US3402578A

US3402578A - Pushbutton latch and lock mechanism

Info

Publication number: US3402578A
Application number: US614137A
Authority: US
Inventors: Wallace E Atkinson
Original assignee: Long Manufacturing Co Inc
Current assignee: Long Manufacturing Co Inc
Priority date: 1967-02-06
Filing date: 1967-02-06
Publication date: 1968-09-24
Anticipated expiration: 1985-09-24

Description

Sept. 24, 1968 w. E. ATKINSON PUSHBUTTON LATCH AND LOCK MECHANISM 3 Sheets-Sheet 1 Filed Feb. 6. 1967 INVENTOR WALLACE E-ArxmsoM p 1958 w. E. ATKINSON 3,402,578

PUSHBUTTON LATCH AND LOCK MECHANISM Filed Feb. 6, 1967 3 Sheets-Sheet 2 INVENTOR WALLACE E-ATK\NSON 7 BY masmgfmwwnu% mm,

7 ATTORNEYS Sept. 24, 1968 w. E. ATKINS-ON PUSHBUTTON LATCH AND LOCK MECHANISM 3 Sheets-Sheet 5 Filed Feb. 6, 1967 INVENTOR United States Patent 3,402,578 PUSHBUTTON LATCH AND LOCK MECHANISM Wallace E. Atkinson, Petershurg, Va., assignor to Long Manufacturing Company, Inc., Petersburg, Va., a corporation of Virginia Filed Feb. 6, 1967, Ser. No. 614,137 Claims. (Cl. 70-70) ABSTRACT OF THE DISCLOSURE A combined latch and lock for containers such as luggage and the like having a hook shaped keeper on one of the container parts and a pushbutton latch and lock mechanism on the other container part, the latch and lock mechanism including a rotatable and axially movable pushbutton having a radial flange provided with gear teeth formations and a tongue formation, a casing having a spherical lip portion outwardly bounding the pushbutton flange apertured at one angular position to receive the tongue and hold the pushbutton against rotation, a spring to bias the pushbutton outwardly to dispose the flange against the lip and to bias the pushbutton to rotate about its axis, a pivoted bolt member having gear teeth in driven engagement with the gear teeth formations of the pushbutton flange and having a latch formation to interlock with the keeper hook, and a key barrel and locking disk operable by a key to lock the pushbutton against inward movement which would release the tongue from the locking aperture of the casing lip portion, the spring being operative to drive the pushbutton in an angular direction to rotate the bolt so as to release the keeper when the locking disk is disposed in a selected position permitting inward axial movement of the pushbutton.

The present invention relates in general to a combined latch and lock structure especially adapted for application to containers or receptacles, such as luggage, having separable parts to be releasably secured in closed position, and more particularly to a combined latch and lock structure for luggage cases and similar containers having a cover section hinged to a body section, employing a rotatable and axially movable pushbutton member constructed and associated with a pivoted bolt lever to control latching and locking of the mechanism.

It has been the usual practice in the design and construction of combined latch and lock mechanisms for luggage cases and the like to provide a spring biased bolt on one of the separable container sections which is urged into latching relation with a keeper on the other separable case section whenever the sections are moved to closed relationship. Frequently, a movable finger piece of some sort, which is usually rectilinearly reciprocated or pivoted through an arc, is provided in such prior devices to permit the operator to overcome the spring bias and release the latch. When key locking facilities were as sociated with such latch and lock mechanisms, usually rather complex structural arrangements were required to achieve the desired locking or unlocking of the latch bolt. Such prior latch and lock mechanisms usually had a large number of parts that required a relatively high degree of skill to assemble and which frequently needed specialized machinery or mechanical jigs to assist assembly. Obviously, a reduction in the number of parts used in the manufacture of such prior structures would make possible a considerable cost saving and could improve the reliability of operation of the mechanism and its longevity in use.

An object of the present invention is the provision of a novel combined latch and lock structure, which is simple in construction, comprised of a relatively few parts,

3,402,578 Patented Sept. 24, 1968 ice and which is compact in arrangement, attractive in appearance, and reliable in operation.

Another object of the present invention is the provision of a combined latch and lock structure having a pivoted bolt lever for cooperation with a keeper, and a manually operable pushbutton member for controlling the bolt lever, which is shifted axially inwardly to effect release thereof, when the mechanism is in unlocked condition, and is then driven through an are by spring means within the lock mechanism to effect release of the keeper.

Another object of the present invention is the provision of a novel latch and lock structure having a pushbutton actuating member which is to be manually shifted axially and automatically rotates through an arc to effect release of the lock, wherein a novel structural arrangement is provided coacting with the pushbutton member to effect latching and unlatching and locking of the mechanism.

Another object of the present invention is the provision of a novel latch and lock mechanism having a manually operable pushbutton to be axially shifted for manipulation of the mechanism, together with a pivoted locking bolt directly geared to the pushbutton member, and a coil spring which effects rotation of the pushbutton member through an appropriate arc to drive the bolt lever to release position upon selected axial displacement of the pushbutton member.

Another object of the present invention is the provision of a combined latch and lock structure of the type described in the immediately preceding paragraph, wherein a novel key-locking mechanism is associated with a pushbutton member to effect locking and unlocking of the same.

Other objects, advantages, and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating the preferred embodycompanying drawings illustrating the preferred embodiment of the invention.

In the drawings:

FIGURE 1 is an exploded perspective view of the latch and lock mechanism embodying the present invention;

FIGURE 2 is a rear elevation view of the latch and lock mechanism assembled on adjoining fragmentary portions of a luggage case, viewed from inside the luggage;

FIGURE 3 is a vertical section view taken along the line 33 of FIGURE 2;

FIGURE 4 is a section view taken along the line 4-4 of FIGURE 3, with the front plate of the lock casing removed to illustrate the position of the internal mechanism contained therein with the mechanism in latched, but unlocked condition;

FIGURE 5 is a section view similar to FIGURE 4; illustrating the internal mechanism in latched but locked condition;

FIGURE 6 is another section view similar to FIGURE 4, illustrating the internal mechanism in unlatched condition; and

FIGURE 7 is a section view taken along the line 7--7 of FIGURE 4, illustrating the details of the key cylinder mechanism.

Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, the combined latch and lock structure of the present invention is indicated generally by the reference character 10, and comprises a latch portion 11 which may, for example, be mounted on a tray or body section 12 of a luggage case, and a keeper portion 13 which may be mounted on a separable cover section 14 of the luggage case. Such latch and keeper portions are usually mounted on the front wall of their respective receptacle sections, adjacent the plane of separation between the 3 receptacle body and cover, indicated by reference character 15.

The keeper portion 13 of the present invention, as illustrated in FIGURE 1 and shown in broken lines in FIGURES 4, 5, and 6, is an integral member fixed against the inner surface of the front wall portion of cover section 14, by any suitable means such as rivets or other fastening devices, and has a depending hook portion 16 which is inwardly offset from the plane of the front wall portion of the cover section to which it is attached, the hook portion 16 defining a laterally opening recess 17 bounded below by a latching shoulder 18.

The latch portion 11 comprises a mechanism housing 20 formed of a forwardly opening, box-like casing 21 and a front plate 22 collectively forming a closed box. The box-like casing 21 has a rear panel 23 bounded by top and

bottom walls

24, 25 and a pair of end walls 26, the latter having outwardly flaring, coplanar mounting flanges 27 integrally extending from the forwardmost edges of the end walls 26 and suitably apertured to receive mounting rivets or other suitable fastening means for securing the same against the inner surface of the front wall of the lower body section 12. The top wall 24 is interrupted to provide a keeper receiving opening 28, and both the top wall 24 and bottom wall 25 are provided with rectangular slots 29 therein to receive outwardly projecting tongues 30 on the perimeter of the front plate 22 for locating the front plate 22 in parallelism with the rear panel 23 at an intermedite location between the latter and the plane of the mounting flanges 27.

Located in the upper right-hand region of the casing 21, as viewed in FIGURE 4, is a pivoted bolt lever 31 having a latching tongue portion 32 normally projecting in an upwardly inclined direction through the opening 28 when the mechanism is in unlatched condition and the tray and cover sections of the luggage are separated from each other. The bolt lever 31 is suitably pivoted to the rear panel 23 of the casing 21, as by a rivet, pivot pin or other suitable pivot structure 33, and the working end portion of the bolt lever 31 below the tongue portion 32 includes a recess 34 of appropriate configuration to accommodate the nose of the hook portion 16 of keeper 13, below which is an integral projecting arm 35 to bear against the lower end of the keeped hook 16 for a purpose to be later described. The bolt lever 31 in the ortion thereof opposite the tongue 32 relative to the pivot pin 33 has a right angle shoulder formed by

surfaces

36 and 37 to nest against confronting surfaces of the top wall 24 and right end wall 26 as viewed in FIGURE 4 when the bolt lever 31 is in latched position as illustrated in FIG- URE 4. The lower edge of the bolt lever 31 is provided with a pair of gear teeth 38.

Immediately below the bolt lever 31 is a pushbutton member 40 of generally cylindrical configuration in the form of a rearwardly opening cup, having a circular front wall 41, a cylindrical sidewall 42 and an enlarged cylindrical flange 43 at the rearmost end thereof extending for a selected axial distance forwardly from the rearmost end and interrupted along an arcuate segment thereof by gear formations, taking the form, for example, of a pair of axially elongated recesses or troughs 44 adapted to selectively interfit with the gear teeth 38 and to permit a selected range of axial movement of pushbutton 40 while at least one of the gear teeth 38 is interfitted in the accommodating recess or trough 44. The pushbutton member 40 is supported for rotation about a selected fore and aft axis with the enlarged cylindrical flange portion 43 thereof located within the housing 20, by means of a rearwardly projecting cylindrical well 45 in the rear panel 23 of the casing 21 appropriately sized to receive and journal for rotation the cylindrical flange portion 43, and by a circular aperture 46 in the front panel 22 aligned concentrically with the well 45. The circular aperture 46 in the front panel 22 is bounded by a forwardly pressed spherical rim 47 or lip to rotatably accommodate the forwardmost portion of the enlarged cylindrical flange 43.

The pushbutton member 40 is normally spring biased to the forwardmost position illustrated in FIGURE 3 by means of a coil spring 48 located within the hollow bore 49 of the pushbutton member 40 with its forward end bearing against the front wall 41 of the pushbutton 40 and its rearward end portion nested within a cup or sleeve member 50 projecting forwardly from the rear wall of the well 45 into the bore 49 of the pushbutton 40 and fixed at its rear end to the rearmost wall of the well 45. The spherical lip 47 of the front plate 22, of course, limits the extent of forward movement which the pushbutton 40 can undergo in response to the coil spring 48. The two opposite ends of the coil spring 48 have a transverse terminal transition, indicated at 48, 48", the forwardmost of which is located between the two rearwardly projecting pins 51 lying within the circular path of the coil spring 48 and the rearwardmost transverse terminal transition 48" being located between pins 52, the sleeve member 50 projecting forwardly within the path of the spiral coils of spring 48. By reason of this location of the transverse terminal transitions of the coil springs 48 between the

holding pins

51 and 52, the respective ends of the coil spring 48 are effectively anchored in relatively immovable relation with respect to the adjacent portions of the pushbutton member 40 and rear panel 23 of the casing 21. The rearmost end portion of the cup member 50 may be fixed to the base wall of the well 45 in the rear panel 23, in any conventional fashion, or may be removably coupled thereto against relative rotation, as for example by providing diametrically elongated rearwardly projecting lugs 50 received in accommodating recesses in the rearmost wall of the well 45.

The pushbutton member 40, when in the forwardly or outwardly projected position illustrated in FIGURE 3 is normally held in the angular position illustrated in FIGURE 4 disposing the bolt lever 31 in the latched position by means of a radially outwardly projecting lug 53 located at a selected circumferential position in the forwardmost zone of the enlarged cylindrical flange 43, which is received in slot 54 in the rim portion 47 of the front plate 22 and is held by the bounding edges of the slot 54 to restrain the pushbutton 40 against rotation from the position shown in FIGURE 4 due to the outward or forward bias of the spring 48 continuously urging the pushbutton member 40 outwardly or to the front of the luggage case. At the angular position in which the pushbutton member 40 is held by the engagement of the lug 53 in the slot 54, one of the gear forming grooves 44 in the enlarged cylindrical flange 43 is located substantially directly above the center axis of the pushbutton 40 and through interengagement with one of the gear teeth 38 extending therein locates the bolt lever 31 in the latched position illustrated in FIGURE 4.

The pushbutton 40 is so assembled with the coil spring 48 as to place the coil spring 48 under torsional strain as well as axial strain whereby the coil spring 48 continuously biases the pushbutton 40 to rotate about its center axis in a counterclockwise direction as viewed in FIGURE 4, such movement being restrained by the location of the lug 53 in the slot 54. It will be apparent therefore, that if the operator pushes axially inwardly on the pushbutton 40 to a sufficient extent to shift the lug 53 inwardly or toward the rear panel 23 to a position released from held relation within the holding slot 54, the torsionally strained coil spring 48 will then rotate the pushbutton 40 in a counterclockwise direction and thereby rotate the bolt lever 31 in a clockwise direction through interengagement of the gear formation 44 with the gear teeth 38 to shift the bolt lever 31 to the released position illustrated in FIGURE 6. The uppermost surface of the leg 35 of bolt lever '31 bearing against the lower surface of the keeper hook 16 exerts an upward force on the keeper 13 for etl'ecting relative separation of the keeper 13 from the latch portion 11, this separating movement being assisted by a leaf spring 55 frictionally held within the casing 21 by suitable pins 56 and having an end portion bearing against the lower surface of the keeper hook 16. The axial length of the grooves or recesses 44 comprising the gear formations in the enlarged cylindrical flange 43 of the pushbutton 40 is of course sufiicient to maintain the gear teeth 38 located in the grooves 44 throughout the range of axial movement of the pushbutton 40.

To effect key locking of the mechanism in the latched position, a rotatable locking disc 58 is provided within the casing 21 alongside the periphery of the enlarged cylindrical flange 43 of the pushbutton 40, which is in the form of a truncated disc cut along a chord to produce a flat 59 along a circumferential portion thereof. The locking disc 58 is supported for rotation about its center axis against the rear panel 23, and, in the preferred embodiment illustrated, has a pair of restraining detents 60 at diametrically opposed positions along a diameter thereof adjacent the periphery of the disc to register with indentations or sockets 61 in the rear panel 23 and releasably restrain the disc 58 in the unlocking position illustrated in FIGURE 4, or at a locking position spaced 180 from the unlocking position illustrated in FIGURE 5. It will be noted from FIGURE 4 that when the locking disc 58 is in the unlocking position, the flat 59 is disposed alongside the path of the lug 53 on the pushbuttton 49, so that no portion of the locking disc 58 is in the path of axial movement of the lug 53 from the outwardly or forwardly projecting position to the inward or rearward, axially displaced position wherein the lug 53 is released from the slot 54. However, when the disc 58' is rotated through 180 to the locked position, disposing the diametrically opposite portion of the disc 58 rearwardly of the lug 53, the lug being relieved or terminated to receive the same, a portion of the locking disc 58, rearwardly underlies the lug 53 in the path of movement thereof from the outermost to the innermost positions of the pushbutton 40, to prevent such inward movement of the pushbutton 40 as would release the lug 53 from the front plate slot 54. Thus, the locking disc 58 when in the locking position prevents inward axial movement of the pushbutton 40' through a range which would effect release or unlatching of the lock. It will be appreciated that the uninterrupted flange portion of the disc 58 opposite the fiat 59 may be raised or otherwise specially deformed to bar inward axial displacement of the pushbutton 40, or the thickness or location of the disc 58 relative to the lug 53 may be closed so as to prevent inward releasing axial movement of the pushbutton member 40, a raised or thickened formation such as illustrated at 58a, being provided on the locking disc 58 in the herein illustrated embodiment. The locking disc 58, may be held against the rear panel 23 by a rotatable key barrel 62 having a conventional keyway therein, the rearmost end of which may 'butt against the center portion of the locking disc 58. In the example herein shown, the rearmost portion of the key barrel has a radially outwardly extending flange and the adjoining, somewhat smaller diameter portion of the barrel extends through an accommodating circular opening in the front plate 22, the bounding portion of this opening bearing against the front surface of the flange on the key barrel to restrain the key barrel against outward movement. If desired, a radial projection 63 may be provided at a point along the perimeter of the flange on the key barrel 62 and suitable inwardly struck abutments 64 may be formed on the front plate 22 in the path of this projection to limit location of the key barrel to 180. The rear wall of the key barrel may, if desired, have a rearwardly opening shallow cylindrical well to accommodate a raised cylindrical center portion of the locking disc 58 to journal the disc 58 for rotation about its center axis.

In the herein described embodiments, an ornamental front plate 65 is adapted to be secured to the outer or exterior surface of the front wall of the luggage body section 12 and is provided with a circular aperture 66 to receive the forward portion of the pushbutton 40, and a smaller circular aperture 67 to receive the forwardmost portion of the key barrel 62. If desired, a pair of inwardly projected mounting posts such, for example, as threaded bolts, may be provided at the transverse ends of the front cover plate 65, to project through the front wall of the luggage body portion 12 and through the apertures in the mounting flanges 27, to which threaded nuts or other fastening members may be aflixed inwardly of the mounting flanges 27 to affix the assembly to the luggage body section 12. It will be understood that these rearwardly projecting mounting posts may be in the form of rivets or any other conventional fastening means.

In the operation of the herein described latch and lock mechanism, the mechanism in the unlocked and unlatched condition is as illustrated in FIGURE 6, wherein the pushbutton member 40 is in axially inwardly displaced condition with the lug 53 circumferentially spaced from the front plate slot 54 and bearing against an uninterrupted portion of the front plate lip 47 which holds the pushbutton member 40 in the inwardly displaced position against the bias of the coil spring 48. With the pushbutton 49 in this angularly displaced position, the bolt lever 31 is in an inclined position disposing the latching tongue portion 32 in upwardly inclined relation projecting through the slot 28 to receive and become engaged with the recess 17 in the keeper hook portion 16 when the luggage cover section 14 is closed upon the luggage body section 12.

Upon movement of the luggage cover section 14 to closed position, the relative downward movement of the keeper hook portion 16 rotates the bolt lever 31 in a counterclockwise direction from the unlatched position upon interengagement of the keeper hook with the tongue portion 32 and leg 35 of the bolt lever 31, causing a correlated clockwise rotation of the pushbutton 40 through interengagement of the gear teeth 38 with the gear formations 44 until the lug 53 on the pushbutton 40 registers with the front plate slot 54. The coil spring 48 then drives the pushbutton 40 axially outwardly or to the front of the luggage, seating the lug 53 in the front plate slot 54 and thereby frictionally latching the pushbutton 49 and the bolt lever 31 in this latched position. If it is desired to lock the mechanism in this latched position, the key is then inserted in the key barrel 62 and rotated through to rotate an uninterrupted portion of the locking disc 58 beneath the pushbutton lug 53 to prevent axially inward releasing movement of the pushbutton 40. When the locking disk 58 is in the unlocked position illustrated in FIGURE 4, the lock mechanism can be manually released to unlatched condition simply by pressing inwardly on the pushbutton 40 a suflicient axial distance to dislodge the lung 53 from the front plate slot 54, whereupon the torsional strain of the coil spring 48 will rotate the pushbutton 40 in a counterclockwise direction and drive the bolt lever 31 to the unlatched or released position concurrently forcing the hook portion 16 of the keeper upwardly and outwardly from the lock casing 21.

While but one specific embodiment of the present invention has been shown, and described, it is apparent that various modifications may be made therein within the spirit and scope of the invention, and it is desired, therefore, only such limitations be placed on the invention as are imposed by the prior art and set forth in the appended claims.

What is claimed is:

1. A combined latch and lock adapted to be mounted on separable parts of a container adjacent a line of separation therebetween, comprising a keeper to be aflixed to one of the separable parts, a latching unit to be mounted on a surface of the other of said separable parts including a latch casing, a bolt lever pivoted in said casing for rotation between latching and release positions engageable with said keeper for latching the latter, a manually operable pushbutton for controlling movement of the bolt lever between latching and release positions, said pushbutton being supported for rotary movement and for axial movement beteween outer and inner axial limit positions, said pushbutton having first and second angular positions disposing said bolt lever at its latching and release positions respectively, holding means for restraining said pushbutton at said first angular position when the pushbutton occupies said outer limit position and being releasable therefrom upon inward axial displacement from said outer limit position, and spring means for rotating said pushbutton to said second angular position upon release thereof by said holding means.

2. A combined latch and lock adapted to be mounted on separable parts of a container adjacent a line of separation therebetween, comprising a keeper to be affixed to one of the separable parts, a latching unit to be mounted on a surface of the other of said separable parts including a latch casing having an access opening to removably receive a portion of the keeper in said casing when the separable parts are in closed position, an externally exposed pushbutton supported in said casing for rotary movement between first and second angular positions and for axial movement in a direciton generally perpendicular to said surface between outwardly projected and inwardly retracted limit positions, spring means resiliently biasing said pushbutton axially to said outwardly projected position and angularly to said second angular position, a bolt lever pivoted in said casing for rotation between latching and release positions relative to said keeper having interlocking formation engageable in latching relation to said keeper, means intercoupling said bolt lever with said pushbutton throughout the range of axial movement of the latter for transmitting rotary driving force therebetween, and abutment means releasably holding said pushbutton in said first angular position disposing said 'bolt lever in latching position when said pushbutton occupies its outwardly projected limit position and for releasing the pushbutton upon selected inward axial movement thereof permit rotation of the latter responsive to said spring means to said second angular position for driving said bolt lever to its release position.

3. A combined latch and lock as defined in claim 2, wherein said intercoupling means comprises interengaging gear teeth formations on said bolt lever and on said pushbutton providing a direct gear drive between said bolt lever and pushbutton.

4. A combined latch and lock as defined in claim 2, wherein said intercoupling means comprises interengaging gear teeth formations on said bolt lever and on said pushbutton providing a direct gear drive between said bolt lever and pushbutton, the gear formations on said pushbutton being axially elongated to be intercoupled with the gear teeth formations on said bolt lever throughout the range of axial movement of said pushbutton.

5. A combined latch and lock as defined in claim 4 wherein said casing includes a front plate having an opening passing said pushbutton therethrough and adjoining bounding wall means defining an annular restraining surface having an outwardly relieved interruption at a selected circumferential location therealong forming said abutment means, said pushbutton including a radial projection restrained in said interruption against rotation of said pushbutton from said first angular position when said pushbutton occupies said outward projected position, said radial projection being released from said interruption upon inward axial displacement of said pushbutton to free the latter for rotary movement and being engaged by said restraining surface when out of registry with said interruption to retain said pushbutton in said inwardly retracted position against outward axial movement while permitting rotation of the pushbutton responsive to said spring means.

6. A combined latch and lock as defined in claim 2 wherein said casing includes a front plate having an opening passing said pushbutton thcrethrough and adjoining bounding wall means defining an annular restraining surface having an outwardly relieved interruption at a selected circumferential location therealong forming said abutment means, said pushbutton including a radial projection restrained in said interruption against rotation of said pushbutton from said first angular position when said pushbutton occupies said outward projected position, said radial projection being released from said interruption upon inward axial displacement of said pushbutton to free the latter for rotary movement and being engaged by said restraining surface when out of registry with said interruption to retain said pushbutton in said inwardly retracted position against outward axial movement while permitting rotation of the pushbutton responsive to said spring means.

7. A combined latch and lock as defined in claim 6, including a key operable locking member supported in said casing alongside said pushbutton for movement between locking and unlocking positions, said locking member in said locking position disposing a portion thereof immediately inwardly of said radial projection when the latter occupies said first position to prevent inward axial displacement of said pushbutton through a range adequate to release said projection from said interruption, and said locking member being shaped to free said projection for inward axial movement and rotation of said pushbutton when said locking member occupies said unlocking position.

8. A combined latch and lock as defined in claim 5, including a key operable locking member supported in said casing alongside said pushbutton for movement between locking and unlocking positions, said locking member in said locking position disposing a portion thereof immediately inwardly of said radial projection when the latter occupies said first position to prevent inward axial displacement of said pushbutton through a range adequate to release said projection from said interruption, and said locking member being shaped to free said projection for inward axial movement and rotation of said pushbutton when said locking member occupies said unlocking position.

9. A combined latch and lock as defined in claim 8, wherein said locking member is a rotatable locking disc having a circular perimeter interrupted by a flat along a chord thereof, an uninterrupted portion of said perimeter being located in the path of inward axial movement of said projection when said disc occupies said locking position and said flat being disposed radially outwardly of the path of said projection when said disc occupies said unlocking position.

10. A combination latch and lock as defined in claim 2, wherein said spring means comprises a torsionally strained coil spring compressed between a stationary portion of said casing and a portion of said pushbutton and restrained at its opposite ends against rotation relative to said respective portions of said casing and pushbutton.

References Cited UNITED STATES PATENTS 2,221,095 11/ 1940 Jacobi 70-84 2,399,302 4/ 1946 Thiele 7070 2,426,754 9/1947 Thiele 70-70 2,624,191 l/1953 Boden 70-70 MARVIN A. CHAMPION, Primary Examiner.

E. I. McCARTHY, Assistant Examiner.