US2938631A

US2938631A - Movable shelf support for kitchen cabinet or the like

Info

Publication number: US2938631A
Application number: US712384A
Authority: US
Inventors: Eugene E Brey
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-01-31
Filing date: 1958-01-31
Publication date: 1960-05-31
Anticipated expiration: 1977-05-31

Description

- May 31, 1960 2,938,631

' E. E. BREY MOVABLE SHELF SUPPORT FOR KITCHEN CABINET OR THE LIKE Filed Jan. 31, 1958 3 Sheets-Sheet 1 56a! mvIsNTOR1 J l. 2. L27/ENE 5f Bef-SY May 31, 1960 E. E. BREY 2,938,631

MovAELE SHELF SUPPORT FOR KITCHEN CABINET 0R THE LIKE Filed Jan. 31, 195e s sheets-sheet 2 INVENTOR.

?" TOP/Veys May 31, 1960 E. E. BREY 2,938,631

MovABLE SHELF SUPPORT FOR KITCHEN CABINET oR THE LIKE Filed Jan. 31, 1958 3 Sheets-Sheet 3 AP/I/G. l?.

. l L I l .-70 45 60 75 @Oma ,4A/64E 0F MoI/EMENT Fea/vf @Ere/K750 Pos/WON INVENTOR.

j@ Ma @ZM rrOe/s/Eys.

Elas/VE El. BQ/Ey,

MOVABLE SHELF SUPPORT FOR KITCHEN CABINET R THE LIKE Eugene E. Brey, 12351 Deerbrook Lane, Los Angeles, Calif.

Filed Jan. 31, 1958, Ser. No. 712,384

14 Claims. (Cl. 211-92) This invention relates to cabinets, particularly to a movable suspension for a shelf, bin or the like, whereby a high shelf may be made accessible by a simple manipulation.

One of the objects of this invention is to provide a device that makes maximum use of available storage facilities in a kitchen or the like without requiring the use of the notoriously hazardous stepladder.

Parallelogram linkages have been provided in order to maintain a movable shelf or the like in a horizontal position throughout its range of movement. Another object of this invention is to provide improved apparatus of this character.

In apparatus of this character, provisions must be made for counterbalancing the shelf. This is essential in order to prevent the loaded shelf or bin from slamming downwardly with substantial impact. Some attempts have been made to achieve a desired counterbalancing system, but in general, these have been unsuccessful. In order to achieve appropriate counterbalancing, attention must be given to the fact that the torque exerted by the shelf and its load varies in accordance with the position of the shelf. It is, accordingly, another'object of this invention to provide a counterbalancing system for a swingable shelf of this character that allows for this variable.

Another problem in connection with counterbalancing arises from the fact that the actual load on the shelf may vary substantially. It is, accordingly, another object of this invention to provide an adjustable counterbalancing system for a swingable shelf support of this character, whereby appropriate counterbalancing is provided for all loads.

Yet another object of this invention is to provide structure that incorporates simple means whereby the user may adjust the counterbalancing system in accordance with the load. Thus, if the user changes the load,the counterbalancing system is readily adjusted to an extent corresponding to the change in load.

Still another object of this invention is to provide a movable shelf support of this character which maintains stability within the cabinet when it is in retracted position.

Still another object of this invention is to provide a device of this character in which the counterbalancing mechanism is located at the movable frame of a platform rather than at the relatively stationary parts of the parallelogram suspension. It is thus possible to mount the entire device Without any interference with other storage space.

Still another object of this invention is to provide a support of this character which takes relatively little room, whereby there is virtually no interference with the storage space beneath the shelf mounted upon the support.

Still another object of this invention is to provide multiple swingable support structures which can be nested or stacked in a single installation.

Still another object of this invention is to provide a simple, readily manipulable latch mechanism for holding the shelf support in projected position. This makes posnited States Patent O 2,938,631 Patented' May 31, 1960 ICC 2 sible simple operation. Thus, it is unnecessary to hold the support manually in projected position or simultaneously to adjust the counterbalancing mechanism when the load is partially removed from the shelf.

Still another object of this invention is to provide a swingable support which, by simple operations, can readily be attached to a cabinet structure or the like.

Still another object of this invention is to provide a shelf support of this character which comprises relatively few parts and that can be made economically.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of one embodiment of the invention. For this purpose, there is shown a form in the drawings accompanying and forming part of the present specilication. This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best dened by the appended claims.

Referring to the drawings: Y

Figure l is a top plan view of the support to a cabinet and illustrated in projected position, the shelf or bin carried by the support being removed in order to illustrate the parts of the support, and the cabinet being shown in section;

Fig. 2 is a sectional View taken along the plane indicated byline 2 2 of Fig. l;

Fig. 3 is an enlarged sectional view similar to Fig. 2, but illustrating the support in its retracted position;

Fig. 4 is an enlarged sectional view taken along the plane indicated by line 4 4 of Fig. 1;

Fig. 5 is a fragmentary front view of the handle and crank structure;

Fig. 6 is an enlarged sectional view taken along the plane corresponding to line 6-6 of Fig. l, and illustrating the rear supporting arms and angularly movable anchor for the counterbalancing springs;

Fig. 7 is a side View of a portion of the support, a part of the apparatus being broken away and illustrated in section, said Fig. 7 showing in detail the manually operable latch mechanism for holding a support in projected position;

Fig. 8 is a diagrammatic view illustrating the manner in which two movable supports may be positioned in juxtaposed or nested relationship; and

Fig. 9 is a graph illustrating the torques exerted by the shelf at diierent loads and the torques exerted by the counterbalancing springs at different adjustments.

A frame 10 (Fig. l) forms a base upon which a shelf or bin 11 (Fig. 2) may be secured. In the present instance, the frame 10 is made of bar stock appropriately bent to provide a generally rectangular configuration.

The front section 10a of the frame 10 has a centrally disposed, forwardly projecting odset portion 10b. Reinforcing bars 10c, in the form of angle irons, extend from the front section 10a (Fig. l) to the rear section 10d of the frame 10 (see also Figs. 4 and 6). The forward ends of the bars 10c have their vertical flanges welded or otherwise suitably secured respectively within the sides of the offset portion 10b. The rear ends of the bars 10c abut the rear section 10d and are appropriately secured thereto, as by welding.

The frame 10 can be made in any other appropriate manner as, for example, by draw die techniques.

The frame 10 is movably mounted by the aid of a parallelogram linkage comprising four

arms

14, 15, 16 and 17. (See Figs. l, 2 and 3.) A generally rectangular bracket 18, aixed suitably to a metal cabinet 19, pivotally mounts corresponding ends 14m, 15m, 16m and 17m of the

arms

14, 15, 16 and 17. The bracket 18 is secured, in the present instance, to a shelf 19a (Fig. 2)

of the cabinet 19. For this purpose, the rear portion of the bracket 18 is welded, as at 20 (Fig. 3), both to the rear wall of the cabinet 19 and to the rear portion of the shelf 19a. The forward portion of the bracket 18 is bolted, as at 21 (Fig. 1), to the forward portion of the shelf 19a.

The

rear arms

14 and 17 are pivotally mounted on the respective side elements of the bracket 18 for angular movement about a common horizontal axis 22 (Figs. l and 3). The

arms

15 and 16 are mounted similarly on the respective side elements of the bracket 18 for movement about a parallel horizontal axis 23 (Figs. 1 and 3). The

axes

22 and 23 lie in a common horizon tal plane and they extend parallel to the plane of the opening 19b in the front wall of the cabinet 19. Y

`Bearing assemblies 24 (Fig. 1) cooperate with apertured attened ends of the

arms

14, 15, 16, 17 for mounting the arms on the outer sides of the bracket 18. The side elements of the bracket 18 are offset (Fig. l) so that the bracket 18 is provided with a corner that can be placed against the inside corner of the cabinet even though the arms are located on the outside of the bracket 18.

The

rear arms

14 and 17 are formed in this instance as the respective ends of a U-shaped rod (Figs. 1 and 6). The central connecting portion 25 joining the upper ends of the rear arms'14 and 17 serves as a means for pivotally joining lthe rear arms to the frame 10. This portion 25 is thus accommodated at opposite sides in upwardly opening recesses 26 and 27 (Figs. l, 6 and 7) -formed at the rear ends of the side sections e and 10jc of the 'frame 10. The connecting portion 25 also extends through corresponding upwardly opening slots 28 and 29 (Figs. l, 3'and 6) in the rear portions of the reinforcing j p 10, confine the connecting portion 25 ot the bottom of Y the

slots

26 and 27. Y

The

forward arms

15 and 16 have inwardly ybent ends 15a and 16a (Fig. 1) respectively passing through apertures 32 in the side 'sections 10e and 10i of the frame 10. The terminal portions of the bent ends 15a and 16a pass through corresponding apertures 33 in the reinforcing bars 10c. Collars 34, secured to the terminal portions of the bent ends 15d and 16a, hold the ends against separating movement relative to the frame 10. The aper tures 32 and 33 form bearingsfor forward

arms

15 and 16, and define an axis 37 of relative movement ofthe frame 10 and the forward arms.

The recesses for the connecting portion 25 define an axis 36 (Fig. 3) of relative movementbetween the frame 10 and the

rear arms

14 and 17. The'four axes 36, 37, 22 and 23 define corners of a parallelogram, the distance between the

axes

36 and 37 at the frame 10 being equal to the distance between the

axes

22 and 23 at the mounting bracket 18, and the distance between the

axes

22 and 36 for the rear arms 14 vand 17 being equal to the distance between the

axes

23 and 37 for the

forward arms

15 and 16. Accordingly, a parallelogram support for the frame 10 is defined, and a plane including the

axes

36 and 37 maintains its horizontal orientation throughout the range of movement of the frame 10.

As shown in Fig. 3, the rear section 10d of the frame 10 (or the shelf 11 should it slightly overhang this. rear section) Vforms an abutment engageable with the rear wall of the cabinet for defining the retracted position of the device.

The rear axis 36 of movement of the frame 10 is substantially closer to the rear section 10d than is the axis 22 from the rear portion of the mounting bracket 18. Accordingly, for a straight wall cabinet, the frame 10 may be positioned such that the

arms

14, 15, 16 and 17 incline rearwardly relative to the cabinet opening when )the frame 10 Ais in retractedv position (Fig. 3). In this orientation, the Weight of the shelf and contents tends to rotate the

arms

14, 15 and 16 in a counterclockwise direction about their

axes

22 and 23, corresponding to further engagement of the frame 10 with the rear wall of the cabinet 19. Accordingly, in this orientation, the frame 10 is self-biased towarda stable, retracted position.

In order'to move the frameoutwardly, a torque must be exerted on the apparatus such that the

upper axes

36 and 37 pass beyond a position of maximum height relative respectively tothe axes 22 and 23. This torque is applied manually, as by the aid of a handle 38 (Fig. 5) axed to the offset portion 10b of the frame 10. This handle is accessible immediately beneath the forward portion of the shelf or'bin 11 (Figs. 2 and 3).

The

arms

14, 15, 16 and 17 (Fig. 2) determine the limiting projected position of the frame 10. In the projected position, a plane including the

movable axes

36 and 37 lies slightly above the plane including the

axes

22 and 23. Thus, the arms do not mofve quite to the position from the orientation in which the axes 36 .and 37 are uppermost.v The

rear arms

14 and 17 have intermediate offset portions, as at 17a, that provide clearance relative to the forward bearing structures 24 and the attened ends of the

forward links

15 and 16. In the projected position illustrated in Fig. 2, the forward portions ofthe

arms

14 and 17 contact the rear portions of the

forward arms

15 and 16. This provides the limit to movement of the frame 10. The `

forward arms

15 and 16 are likewise offset, as at 15b and 16b, in order to clear the ends ofthe

rear links

14 and 17.

When the arms V14, 15, 16 and V17 pass beyond -the position of maximum elevation, the weight of the loaded frame 10 tends to move it toward the projected Yposition illustrated in Fig. 2. The horizontal lever arm at which the loa-ded shelf Vacts to produce a torque varies from zero to the length ofthe arms themselves, depending upon the position of the frame 10. The torque, ldue to weight, tending to so move the frame 10, can be recognized asa simple trigonometric function, varying as the sine of the angle of the arms from the position of maximum height of the frame axes 36 and 37. This function is illustrated by the lines a1 and a2 in Fig. 9, the different lines cor` responding to different loads. Obviously the counterbalancing torque should similarly vary. A spring structure is provided for this purpose. In the present instance, the spring structure includes companion tension coil springs 39 and 4t) (Fig. 1). Opposite ends of -each of the coil springs 39 and 40 are attached respectively to the frame 10 and a crank 25a (Figs. l, 3 and 6) forming a part of the arm structure 14-17. In the present instance, the crank 25a is formed vas an offset portion ofthe joining portion 25.

The right-hand ends of theV springs 39 and 40'pass through apertures 41 (Figs. 3 and 4) in a movable transverse bar 42 mounted on the horizontal flanges of angle irons 10c attached to the Yframe 10. The terminal portions of lthe `springs 39, are anchored as, for example, by hook portions 39a and 40a engaging the upper edges of the bar 42. Optionally a pivotal connection may be provided between thefend of the springs and the'bar 42.

The bar 42 forms a part of a carriage structure 43 opposite sides of whichrest upon the horizontal flanges of the reinforcing bars 10c (Fig. 1). A lead screw 44 passes through a threaded element 45 (Figs. -1 and 3) joined to the carriage 43, and determines the position of the carriage 43 and hence the position of the Vright-hand ends of the springs along the frame 10. The leadscrew 44 is joined to the handle 38 and passes inwardlyof thc frame 10 througha front opening 46 in the offset portion 10b of the frame 10. Y v

A crank 47 (Fig. 5,), fitting Withina transverse vslot `38a of the .handle v38, vfacilitates Yrotation .of the lead screw 44 and hence adjustment of '.spring tension. The

crank 47 is movable to operative position by rotation about a mounting pin 48 at one end of the slot 38a.

The left-hand or rear ends of the

springs

39 and 40 are looped (Figs. 3 and 6) about the central portion of the offset crank 25a.

A cover plate 56 (Figs. 3 and 6) is secured to the bottom of the frame and cooperates with the shelf 11 on top of the frame to provide a complete protective enclosure. The plate 56 has a central depression, as at 56a, to allow movement of the

springs

39 and 40 to the position illustrated in Fig. 2.

The offset portion 25a, about which the

springs

39 and 40 are looped, is disposed at an angle of somewhat less than 90 to the line joining the

axes

22 and 36 of the

rear arms

14 and 17. The angularity is such that lines joining the ends of each of the springs (Fig. 3) pass through the axis 36 when the apparatus is in the retracted position of Fig. 3. Thus, the angle (in this instance about 72) is the complement of the rearward angle of inclination of the arms (in this instance about 18). The

springs

39 and 40 in this position accordingly exert no torque tending to urge the connecting rod 25 angularly about its axis of mounting 36. Thus, the springs 39 and 4i? exert no 'effect upon the position of the sup port in the orientation illustrated in Fig. 3.

When the support is moved from the position illustrated in Fig. 3, a line joining the ends of the

springs

39 and 40 passes beneath the axis 36, the crank 25a rotating about this axis. Hence, the

springs

39 and 40 now exert a restoring torque opposing such movement. It may be noted that the spring force tends at all times to seat the carriage on the flanges of the bars c since the offset 25a always projects downwardly relative to the axis 36. lf the force exerted by the

springs

39 and 40 be considered constant and if it is assumed that the spring force is always parallel to the frame 10, obviously the restoring torque will be a sine function. But the

springs

39 and 40 lengthen during this movement, and an extra restoring torque arises due to this. The elongation is significant only near the projected position of the device.

Ftuthrmore, the springs do not act in a direction parallel to the frame, and hence, the lever arm increases at a faster rate than a sine function, but the same maximum lever arm is reached at an angle of less than 90, corresponding to the tangent position of the springs to the circle described by the crank, as illustrated by phantom lines in Fig. 2. This factor is most noticeable near the retracted position of the device. Hence, the two factors complement each other in generally preserving a sinusoidal restoring torque function. By appropriate choice of the spring constant and length of the crank arm radius relative to the length of the springs, an exceptionally good complementary relationship can be obtained.

Lines b1, b2 illustrate in Fig. 9 the total restoring torque, dierent lines corresponding to different preset tensions in the springs.

By adjusting the tension of the springs 39 and 4i), as by rotation of the handle 38, the restoring torque can be made slightly less than the torque due to weight at the projected position of Fig. 2. This is indicated by the lines a2 and b2 in Fig. 9. Thus, by slight overpowering of the springs, the weight holds the device in projected position. The counterbalancing torque is, however, always greater than the torque due to weight, except at the projected position, because the counterbalancing force increases steadily from the position of Fig. 3, while the torque due to weight opposes the springs only after the

arms

14, 15, 16 and 17 are moved to the vertical position. However, as may be appreciated from Fig. 9, the difference between the torque curves is small and, accordingly, only a slight effort is required to move the device to the projected position.

Before load is removed from the support, the frame l10 is locked in projected position to ensure against abrupt upward swinging of the device.

In order to lock the frame 10, a latch mechanism (Figs.- l and 7) is provided. A latching lever 51 has an end 49 movable outwardly of the side frame section 10j via a recess 50 in which it is guided. The end 49 extends in a path of the forward arm 15 when the projection 49 is moved to its maximum outward position. When the frame 10 is in a projected position, the projection 49 lies beneath the arm 15. Upon attempted movement of the frame 10 to the retracted position, the arm 15 tends to move relative to the frame 10 in a counterclockwise direction about the axis 37, and hence downwardly toward the lever end 49. When the end 49 is shifted inwardly, the device can be retracted.

The lever 51, on which the latching element `49 is formed, is pivoted intermediate its length on a lug 52 secured on the inside of the frame 10, the lever 5-1 passing through an adjoining aperture 53 which permits angular reciprocation of the lever 51. A bolt 54, cooperating respectively with the lever S1 and the lug 52, mounts the lever 51 for angular adjustment about a vertical axis.

The forward end of the lever 51 is upwardly bent, as at 51a. This end of the lever 51 lies adjacent the offset portion 10b of the frame 10 and is readily accessible for manipulation by the operator.

The size of the shelf or bin supported on the frame 10 is not critically dependent upon the size of the frame 16 itself. The same mechanism may support a shelf of any desired length.

As shown in Fig. 2, the frame 10 always lies on the outer side of an arc 55 centered at the rear axis 22. Hence, articles stored on the shelf 19a within the area described by the arc will not be disturbed by movement of the frame 10. Providing extra tall articles are not stored at the forward portion of the shelf below, the device does not interfere with any other storage facilities.

As illustrated in Fig. 8, a pair of swingable support structures are provided whereby two relatively high shelves can be made accessible. The upper support has arms substantially longer than those illustrated in Figs. 1, 2 and 3, and the support accordingly projects a substantial distance forwardly of the cabinet opening. It is pos sible to move both devices to projected position so that the shelves or bins are simultaneously accessible. However, both devices operate independently and without interference with respect to each other.

The inventor claims:

l. In a retractable device for facilitating access to a high space: at least two parallelogram linkage parts; mounting means for correspon-ding ends of the parts; support means secured to the other ends of the parts; the support means being swingably mounted by the parts for movement through an angle of approximately ninety degrees between a retracted upper position in which the support means extends above said mounting means, and an accessible lower projected position in which the support means projects laterally on one side of the mounting means; said linkage parts defining with both said means at least four parallel axes that define the apices of a parallelogram in a plane normal to said axes, the first two of said axes being located at the support means and the second corresponding two of said axes being located at said mounting means; the first two axes being substantially vertically above the second two axes at retracted position; the inkage parts being relatively angularly movable with respect to said support means about said first axes, and relatively angularly movable with respect to said mounting means about said second axes; a tension spring device secured at one end to one of said means, and at the other end to one of said parts, the place of securing of said spring device to said one part being spaced from the axis of relative angular movement of the said one means and said part, whereby said placemoves relative to said one means angularly about said axis as a center as the linkage parts are moved; the place of securing of the spring device to said one part being substantially aligned with a line joining said one axis and the place of securing of said one part to said one means when said support is in re tracted position,and both of said places then being on one side of said axis whereby said spring device exerts a torque increasing substantially sinusoidally as the support means and linkage parts are moved from said retracted position to said projected position.

2. The combination as set forth in claim l together with means movable along the said one means providing an adjustable place of securing of said tension spring device to said one means; and means for determining one of a number of positions of said movable means.

3. The combinationV as set forth in claim 1 in which said one means is said support means; adjustable means mounted on said support means for moving the said place of securing of said spring device to said support means in a direction away from said axis along the direction of said alignment; an angularly adjustable handle carried by the support means; and means operated by angular movement of said handle for determining any one of a number of positions of said adjustable means.

4. The combination as set forth in cla-im 1- in which abutment means determines the retracted position of said support means, and so located that the load of said support means, when Vin retracted position, provides a torque urging said linkage parts toward retracted position.

5. The combination as set forth in claim l in which abutment means determines the retracted position of said support means, and so located that the load of said support means, when in retracted position, provides a torque urging said linkage parts toward retracted position; and means for adjusting the force exerted by said spring device whereby the `torque due to said spring device substantially counterbalances the torque due to the load of said support lmeans when said support means is at projected position.

6. The combination as set forth in claim 1 in which abutment means determines the retracted position of said support means, and so located that the load of said support means, when in retracted position, provides a torque urging said linkage parts toward retracted position; and means for shifting the place at `which said spring device is secured to said one means for compensating for a changed load of said support-means; the spring constant of said spring device and the relative location of said places being so chosen that the incremental torque dueto expansion of said spring device and the shifting of the line of action of said spring device complement each other -to maintain a substantially sinusoidal variation in torque due to said spring device. l

7. The combination as set forth in claim l in which abutment means determines the retracted position of'said support means, and so located that the load of said support means, when in retracted position, provides a torque urging said linkage `parts toward retracted position; and means for shifting the place at which said spring device is secured to said one means for compensating for a changed load of said support means; the spring constant of said spring device and the Arelative location of said places being so chosen that the incremental torque due to expansion of said spring device and the shifting of the line of action of said spring device complement each other to maintain a substantially sinusoidal variation in torque due to said spring device; movement of the support means to an intermediate position, corresponding to an initial angle from retracted position, being Yrequired before the support means exerts a torque urging the support means to projected position whereby the spring device Vmay be adjusted so that the torque exerted thereby exceeds `the torque due to said support means by a small amount decreasing substantially to zero as the support means is moved from said intermediate rposition to said projected position. i

8. In a retractable supporting device: a support; a parallelogram linkage having a pair of stationary parallel axes and a pair of parallel movable axes, and including a pair of links respectively joining a stationary Vand a movable axis; said support being carried by those ends of the links which are connected to the movable axes; resilient means for urging the linkage toward retracted position; said means being resiliently expandible; means anchoring Opposite ends of the resilient means so that both anchors move as the support is moved, one anchor moving angularly about a movable axis, and so that the anchors move apart as the support moves toward extended position.

9. The combination as set forth in claim l together with means for adjusting the force exerted by said spring device whereby the torque due to said spring device substantially counterbalances the torque due to said support means when said support means is at projected position; and a manually operable latch for holding said support means at projected position to allow adjustment of said force adjusting means when the load on said support means is changed, said latch comprising `a lever pivotally mounted on said support having one end adjacent said force adjusting means and having another end movable in the path of angular movement of one of said linkage parts relative to said support means.

l0. In a retractable device for facilitating access to a high space: a iirst pair of arms; a second pair of arms; means mounting the rst pair of arms for movement about a common rst axis; means mounting the second pair of arms for movement about a common second axis parallel to the first axis; a support pivotally connected to the rst and second pairs of arms at third and fourth parallel axes to provide a parallelogram mounting therefor, the gsupport being swingable between a retracted upper position in which the third and fourth axes extend substantially above the iirst and second axes respectively and -a lower projected position in which the third and fourth axes extend to one side of the first and second axes; Va bar joined t0 the movable ends of the iirst arms adjacent said vthird axis for movement with said rst arms, and having at least a portion offset from said third axis, said portion extendying in a direction from said third axis toward said fourth axis when said support is in-retracted position whereby said portion moves angularly about said third axis and beneath said support upon movement of said support away from retracted position; and a tension spring secured at one end to the support at a place substantially aligned with said third and fourth axes, and at the other end to said offset portion for counterbalancing the support.

l1. In a retractable device for facilitating access to a high space: a first pair of arms; a second pair of arms; means mounting the first pair of arms for movement about a common first axis; means mounting the second pair of arms for movement about a common second axis parallel to the first axis; a support pivotally connected to the first and second pairs of arms at third and fourth parallel axes to provide a parallelogram mounting therefor, the support being swingable between a retracted upper .position in which the third and fourth axes extend substantially above the first and second axes respectively and a lower projected position in which the third and fourth axes extend to one side of the first and second axes; a bar joined to the movable ends of the first arms adjacent said third axis for movement with said first arms, and having at least a portion offset from said third axis, said portion extending in a direction from said third axis toward said fourth axis when said support is in retracted position whereby said portion moves angularly about said third axis and beneath saidisupport upon movement of said support away from retracted position; a carriage guided by the support for movement along a path corresponding substantially to a line between said third and fourth axes; a tension spring secured at one end to said offset portion and at the other end to said carriage for counterbalancing the support; and means for Yadjusting the position of said carriage for compensating for difierent loads on said support.

12. In a retractable device for facilitating access to a high space: a first pair of arms; a second pair of arms; means mounting the first pair off arms for movement about a common rst axis; means mounting the second pair of arms for movement about a common second axis parallel to the first axis; a support pivotally connected to the rst and second pairs of arms at third and fourth parallel axes to provide a parallelogram mounting therefor, the support being swingable between a retracted upper position in which the third and fourth axes extend substantially above the first and second axes respectively and a lower projected position in which the third and fourth axes extend to one side of the first and second axes; a bar joined to the movable ends of the rst arms adjacent said third axis for movement with said lirst arms, and having at least a portion offset from said third axis, said portion extending in a direction from said third axis toward said fourth axis when said support is in retracted position whereby said portion moves angularly about said third axis and beneath said support upon movement of said support away from retracted position; a carriage guided by the support for movement along a path corresponding substantially to a line between said third and fourth axes; a tension spring secured at one end to said offset portion and at the other end to said carriage for counterbalancing the support; a handle mounted on the support for angular movement about an axis substantially aligned with said path; and means operated by angular movement of said handle for determining the position of said carriage for compensating for different loads on said support.

13. In a retractable device for facilitating access to a high space; a rst pair of arms; a second pair of arms; means mounting the rst pair of arms for movement about a common first axis; means mounting the second pair of arms for movement about a common second axis parallel to the first axis; a support pivotally connected to the first and second pairs of alms at third and fourth parallel axes to provide a parallelogram mounting therefor, the support being swingable between a retracted upper position in which the third and fourth axes extend substantially above the rst and second axes respectively and a lower projected position in which the third and fourth axes extend to one side of the flrst and second axes; a bar joined to the movable ends of the rst arms adjacent said third axis for movement with said first arms, and having at least a portion offset om said third axis, said portion extending in a direction from said third axis toward said fourth axis when said support is in retracted position whereby said portion moves angularly about said third axis and beneath said support upon movement of said support away from retracted position; a carriage guided by the support for movement along a path corresponding substantially to a line between said third and fourth axes; a tension spring secured at one end to said offset portion and at the other end to said carriage for counterbalancing the support; a handle mounted on the support for angular movement about an axis substantially aligned with said path; means operated by angular movement of said handle for determining the position of said carriage for compensating for different loads on said support; and a selectively operable latch mounted on the support and having a manually engageable part adjacent said handle for holding said support in projected position.

14. In a retractable device for facilitating access to a high space: a first pair of arms; a second pair of arms; means mounting the first pair of arms for movement about a common first axis; means mounting the second pair of arms for movement about a common second axis parallel to the lirst axis; a support pivotally connected to the first and second pairs of arms at third and fourth parallel axes to provide a parallelogram mounting therefor, the support being swingable between a retracted upper position in which the third and fourth axes extend substantially above the first and second axes respectively and a lower projected position in which the third and fourth axes extend to one side of the first and second axes; a bar joined to the movable ends of the first arms adjacent said third axis for movement with said first arms, and having at least a portion offset from said third axis, said portion extending in a direction from said third axis toward said fourth axis when said support is in retracted position whereby said portion moves angularly about said third axis and beneath said support upon movement of said support away from retracted position; a carriage guided by the support for movement along a path corresponding substantially to a line between said third and fourth axes; a tension spring secured at one end to said offset portion and at the other end to said carriage for counterbalancing the support; a handle mounted on the support for angular movement about an axis substantially aligned with said path; a lead screw carried by the handle for rotation therewith; means carried by the carriage engaging the lead screw for determining the position of said carriage for compensating for different loads on said support; and a crank foldable within the handle for facilirating rotation of said handle.

References Cited in the le of this patent UNITED STATES PATENTS 1,824,822 Kradolfer Sept. 29, 1931 2,152,946 Barltrop Apr. 4, 1939 2,170,098 Stephenson Aug. 22, 1939 2,531,140 Linde Nov. 21, 1950 2,545,515 Gannett Mar. 20, 1951 2,547,382 Freeman Apr. 3, 1951