US2919966A - Retractable shelf - Google Patents

Description

Jan. 5, 1960 D. F. PRESTON 7 2,919,966

RETRACTABLE SHELF Filed April 1, 1957 2 Sheets-Sheet 2 Ill re. 3.

i i I10 .Daw .Pessrwg 96 INVENTOR.

60 72 BY 14/5" 4rrafiws'z s 11/3205, I'd/Few, JZsrE/e lzgekrs.

RETRACTABLE SHELF Don F. Preston, Covina, Califi, assignor to Acme Apments being interengageable to lock the shelf in its extended position in response to movement thereof into such position, and being disengageable to permit movement of the shelf into its retracted position in response to .upward movement of the shelf beyond its extended position.

pliance Manufacturing Company, Pasadena, Calif., a

corporation of California Application April 1, 1957, Serial No. 650,040 6 Claims. Cl. 312-27 The present invention relates generally to mechanisms for moving such articles as shelves between retracted and extended positions and for locking them in their extended positions. For convenience, the invention will be considered hereinafter in connection with mechanisms or hardware for moving a retractable shelf upwardly and forwardly from a retracted position under a counter into an extended position forwardly of and at generally the same level as the counter, and for locking the shelf in such extended position, the. shelf carrying a mixer, or other appliance, or device. However, it will be understood that other applications of the invention are also possible.

Basically, the invention contemplates retractable shelf hardware which comprises a parallelogram linkage, including parallel, horizontal mounting and shelf brackets interconnected by two parallel arms each pivotally connected at one end to the mounting bracket and at its other end to the shelf bracket, the shelf bracket being movable upwardly and forwardly from a retracted position below and rearwardly of the mounting bracket into an extended position forwardly of the mounting bracket. A counterbalance spring acting in tension is connected at one end to one of the arms and is connected at the other end to the mounting bracket. The counterbalance spring counterbalances the weight carried by a shelf attached to the shelf bracket and means for adjusting the spring tension to counterbalance various loads on the shelf is provided. Retractable shelf mechanisms of the foregoing general nature are well known.

-An important object of the present invention is to provide an improved means for adjusting the counterbalance spring tension. More particularly, an object of the invention is to provide adjustable means connecting one end of the counterbalance spring to the mounting bracket which includes a pin having an annular groove therein, means connecting the spring to the pin, and two or more vertically spaced, keyhole shaped openings in the mounting bracket each having an enlarged head portion into which the pin as a whole is insertable and a smaller stem portion into which the grooved section of the. pin is insertable, the stem portions of the openings extending downwardly and forwardly from the head portions thereof toward the path of movementof the shelf bracket between the retracted and extended positions thereof. With this construction, the pin may be inserted into the head portion of the keyhole shaped opening which will provide the desired spring tension, whereupon the spring tension will pull the grooved section of the pin into the smaller stem portion of the opening to positively lock the pin in place, which is an important feature.

Another important object of the invention is to provide an improved means for locking the shelf in its extended position. More particularly, an object is to provide a locking means which includes a rotatable, lobed locking element on one of the arms and a stationary locking element on the mounting bracket, these locking ele- Another object is to provide the stationary lockingelement with first means engageable by one of the lobes of the rotatable locking element to lock the shelf in its extended position, and to provide the stationary locking element with second means engageable with another lobe of the rotatable locking element for rotating the rotatable locking'element to bring the first lobe mentioned into engagement with the first means of the stationary locking element in response to movement of the shelf into its extended position.

A further object is to provide the stationary locking element with third means engageable with the second lobe mentioned in response to movement of the shelf beyond its extended position for rotating. the rotatable locking element to disengage the first mentioned lobe thereof from the first means of the stationary locking element, .whereby the shelf may be moved through its extended position into its retracted position.

Another object is to provide a three-lobe rotatable locking element which is generally triangular and any two lobes of which may function in the manner hereinbefore outlined.

The foregoing objects, advantages, features and results of thepresent invention, together with various other objects, advantages, features and results thereof which will become apparent in the light of this disclosure may be attained with the exemplary embodiment of the inven-. tion described in detail hereinafter and illustrated in the accompanying drawings, in which:

Fig. 1 is a perspective view illustrating a typical installation of the invention and showing a shelf carried by the invention in its retracted position;

Fig. 2 is a perspective view similar to Fig. 1, but showing the shelf in its extended position;

Fig. 3 is an enlarged, fragmentary sectional view taken alon the arrowed line 33 of Fig.2;

Fig. 4 is an enlarged, fragmentary sectional view taken along the arrowed line 4-4 of Fig. 3; and I Figs. 5 to 11 are semidiagrammaticviews illustrating successive relative positions of locking elements constituting a locking means for locking a shelf in its extended position.

i In the drawings, the numeral 20 designates a cabinet topped by a counter 22 and providing a compartment 24 having a front opening 26, which may be closed by a door, if desired. Movable into and out of the compart ment 24 through the front opening 26 between a retracted position below the counter 22 and an extended position forwardly of the cabinet 20 and at the same general level as the counter 22 is a shelf 28. This shelf is supported by hardware units or mechanisms 30 and 32 respectively mounted on opposite side walls of the compartment 24 below the counter 22. While the compartment 24 is shown as provided with side walls on which the hardware units 30 and 32 are mounted, it will be understood that these units may simply be mounted on the frame structure of the cabinet 20.

- The hardware units 30 and 32 are similar, differing only in that one is a mirror image of the other, i.e., one is a left-hand unit and the other right-hand. Consequently, only the unit 30 will be considered hereinafter,

it being understood that the description of the unit 30 is equally applicable to the unit 32.

Considering the mechanism 30, it comprises a pan: tograph or parallelogram linkage which includes parallel, horizontal, mounting and shelf brackets 34 and 36 inter-'- Patented Jan. 5, 1 960.v

connected by parallel arms 38 and 40, the arms 38 and 40 being connected to the mounting bracket 34 at spaced points by pivots 42 and 4 respectively, and being connected to the shelf bracket 36 at spaced points by pivots 46 and 48, respectively. As is characteristic of a mechanism of this type, the shelf bracket 36 remains hori zontal at all times as it is swung from a retracted position below and rearwardly of the center of the mounting bracket 34 to an extended position forwardly of the mounting bracket, as will be apparent from Figs. 1 and 2, respectively.

The mounting bracket comprises a plate 50 the major portion 52 of which is offset inwardly relative to the compartment 24, the plate 50 also including portions 54, 56 and 58 which are offset outwardly relative to the compartment 24- and which are seated against the corresponding side wall of the compartment and secured thereto by screws, or the like. The inwardly offset portion 52 of the plate 50 provides space behind the plate for heads, not shown, of the pivots 42 and 44. The outwardly offset portion 56 provides space therein for a locking means 60 to be described while permitting the arms 38 and 40 to lie substantially fiat against the inwardly offset portion 52 of the plate 50. With this construction, a relatively thin unit 30, occupying a minimum of space in the compartment 24, results, which is an important feature. The plate 50 is provided along its upper edge with a flange 62 which is secured to the under side of the counter 22 by means of screws, or the like.

The shelf bracket 36 comprises a plate 64 to which the arms 38 and 40 are connected by the pivots 46 and 48, and comprises a flange 66 to which the shelf 28 is connected by means of screws, or the like. The shelf 23 is provided with a handle 68 by means of which it may be moved between its extended and retracted positions The hardware unit 30 is provided with a counterbalance spring 70 acting in tension between the arm 40 and the mounting bracket 34 to counterbalance the load carried by the shelf 28, the spring tension being adjustable in a manner to be described to counterbalance different weights on the shelf. The spring 70 is connected at one end to an intermediate point on the arm 40 by engaging a hook 72 at such end of the spring with a pin 74 carried by the arm 40, this pin having therein an annular groove 76 receiving the hook 72.

The other end of the spring 70 is adjustably connectible to the mounting bracket 34 at points spaced different distances from the path of movement of the shelf 28, i.e., different distances from the pivot 44, to vary the spring force applied to the parallelogram linkage. The inwardly oifset portion 52 of the plate 50 is provided with a plurality of vertically spaced, keyhole shaped openings 78 each having an enlarged head portion 80 and a smaller stem portion 82, these stem portions all sloping downwardly and forwardly toward the path of movement of the shelf 23, i.e., toward the path of movement of the pin '74. A pin 84 is insertable into each of the head portions 80 of the keyhole shaped openings 78 and is provided therein with an annular groove 86, Fig. 4, forming a reduced diameter portion 88 receivable in each of the stem portions 82 of the keyhole shaped openings. The spring 70 is provided with another hook 90 engageable with the pin 84 and receivable in an annular groove 92 therein.

As will be apparent, since the stem portions 82 of the keyhole shaped openings 78 extend toward the path of movement of the pin 74, the spring tension biases the pin 84 toward the extremity of the particular stem portion in which it is disposed, the inwardly offset portion 52 of the plate 50 adjacent each stem portion fitting snugly within the groove 86 in the pin 84 so as to provide a rigi connection between the spring '70 and the mounting bracket 34. However, the spring tension may be varied easily by disengaging the hook from the pin 84, moving the pin to another of the openings 78, and then reengaging the hook 90 with this pin. Thus, the spring tension may be adjusted to counterbalance different loads on the shelf 28 very readily while still providing a rigid anchor for the spring, due to the fact that the spring force acts to bias the reduced diameter portion 88 of the pin 84 into the closed end of the stem portion 82 in which it is disposed and due to the snug fit between the sides of the groove 36 in the pin and the inwardly offset portion 52 of the plate 50 adjacent such stem portion. It will be noted that since the openings 78 are formed in the inwardly offset portion 52 of the plate 50, space behind the plate is provided for that portion of the pin $4 which projects therethrough, which is another advantage of the offset construction shown for the plate 50.

Considering the action of the counterbalancing spring 70 in more detail, when the shelf 28 is in its retracted position, the arms 33 and 40 slope downwardly and rearwardly, the shelf bracket 36 being located below and rearwardly of the center of the mounting. bracket 34. Con: sequently, as the shelf 28 is moved into its retracted position, the spring crosses the axis of the pivot 44 so that, when the shelf is in its retracted position, the spring acts to retain it in such position because of this over: center action. Movement of the shelf 23 rearwardly be? yond its retracted position is prevented by engagement of a stop 94 on the shelf bracket 36 with the arm 40.

When the shelf 23 is moved toward its extended posi: tion, the spring 70 crosses the axis of the pivot 44 in the opposite direction and, as soon as it does, the spring acts to bias the shelf toward its extended position. The shelf 28 is locked in its extended position by the locking means as, which will now be described.

The locking means 60 automatically locks the shelf 23 in its extended position as it is moved thereinto, and is releasable by moving the shelf upwardly slightly beyond its extended position. The locking means 60 includes a stationary locking element 96 mounted on the outwardly offset portion 56 of the mounting bracket plate 50 and disposed in the recess formed thereby, which further assists in reducing the over-all thickness of the unit 30. The locking means 60 also includes a rotatable locking element 98 mounted on a pin 100 carried by the arm 40. This rotatable locking element is generally triangular and is provided with three lobes 102, 104, and 106. These lobes cooperate with various means on the stationary locking element 96 to lock the shelf 28 in its extended position and to release the shelf in response to movement thereof upwardly beyond its extended position, as will now be described.

Referring to Fig. 5 of the drawings, as the arm 40 is moved toward its extended position, i.e., the position thereof corresponding to the extended position of the shelf 28, one of the lobes of the locking element 98, such as the lobe 104 thereof, moves upwardly past an end 108 of a lower leg 110 of the locking element 96 as shown. If the lobe 104 had not been in the position shown so as to clear the end 108 of the leg 110, it would have struck the lower surface of the leg 110 to rotate the locking element 98 into a position such as to permit one of the other lobes to clear the end 108 of the leg 110. In either event, as upward movement of the arm 40 COD? tinues, the locking element 98 ultimately assumes a position corresponding to that shown in broken lines in Fig. 5.

As the arm 40 reaches a position corresponding to the broken-line position of the locking element 98, the lobe 102 of the locking element 98 engages the end 108of the leg 110 of the locking element 96 to rotate the locking element 98 in the clockwise direction, if this is necessary to cause the locking element 98 to assume the brgken line position of Fig. 5.

Referring now to Fig. 6, continued upward movement of the arm 40 causes the lobe 104; to engage a lower sure nine;

face 112 of an upper leg 122 of the locking element 96, such, surface sloping upwardly and forwardly in such a way as to rotate the locking element 98 in the counterclockwise direction to bring the lobe 104 into engagement with a shoulder 114. When the lobe 104 is inserted into the angle between the surface 112 and the shoulder 114, upward movement of the arm 40 is terminated.

Such insertion of the lobe 104 into the angle between the surface 112 and the shoulder 114 results in positioning the lobe 102 above an upper surface 116 of the leg 110 of the locking element 96. Consequently, if the shelf 28 is now released so that the load thereon tends to move it downwardly again, the lobe 102 engages the surface 116, as shown in Fig. 7. A slight additional movement of the arm 40, as shown in Fig. 8, results in rotation of the locking element 98 to bring the lobe 102 thereof into engagement with a shoulder 118, the lobe 102 being inserted into the angle between the surface 116' and the shoulder 118. The shoulder 118 is generally vertical and is located a distance from the path of the pin 100 less than the length of the lobe 102 so that the locking element 98 cannot rotate beyond the position shown in Fig. 8 to permit downward movement of the pin 100 and the arm 40. Consequently, the shelf 28 is now locked in its extended position. g.

Referring now to Fig. 9 of the drawings, in order to release the locking means 60, the arm 40 is moved upwardly slightly above its extended position. At this juncture, the lobe 104 engages an end 120 of the upper leg 122 of thelocking element 96, on which the surface 112 and the shoulder 114 are formed. The lobe 104 is engageable with the end 120 of the leg 122 at this stage due to the fact that it was rotated clear of the shoulder 114 during the events illustrated in Figs. 7 and 8. The end 120 of the leg 122 slopes upwardly and forwardly so that, as the arm 40 is moved upwardly, the locking element 98'is rotated in the counterclockwise direction, as shown in Fig. 10. The stop 94 engages the arm 38 to terminate the upward travel of the arm 40 with the element 98 in a final position slightly short of that shown in Fig. 10 for the purpose of relieving the elements 96 and 98 of unnecessary shock and wear.

If the shelf 28 is now lowered to move the arm 40 downwardly toward its retracted position, as shown in Fig. 11, the lobe 102 is now aligned with a surface 126 formed by the upper edge of the lower leg 110 of the locking element 96. Engagement of the lobe 102 with the surface 126 results in rotation of the locking element 98 in the counterclockwise direction as the arm 40 continues to move downwardly, whereby the lobe 102 clears the end 108 of the leg 110 to permit the locking element 98 to move downwardly out of engagement with the locking element 96. Consequently, the shelf 28 is now free to move to its retracted position. When the shelf 28 is returned to its extended position, the foregoing events are repeated.

Thus, the present invention provides a simple, effective means for latching the shelf 28 in its extended position, while still permitting ready release of the shelf for movement back to its retracted position merely by moving the shelf upwardly slightly above its normal extended position.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various minor changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims which follow:

1. Retractable hardware, including: a parallelogram linkage comprising parallel mounting and movable brackets and two parallel arms each pivotally connected at one end to said mounting bracket and at its other end to said movable bracket, said movable bracket being movable from a retracted position into an extended position; a tension counterbalance spring; means connecting one end of said spring to one of said arms intermediate its ends;radjustable means connecting the other end of said spring to said mounting bracket, said adjustable means including a pin having an annular groove therein, including means connecting said other end of said spring to said pin, and including at least two keyhole shaped openings in said mounting bracket each having an enlarged head portion into which said pin as a whole is insertable and a smaller stem portion into which the grooved portion of said pin is insertable, said openings being located different distances from the path of movement of said movable bracket between said retracted and extended positions and said stem portions of said openings being closer to said path than said head portions thereof; and means, including interengageable locking elements on said mounting bracket and one of said arms, for locking said movable bracket in said extended position.

2. Retractable shelf hardware, including: a parallelogram linkage comprising parallel, horizontal mounting and shelf brackets and two parallel arms each pivotally connected at one end to, said mounting bracket and at its other end to said shelf bracket, said shelf bracket being movable upwardly and forwardly from a retracted position below and rearwardly of said mounting bracket into an extended position forwardly of said mounting bracket; a tension counterbalance spring; means connectingone end of said spring to one of said arms intermediate its ends; adjustable means connecting the other end of said spring to said mounting bracket, said adjustable means including a pin having an annular groove therein, including means connecting said other end of said spring to said pin, and including at least two vertically spaced, keyhole shaped openings in said mounting bracket each having an enlarged head portion into whichsaid pin as a whole is insertable and a smaller stem portion into which the grooved portion of said pin is insertable, said stem portions of said openings extending downwardly and forwardly from said head portions thereof toward the path of movement of said shelf bracket between said retracted and extended' positions; and means, including interengageable locking elements on said mounting bracket and one of said arms, for locking said shelf bracket in said extended position.

3. Retractable shelf hardware, including: a parallelogram linkage comprising parallel, horizontal mounting and shelf brackets and two parallel arms each pivotally connected at one end to said mounting bracket and at its other end to said shelf bracket, said shelf bracket being movable upwardly and forwardly from a retracted position below and rearwardly of said mounting bracket into an extended position forwardly of said mounting bracket; a tension counterbalance spring; means connecting one end of said spring to one of said arms intermediate its ends; adjustable means connecting the other end of said spring to said mounting bracket, said adjustable means including a pin having an annular groove therein, including means connecting said other end of said spring to said pin, and including at least two vertically spaced, keyhole shaped openings in said mountingbracket each having an enlarged head portion into which said pin as a whole is insertable and a smaller stem portion into which the grooved portion of said pin is insertable, said stem portions of said openings extending downwardly and forwardly from said head portions thereof toward the path of movement of said shelf bracket between said retracted and extended positions; and means, including interengageable locking elements on said mounting bracket and one of said arms, for locking said shelf bracket in said extended position, said locking means including means responsive to movement of said shelf bracket upwardly beyond said extended position for releasing said locking elements from locking interengagernent.

4. Retractable shelf hardware, including: a parallelogram linkage comprising parallel, horizontal mounting and shelf brackets and two parallel arms each pivotally connected at one end to said mounting bracket and at its other end to said shelf bracket, said shelf bracket being movable upwardly and forwardly from a retracted position below and rearwardly of said mounting bracket into an extended position forwardly of said mounting bracket; a tension counterbalance spring; means connecting one end of said spring to one of said arms intermediate its ends; means connecting the other end of said spring to said mounting bracket; and means, including a rotatable, lobed locking element on one of said arms and a stationary locking element on said mounting bracket, for locking said shelf bracket in said extended position, said lobed locking element including straight-sided triangular lobes, said locking means including first means on said stationary locking element engageable by one of the lobes of said rotatable locking element for locking said shelf bracket in said extended position, said locking means also including second means on said stationary locking element and engageable by another of said lobes of said rotatable locking element for rotating said rotatable element to engage said one lobe with said first means in response to movement of said shelf bracket into said extended position, said locking means further including third means on said stationary locking element and engageable by said other lobe of said rotatable locking element for rotating said rotatable locking element to disengage said one lobe from said first means in response to movement of said shelf bracket beyond said extended position.

5. In combination: a stationary member; an arm pivotally connected to said stationary member and movable relative thereto between retracted and extended positions; a lobed, rotatable locking element carried by said arm and having triangular straight-sided lobes; a stationary locking element carried by said stationary member; first means on said stationary locking element engageable by one of the lobes of said rotatable locking element to lock said arm in said extended position; second means on said stationary locking element and engageable by another of the lobes of said rotatable locking element for rotating :e. or said rotatable locking element to engage said one lobe thereof with said first means in response to movement of said arm into said extended position; and third means on said stationary locking element and engageable by said other lobe of said rotatable locking element for rotating said rotatable locking element in response to movement of said arm beyond said retracted position to disengage said one lobe from said first means,

6. In combination: a parallelogram linkage comprising parallel mounting and moving brackets and two parallel arms each pivotally connected to said movable bracket at one end, said mounting bracket having a first portion offset in one direction and the other ends of said arms being pivotally connected to said first portion of said mounting bracket, said mounting bracket having a second portion offset in the opposite direction; and locking means including a locking element on one of said arms and a locking element on said second offset portion of said mounting bracket, for locking said movable bracket in a predetermined position relative to said mounting bracket. 7

References Cited in the file of this patent UNITED STATES PATENTS 633,651 Kohn Sept. 26, 1899 693,127 Gardner Feb. 11, 1902 883,305 Fetch Mar. 31, 1908 1,137,261 Dyke Apr. 27, 1915 1,529,032 Meisner Mar. 10, 1925 2,206,909 Lustig July 9, 1940 2,358,917 Emde Sept. 26, 1944 2,656,234 Koch Oct. 20, 1953 2,710,783 Chaft June 14, 1955 2,733,037 Dunham a Jan. 31, 1956 2,802,711 Ulrich Aug. 13, 1957 2,822,229 Carlson Feb. 4, 1958 FOREIGN PATENTS 159,220 Australia Oct. 7, 1956

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