports Iii and I2, and extends beyond these supports (Fig. 4). The slots 23 extend in a direction parallel to the supports I8 and i2, which direction is normal to the direction of movement of the support 's' when it is in the elevated position of Fig. 3. A pair of tension springs 23 is anchored at one end around the bar 21. At the other end, they are anchored on the spring anchor I 9. 29 urge the bar 21 into the slot 33 of each of the hooks 25.

The upper surface 3| of each of the hook members 25 is sloping so that, as the hook members are brought up to the position of Fig. 3, these sloping surfaces engage the bar 21 and urge the bar 21 outwardly of the groove 23. Then, as the sloping surface SI moves further upwardly, the bar 28 moves inwardly to engage the slots 30. In the engaged position illustrated in Figs. 3 and 4, the bar 31 is hooked at eachrof its extremities. Since the support is suspended by hooks at each edge of the support, it is eiectively prevented from tilting, as well as from movingY downwardly, under the weight of the typewriter 24.

In order to release the bar 28 from the hooks 25, use is made of a lever 32 pivoted in a clevis 33 mounted on the support 1. rihis lever 32 has an arm provided with a sloping surface 3d. This sloping surface, when the support 1 is in the raised position, underlies the bar 21, as shown These springs most clearly in Fig. 3. In order to release the bar 21, the lever 32 is moved in a counterclockwise direction, and the sloping surface 34 engages the bar 21 and moves it to the disengaged position of Fig. 5. In this position, the support 1 may be lowered, as the hooks 25 are no longer engaged by the bar 21.

In order to form a limit to the upward movement of the support 1, a cross member 35 is mounted in front of the clevis 33 on the support i. This cross member is provided with a slot Se to permit the passage of the lever 32. Its upper surface closely underlies the upper frame portion 31 of the opening to the typewriter space 53.

The inventor claims:

1. In a lift mechanism: a pair of parallel spaced frame elements having provisions for attachment to a cabinet or the like; a mechanism movably carried by said frame elements and comprising: a support, and a plurality of links pivoted at one end to said support, the other ends of some of the links being pivoted to one of said frame elements, the other ends of the other of said links being pivoted tothe other of said frame elements, said links being of equal length between their pivotal mountings for providing a parallelogram suspension for said support; said support being swingable through substantially a quarter revolution from a first position to second position; said frame elements each having at corresponding ends a slot extending in a direction transverse to the direction of movement of said support when said support reaches said second position; a bar extending between said frame elements and guided by said slots respectively for translation of said bar; a pair of spring members urging said bar to one position in said slots; and a hook member rigidly carried by said mechanism and having a cam surface engageable with said bar when said support is moved to said second position, and also having a latching recess engageable with said bar upon continued movement of said support, said recess extending substantiaily parallel to said slots when said support is in said second position.

2. In a lift mechanism: a pair of parallel spaced elongate frame members having provisions for attachment to a cabinet or the iike; a mechanism movably carried by said frame members, and comprising: a support, a iirst pair of links each having one end respectively pivoted to one side of said support and each having another end respectively pivoted to one of said frame members, and another pair of links each having one end respectively pivcted to the opposite side of said support and each having another end respectively pivoted to the other oi said frame members; said linksV all'being of equal length between their pivotal connections for providing a parallelogram suspension for said support, said support being swingable from a rst juxtaposed position with respect to said frame members to a second position in which said supe port is out of juxtaposed relationship with ren spect to said frame members, the length of each pair of links respectively between their pivotal connections being substantially parallel to said frame members when said Suppenl in said second position; said frame members each having at corresponding ends a slot extending substantially parallel to thelength of said frame inembers; a bar extending between said frame members and guided by said slots respectively for translation of said bar; spring means urging said bar to one position in said slots; a hook member rigidly carried by said mechanism and having a cam surface engageable with said bar for moving said bar away from said one position when said support is moved to said second position. said hook member also having a latching recess engageable with said bar upon continued movement of said support, said recess extending substantially parallel to said slots when said support is in said second position; and manually operated means for moving said bar away from said one position and out of latching relationship with said bar.

3. In a lift mechanism: a pair of parallel spaced frame elements having provisions for attachment to a cabinet or the like; a mechanism movably carried by said frame elements and comprising: a support, and a plurality of links pivoted at one end to said support, the other end of some of the links being pivoted to one of said frame elements, the other ends of the other of said links being pivoted to the other of said frame elements, said links being of equal length between their pivotal mountings for providing a parallelogram suspension for said support; said support being swingable through substantially a quarter revolution from a rst position to a second position; a pair of elements rigidly carried by said mechanism and each having a slot extending in a direction transverse to the direction of movement of said support when said support reaches saidv second position; said slots of said elements of saids mechanism having a substantial length movable into alignment with a substantial length of the slots of said frame members when said mechanism is in said second position; a bar guidingly carried at opposite ends in the slots of one of the pairs of elements; a spring exerting a force urging said bar to one position in said one pair of slots; said bar being movable to another position in said slots of said one pair of elements against the force of said spring; the slots of the other of said pairs of elements being open to provide a latching recess receiving said bar when said mechanism is in said second position; said bar, when said slots are aligned, clearing the open ends of the slots of said other pair of elements when said bar is moved from said one position to said other position; and means providing cam surfaces on each of said other of said pairs of elements adjoining the slots thereof, and engageable with said bar upon movement of said support toward said second position to move said bar to said otherl position.

4. In a lift mechanism: a pair of parallel spaced elements forming a frame member, said elements having provisions for attachment to a cabinet or the like; a mechanism movably carried by said frame member and comprising: a support member, and a plurality of links each pivoted at one end to said support member, and at the other end to said frame member, said links being of equal length between their pivotal mountings for providing a parallelogram suspension for said support member; said support member being swingable through substantially a quarter revolution from a first position to a second position; a latch bar extending transversely of the mechanism; means carried by one of the members for guiding the bar for movement ci translation transverse to the axes of the link pivots, and transverse to the direction of movement of said support member when said support is in said second position; a hook carried by the other member for engaging the latch bar; said hook having a cam surface engageable with said bar when the support member is moved to said second position, and also having a latching recess engageable with said bar upon continued movement of said support, said recess extending in the direction of movement of said bar; and means resiliently urging said bar into engaging position With respect to said recess.

References Cited in the le 0f this patent UNITED STATES PATENTS Number Name Date 883,305 Fetch Mar. 31, 1908 1,137,261 Dyke Apr. 27, 1915 2,358,917 Emde Sept. 26, 1944 2,561,505 Fox July 24, 1951 FOREIGN PATENTS Number Country Date 162,'103 Switzerland June 15, 1933