US1747491A - Switch mechanism - Google Patents

Description

Feb. 18, 1930. w. H. SCHRAMM 1,747,491

SWITCH MECHANISM 2 Sheets-Sheet 2 Filed May 26, 1927 F175. 2. I w

Fig. 3.

\ ri' i INVENTOR WaizerH. Schmmm.

Patented Feb. 18, 1930 warren srres WALTER H. SGHRAMM, OF PITTSBURGH, PENNSYLVANIA, ASSIG'NOB TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA SWITCH MECHANISM Application filed May 26,

My invention relates to switch mechanism and particularly to disconnecting switches of the back-of-board type, wherein an insulating panel is mounted at the rear of a sheet metal switchboard and serves to support fuses and knife switches having an operating handle projecting through an opening in the switchboard.

An object of my invention is to provide a back-of-board knife switch that is assembled entirely upon an insulating base and mounted at the rear of the switchboard and having an operating handle that is also mounted upon the insulating panel in order that the switch may be assembled upon the insulating base as a unit, thereby facilitating assembly and inspection of the switch apparatus.

Another object of my invention is to provide a back-of-board type disconnecting switch having characteristics of design which enables the mounting of the insulating panel supporting switch, closer to the switchboard than is the usual custom, thus reducing the distance of the fuse receptacles mounted on the insulating base, from the front of the board, and thereby rendering its operation more safe, because it is unnecessary for the operator to reach into a deep and dark recess to replace a fuse.

Another object of my invention is to provide a back-of-board type knife switch wherein the over-all dimensions of the switch blade assembly are shortened, in order to reduce the space necessary for the safe operation of the switch.

A further object of my invention is to provide a back-of-board type disconnecting switch having the above-noted characteristics that is inexpensive to manufacture, and which may readily be assembled and installed upon the usual type of metal front switchboards.

These and other objects of my invention, that will be made apparent throughout the further description thereof, are attained by means of the switch apparatus hereinafter described and illustrated in the accompanying drawings, wherein:

Figure 1 is an elevational View of switch apparatus embodying features of my inven- 1927. Serial No. 194,248.

tion showing the metal front switchboard in section.

Fig. 2 is a plan view of the apparatus shown in Figure l with the cover removed to expose parts of the apparatus, and

Fig. 3 is an elevational view of a fragment of the switch apparatus with the insulating panel shown in section.

Referring to the drawings, the switch apparatus includes a sheet metal switchboard at, and an insulating base or panel 5 that is attached to the switchboard f by brackets 6. Contact jaws 7 and pivot jaws 8 are mounted upon the panel 5, the pivot jaw 8, )ivotally supporting a knife switch blade 9 that engages the contact jaw 7. Fuse receptacles or clips 11 are mounted upon the panel 5 for supporting standard cartridge fuses 12. The pivot jaws 8 and the adjacent fuse clip 11 are electrically connected by the conductor strap 13 that is secured to the insulating panel by screws 14.

A three-pole knife switch is illustrated in Fig. 2. Fig. l is a typical side elevation of a 2 or 4 pole switch. A pedestal 15 is mounted upon the central conductor or strap 13 he tween the contact jaw 8 and the fuse clip 11 on 1 or 3 pole switches, as shown in Fig. 3.

The pedestal is adapted to support the switch operating handle, to be hereinafter described, and comprises a square shaft 16 having one end extending through the panel 5 and threaded to receive nut 17 for attaching the shaft to the panel. The shaft is provided with a shoulder collar 18 which engages an insulating bushing 19 that is disposec be tween the collar 18 and the base 5 on 2 or l pole switches, or the conductive strap 13 for 1 and 3 pole switches. The threaded end of the shaft 16 is insulated from the strap 13 by an insulating bushing 21 which extends through an opening 22 in the strap 13. The bushing 21 extends into the bore 23 of the bushing 19.

By reason of the relatively wide diameter of the insulating bushing 19, the pedestal 15 is provided with a wide supporting base and therefore is rigidly mounted upon the base 5.

The operating handle 26 for the switch mechanism comprises a single bent strap 27,

of U-shape, that is disposed on opposite sides of the shaft 16 in spaced relation thereto, the bars being pivotally mounted upon the shaft 28 adjacent the center of the bars. Interlocking cams 29, the purpose of which will hereinafter appear, are mounted in the spaces between straps 27 of the operating handle and on the shaft 16, the cams being secured in place by rivets-30.-

Each switch blade 9 is provided with an insulating clip 31 that is secured thereto by rivets The clips are connected for simultaneous operation by means of a metal shaft 33 that extends through holes 34, in the ends of the clips. Longitudinal displacement of the shaft is prevented by cotter to a pivoted operating handle upon the front plate of the switchboard. This construction required a greater space between the front plate of the switchboard and the insulating panel, in order to accommodate the greater length of the switch blade and to provide proper clearance for live'parts. Switches'of this character also had disadvantages the assembly thereof, because the operating mechanism is usually mounted upon the front plate of the switchboard. In my improved switch blade apparatus, the entire switch assembly is mounted upon the switch base and is independent of the cover or front switchboard.

The switchboard 4 is provided with an opening 37' through which the cartridge fuse 12 is accessible. The opening is closed by a door 38 that is hinged at 39 to the switchboard 4. The operating handle 26 projects through an opening 41 in the switchboard panel a and is provided with an insulating handle 42. V

The door 38 is interlocked with the switch handle in such manner that the door cannot be opened so long as the switch is in open position and the switch cannot beclosedso long as the door is in open position. The interlock mechanism comprises an arcuate cam member 4L0'that is'attached to'the door 38 by means of a bolt 43. The camis slightly less in width than the space between the bars 27 of the operating handle and fits within that space when inthe closed position shown in full lines in Figures 1 and 2. The cam plates 29 on the operating handle are provided with arcuate cam surfaces 44 which provide clearance for the cam 40 when the operating handle is in the open position shown in dotted lines. It will be seen that the door cannot be opened so long as the switch is in the closed position because the upper end of the cam 40 engages'the convex surface 39 of the cam 29 and prevents-movement of the door. The convex cam surface is of such length that it'prevents'movement of the door until the-switchhas'been moved to its full open position. At this time, cam 40 will clear the cam 29 and permit opening movement of the door. However, when the cam a0 has moved to the open position, the switch cannot be closed because the concave surface 4% of the cam'29 will then'engage the convex cam surface of the cam 40'a-nd prevent closing'movement ofthe switch so; long as the door 1s in open positlon. The arrangement of-the cams issuch that in orderto close the switch, the door must be in fully closed position.

The switch construction, above described, is relatively compact and rugged and isrendered more safeinoperation by.- reason' of the fact that the fuses l-2-are'disposed relatively close to the front switchboard 4:.

It will be understood that theiswitchboard 4 is of theme'tal panel type and may be as sembled in panels or sections which; may.-

be removed for inspection of the switch mechanism. v

While I have shown and described my invention in considerable detail for the purpose of completely illustrating the same, it is my intent-ion that the appended claims shall be as broadly construed asis' permitte'dby the'langu-age thereofand thei prior art.

I c'laiin as my invention:

1. Switch mechanism comprising a'- sup portingbase, a switch blade member pivoted thereon for movement in a plane normal to the plane of the base, a pedestal mountedupon the base and extendingperpendicularlytherefrom, and an operating handle comprising a forked member having portions disposed on opposite sides of the pedestal and pivoted thereto inter-mediate their ends, the inner ends of the said portions being pivotally connected to the said switch menr ber.

2. Switch mechanism comprising a supporting base, a plurality of switch blade that the links may move past the pedestal when their operating handle is actuated.

3. Switch mechanism comprising a supporting base, a switch blade member pivoted

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