US3799638A

US3799638A - Drawer interlock

Info

Publication number: US3799638A
Application number: US00281421A
Authority: US
Inventors: F Faiks
Original assignee: Steelcase Inc
Current assignee: Steelcase Inc
Priority date: 1972-08-17
Filing date: 1972-08-17
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26
Also published as: DE2341792B2; JPS532381B2; CA976593A; DE2341792C3; DE2341792A1; GB1382784A; JPS4957964A

Abstract

A drawer interlock employs a ribbon stop member positioned on the inside of a cabinet and extending along the cabinet in a slack fashion adjacent a plurality of cam members positioned on the cabinet to be actuated by an associated catch member positioned on each of a plurality of drawers. As a drawer is extended from the cabinet, the camming member associated with the drawer is rotated to allow the passage of the catch thereby, while simultaneously engaging the ribbon to take up the slack in the ribbon such that no additional cams can fully rotate to allow the opening of associated drawers. When the drawer is closed, the drawer catch rotates the cam as it passes returning the stop member to the slack condition so that another or the same drawer can be opened.

Description

United StatesPatent [1'91 Faiks 1 DRAWER INTERLOCK [75] Inventor: Frederick S. Faiks, Comstock Park,

Mich.

[73] Assignee: Steelcase, Inc., Grand Rapids, Mich.

[22] Filed: Aug. 17, 1972 [21] Appl. No.: 281,421

[52 us, ci.. 312/216, 31'2/333 12/1969 Great Britain..' 312/222 a 111 3,799,638 Mar. 26, 1974 Primary Examiner-Paul R. Gilliam Attorney, Agent, or Firm-Price, l-Ieneveld, Huizenga & Cooper 1 57 ABSTRACT A drawer interlock employs a ribbon stop member positioned on the inside of a cabinet and extending along the cabinet in a slack fashion adjacent a plurality of cam members positioned on the cabinet to be actuated by an associated catch memberpositioned on each of a plurality of drawers. As a. drawer is extended from the cabinet, the camming member associated with the drawer is rotated to allow the passage of the catch thereby, while simultaneously engaging the ribbon to take up the slack in the ribbon such that no additionalcams can fully rotate to allow the openingv of associated drawers. When the drawer is closed, the drawer catch rotates the cam as it passes returning the stop member to the slack condition so that another or the same drawer can be opened.

26 Claims, 12 Drawing Figures 7 1970 Germany 312/222 FIG. 8. F15.

DRAWER INTERLOCK BACKGROUND OF THE INVENTION a rotatable rod extending vertically in the cabinet and coupled to a spring-loaded engaging mechanism. When a drawer is opened, the rod rotates and locks the remaining drawers in a closed position. Some systems employ a rope or wire which is interconnected to each of the drawers and has sufficient slack to permit the full extension of one of the drawers but will not allow the remaining drawers to be extended.

Although some of these systems perform adequately, they do not prevent the simultaneous opening of two drawers. Even the rope type allows two drawers to be partially opened simultaneously. Some prior artsysterns are relatively complex and, therefore, costly to manufacture. Others lack the durability necessary for cabinets which are frequently used.

' SUMMARY OFTHEINVENTION The apparatus of the present invention, however,

prevents even the simultaneous opening of two drawers and-employs a mechanism which can be fitted within a cabinet and on the drawers thereof to provide a durable yet-inexpensive system for preventing the opening of more than one drawer. Theapparatus can be installed as an integral part of new cabinets or can be added to many existing cabinets. With the present system, a cam can easily be removed from the mounting bracket for replacementor repositioning by simply removing the drawer. This allows a great degree of flexibility in mod- .ular file cabinet construction where a variety of drawer positions are available for use.

The drawerinterlock of thepresent invention employs a single stop member extending between two or more drawer levels and which interacts with camming meansactuated by a catch positioned on a drawer to move the stop from a slack position which permits the opening of a drawer to a taut position which prevents the opening of a second drawer.

Apparatus embodying the present invention includes a catch positioned on each drawer of a cabinet having two or more drawers, and camming means positioned onthe wall of the cabinet in alignment with each drawer catch to be engaged thereby as a drawer is opened or closed. Stop means is positioned on the cabinet to extend across each of the camming means and has a slack position which permits one of the camming means to rotate and permit the passage of a drawer catch thereby while simultaneously engaging the stop to take up the slack thereby preventing additional camming means from rotating to permit the passage of a second drawer thereby.

BRIEF DESCRIPTION OF THE DRAWINGS FIG-1' is a fragmentary side elevational view of the portion of the apparatus of the present invention adapted to be positioned on a cabinet having two or more drawers;

FIG. 2 is a cross section of a portion of the apparatus shown in'FIG. 1 taken along plane II-II in FIG. 1;

FIG. 3 is a fragmentary side elevational view showing one of the'cam members shown in FIG. I taken from the side opposite that shown in FIG. 1 and showing the relationship of the member to a drawer catch with the drawer illustrated in a closed position;

FIG. 4 is a side elevational view-of the apparatus shown in FIG. 3 with the drawer shown in the process of being opened;

FIG. 5 is a side'elevational view of the apparatus shown in FIG. 4 showing the drawer in the process of being closed;

FIG. 6 is a side elevational-view of the apparatus shown in FIGS. 3 through 5 during the initial installation of a drawer; I

FIG. 7 is a front elevation view of the camming means; I

FIG. '8 is a fragmentary side elevational view of one embodiment of the stop member;

.FIG. 9 is a fragmentary side elevational view of an ternative embodiment of the stop member;

' FIG. 10 is a side elevational view of an alternative arrangement .for mounting cam members and the stop member to awall of a cabinet;

FIG. 11 is a plan view of'the cam member mounting bracket shown in FIG. 10; and

. FIG. 12 is a plan view of the stop member mounting bracket shown in FIG. 10. 1

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 20 are a plurality of earns 40. When a drawer 60 is opened, a catch 62 thereon engages cam 40 and passes thereby. As catch 62.passes, it rotates cam40 to the position of cam 40b shown in FIG. 1. This takes up all available slack in ribbon 30 and prevents other drawers 60 from opening. Each cam 40 and catch 62 are designed to cooperate in such a way that if one attempts to open two drawers simultaneously, all of the slack in ribbon 30 is taken up before either catch 62 is free to pass by its cam 40.

In the embodiment shown in FIG. 1, guide 20 is formed integrally with a cabinet reinforcing and drawer suspension mounting bracket 12. Bracket 12 is vertically mounted to the wall 10 of the cabinet near the front thereof by means of a plurality of mounting screws or bolts 14 extending from one of the convoluted walls of the bracket into the side wall of the cabinet or'by spot welding. The bracket 12 includes a plurality of apertures 16 and flanges 18 which are conveniently formed in the bracket for supporting drawer suspending members for the file cabinet but form no part of the present invention.

Bracket 12 further includes a wall portion 11 with guide 20 comprising a guide wall 22 extending outwardly from wall 11 and having an overturned edge or lip 24 as seen in FIG. 2. Guide 20 guidably supports a open spaces 13 between adjacent guide segments and being positioned at each possible drawer level location. The guide wall 22 of guide member 20 is inwardly bent to form a land 25 on each side of each open space 13 which, when the stop ribbon 30 is deflected inwardly, provides a smooth ribbon support area. Integrally formed with wall 11 of the mounting bracket are a plurality of tabs 26 which are positioned generally. centrally within the open space 13 of the guide wall 22 and include raised areas 28 having an aperture therein (not shown) for supporting cam means 40 in spaced relationship from the inside wall of the cabinet. Adjacent raised areas are raised detents which insure that a cam 40 will stay in its drawer open position (cam 40b) when rotated thereby by its associated drawer catch 62 (FIG. 1).

Stop ribbon 30 comprises a ribbon 31 of flexible highly'stretch resistant material such as ribbon steel or other suitable material. One embodiment of the stop ribbon is shown separately and in detail in FIG. 8. As seen in FIG. 8, hooks 32 are positioned at opposite ends of the ribbon 31 and are secured to ribbon 31 by means of a crimping connection 34. Ribbon 31 has a take-up loop 35 formed therein to take up the slack of I ribbon. 31 when all of the drawers 60 are closed. Takeup loop 35 is flexible, however, and permits, as described below, the stop ribbon 30 to be deflected around a camming member 40 to take up the slack and pull stop member 30 taut when one of the drawers of the file cabinet is opened. As seen in FIG. 1, the hooks 32 are positioned over opposite ends of guide which provide fixed mounting points for the stop ribbon 30.

I FIG. 9 illustrates an alternative embodimentof the stop ribbon 30 like the FIG. 8 embodiment but employ- Y bracket 12.

The cam member 40 can be molded from a suitable polymeric material such as polyvinyl chloride, polyethylene or like moldable material. Each cam member 40 comprises a center sleeve 42 having an aperture therein adapted to receive a mounting screw 41 or the like which rotatably mounts cam member 40 to raised area 28 of bracket 12 (FIGS. 1, 3 and 7). As best seen in FIGS. 3 and 7, each of the cams further includes a spring arm 44 extending tangentially from the sleeve 42 and including a right angled tip 45 thereon. Spring arm 44 acts as a cam return during installation of a drawer 60 as will be hereinafter explained.

The cam member 40 additionally includes a support wall 46 extending from approximately the middle of sleeve 42 and at right angles to the axis of the sleeve. Supported orthogonally around the peripheral edge of wall 46 by means of a plurality of ribs 48 (shown only in FIGS. 4 and 5 for clarity) is a generally curved lip 50. Lip 50 includes three stop

member engaging surfaces

51, 52 and 53 which are integrally formed at obtuse angles relative to the adjacent engaging surface. The junctions of

surfaces

51, 52 and 53 are generally rounded and the junction of

surfaces

52 and 53 is spaced somewhat farther from the axis of rotation of cam 40 than is the junction of

surfaces

51 and 52 to form an eccentric cam. Surface 51 extends tangentially from sleeve 42 approximately opposite spring arm 44 (FIG. 3).

Surfaces

51, 52 and 53 are shaped to permit easy deflection of the ribbon for drawer operation and to prevent the cam from returning to the position 40a (FIG. 1) when tension is applied to the ribbon by another drawer.

Lip 50 includes ribbon guides 54 and 54a projecting outwardly from the junction of

surfaces

51 and 52 as seen in FIG. 7. Guide 54 includes a stand-off tip 55. The

guides

54 and 54a hold ribbon stop 31 in alignment with the

surfaces

51, 52 and 53 of cam 40 and are spaced from the side of bracket 12 such that the ribbon is freely deflectable when cam 40 is rotated as described below.

Extending from sleeve 42 along an edge of support wall 46 is a first cam arm 47 which is a flat rectangular member extending from the middle of sleeve 42 outwardly in a direction opposite lip 50 (FIGS. 1, 3 and 4). Arm 47 has a rounded tip 49 as best seen in FIGS.- 1 and 3. A second cam arm 58 having a rounded tip 59 extends radially outwardly from the sleeve 42 as seen in FIG. 3.

Cam arms

58 and 47 are spaced from each other by approximately 80 in the embodiment shown, although with different drawer catches, this spacing may be varied. This spacing should be such that the two

cam arms

58 and 47 act in conjunction with catch 62 to provide for smooth, even rotation of cam 40 through an are greater than 90 when drawer 60 is closed. The closing action should begin with the engagement of arm 58 and proceed until the angle of arm 47 with respect 0t catch 62 is less steep, at which point engagement of arm 47 should finish the closing. Likewise, spring arm 44 is spaced approximately 45 from cam arm 58 in the preferred embodiment. Again, this spacing can be varied somewhat and is not critical except to the extent that it must insure that cam 40 will be sprung into its neutral, drawer closed position during drawer installation.

On the left side of each drawer'60 of the cabinet and positioned slightly below the axis of each cam member 40, as shown in FIG. 3, is a drawer catch 62 comprising three generally

vertical walls

64, 66 and 68. These act as cam engaging surfaces extending outwardly from the side of the drawer. An angled surface 65

couples walls

64 and 66 and a rear wall 67 joins

walls

66 and 68. Catch 62 is attached to one side of the drawers by suitable fastening bolts through wall 67 or, in the embodiment shown where the drawers are steel, is spot welded to the drawer. By providing a catch of this configuration for each drawer, a plurality of cam engaging surfaces are provided which cooperate with cam 40 to smoothly rotate the associated cam 40 as the drawer is opened and closed.

Middle wall 66 provides the cam engaging surface which engages cam arm 47 to rotate cam 40 to its open position (FIG. 4). Front wall 68 extends just a little higher than the middle wall 66 to insure that it will engage cam arm 47 as the drawer is closed thereby insuring rotation of cam 40 back to its neutral position. To insure that rotation back to the neutral position is smooth, the third cam engaging surface, wall 64, is spaced behind wall 66 and engages the second cam arm 58 to initiate rotation. Once cam 40 reaches a certain point, front wall 68 insures complete return of cam 40 by engaging cam arm 47. Actually, wall 65 can be con sidered part of the rear cam engaging surface since it is thejuncture of

walls

64 and 66 which does most of the engaging of cam arm 58.

OPERATION Referring now to FIGS. 3 through 6 for a detailed discussion of the operation of the interlock, it is noted initially taht the cam 40 has two at rest positions, one of which is the neutral position illustrated in FIG. 3 with the associated drawer closed. In the neutralposition, the first cam arm 47 is positioned between

cam mingengaging walls

66 and 68 of the drawer catch 62. The other at rest position is the inverted or .drawer open position illustrated in FIG. 1 (cam member40b in which the cam is rotated approximately 120 to take up the slack in the stop ribbon 30. The cam is progressively movedbetween these positions by the opening and closing of the drawer and the interaction between the cam engaging walls of the drawer catch and the cam arms of. cam- 40.

With the drawer closed, the slack stop member 30 is guidably positioned between ribbon guides 54 and 54a of the member 40, and cam arm 47 is positioned between

walls

66 and 68 of catch 62 (FIG. 3). As the drawer is opened,as illustrated in FIG. 4, the drawer and catch 62 move in adirection indicated by arrow B junctions of

surfaces

51, 52 and 53 thereof (which are the cam member 40. As the drawer is more completely closed, wall 68 of drawer catch 62 contacts cam arm 4'7 of cam member 40 to complete the clockwise rotation of the cam back to its neutral position as the drawer is fully closed. This dual interaction of cam arm 58 with cam engaging wall 64 and cam arm 47 with cam engaging wall 68 produces smooth operation of the cam when the drawer is closed.

Installation of drawers 60 can be effected automatically regardless of what position an associated cam 40 is in. This installation is best understood by referring to FIG. 6 where it is seen that the cam is in the neutral or downward position and a drawer 60 is being initially inserted into the cabinet such that its associated catch progressively spaced from the center of rotation of cam 40) take up slack in the stop ribbon 31 smoothly. As thedrawer continues its outward motion, catch 62 will cause the cam to rotate sufficiently counterclockwise This results since the net reactive force of the taut ribbon 31 against cam 40 is directed above the center of rotation of the cam member. Detent 15 in bracket 12 also acts as insurance against cam 40 rotating inadvertently back to its drawer closedposition, because stand-off tip' 55 has to ride over detent 15 in order to move cam 40 between its two rest positions. The detent has a tapered leading edge which, as tip 55 reaches the detent, tends to snap the cam into the drawer open position (40b in FIG. 1).

With the stop ribbon held in the taut position, if a second drawer is pulled outwardly, the cam 40 associated therewith is restricted from rotating since the taut stop member 30 will not yield to permit rotation of the cam. The relatively elongated leading surface 51 oflip 50 will contact the taut stop member and prevent the movement of catch 62, since cam engaging wall 66 contacts the arm 47 of the blocked cam. Likewise, if one attempts to open two drawers simultaneously, the combined partial rotation of two cam members associated therewith will cause the stop member 30 to become taut. This, in turn, prevents further rotation of either of the cam members sufficiently to allow drawer catch 62 to clear cam arm 47.

As an opened drawer is closed in a direction indi- 62 is in an engaging position with the cam 40 for that catch. It is desired to position the cam arm 47 between the

cam engaging walls

66 and 68 of catch 62 as seen in FIG. 3. This is accomplished by the angled cam engaging surface 65 which, as the drawer is closed (moving in a direction indicated by arrow A), contacts the cam arm 47 as shown in FIG. 6.

As the drawer closes, the engaging surface defined by wall 64 and surface 65 rotates cam 40 in a clockwise direction such that the tab 45 of spring arm 44 contacts the guide wall 22 and deflects to provide spring tension against which the cam is rotated. As soon as the cam arm 47 clears the apex of surface 65, the spring action of arm 44 will snap cam 40 in a counterclockwise direction until the cam arm 47 strikes cam engagingwall 68 of catch 62 thereby capturing arm 47 between walls 66 and68. The drawer catch is positioned on the drawer and the bracket holding the cam members40 on the file cabinet such that this occurs at approximately the closed position of drawer 60.

In place of mounting the cam member on wall 11 integrally formed with guide member 20 and bracket 12 as shown inFIGS. 1 and 2, cam member 40 and the stop ribbon30 can be separately attached to a mounting bracket 70, shown in FIG. 10, by means of a separate cam mounting bracket 80 and stop ribbon mounting bracket 90. As seen in FIGS. 10 and 13, the stop ribbon bracket 90 includes upper and

lower walls

91 and 92 which include integrally formed U-shaped guide members 94 along outer edges thereof and which in clude inwardly directed guiding lands 95 which span'an open area between walls 91 and92. The bracket additionally includes an integral L-shaped section 96 joined to

walls

91 and 92 for mounting the bracket to a raised ridge-72 on bracket 70. Member 96 has a flange 97 which fits within the apertures 74 of bracket and an aperture 98 which permits a mounting screw 99 to be attached therethrough.

Bracket shown in FIG. 11 is a generally Z-shaped bracket having a mounting leg 82 with an aperture 83 therein that is aligned with aperture 98 in bracket when bracket 80 is fitted over bracket 90 as seen in FIG. 10. Bracket 80 includes a second leg 86 with an inwardly directed post 84 positioned thereon to hold cam member 40 by extending through theaperture in sleeve 42 of the cam member. This positions the cam in the central open area between guides 94 of bracket 90 such that the ribbon 31 is engaged by the rotatable cam in the same manner as discussed above.

It will be apparent to those skilled in the art that various modifications to the present invention can be made. For example, the cam design and guiding means for the stop member, as well as the mounting means for the cam and the stop member, can be varied without departing from the spirit of the present-invention as de-, fined in theappended claims.

The embodiments of the invention in which an exclusive property or privilege is claimedare defined as follows.

1. In a cabinet having at least two drawers, a drawer interlock for preventing the simultaneous opening of two drawers comprising:

a cam operably connected to the cabinet adjacent each drawer, said cam being movable between first and second positions and including at least a first cam arm extending therefrom into the path followed by an engaging means on a drawer when the drawer is opened;

engaging means on each of said drawers for engaging said first cam arm of said cam and for moving said cam from said first position to said second position as a drawer is opened, said engaging means disengaging said cam as said cam reaches said second position whereby said drawer is free to pass by said cam and open;

stop means mounted on said cabinet adjacent all of said cams, said stop means being movable between first and second positions, without itself effecting movement of other cams, when engaged by any one of said cams, each of said cams being blocked from movement from its said first position into its said secondposition when said stop means is in its said second position; said stop means in said second position being movable only back to said first position thereby preventing more than one of said cams being moved to their said second positions at any one time whereby only one drawer and engaging means can be moved past an associated cam and opened at any one time.

2. The drawer interlock as defined in claim 1 wherein said cam comprises an eccentric cam rotatably positioned on the cabinet.

3. The drawer interlock as defined in claim 2 wherein said cam includes asecond cam arm which moves into the line of travel of said engaging means after said engaging means has disengaged said cam as a drawer is opened whereby as the drawer is closed, said engaging means engages said second arm to rotate said cam in a direction toward said first position. i 4. The drawer interlock as defined in claim 3 wherein said cam engaging means includes first and second spaced cam-engaging members wherein said first camengaging member engages said first cam arm to rotate said cam from said first to second positions as a drawer is opened and said second cam arm as a drawer is closed to partially rotate said cam from said second to first positions, and said second cam engaging member engages said first cam arm to complete the rotation of said cam to said first position as a drawer is closed.

5. The drawer interlock as defined in claim 1 wherein said engaging means comprises a drawer catch including at least three cam engaging surfaces and said cam includes a second cam arm extending therefrom in spaced relationshp whereby one of said cam engaging surfaces contacts said first cam arm as a drawer is opened to rotate said cam to said second position, and whereby a second cam engaging surface contacts said second cam arm to partially rotate said cam in a direction toward said first position as a drawer is partially closed, and a third cam engaging surface contacts said first cam arm to finally rotate said cam into said first position as a drawer is closed.

6. The drawer interlock as defined in claim 5 wherein said cam further includes a spring arm extending therefrom and means fixedly positioned on the cabinet to engage said spring arm such that during installation of a drawer into the cabinet, said cam is rotated by said second cam engaging surface pushing against said first cam arm until said spring arm contacts said means fixed on the cabinet, and as the drawer is moved to a closed position, said second cam engaging surface clears said first cam arm and said spring arm rotates said cam in an opposite direction such that said first cam arm is captured between said first and third cam engaging surfaces.

7. A drawer interlock mechanism for cabinets and the like having a plurality of drawers, said mechanism comprising:

a flexible stop means mounted on a cabinet between two fixed points adjacent a plurality of drawers, said flexible stop means being movable between slack and taut positions;

a cam means movably mounted to a cabinet adjacent each drawer and adjacent said stop member;

cooperating means on said cam and said drawer cooperating to move said cam means into said flexible stop means when a drawer is moved from a closed position in the cabinet; said flexible stop means being dimensioned such that movement of one of said cam means into said flexible stop means takes up the slack in said flexible stop means and said flexible stop means restricts movement of additional cam means causing said cooperating means to act as a stop preventing movement of an additional drawer therepast.

8. The drawer interlock as defined in claim 7 wherein said cooperating means comprises a cam arm extending from said cam means, and a cam engaging member positioned on a drawer to engage said cam arm as a drawer is moved between closed and open positions.

9. The drawer interlock as defined in claim 7 wherein said cam means is movable by the opening of a drawer from a first position in which said stop member is slack,

to a second position in which said cam means deflects said stop member into a taut position and during the motion of said cam means from said first to second positions, said cam arm moves to allow said cam engaging member to clear said cam arm permitting the opening of said drawer.

10. The drawer interlock as defined in claim 9 wherein said cam means is eccentric and rotatably positioned in a cabinet and is rotated by the movement of said cam engaging member.

11. In a cabinet having at least two drawers, a drawer interlock for preventing the simultaneous opening of two drawers comprising:

a flexible ribbon positioned between two fixed points on the cabinet;

a catch positioned on each drawer; and

a cam operably positioned on the cabinet adjacent each drawer and adjacent said ribbon; said cam being movable between first and second positions, said cam engaging said flexible ribbon and taking up slack in said flexible ribbon between said fixed points when in said second position; said cam and said catch including first cooperating means which engage as a drawer is opened to move said cam from said first to said second position; said first cooperating means disengaging when said cam reaches said second position to allow said drawer catch and drawer to pass by said cam; said flexible ribbon having sufficient slack between said two fixed points to allow'one and only one of said cams to be moved into said second position whereby only one drawer in the cabinet can be opened at a time.

12. The drawer interlock as defined in claim 11 wherein said cam comprises an eccentric cam rotatably positioned on the cabinet and wherein said first cooperating means comprises a first cam arm extending from said cam and a first cam arm-engaging member on said catch to selectively contact said cam arm.

13. The drawer interlock as defined in claim 12 wherein said cam includes a second cam arm which moves into the line of travel of said first cam engaging member after said first cam engaging member has disengaged said cam as a drawer is opened whereby as the drawer is. closed, said first cam engaging member engages said second arm to rotate said cam in a direction toward'said first position. i i

14. The drawer interlock as defined in claim 13 wherein said catch includes a second cam-engaging member wherein said first cam-engaging member engages said first cam arm to rotate said cam from said first to second positions as a drawer is opened and said second cam arm as a drawer is closed to partially rotate said cam from said second to first positions, and said second cam engaging member engages said first cam arm to complete the rotation of said cam to said first position as a drawer is closed.

15. The drawer interlock as defined in claim 14 and further including guide means adjacent each cam and constraining said ribbon on either side of each of said cams whereby movement of said ribbon by said cam is localized deflection of said ribbon.

16. The drawer interlock as defined in claim 15 wherein said guide means comprises a bracket segmented into ribbon guiding channels between which are positioned a plurality of cam mounting locations.

17. Thedrawer interlock as defined in claim 11 wherein said drawer catch includes at least three camengaging surfaces and said cam is rotatably positioned on the cabinet and includes two cam arms extending therefrom in spaced relationship whereby one of said cam-engaging surfaces contacts a first one of said cam arms'as a drawer is opened to rotate said cam to said second position, and whereby a second cam-engaging surface contacts a second one of said cam arms to partially rotate said cam in a direction toward said first position as a drawer is partially closed, and a third camengaging surface contacts said first one of said cam arms to finally rotate said cam into said first position as a drawer is closed.

, 18, The drawer interlock as defined in claim 17 wherein said cam further includes a spring arm extending therefrom and means fixedly positioned on the cabinet to engage said spring arm such that during installation of a drawer into the cabinet, said cam is rotated by said second cam-engaging surface pushing against said first cam arm until said spring arm contacts said means fixed on the cabinet, and as the drawer is moved in a closed position, said second cam-engaging surface clears said fist cam arm and said spring arm rotates said cam. in an opposite direction such that said first cam arm is captured between said first and third camengaging surfaces.

19. The drawer interlock as defined in claim 15 wherein said cam includes a cam surface which progressively deflects said ribbon as said cam is rotated and a ribbon guide integrally formed therewith for holding said ribbon'in alignment with said cam as it is rotated.

20. The drawer interlock as defined in claim 19 and further including guide means positioned on the cabinet for permitting only a section of said ribbon to be deflected by the movement of a drawer.

21. The drawer interlock as defined in claim 11 wherein said ribbon includes take|up means to control the slack in said ribbon.

22. The drawer interlock as defined in claim 21 wherein said take-up means comprises a loop integrally formed in said ribbon.

23. The drawer interlock as defined in claim 21 wherein said take-up means comprises a leaf spring anchored at one end to said bracket and extending into biased contact with said ribbon.

24. The drawer interlock as defined in claim 21 wherein said ribbon is positioned in the cabinet in a generally straight line and is deflected in a direction generally perpendicular to the length of said ribbon.

25. The drawer interlock as defined in claim 16 wherein said bracket includesribbon supporting lands extending from an edge of each channel into said cam mounting locations in the direction of deflection of said ribbon by said cam.

26. The drawer interlock as defined in claim 25 wherein each cam mounting location of said mounting bracket includes a detent, and wherein each of said cams includes a deflectab le detent engaging member to contact said detent when said cam is in said second position to insure said cam remains in said second position until'the associated drawer is closed.

Claims

1. In a cabinet having at least two drawers, a drawer interlock for preventing the simultaneous opening of two drawers comprising: a cam operably connected to the cabinet adjacent each drawer, said cam being movable between first and second positions and including at least a first cam arm extending therefrom into the path followed by an engaging means on a drawer when the drawer is opened; engaging means on each of said drawers for engaging said first cam arm of said cam and for moving said cam from said first position to said second position as a drawer is opened, said engaging means disengaging said cam as said cam reaches said second position whereby said drawer is free to pass by said cam and open; stop means mounted on said cabinet adjacent all of said cams, said stop means being movable between first and second positions, without itself effecting movement of other cams, when engaged by any one of said cams, each of said cams being blocked from movement from its said first position into its said second position when said stop means is in its said second position; said stop means in said second position being movable only back to said first position thereby preventing more than one of said cams being moved to their said second positions at any one time whereby only one drawer and engaging means can be moved past an associated cam and opened at any one time.

3. The drawer interlock as defined in claim 2 wherein said cam includes a second cam arm which moves into the line of travel of said engaging means after said engaging means has disengaged said cam as a drawer is opened whereby as the drawer is closed, said engaging means engages said second arm to rotate said cam in a direction toward said first position.

4. The drawer interlock as defined in claim 3 wherein said cam engaging means includes first and second spaced cam-engaging members wherein said first cam-engaging member engages said fIrst cam arm to rotate said cam from said first to second positions as a drawer is opened and said second cam arm as a drawer is closed to partially rotate said cam from said second to first positions, and said second cam engaging member engages said first cam arm to complete the rotation of said cam to said first position as a drawer is closed.

7. A drawer interlock mechanism for cabinets and the like having a plurality of drawers, said mechanism comprising: a flexible stop means mounted on a cabinet between two fixed points adjacent a plurality of drawers, said flexible stop means being movable between slack and taut positions; a cam means movably mounted to a cabinet adjacent each drawer and adjacent said stop member; cooperating means on said cam and said drawer cooperating to move said cam means into said flexible stop means when a drawer is moved from a closed position in the cabinet; said flexible stop means being dimensioned such that movement of one of said cam means into said flexible stop means takes up the slack in said flexible stop means and said flexible stop means restricts movement of additional cam means causing said cooperating means to act as a stop preventing movement of an additional drawer therepast.

9. The drawer interlock as defined in claim 7 wherein said cam means is movable by the opening of a drawer from a first position in which said stop member is slack, to a second position in which said cam means deflects said stop member into a taut position and during the motion of said cam means from said first to second positions, said cam arm moves to allow said cam engaging member to clear said cam arm permitting the opening of said drawer.

11. In a cabinet having at least two drawers, a drawer interlock for preventing the simultaneous opening of two drawers comprising: a flexible ribbon positioned between two fixed points on the cabinet; a catch positioned on each drawer; and a cam operably positioned on the cabinet adjacent each drawer and adjacent said ribbon; said cam being movable between first and second positions, said cam engaging said flexible ribbon and taking up slack in said flexible ribbon between said fixed points when in said second position; Said cam and said catch including first cooperating means which engage as a drawer is opened to move said cam from said first to said second position; said first cooperating means disengaging when said cam reaches said second position to allow said drawer catch and drawer to pass by said cam; said flexible ribbon having sufficient slack between said two fixed points to allow one and only one of said cams to be moved into said second position whereby only one drawer in the cabinet can be opened at a time.

13. The drawer interlock as defined in claim 12 wherein said cam includes a second cam arm which moves into the line of travel of said first cam engaging member after said first cam engaging member has disengaged said cam as a drawer is opened whereby as the drawer is closed, said first cam engaging member engages said second arm to rotate said cam in a direction toward said first position.

17. The drawer interlock as defined in claim 11 wherein said drawer catch includes at least three cam-engaging surfaces and said cam is rotatably positioned on the cabinet and includes two cam arms extending therefrom in spaced relationship whereby one of said cam-engaging surfaces contacts a first one of said cam arms as a drawer is opened to rotate said cam to said second position, and whereby a second cam-engaging surface contacts a second one of said cam arms to partially rotate said cam in a direction toward said first position as a drawer is partially closed, and a third cam-engaging surface contacts said first one of said cam arms to finally rotate said cam into said first position as a drawer is closed.

18. The drawer interlock as defined in claim 17 wherein said cam further includes a spring arm extending therefrom and means fixedly positioned on the cabinet to engage said spring arm such that during installation of a drawer into the cabinet, said cam is rotated by said second cam-engaging surface pushing against said first cam arm until said spring arm contacts said means fixed on the cabinet, and as the drawer is moved in a closed position, said second cam-engaging surface clears said fist cam arm and said spring arm rotates said cam in an opposite direction such that said first cam arm is captured between said first and third cam-engaging surfaces.

19. The drawer interlock as defined in claim 15 wherein said cam includes a cam surface which progressively deflects said ribbon as said cam is rotated and a ribbon guide integrally formed therewith for holding said ribbon in alignment with said cam as it is rotated.

21. THe drawer interlock as defined in claim 11 wherein said ribbon includes take-up means to control the slack in said ribbon.

25. The drawer interlock as defined in claim 16 wherein said bracket includes ribbon supporting lands extending from an edge of each channel into said cam mounting locations in the direction of deflection of said ribbon by said cam.

26. The drawer interlock as defined in claim 25 wherein each cam mounting location of said mounting bracket includes a detent, and wherein each of said cams includes a deflectable detent engaging member to contact said detent when said cam is in said second position to insure said cam remains in said second position until the associated drawer is closed.