US3123685A

US3123685A - maier

Info

Publication number: US3123685A
Authority: US
Publication date: 1964-03-03
Anticipated expiration: 1981-03-03

Description

March 3, 1964 A. E. MAIER 3,123,685

FRONT OPERATED ENCLOSED SWITCHING APPARATUS Filed Oct. 5, 1959 2 Sheets-Sheet 1 I l g IN V EN TOR. l

ALFRED E. MAIER ATTORNEY A. E. MAIER March 3, 1964 FRONT OPERATED ENCLOSED SWITCHING APPARATUS 2 Sheets-Sheet 2 Filed Oct. 5, 1959 D E R F L A ATTORNEY United States Patent Ofi 3,123,685 Patented Mar. 3, 1964 ice 3,123,685 FRONT OPERATED ENCLOSED SWITCHING APPARATUS Alfred E. Maler, Colonia, N.J., assignor to Federal Paclfic Electric Company, a corporation of Delaware Filed Oct. 5, 1959, Ser. No. 844,578 Claims. (Cl. 20050) I This invention relates generally to front operated circuit breakers or switches and, more particularly, to enclosed front operated circuit breakers or switches having a twist handle supplied as a standardized unit which may be used with an enclosure having a front openable cover provided with an opening for the projection therethrough of the twist handle for accessibility for manual actuation, or with a front trim plate, or, if desired, without such enclosure or trim plate.

' One important object of the present invention is the provision of enclosed front operated circuit breakers or switches supplied as a standardized unit for installation without a cover interlock device in applications not requiring the same or for the ready convertibility of such unit to include a cover interlock device for applications requiring the same. Pursuant to this object of the present invention the standardized unit, as supplied, contains concealed interlock mechanism which is operational eX- cept for the latch member which is supplied as a separate component that is option-ally installable in the unit so that the latter may be used without such component in installations not requiring interlocking or with such component installed for installations requiring the same. A feature of the present invention is the unique and novel manner of engaging the latch member supplied as a separate component with the interlock mechanism contained in the standardized unit, said engagement requiring a simple deliberate plug-in operation of the latch member with the latter being locked against removal subsequent to such engagement. A further feature of the present invention, pursuant to one embodiment thereof, is the provision for installation of the optionally installable latch member :at either side of the unit so that in applica tions having a front openable cover the latter may be hinged at either side and interlocked at the opposite side. If desired, a latch member may be installed at both sides of the unit providing a dual interlock with an openable cover of the unit enclosure.

Another object of the present invention is the provision of an enclosed front operated circuit breaker or switch having a twist handle which projects through an opening in a front openable cover in which there is provided novel mechanism for selectively latching or locking the cover closed in one or more predetermined positions of such handle corresponding to the opened and closed condition of the circuit breaker. Pursuant to this object of the present invention, the front cover may be releasably latched or externally locked on the locking of the handle in either the opened or closed condition of the circuit breaker. A feature of such mechanism is the novel transmission of motion from the twist handle to the latch member in which the latter is given a relatively large angular stroke for a short twisting movement of the operating handle.

Another object and feature of the present invention is the provision of an enclosed front operated circuit breaker of the aforenoted character in which the cover latching mechanism and actuating handle are operatively interconnected so that the cover is latched closed in both the on and off positions of such handle and locked concomitantly with the locking of the handle, the handle in its unlocked position being movable to an open cover position to release the cover latch so that the cover may be opened. The cover latching mechanism may be defeated with the handle locked in either the on or off position for access to the interior of the enclosure, but this arrangement introduces a substantial safety factor in that the handle and the mechanism controlled thereby is locked in position notwithstanding cover latch defeat.

Yet another object of the present invention is the provision of generally improved latching mechanism for a front operated circuit breaker of the aforenoted character.

The illustrative embodiment of the invention, which has been outlined above as incorporating certain novel features forming part of the invention, is more fully described in the remainder of this specification, from which further novel features and objects and advantages will become apparent. :In the following description reference is made to the accompanying drawings forming part of this disclosure, in which drawings:

FIG. 1 is a front elevational view of an enclosed circuit breaker formed in accordance with the present invention with parts broken away to reveal the internal cover interlock structure, the handle being shown in the off position in solid lines and in the on and open cover positions in broken lines;

FIG. 2 is a side elevational view thereof with parts broken away to reveal internal structure of the breaker;

FIG. 3 is a detail view showing the cover latch interlocked with the latch member, said view being taken on the line 3-3 of FIG. 1;

KG. 4 is a perspective view of the latch member which is supplied as a separate component;

FIG. 4A is a fragmentary front view of the breaker cover plate with the operating handle removed illustrating locking member interlocking with a companion slot of the cover plate for handle locking;

FIG. 5 is a front elevational view of another embodiment of enclosed circuit breaker with the front cover plate and handle removed; and

FIG. 6 is a perspective view of the latch member provided for the embodiment of FIG. 5.

Referring to the drawings and, more particularly, to FIGS. 1-4 thereof, there is shown a front operated circuit breaker 10 which may be a single pole or multi-pole type, the latter type being exemplified in the illustrated embodiments. The circuit breaker or unit is suitably mounted in an enclosure or receptacle 1 2 having a front cover 14- which is hinged to said receptacle at one side thereof by hinges 16 so that the cover may be swung to open and closed positions. The cover is provided with an opening 18 which interfits with the peripheral flange 22 of the breaker cover plate 20 in the closed position of the cover to exclude foreign matter from the enclosure and to prevent insertion of a tampering tool. The cover may be releasably latched or locked closed in the manner to be described in detail hereinafter. The actuating handle 24 projects through the cover opening 18 and is of the front operated twist type being pivotally movable about an axis substantially perpendicular to the cover to on and off positions to correspondingly actuate the breaker. The handle is also movable a short distance beyond the off position shown in solid lines in FIG. 1 to the reset position shown in broken lines 24' in said figure for resetting the breaker after tripping, said resetting position -also coinciding with the open cover position of the illustrated embodiments. The handle 24 in all of its positions is disposed within the flange 22 and thus clears the cover so that the latter may be swung open, when unlatched, irrespective of handle position.

The circuit breaker comprises a casing 26 of molded insulating material which houses and supports the elements of the breaker mechanism, the casing 26 comp-rising a base 28 and cover 30 secured together in casing-defining relation. The particular circuit breaker mechanism illustrated and described herein is given by way of example only and any suitable breaker mechanism may be used. The circuit breaker is provided at each pole with stationary and movable main contacts 3 2 and 34, respectively and stationary and movable arcing contacts 32 and 34, respectively. Each of the contacts 34 is mounted on a contact block 36 and the arcing contact 34 is mounted on arcing block 38 having an arcing tip 40. The

blocks

36 and 38 are pivotally mounted on a movable contact member 42 by pivot pin 44. The arcing block 38 is biased downwardly to bias contact 34 into contacting relation with contact 32' by compression spring 46 seated in fitting 48 secured to the movable contact member. The nut 50 coacts with the movable contact member to form a stop for the arcing block on contact opening. Contact pressure for each of the contact blocks 36 is achieved by a compression spring 52 and the nut 54 forms a stop for limiting pivotal movement of said block on contact opening.

The movable contact member 42 is pivotally mounted in a companion frame 56 by pivot pin 58 for movement between circuit open and closed positions by the actuating mechanism indicated generally at 60. The movable contact members 42 are rigidly interconnected for conjoint movement by the insulated tie-bar '62 extending across all of the poles of the breaker. The breaker includes a suitable trip device (not shown) for effecting the automatic opening of the breaker in response to predetermined overload conditions. The actuating mechanism 60 is of the quick make and break type and includes an operating member 64 which is pivotally movable to actuate the movable contact members, said member having an upstanding flange or fitting 66 which interfits in companion slot 68 of the actuating plate 70. The breaker is trip-free so that it is operative automatically in response to predetermined abnormal circuit conditions irrespective of the position of the actuating handle. A further description of the breaker mechanism is considered unnecessary for an understanding of the present invention.

The actuating plate 70 is received in a recess 72 of cover 30 and is provided with an aperture 74 for the reception of complementary pin 76 of the handle actuating 7 plate 78, the latter being secured to the hub 80 of the handle 24 by screws 82. The cover plate 20 is provided with a downwardly extending peripheral flange 84 which interfits with the integral forwardly projecting part 86 of cover 30'. The cover plate 20' is suitably secured in position on the cover 30. The plate 20 is preferably of sheet metal construction and is provided with an aperture 88 for the mounting of the handle 24-, there being a spacer 9t interfitting in said aperture. The plate 78 is secured to the hub 80" of the handle by screws 82 which extend through companion apertures of said spacer and are received in threaded registered apertures 94 of said hub.. Thus the plate 78 serves to transmit motion from the handle to plate 70, the latter sliding in recess 72 on handle rotation. The recess 72 is dimensioned to provide requisite clearance for plate 70 for the range of movement thereof under the control of the handle. Thus the turning movement of the handle is effective to slide the plate 70 in recess 72 through the cooperation of aperture 74 and pin 76 to thereby actuate member 64 and the breaker mechanism to a corresponding position.

The operating handle. 24 may be locked in either the on or off position by either, or both, of two locking systems as described in detail in copending application Serial No. 844,577 filed October '5, 1959, now Patent No. 3,022,391, said application being assigned to the assignee herein. The handle hub is slotted to receive a rectilinearly movable locking member 96 which is spring biased'in an unlocking or handle-releasing direction by compression spring 9 8. The locking member 96 is movable from a handle-releasing position to an extended handle-locking position and in thisllatter position the locking member interlocks with a

companion slot

99 or 99" of cover plate .20 corresponding to the position of the handle 24 (FIG. 4A), there being

slots

99 and 99" corresponding to the on and oil handle positions, respectively as described in detail in the aforereferred to copending application. The locking member 96 may be actuated to, and locked in, handle-locking position by the key-operated lock 10%) or the dock ring 102 both of which are operatively associated with the locking member 96. The lock ring 102 is pivotally movable about pivot 104 from a handle-releasing position, as shown in FIG. 2, in which the lock ring is in flush relation with the hub of the handle to a handle-locking position in which the lock ring is angulanly' displaced from the hub. On the raising of the lock ring about pivot 104, the portion 106 of the lock ring engages the locking member to slide the latter into locking engagement with a registered cover plate slot to thereby lock the handle in position. The ring is padlocked in locking position by engaging one or more padlocks through the lock ring which blocks the return of the lock ring to handle-releasing position. Thus the common locking member 96 must be unlocked by both the lock and lock ring 102 to permit handle rotation to another position.

Enclosed between the cover plate 20 and cover 30 is cover interlock mechanism now to be described. Seated in recess 108 of the cover in superposed relation with plate 70 is an interlock plate 110 comprising a base part 112 and laterally spaced

legs

114 and 116 of diflerential length. The base part 112 has a depending flange 118 which extends into recess 72, as shown in FIG. 2, for cooperation with the terminal end 120 of plate 70 when the handle is rotated beyond the off position to the reset position 24' (FIG. 1) which is also the open cover position in the exemplified embodiment. The broken line position 24", shown in FIG. 1, is the on position of the handle. Accordingly when the handle is rotated to the open cover or reset position 24 theinterlock plate 110 is linearly advanced a short stroke adjacent to the shoulders 122 at the end of recess 108 through the cooperation of flange 118 and terminal end 120 of plate 70. The interlock plate is biased away from shoulders 122 and the open cover position by compression spring 124 which is seated in recess 126 of the cover and bears against flange 118. The interlock plate has a centrally disposed terminal end portion 128 which extends from the inclined portion 130 of leg 114, said end portion being biased by spring 124 towards the shoulder 132 of the recess portion 108 extending from recess 108. The end portion 128 engages said shoulder except when the interlock plate is actuated by the handle on movement thereof from the off? to the open cover position.

Communicating with the recess 108 and extending transversely thereof to the opposite sides of the cover 30 are a pair of

slots

134 and 134 which register with and open to the

elongated slots

136 and 136, respectively of the flanges 84. The slots 134 and 134' are closed by the cover plate 20 and the flange slots provide entrance to

slots

134 and 134'.for the latch member 138 at the sides of the breaker casing. The

slots

134 and 134 are adapted to receive a companion latch member138 through the

flange slots

136 and 136, respectively to condition the breaker for cover interlock. Each slot 134, 134' has projecting therein a stacked series of leaf springs 140 which are captured in recess 141, said springs having one end thereof mounted in slot 142 with the opposite end 7 being biased against the forward edge of recess 141 as shown at the right in FIG. 1 prior to the engagement of the latch member 138 in the slot. Each recess 141 extends from a slot 134, 134b'elow the level thereof.

The latch member 138 is constituted by a flat elongated plate symmetrical about the longitudinal and lateral axes and may be engaged in either

slot

134, 134 through their entrance slots in the flange 22. The latch member 133 is provided with a pair of aligned cutouts 144 centrally disposed at the opposite sides thereof. On insertion of a latch member in a slot 134, 134', an edge 147 thereof engages springs 140 which yield towards wall 146 of the slot until said springs snap over said edge into engagement in a cutout 144 (FIG. 1). In this engaged position of the latch member the latch portion 148 thereof overhangs the side of the breaker casing and the latch member is locked against disengagement from its slot because of the interengagement of the springs 140 with a shoulder 150 defined by the cutout 144. The inner end of the latch member disposed in the slot interfits with the T-shaped end portion 128 which is provided with laterally projecting parts 152. The latch member 138 is movable from the solid line latching position shown in FIG. 1 to the broken line unlatching position 138' on the turning movement of the handle to the open cover position 24'. More particularly, on such handle turning movement the inner end portion 154 of the latch member is engaged by a companion projecting part 152 of the interlock plate to rock the latch member about the fulcrum point 156 at the edge of the slot 134 to position 138'. The slot enlarges in width from the fulcrum or pivot point 156 to the interlock plate to provide the requisite clearance for the rocking or pivotal movement of the latch member. Similarly the

slots

134 and 134 enlarge in width adjacent the sides of the breaker at the flange slots to provide for latch member movement to the cover unlatched position 138. On return of the handle from the open cover position, the latch member will be returned to the cover latched position by spring 140. The symmetrical construction of the latch member 138 permits the same to be snap engaged in either

slot

134, 134 with either face up. It will be observed that the fulcrum point 156 of the latch member is substantially oifset from the longitudinal center thereof towards the interlock plate 110 so that a short turning movement of the handle and a correspondingly short stroke of the interlock plate results in a relatively large angular stroke of the latch portion 148. Expressed differently, the lever arm between the fulcrum point 156 and latch portion 148 is substantially longer than the lever arm between said fulcrum point and the inner end 154 of the latch member so that a short linear movement of the interlock plate produces a large angular movement of latch portion 148.

In the cover latched position of the latch portion 148, the latter interlocks with the cover latch 158 (FIG. 3) which is suitably secured to the cover 14 at the side opposite hinges 16. The cover latch 158 has a latch portion or shoulder 16! which interlocks with latch portion 148 in the closed position of the cover, and a cam edge 162 which engages said latch portion and rocks the same against springs 146 until said latch portion snaps over latch portion 168 on the closing of the cover. Thus on closing the cover the latter will be releasably latched closed by latch portion 148 of the latch member. The cover is conditioned for opening movement on the movement of the handle to the open cover position in which latch portion 148 is rocked to clear the cover latch. The handle may be locked in either the opened or closed condition of the circuit breaker as described above and on handle locking the cover will be concomitantly locked closed.

in order to provide for the release of the cover interlock for access to the enclosure in the handle locked condition, there is provided a rotatable interlock defeat member 164 which has a laterally extending portion 166 projecting into the slot 168 of leg 114 of the interlock plate (FIG. 1). The member 164 has a non-circular or hexagonal aperture for the reception of a complementary shaped actuating part 170 which is suitably journalled for rotation in the cover. The part 178 has a slotted stud 172 upstanding therefrom and extending through an opening 174 provided in the cover plate for access thereat. Thus the interlock defeat constituted by member 164 and part 178 may be rotated counter- 6 clockwise, in the direction of the arrow shown in FIG. 1 for actuating the interlock plate and releasing the cover interlock independent of the actuating handle. With the handle and mechanism controlled thereby locked in position notwithstanding cover latch defeat, a substantial safety factor is introduced.

The standardized circuit breaker unit, as supplied, thus contains concealed interlock mechanism which is complete and operational except for the latch member or members which are supplied as separate components that are optionally installable in the unit in the manner aforedescribed. In installations not requiring cover interlocking the unit will be used as supplied without installing a latch member. In installations requiring cover interlocking the latch member will be installed in the unit in the manner described above, the latch member being nonremovable subsequent to installation. A latch member may be installed in either side of the breaker unit or, if desired, on both sides thereof depending on the installation. The versatility and adaptability of the unit will be manifestly evident.

With reference to FIGS. 5 and 6, there is shown a modified form of standardized circuit breaker unit 10 which is similar to unit 10, differing therefrom in the respects to be described in detail below. While unit 10 has provision for latch member installation on either side thereof, unit 10' has provision for latch member installation on only one side thereof. The operating handle of the circuit breaker unit 10' has an actuating plate 78' which is operatively connected to the actuating plate 70' by the engagement of pin 76' in elongated slot 74'. As in the previous embodiment, on turning movement of the handle the plate 70 will be linearly reciprocated to correspondingly actuate the breaker mechanism coupled therewith. The plate 70 is cutaway as indicated at 180 to define a shoulder 182 which engages the latch member carrier 184 on reciprocation of said plate by the handle to the open cover position. The breaker casing is recessed as indicated at 186 for the reception of carrier 184 which is pivotally mounted on a post 188 formed integrally with the casing. The carrier 184 includes a lateral projection 1% upwardly offset to the level of the breaker casing, i.e., the inside of the cover plate (not shown), which is disposed for engagement by shoulder 182 on reciprocation of plate 71) to the open cover position. The carrier 184 also includes upstanding side flanges 192 and 192' which are adapted for the engagement of a companion latch member 184 therebetween.

Communicating with the recess 186 and laterally extending therefrom is a recess 196 seating a compression spring 1% which surrounds the pin 280, the latter having a collar 282 against which one end of the spring seats. The pin 2% has an end 284 of reduced diameter which extends through an opening 206 in side flange 192 into the channel 208 defined between the flanges 192 and 192'. The recess 186 increases in width towards the side 218 of the casing, opening thereat, and it will be understood that such casing has a cover plate secured thereto, corresponding to the cover plate 20 previously described, the cover plate flange at side 210 having an elongated slot corresponding to slot 136 or 136 in registry with the open end of recess 186. Screws 212 secure the cover plate and casing in assembled relation.

The latch member 194 has a rounded or cam-shaped end 214 and an opposite pair of aligned side slots 216 spaced from said rounded end, the opposite end portion 218 defining a latch portion corresponding to latch portion 148 of the previous embodiment. The latch member 194 is interlockably engageable with the carrier 184 and this engagement is achieved by inserting the latch member into channel 208 through the slot of the cover plate flange with the rounded end 214 forward until the end 284 of pin 200 snaps into engagement with a companion slot 216 as shown in FIG. 5. The rounded end 214 cams end 204 out of the path of movement of the latch member against the action of spring 198 until said terminal end snap engages in companion slot 216. The spring 198 biases the carrier and engaged latch member assembly in a counterclockwise direction, viewing FIG. 5, into engageinent with the side edge portion 220 of the recess 186. The latch member 194 is engageable with the carrier 184 with either face up and end 214 forward as the latch member is symmetrical with respect to the longitudinal axis thereof. The latch member, once engaged, is locked against disengagement from the carrier by the interlocking between

parts

204 and 216.

The carrier and latch member assembly are pivotally movable about pivot or post 188 from the cover latched position shown in solid lines in FIG. in which the latch portion 218 interlocks with the cover latch 158 in the manner previously described to the cover released position 218 shown in broken lines in said figure in which the latch member is moved in the plane thereof to clear the cover-latch, on the turning movement of the operating handle to the open cover position in which the pin and slot assume positions 76" and 74", respectively, said handle turning movement sliding plate 70 in the direction of the arrow to rock the latch member in the direction of its arrow through the engagement of shoulder 182 and part 190. On the return movement of the handle away from the open cover position the spring 19? returns the carrier and latch member assembly to the cover latched position. The pivot axis of the latch member and carrier assembly is offset from the longitudinal center thereof relatively remote from the latch portion 218 thereof so that a short stroke of the plate 70' and a narrow turning movement of the handle results in a large angular stroke of said latch portion, in the manner of the previous embodiment. More particularly, the lever arm between the pivot axis and part 190 is substantially shorter than the lever arm between said pivot axis and the latch portion 218., The manner of handle locking and concomitant cover locking corresponds to the previous embodiment. Similarly the manner of cover interlock defeat corresponds to the previous embodiment, said interlock defeat being constituted by member 164 and part 170 which are rotatable as a unit counterclockwise (FIG. 5) to engage the laterally projecting fiange 193 of the carrier 184 and thereby rotate the latch member and carrier assembly to the cover released position; The interlock defeat unit is limited in its rotation in the opposite direction by stop post 222 upstanding from the breaker casing. Thus breaker unit 10 possess the advantageous features and characteristics of unit 10 as well as the versatility and adaptability thereof except that unit 10 has provision for latch member installation on only one side thereof.

The mechanisms described achieve the desirable functions of the widely used comparable mechanism in which a twist or rotary handle is carried by the cover of an enclosure, but has many further advantages some of which are noted above. When the cover or door of the enclosure is opened, there is no risk of misalignment de- 7 veloping here because the handle and the handle lock remain permanently identified with the circuit breaker. Further, release of the cover for access here does not require unlocking of the operating handle when in the oifposition (as in the case of door-carried handles) so the defeat of this cover interlock with the handle in the off position is safely aiforded: the cover latch is here defeatable both in the on and the off positions of the handle, and if the handle is locked in its oif posi: tion, it remains off even after the coverris opened.

Problems of critical adjustment and misalignment that characterized heretofore widely used cover-carried handle mechanisms are completely avoided as to the relationship between the handle and the circuit breaker which here carries the handle as an integral part. Additionally the mechanical advantage available between the handle and the latch in each embodiment renders the cover interlock non-critical.

Provision of the latch in FIG. 1 at either or both sides is of special advantage where the door of the enclosure may need to be hinged at either side. Latches at both sides will safely look a panel that is not hinged to the flanged opening, since the panel cut-out is centered around rib or flange 22 and cannot be lifted away from that flange.

Various additional modifications of the above embodiments of the invention will readily occur to those skilled in the art, and therefore the invention should be broadly construed in accordance with its full spirit and scope.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An enclosed switching device having a front operated handle mounted thereon and turnable to a plurality of different positions for correspondingly actuating the switching mechanism, said device having cover interlock mechanism including a latch part operable by said handle between latching and released positions, said latch part having a laterally open notch at one side thereof, said device having a guide recess for said latch part open to the side of the device, and spring means disposed in said recess and biased toward and engaged in said latch part notch for biasing said latch part in said latching position and providing for the non-releasable engagement of said latch part in said device.

2. An enclosed switching device having a switching mechanism, a front-operated twist handle mounted thereon and turnable to a plurality of diiferent positions for correspondingly actuating the switching mechanism, said device having means defining an internal passage that opens to the exterior of the switching device for admitting part of a cover latch that may be inserted while providing for external extension of a projecting part of such latch, an internal actuating mechanism in said device coupled to said handle and operable under control of said handle between latch and release configurations in co-ordination with said switching mechanism, said actuating mechanism having a movable element adjacent said passage for driving a latch, when inserted, from one of said configurations to the other, said switching device also having resilient latch-retention means mounted adjacent and extending into said passage and concealed within the switching device, said latch-retention means acting laterally in the direction toward the space in the passage provided for a latch.

3. An enclosed switching device having a switching mechanism, a front-operated twist handle mounted thereon and turnable to a plurality of different positions for correspondingly actuating the switching mechanism, said device having means defining an external opening and defining an elongated internal passage extending from said opening for admitting a shouldered part of an elongated cover latch that may be inserted therein while providing for external extension of a projecting part of such latch,

an internal actuating mechanism in saiddevice coupled to said handle and operable under control of said handle between latch and release configurations in co-ordination with said switching mechanism, said actuating mechanism having an element adjacent said elongated internal passage and movable transversely of said elongated internal passage for driving the aforementioned latch, when inserted, from one of said configurations to the other, said switching device also having a spring detent laterally adjacent and extending into said elongated passage and concealed within said switching device and acting transverse of the passage toward the space in the passage provided for such cover latch for engaging a shoulder of the aforementioned latch when inserted and for thereby retaining such latch, said spring detent also being disposed in relation to said passage'for biasing the aforementioned latch,

when inserted, to return fromjsaid other configuration to said one configuration.

4. A switching device in accordance with claim 3 wherein said spring detent is in the form of a leaf-spring having a fixed portion, said leaf-spring extending from said fixed portion along said passage and slantwise toward said passage and having a portion remote from said fixed end that is disposed in said passage in the absence of a latch, whereby the leaf-spring may engage the aforementioned shoulder of the aforementioned latch, when inserted, to retain the latch and to provide resilient bias in a direction transverse to said passage.

5. A switching device in accordance with claim 3 wherein said element adjacent said elongated internal passage has upstanding side flanges to engage opposite lateral edges of the aforementioned latch, and wherein said spring detent includes a pin and a compression spring surrounding and biasing the pin transverseiy of and into the space between said flanges.

References Cited in the file of this patent UNITED STATES PATENTS Rowe June 20, Rowe Sept, 23, Smith June 15, Santangelo Apr. 29, Wills Sept. 11, Cole Oct. 6,

FOREIGN PATENTS Germany Apr. 11,

Claims

2. AN ENCLOSED SWITCHING DEVICE HAVING A SWITCHING MECHANISM, A FRONT-OPERATED TWIST HANDLE MOUNTED THEREON AND TURNABLE TO A PLURALITY OF DIFFERENT POSITIONS FOR CORRESPONDINGLY ACTUATING THE SWITCHING MECHANISM, SAID DEVICE HAVING MEANS DEFINING AN INTERNAL PASSAGE THAT OPENS TO THE EXTERIOR OF THE SWITCHING DEVICE FOR ADMITTING PART OF A COVER LATCH THAT MAY BE INSERTED WHILE PROVIDING FOR EXTERNAL EXTENSION OF A PROJECTING PART OF SUCH LATCH, AN INTERNAL ACTUATING MECHANISM IN SAID DEVICE COUPLED TO SAID HANDLE AND OPERABLE UNDER CONTROL OF SAID HANDLE BETWEEN "LATCH" AND "RELEASE" CONFIGURATIONS IN CO-ORDINATION WITH SAID SWITCHING MECHANISM, SAID ACTUATING MECHANISM HAVING A MOVABLE ELEMENT ADJACENT SAID PASSAGE FOR DRIVING A LATCH, WHEN INSERTED, FROM ONE OF SAID CONFIGURATIONS TO THE OTHER, SAID SWITCHING DEVICE ALSO HAVING RESILIENT LATCH-RETENTION MEANS MOUNTED ADJACENT AND EXTENDING INTO SAID PASSAGE AND CONCEALED WITHIN THE SWITCHING DEVICE, SAID LATCH-RETENTION MEANS ACTING LATERALLY IN THE DIRECTION TOWARD THE SPACE IN THE PASSAGE PROVIDED FOR A LATCH.