US1873426A - Electrical apparatus - Google Patents

Description

Aug. 23, 1932. R. H. KINGDON ELECTRICAL APPARATUS Filed June 30, 1930 -15 Sheets-Sheet l Aug. 23, 1932- .R H. KINGDON ELECTRICAL APPARATUS Filed June 30, 1930 3 Sheets-Sheet 2 4 AU? m M/LM' I W' Aug. 23,1932. R. H. KINGDON 1,873,426

ELECTRICAL APPARATUS Filed June 30, 1930 I5 Sheets-Sheet 3 Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE RALPH H. KINGDON, OI DETROIT, MICHIGAN, ABSIGNOR '10 SQUARE D COMPANY, 01'

DETROIT, MICHIGAN, A CORPORATION 01' MICHIGAN nmo'rmoar. arrmrus Application and June so,

In certain t pes of electrical apparatus it is necessary, mm the standpoint of safet to provide casings or housings for the switc ing mechanism, fuses and the like. ThlS 1s particularly true in the case of switches for controlling main line lightin and power clrcuits and the like. In such installations the switching mechanism itself is frequently encased so that it is entirely inaccessible but it is essential that the fuses be so positioned that access may be had thereto for renewals and replacements.

Accordin ly, the casing or housing for a fused switc of this character is normally provided with a door which may be opened to ermit access to the fuse compartment. As a fleature of safety, however, the fuses are disposed on the load side of the switch so that no electrical potential is applied thereto when the switch is open. Consequently, if the door to the fuse compartment be so interlocked with the switching mechanism that the door cannot be opened except when the switch is open, and the switch cannot be closed except when the door is closed, there is no possibility of the potential being applied to the conducting parts within the fuse compartment while the door for said compartment is open.

The primary object of this invention is to 3 provide an a paratus of the above-indicated character emgodying an improved type of interlocking mechanism for accomplis ing the results specified.

Other obi'ects and advantages of the inventi on wi] appear from a consideration of the followin detailed description in connection with t e accompanying drawings, in which:

Figure 1 is a side elevational view of an encased fused electrical switch embodying the 1980. Serial No. 484,731.

present invention, showing the switching mechanism thereof in closed position;

Fig. 2 is a side elevational view similar to Fig. 1 in every respect, except that the switchingmechanism is shown inopen position;

ig. 3 is a front elevationa view of the device shown in Figs. 1 and 2, with certain parts broken away to show some of the operatin mechanism more clearly, the switching mec anism being shown in this instance also in closed position; I

Fig. 4 1s a bottom plan view of the device shown in Fig. 3;

Fig. 5 is a fragmentary front elevational view showing certain of the switch operating and interloc ing mechanism in the positions correspondin to the open position of the switch and t e unlatched condition of the door for the fuse compartment, all of which will appear more clearly hereinafter;

Fig. 6 is a fragmentary vertical sectional view taken on the line 6-6 of Fig. 3; and

Fig. 7 is a fragmentary vertical sectional view taken on the line 7--7 of Fig. 3.

Referring to the drawings, the electrical apparatus specifically disclosed herein comprises a casing constituted in part by two metallic side members 11 which are of channel formation, with the flanges thereof extending inwardly, as best illustrated in Fig. 4. The front of the casing is constituted by a metal panel 12 which is suitably secured to the forward flanges of the channel members 11, as by screws 13. The upper portion of this front panel 12 of the casing includes a door 14 mounted on hinges 15 at the top thereof. Within the upper portion of the casing, behind the door 14, are located an upper group of fuse terminal clamps 16, and a corresponding lower group 17 of similar clamps. In the drawings, three of these clamps are shown in each of the two groups, it being understood that provision is thus made'for the reception of a fuse in each wire of the circuit to be controlled by the apparatus.

The upper group of fuse terminal clamps 16 is mounted upon an insulating base member 18 that is secured to the rearward flanges of the side casing members 11 by means of metal straps 19. The base member 18 is secured to these straps in any suitable manner, and the straps are likewise suitably secured to the side casing members, as, for example, by screws 20. Each of the fuse terminal clamps 16 is )rovided with a terminal portion 21 where y the load circuit conductors may be secured thereto, the upper wall of the switch housing or casing being left partly or entirely open to permit the entrance of such conductors into the casing.

The lower fuse terminal clamps 17 are individually mounted on another insulating base member 22 that is suitably secured to metal straps 23, as by screws 23a, shown in Fig. 6. The latter straps are secured to the rearward flanges of the side portions 11 of the casing in any suitable manner, as by screws 24. The base member 22 is thus held in position at the rear of the casing in the same manner that the base member 18 is held in a similar posi-' tion. In this manner the two base members 18 and 22 constitute an interrupted rear wall for the casing.

A conducting and switch terminal member 25 is connected to each of the lower fuse terminal clamps 17 and extends downwardly therefrom a short distance. These members 25 are then bent to extend forwardly and again to extend downwardly whereby downwardly extending portions 25a are provided in spaced relation to the rear of the casing. These portions 25a constitute one set of terminals for the switching mechanism of the apparatus. The latter mechanism comprises a plurality of resilient movable contact members 26 which are carried in insulated relation upon a shaft 27 that is pivotally mounted in the side walls 11 of the casing. The movable contact members 26 have portions extending both upwardly and downwardly from the point of support upon the shaft 27, and it is the upper portions which are adapted to contact with the fixed contact portions 25a. The lower portions of the movable contact members 26 are similarly adapted to contact with flat fixed contact members 28 which are secured on the front face of the insulating base member 22. A terminal member 29 is suitably secured to each of the fixed contact members 28 to facilitate the connection of the main line conductors to the switching apparatus.

The movable contact members 26 of the switching mechanism are adapted to be actuated between circuit closing and circuit opening positions by pivotal movement of the shaft 27, upon which said contact members are mounted. For the purpose of effecting such pivotal movement, a lever or crank arm 30 is secured to the shaft 27 near each extremity thereof and just outside the side walls 11 of the casing. The other extremity of each of these levers or crank arms 30 is pivot-ally connected to the outer extremity of a toggle link 31, the other extremity of which is pivotally connected to one end of another toggle link 32 and also to one end of an actuating link 33. The outer extremity of the second toggle link 32 is pivoted upon a fixed stud 34 carried by the adjacent side wall 11 of the casing.

The other extremity of each of the actuating links 33 is provided with an elongated slot 33a, within which a pin 35 is freely slidable. This pin is carried by a plate member 36 which is freely pivoted on a fixed stud 37 carried by the adjacent side wall 11 of the casing. Each of the plate members 36 is notched, as indicated at 360, to receive the rounded extremity of a crank or lever member 38, one of which is secured to each extremity of a shaft 39 that extends transversely of the casing at the front thereof. The shaft 39 is adapted to be turned in response to manual operation of a handle member 40 which is'connected to said shaft, subject to the control of certain interlocking mechanism to be described hereinafter.

A compression spring 41 is mounted on the inner surface of each of the side walls 11 of the casing, and is adapted to provide a desired snap action for the switching mechanism. One end of each of the springs 41 abuts against a bracket member 42 that is pivotally carried at the outer extremity of a lever or crank arm 43 secured to the movable contact carrying shaft 27. The other extremity of each of the springs 41 abuts against an outstanding portion of a. bracket 44 that is secured to the inner surface of the corresponding side wall 11 of the casing. This outstanding portion of each of the brackets 44 is apertured to receive a guiding rod 45 in freely slidable relation- This rod 45 is secured to the corresponding pivoted bracket member 42 and extends therefrom coaxiall with the spring 41 to prevent such spring rom getting out of alignment.

From this construction it will be seen that the two compression springs 41 constantly urge the free extremities of the levers or crank arms 43 downwardly so that the movable contact carrying shaft 27 is constantly urged to rotate in a counterclockwise direction, as viewed in Figs. 1 and 2. hen the switching mechanism is in its closed position, as shown in Fig. 1, it will be seen that the toggle mechanism constituted by the links 31 and 32 has moved past the center position and that the said links abut against a fixed stud 46 that is secured to the corresponding side wall 11 of the casing. Thus the lever or crank arm 30 is prevented from rotating in a counterclockwise direction, and

' the shaft 27 is similarly heldagainst such rotation. This means that the movable contact members 26 of the switching mechanism are securely held in circuit-closing osition until the toggle constituted by the links 31 and 32is broken by retraction of the actuating link 33 in an upward direction, as shown in Fig. 1.

Such actuation may be accomplished by rotating the handle member 40 outwardly and downwardly about the transverse shaft 39 in such manner that the rounded free extremities of the levers or crank arms 38 are brought intocontact with the notches 36a in the plates 36. Upon actuation of the mechanism in this manner the plates 36 are rotated in a counterclockwise direction about their fixed pivots 37, and after a predetermined amount of such movement the pin 35 that is secured to each of said plates comes into contact with the upper extremity of the elongated slot 33a in the correspon ing actuating link 33. Further movement of the plates 36 under the influence of the levers or crank arms 38 causes the pins 35 to move the links 33 upwardly, and thus to draw the middle pivots of the toggle mechanisms also upwardly.

As soon as these pivots pass the central position the springs 41, which are considerably compressed, cause the contact carrying shaft 27 to be actuated in a counterclockwise direction with a snap action, whereby the movable contact members 26 are rapidly actuated out of engagement with the fixed contact members 25a and 28. It is during this movement that the elon gated slots 33a fulfill their function, which is to permit the switching mechanism to be actuated rapidly in the manner described without transmitting the snap action to thehandle member 40. The lost motion between each of the actuating links 33 and the corresponding plate 36, which is provided by the pin and slot connection, permits the free actuation of the switching mechanism in the manner described.

Fig. 2 illustrates the parts of the switch and actuating mechanism in the positions which are assumed after the switch has been opened, as above set forth. The toggle constituted by the links 31 and 32 at each side of the casing is then broken in the manner shown, and the movable contact members 26 of the switching mechanism are actuated a substantial distance away from the cooperating fixed contact members 25a and 28, so that the circuit connection between said fixed contact members is broken. Under these conditions the handle member 40 occupies the position shown against the front wall of the casing near the lower portion thereof, and the levers or crank arms 38 extend upwardly from the transverse shaft 39. The corre- 'will be en aged by the rounded extremities of the cran arms 38 when the handle member 40 is rotated outwardly and upwardlyabout the transverse shaft 39.

When the plates 36 are thus engaged they are rotated in a clockwise direction about their fixed pivots 37 with the result that the pins 35 engage the lower extremities of the slots 33a in the toggle actuatinglinks 33, thereby forcin the middle pivot of each of the toggle mec anisms downwardly and effecting a corresponding clockwise rotation of the levers or crank arms 30 which are secured to the extremities of the contact carrying shaft 27. This shaft is, therefore, rotated in a clockwise direction, as viewed in Figs. 1 and 2, against the force of the compression springs 41.

After a predetermined extent of such actuation the extremities ofthe resilient movable contact members 26 come into contact with the corresponding fixed contact members 25a and 28, and are firmly forced thereagainst. The middle pivot of each of the toggle mechanisms constituted by the links 31 and 32 is then brought to its center position and a slight further movement in the same direction results in the springs 41 forcing the toggle links against the fixed studs 46, with the switching mechanism in its closed position, as shown in Fig. 1. v

Having now described the general construction of the apparatus shown in the drawings, as well as the details of construction and operation of the'switch operating mechanism,

reference will now be had to the interlocking mechanism heretofore mentioned. As best shown in Figs. 3 and 5, the handle member 40 is secured at its respective extremities to two lever arms 47 which are apertured at their inner extremities to permit the extension of the transverse shaft 39 therethrough in freely rotatable relation.

A brace member 48 is also secured at its respective extremities to the two lever arms 47 to maintain the same securely in their properly spaced relation. The transverse shaft 39 is of substantially octagonal or other polygonal cross-section, but the apertures in the inner extremities of the handle levers 47 are not made to conform to this cross section, said apertures being round and of sufiicient size to permit free relative rotation between the shaft 39 and the handle levers 47.

A collar member 49 is disposed on the trans verse shaft 39 and is fitted to said shaft in freely slidable relation. Another collar member 50 is disposed on the transverse shaft 39 and comprises a bar portion 50a connecting two portions 506 and 500 of said member, which latter two portions are located on opposite sides of the collar member 49. The connecting bar portion 500 lies in closely fitting relation to a longitudinal slot in the collar member 49 whereby relative rotation of the members 49 and 50 is prevented. The portions 50?) and 500 of the member 50 are disposed in relatively closely spaced relation to the opposite ends of the collar member 49 whereby lateral movement between the members 49 and 50 along the transverse shaft 39 is also prevented.

The portions 50?) and 500 of the member 50 are formed around the transverse shaft 39, but need not be closely fitted thereto, except insofar as is necessary to provide suitable bearing surface for the sliding movement of the member 50 along the shaft 39. The portion 50?) of the member 50 is connected through a bar portion 50d to an end portion 506' which also surrounds the shaft 39 in I collar-like relation. The aperture in the end member 506, however, is made to conform closely to the periphery of the shaft 39 so that relative rotation between the portion 506 and the shaft 39 is prevented. The portion 500 of the member 50 is similarly connected through a bar portion 50f to an end member 50g which is apertured in the same manner as the end portion 506 to prevent relative rotation between said portion and the shaft 39. It will be noted that the end portions 50c and 509 are respectively located to the right of the two handle levers 47, as shown in Fig. 3. In order to provide this arrangement it is necessary that the connecting bar portion 50 extend across the inner extremity of the right-hand handle lever 47, and it will be understood that this portion 50f is spaced outwardly from the shaft 39 a suflicient distance to clear this portion of said righthand handle lever.

The end portion 506 of the member 50 isv provided with an integral portion that is bent at substantially right angles to form an engaging finger portion 50h which extends to the left from the end portion 506, as viewed in Fig. 3. The left-hand handle lever 47 is apertured to receive the engaging finger portion'50h in relatively closely fitting but slidable relation, so that, when the parts occupy the positions shown in Fig. 3, relative rotation between the handle levers 47 and the transverse shaft 39 is prevented. The opposite end portion 509 of the member 50 is similarly provided with an engaging finger portion 502' which is bent to extend to the left and to enter a corresponding opening in the right-hand handle lever 47.

Thus, both of the handle levers 47 may'be locked against rotation with respect to the transverse shaft 39 when the fingers 5011. and 502' enter the corresponding openings in the two handle levers, it being remembered that the end portions 50c and 50g, with which the engaging finger portions 50k and 502', respectively, are integral, are fitted to the octagonal or other nonround cross section of the shaft 39.

It will be seen from the above description that the member 50 is at all times prevented from having any rotative movement with respect to the transverse shaft 39, and that the collar member 49 is so interfitted With the member 50 that neither rotative nor lateral movement between the latter two members is possible. If desired, the two members 49 and, 50 might be replaced by a single member, slidably but non-rotatably mounted on the shaft 39. For manufacturing purposes, however, it is more expedient to utilize the two separate members as described, the member 49 being preferably made of machined material, whereas the member 50 may be made of sheet material if desired.

Since the members 49 and 50 are slidable upon the transverse shaft 39, it will be seen that the operative connection between said shaft and the handle levers 47 may be re leased by moving said members to the right, as viewed in Fig. 3, so that the engaging linger portions 50k and 502' are moved out of the corresponding openings in the two handle levers 47. \Vhen this connection is thus released, the handle levers 47 are freely rotatable on the shaft 39, and may be thus rotated at will without transmitting any movement to said shaft. This provides a free handle condition whereby operation of the switching mechanism is impossible until the operative connection between the handle levers 47 and the transverse shaft 39 is restored by movement of the members 49 and 50 back to the positions in which the engaging finger portions 50k and 595 enter the corresponding openings in the handle levers 47.

The condition under which it is desired to render the switching mechanism inoperative, as above described, is when the door 14 for the fuse compartment of the apparatus casing is open or in condition to be opened. This door is adapted to be held closed by a latching member 51, carried by a pin 52 that is pivotally mounted in the door 14 at the center and near the bottom thereof. This latching member 51 is located on the inside of the door 14, and the pin 52, which carries the same, extends through a suitable aperture in said door and engages a manually operable knob her, and the fixed front wall or trim of the casing, thereby preventing opening of the door 14.

The lower extremity of the latching member 51 is rounded and intermeshes with a similarly rounded notch 54a in a pivoted interlocking member 54. This member 54 is pivoted upon a pin 55, carried by the fixed front wall 12 of the casing, and lies against the inner surface of said wall just below the opening for the door 14. The interlocking member 54 comprises a downwardly extending portion 54?), carrying a-forwardly extending pin 56 which lies in an annular groove 49a in the collar member 49.

When the switching mechanism is in open circuit position and the knob 53 is manually turned in a clockwise direction, as shown in Fig. 5, to release the latching member 51 so that the door 14 may be opened, the lower rounded extremity of said latching member engages the sides of the rounded notch 54a in the interlocking member 54 and causes said interlocking member to be rotated in a counterclockwise direction about its fixed pivot 55. Accordingly, the downwardly extending portion 54b of the interlocking memin 56 carried by'said downwardly exten ing portion, are moved to the right, and this motion is transmitted to the members 49 and which are slidably mounted on the transverse shaft 39. This movement causes the engaging finger portions 50h and 5027 to move out of the corresponding openings in the handle levers 47, thereby releasing the operative connection between said handle levers and the transverse shaft 39.

This condition of the mechanism is illustrated in Fig. 5, in which the openings in the handle levers 47 for receiving the engag- M ing finger portions 50h and 502' of the'member 50 are indicated in dotted lines at 47a and 477), respectively. When the latching member 51 has been released. the door 14 may be opened for the renewal or replacement of fuses which the terminal clamps 16 and 17 are adapted to receive.

Under these conditions, however, the switching mechanism cannot be actuated as the operative connection between the handle levers 47 and the shaft 39 is released, as above described. and the handle member 40 is freev movable without transmitting any movement to the shaft 39 and the switch actuating mechanism that is connected thereto. This provides the desired safety feature of preventing closure of the switching mechanism while the door 14 is open, or unlatched so that it may be opened at will.

is bowed outwardly to form a portion 12a which encloses the transverse shaft 39 and the .mechanism associated therewith, including the parts 49 and 50 which are slidablymounted on said transverse shaft, as previously set forth. This outwardly bowed portion of the front wall of the casing is slotted, as indicated at 125 and 120 in Fig. 4, to permit the outward extension of the handle levers 47.

A pin 57 is secured to the inner surface of this portion 12a of the casing, and extends inwardly therefrom at a position just to the right of the right-hand end surface of the end portion 50g of the slidable connecting member 50. The length of the pin 57 is such that the end portion 509 of the member 50 will abut thereagainst whenever an attempt is made to slide the member 50 to the right, except when the switching mechanism is in its circuit opening condition. This fact is best exemplified in Fig. 7 of the drawings, in which it will be seen. that the end portion 50g is slotted at 50 which slot will be in alignment with the pin 57 when the handle member 40 is moved to its extreme downward position, indicating that the switching mechanism has been actuated to its circuit opening position.

Whenever the handle member 40 occupies any other position without the member 50 having been first slid to the right, the pin 57 will obstruct such movement of the said member 50, and, therefore, the member 49 will likewise be prevented from moving in a similar manner. Thus, the interlocking member 54 is'prevented from moving about its pivot in a counterclockwise direction. as viewed in Figs. 3 and 5, and any attempt to releasethe latching member 51 by turning the knob 53 in a clockwise direction will result in the lower extremity of said latching member abut-- ting against the left-hand side of the slot 54a in the interlocking member 54. Therefore, the latching member 51 cannot be released and the door 14 cannot be opened while the switching mechanism occupies its closed position.

It may be noted at this point that the latchreleasing knob 53 cannot be turned in a counterclockwise direction from the latching position, because such movement would necessarily result in the interlocking member 54 being rotated in a clockwise direction about its pivot, and such rotation of the interlocking member is impossible because the end portions 500 and 50g abut against the righthand surfaces of the handle levers 47 when the mechanism occupies the positions corresponding to the latched condition of the door 14.

The slots 12?) and 12a in the outwardly bowed portion 12a of the front casing wall 12 serve to hold the handle levers 47 in their proper positions and to prevent displacement of said levers along the transverse shaft 39.

The latter shaft is suitably journaled in bearing members 58 that are secured to the forward flanges of the side walls 11 of the easing, preferably between said flanges and the inner surface of the front casing wall 12. It will be understood that either said flanges or said front casing wall may be recessed to accommodate the securing portions of the bearing members 58, so that the inner surface of the front casing wall will lie snugly against the front surfaces of the forward flanges of the side walls 11.

It is also preferable that a sheet of asbestos, or other insulating and fire-resisting material, be disposed in front of'the switching mechanism to protect the actuating and interlocking mechanism, as well as the front casing wall, from any arcing which may take place during actuation of the switch. Such a protective sheet is shown at 59 in Fig. 4;, where it is suitably held in position by screws 60 and spacing members 61, in spaced relation to the rear face of the front casing wall 12 and immediately in front of the switching mechanism.

It will be seen from an examination of the drawings, particularly Figs. 1 and 2, that the levers or crank arms 38 are entirely disengaged from the notched plates 36 when the switching mechanism is either in its fully closed or fully open position. It is desired,

however, that the operating handle 40 be held in position against the front wall of the easing, as shown in Fig. 1 when the switch is closed, and as shown in Fig. 2 when the switch is open. These conditions are desirable in order to prevent accidental engagement of the handle 40, which might frequently result if said handle were allowed to project a substantial distance from the front of the casing when the switch is not being operated. This arrangement also makes the device as compact as possible and eliminates the necessity of dismantling the device in any manner for the purposes of shipment or handling.

The handle is maintained in either of the positions shown in Figs. 1 and 2 when the device is not being operated, by means of tension springs 62, one of which is located at each end of the transverse shaft 39. One end of each of these springs is connected to the outer extremity of the corresponding lever or crank arm 38, and the other extremity is suitably connected to the inside of the front Casing wall. For the purpose of accommodating these springs and the levers or crank arms 38 when the handle is in either of its positions shown in Figs. 1 and 2, the front casing wall is preferably bowed outwardly, as indicated at 12d, these bowed-out portions being slightly greater in vertical dimension than the intermediate bowed-out portion 12a which covers the shaft 39 and the members 49 and 50. It will be seen upon reference to Figs. 1 and 2 that the springs 62 function to hold the levers or crank arms 38 in substantially vertical positions, extending either downwardly or upwardly from the shaft 39, depending upon whether the switch is closed or open.

lVhen the switching mechanism is in circuit opening condition the handle 40 must necessarily have been actuated toward its lowermost position, as indicated in Fig. 2, and if the latching mechanism for the door 14 is released while the handle occupies this position, so that the interlocking mechanism functions as heretofore described to release the operative connection between the handle levers 47 and the transverse shaft 39, then the handle member 40 and the levers 47 will remain by gravity in their lowermost positions.

From the foregoing description it will be seen that the present invention provides means whereby it is assured that the necessarily accessible portions of an encased electrical apparatus are disconnected from the source of electrical potential before the door permitting access to said portions can be opened. During the time that said door is open, or in condition to be opened by reason of the fact that the latching mechanism therefor is released, the actuating handle for the switch is freely movable without transmitting its movement to the switch actuating mechanism itself, so that the switch cannot be closed until the door is first closed and latched.

This assures complete protection of operators and attendants against personal injury by reason of electrical shocks, which is one of the primary objects of the invention. The apparatus itself is also protected against damage which might result fromshort circuits or arcs in case access were permitted to the current conducting parts while the same are in energized condition.

While only one specific embodiment of the invention has been shown and described herein, it will be understood that various modifications and changes may be made in the details of construction, without departing from the spirit and scope of the invention, as set forth in the appended claims.

\Vhat is claimed as new and desired to secure by Letters Patent, therefore, is:

1. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and means operated by the releasing of said latch for disconnecting said manually operable member from the remainder of said switch operating mechanism.

2. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, means operated by the releasing of said latch for disconnecting said manually operable member from the remainder of said switch operating mechanism, and means for preventing the operation of said disconnecting means when said switch is closed. a

3. In an electrical apparatus, a switch, a casing, a door in said casing, a latch'for said door, operating mechanism for said switch including a manually operable member, means operated by the releasing of said latch for disconnecting said manually operable member from, the remainder of said switch operating mechanism, and means for preventing the release of said latch when said switch is closed 4. In an electrical apparatus, a switch, a casing, adoor in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, means operated by the releasing of said latch for disconnecting said manually operable member from the remainder of said switch operating mechanism, and means for preventing the operation of said disconnecting means and thereby preventing the release of said latch when said switch is closed.

5. In an electrical apparatus, a switch, a

a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and means operated by the releasing of said latch for disconnecting said manually operable member from the remaindermf said switch operating mechanism, said means being restorable to reconnect said manually o erable member to the remainder of said switc operating mechanism by the return of said latch to latching position, only when said door is closed.

6. In an electrical apparatus, a switch, a. casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release ofsaid latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising means releasably connecting said manually'operable member and the remainder of said switch operating mechanism, and said interlocking mechanism comprising means operated by the release of said latch for releasing said connecting" means. 7

7. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, an interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released. said switch operating mechanism comprising means releasably connecting said manually operable switch operating mechanism 8. In an electrical apparatus, a switch, a

casing, a door in said casing, a latch fors'aid door, operating mechanism for saids'witch including a manually operable member, and

interlocking mechanism for preventing the release of said latch while ksaid switch is closed and for preventing the closing of said switch while a said latch is released, said comprising means releasably connecting said manually operable member and the remainder of said switch operating mechanism, and said interlocking mechanism comprising means operated by the release of said latch for releasing said connecting means and means preventing the release of said latch when said switch is closed.

9. In an electrical apparatus, a-switch, a.

casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising means releasably connecting said manually operable member and the remainder of said switch operating mechanism, and said interlocking mechanism comprising means operated by the release of said latch for releasing said connecting means and means preventing the release of said connecting means and thereby latch when said switch is closed.

10. In an electricalap aratus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising means releasably connecting said manually operable member and the remainder of said switch operating mechanism, and said interlocking mechanism comprising means operated by the release of said latch for releasing said connecting means, said releasable connecting means being restorable to connecting condition by the return of said latch to latching position, only when said door is closed.

11. In an electrical apparatus, a switch, a casing, a door insaid casing, a latch for said door, operating mechanism for mid switch including a manually operable member, and interlocking mechanism for preventing the reventing the release of said release of said latch-while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted on said rotatable member but -fiX8d against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said latch is in latching position and to disengage said manually operable member when said latch is released.

12. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotat able relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said latch is in latching position and to disengage said manually operable member when said latch is released and means for preventing the sliding of said connecting member out of engagement with said manually operable member when said switch is closed.

13. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventingthe release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually ber, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said coimecting member to engage said manually operable member when said latch is in latching position and to disengage said manually operable member when said latch is released and means for preventing the sliding of said connecting member out of engagement with said manually operable member, and thereby preventing the release of said latch, when said switch is closed.

14. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said latch is in latching position and to discharge said manually operable member when said latch is released and means for preventing the sliding of said connecting member out of engagement with said manually operable member, and thereby preventing the release of said latch, when said switch is closed, said interlocking mechanism being operable to return said connecting member into engagement with said manually operable member by the return of said latch to latching position only when said door is closed.

15. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operatingmechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, said operable member to hold the latter against rotatable member, said connecting member rotation with respect to said rotatable memand the engageable portions of said manually operable member being located within a por tion of said casing having slots therein through which said manually operable member extends, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said latch is in latching position and to disengage said manually operable member when said latch is released.

16. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said I door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising a rotatable member upon which said manually member is mounted in freely rotatab e relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with res ect to said rotatable memher, said rotatab e member, said connectin member and the engageable portions of sai manually operable member being located within a portion of said casing having slots therein through which said manually operable member extends, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said latch is in latching position andto disengage said manually operable member when said latch is released and a detent pin fixed to a wall of said casing and projectin inwardly therefrom for preventin the sliding of said connecting member out 0 en agement with said manually operable mem er when said switch is closed.

17. In an electrical apparatus, a switch, a casing, a door in said casing, a latch for said door, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism comprising a rotatable member upon which said manually o erable member is mounted in freely rotatab e relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, said rotatable member, said connectin member and the engageable portions of sai operable manually operable member being located within a portion of said casing having slots therein through which said manuall operable member extends, and said inter ockin mechanism comprising means for sliding sai connecting member on said rotatable member to cause said connectin member to engage said manually operab e member when said latch is in latching position and to disengage said manually operable member when said latch is released and a detent pin fixed to a wall of said casing and projecting inwardl therefrom for reventin the sliding of sai connecting mem er out o engagement with said manually operable member, and thereby preventing the release of said latch, when said switch is closed.

18. In an electrical appartus, a switch, a

release of said latch while said switch is closed and for preventing the closing of said switch while said latch is released, said switch operating mechanism com rising a rotatable member upon which sai manually operable member is mounted in freely rotata le relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, said rotatable member, said connecting member and the engageable portions of said manually operable member being located within a portion of said casing having slots therein through which said manually operable member extends, and said interlockingmechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said latch is in latching position and to disengage said manually operable member when said latch is released and a detent pin fixed to a wall of said casing and projecting inwardly therefrom for preventmg the sliding of said connecting member out of engagement with said manually operable member, and thereby preventing the release of said latch, when said switch is closed, said interlocking mechanism being operable to return said connecting member into engagementv with said manually operable member by the return of said latch to latching position, only when said door is closed. I

' 19. In an electrical apparatus, a switch, a casing, a door in said casing, releasable means for holding said door closed, operating mechanism for saidswitch including a manually operable member, and interlocking mechanism for preventing the release of said door-holding means while said switch is closed and for preventing the closing of said switch while said door is open, said switch operating mechanism comprising a 5 rotatable member upon which said manually operable member is mounted in freely rtatable relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, said rotatable member, said connecting member and the engageable portions of said manually operable member being located within a portion of said casing having slots therein through which said manually operable member extends, and said interlocking mechanism comprising means for 20 sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said door-holding means are in condition to hold said door closed and to disengage said manually operable member when said door is open.

20. In an electrical apparatus, a switch, a casing, a door in said casing, releasable means for holding said door closed, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said doorholding means while said switch is closed and for preventing the closing of said switch while said door is open, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted 40 on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, 5 said rotatable member, said connecting member and the engageable portions of said manually operable member being located within a portion of said casing having slots therein through which said manually operable member extends, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said door-holding means are in condition to hold said door closed and to disengage said manually operable member when said door is open and a detent pin fixed to a wall of said casing and projecting inwardly therefrom for preventing the sliding of said connecting member out of engagement with said manually operable member when said switch is closed.

21. In an electrical apparatus, a switch, a 65 casing, a door in said casing, releasable means for holding said door closed, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said doorholding means while said switch is closed and for preventing the closing of said switch while said door is open, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, said rotatable member, said connecting member and the engageable portions of said manually operable member being located within a portion of said casing having slots therein through which said manually operable member extends, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said door-holding means are in condition to hold said door closed and to disengage said manually operable member when said door is open and a detent pin fixed to a wall of said casing and projecting inwardly therefrom for preventing the sliding of said connecting member out of engagement with said manually operable member, and thereby preventing the release of said door-holding means when said switch is closed.

22. In an electrical apparatus, a switch, a. casing, a door in said casing, releasable means for holding said door closed, operating mechanism for said switch including a manually operable member, and interlocking mechanism for preventing the release of said doorholding means while said switch is closed and for preventing the closing of said switch while said door is open, said switch operating mechanism comprising a rotatable member upon which said manually operable member is mounted in freely rotatable relation and a connecting member slidably mounted on said rotatable member but fixed against rotation with respect thereto and having portions engageable with said manually operable member to hold the latter against rotation with respect to said rotatable member, said rotatable member, said connecting member and the engageable portions of said manually operable member being located within a portion of said casing having slots therein through which said manually operable member extends, and said interlocking mechanism comprising means for sliding said connecting member on said rotatable member to cause said connecting member to engage said manually operable member when said door-holdmg means are in condition to hold said door closed and to disengage said manually operable member when said door is open and a detent pin fixed to a wall of said casing and projecting inwardly therefrom for preventing the sliding of said connecting member out of engagement with said manually 0perable member, and thereby preventing the release of said door-holding means when said switch is closed, said interlocking mechanism being operable to return said connecting member into engagement withsaid manually operable member by the return of said doorholding means to the condition in which said door is held closed.

In witness whereof, I have hereunto subscribed my name.

RALPH H. KINGDON.

CERTIFICATE OF CORRECTION.

Patent No. 1,873,426. August 23, 1932.

RALPH H. KINGDON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 7, lines and 71. claim 7, strike out the word "connecting"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of November, A. D. 1932.

M. J. Moore, (Seal) Acting Commissioner of Patents,

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