US2284206A - Safety switch - Google Patents

Description

May 26, 1942. A. J. HAEQMON ETAL SAFETY SWITCH 2 Sheets-Sheet l Filed Oct. 14, 1940 Ja /am.- Arthur Il-[m'mon n L/dfber @dhley @ZM May 26, 1942. A. .1. HARMON ETAL SAFETY SWITCH Filed Oct. 14, 1940 2 Sheets-Sheet 2 Patented May 26, 1942 UNITED STATES PATENT OFFICE SAF-ETY SWITCH Arthur J. Harmon and Walter vG. Coakley,

Chicago, Ill. Application October 14, 1940, Serial No. 361,026 Claims. (Cl. 2 0017) Our invention relates to casing-housed multibladed switches of types commonly used for controlling the. supply of current to industrial motors, such as the fused safety switches and the unfused motor starter switches, in each of which types a multi-bladed switch is mounted in a casing and presents a switch-controlling handle outside the casing, each switch casing being usually installed upright.

Since the current supply for industrial motors is almost always obtained from overhead wires, such switches have heretofore been commercialized only in constructions designed for having the current flow downward through the switch casing, namely, with the inlet or line terminals disposed in the upper part of the casing and the outlet or load terminals in the lower part of the casing, thus requiring only short portions of the line wires and theload Wires to be disposed inside the casing. Moreover,

class must be installed for an upward flow of 3 current, namely, with the lines entering the lower part of the switch casing and the load wires issuing from the upper part of the casing. In such cases, a mere inversion of the now well standardized switches would not meetthe code requirements, because this would dispose the each such switch commonly includes a switchswitch handle in a depending position when the switch is closed, thereby misleading workmen into believing the motor to be disconnected from the circuit when the current is still on them. Moreover, such an inverted switch would dispose the handle for a left-hand operation, and for a counter-clockwise rotation to which switch users are not accustomed.

Consequently, when a switch of this class is required to have an upward flow of current through it, the insta ler has invariably been obliged to mount a standard (and only available) down-flow switch in its usual upright position and then to have Wires within the casing extend from each casing inlet to the terminals near the opposite end of the casing. This, as shown in Figure 3 of our drawings, requires additional lengths of interior wires and decidedly increases the installation cost because of the difficulty in making the needed wire bends within the space around the insulating panel. Moreover, and particularly when the amperage and voltage requires wire of considerable outside diameter, the installing'is apt to damage insula- 1 tion on the wires so that projecting insulation portions have been set on fire by flashes either from the breaker portions of the switches or from breaks in sharply bent wire cores. Since every such accident may lead to a more extensive fire in addition to halting the use of the corresponding motor until a new switch is installed, the thus pictured flow-reversing wiring has been tolerated as a make-shift only because no allied type of switches designed for an upward flow of current has been commercially available during the many decades in which both safety switches and motor switches have been extensively manufactured and carried in stock of distributors'in a large number of cities.

Our present invention aims to meetv this long felt need and to avoid the objections due to the use of such make-shift wiring by providing switches of the recited class specifically'designed for use withan upward flow of current, which switches will fully meet the electrical code requirements, which will be just as easy and inexpensive to install as the long standardized downflow types now so universally marketed.

Furthermore, our invention aims to have such.

up-flow switches include provisions preventing any electrician from using them with makeshift wiring (of the type shown in Figure 3) for a reversing of the current flow.

Illustrative of our invention and of the difficulties overcome by it,

Figure l-is a front elevation of a simple threepole safety switch of conventional type, with the usually latched frontal door of the upright casing omitted, with a somewhat diagrammatic representation of its major parts when the switch is open, showing the simple and easily installed wiring which suflices for an acceptable wiring when the current is to flow downward through the switch. a

Figure 2 is an enlarged side elevation of actual switch parts corresponding to those which enter at the bottom of the casing and the load wires issue'from the top of a casing.

Figure 4 is a front elevation of a three-pole up-fiow safety switch embodying our invention, showing the changes whereby we avoid the extra expense and fire hazard occurring with the make-shift wiring illustrated in Figure 3 and even prevent the installing of flow-reversing wiring, while fully meeting the code requirements.

Figure 5 is an enlarged vertical section, taken along the line 5-5 in Figure 4, showing the rotation reversing means interposed between the handle carrying shaft and the blade-moving crank, and showing the position of certain parts when the switch is open.

Figure 6 is a similarly enlarged vertical sec tion, taken along the line 6-6 in Figure 4, showing essential parts of the throw-over means associated with the blade-moving crank.

Figure '7 is an enlarged plan-section, taken along the line 1-1 of Figure 4, showing the position of one of the barriers for preventing a reverse Wiring.

Figure 8 is a perspective view of the slotted bracket against which the throw-over spring of 1 Figure 6 presses.

Figure 9 is a View similar to Figure 5.but show ing the parts when the switch is closed.

In the conventional down-flow safety switch shown in Figure l, the casing C has Wire inlets w in its top and bottom, and has an insulating panel I fastened to its back, this panel being so much smaller than the back (3 of the casing as to leave considerable space for wires all around it. Mounted on the upper portion of this panel are line terminals L, easily reachable by short end portions of the current-supply or line wires S, which line terminals aline with load terminals 0 mounted on the lower portion of the said panel and easily reached by short portions of the load wires M.

Interposed between each line terminal and the corresponding load terminal is a single throw knife switch which in a fused embodiment of our invention has a fuse interposed between the pivot .15 member P of the switch and the line terminal.

Thus, in Figure 1 each such switch has its blade clip 9 integral with the line terminal L, and its blade pivot connected tothe load terminal M by a fuse F.

Fastened to each switch blade is a connector plate 1 of insulating material which has a hook formation I near its normally upper end for interlocking with the U-back 8 of a switchthrowing crank which'includes a main Ushaped 5;

part and two axially alined end parts 8 These crank end parts are journaled respectively in the opposite sides of the casing, and the right-hand end part has a handle H fastened to it outside the casing and disposed for depending (as in Figure 1) when the switch is open so that the switch blades, switch pivots and fuses are all dead.

Illustrative of an up-flow safety switch embodying our invention, Figure 4 shows an insulating panel I similarly mounted in the casing C with space all around it, but with line terminals L near the bottom of the panel and load terminals M near the top. In this case each fuse F is disposed above the corresponding blade pivot P, .each blade B has its free end at the bottom when the switch is closed, and to close switch, the usual crank has to. be rotationally moved about the axis of its alined end portions 8* in a direction which will appear counter-clockwise when Viewed from the right of Figure 4.

To actuate the switch-throwing crank by movement of a handle in the same rotational direction as that customary in the standard downflow switches, we mount a gear G on the righthand crank-end part but do not fasten a handle directly to that crank end. Instead, we also journal an auxiliary shaft H (Figure 5) in the right-hand side of the casing with its axis parallel to and near that of the similarly journaled adjacent crank end. Next, we fasten a pinion 12 on the auxiliary shaft, intermesh this with the said gear, and fasten a handle H to the auxiliary shaft outside the adjacent casing side, the handle being so positioned that it will depend (as shown in full lines in Figures 4 and 5) when the switch is open. With the two gear members thus intermeshed, a right-handed rotational movement of the handle about the axis of the auxiliary shaft will rotate the crank in the opposite direction, so that the handle may extend upwardly (as shown in dotted lines in Figure 4) when the switch is closed. -Moreover, if the gear member G mounted on the crank is suitably larger than the companion pinion l2, the manual power required for throwing the switch will be reduced and the handle H can then extend upwardly, as shown in dotted lines in Figure 4, to indicate the closure of the switch more emphatically.

For cheap switches the gear G may be fastened rigidly to the crank end which extends through it, but for high voltage or high amperage we desirably journal this gear on that crank end and provide it with projecting thrust pins (13 and I4) spaced rotationally of the gear and disposed for respectively engaging opposite sides of the adjacent U-shank portion of the switch-throwing crank. Thus, Figure 5 shows the relative positions of these pins and of the handle when the switch is open, and Figure 9 shows the pin positions when the switch is closed so that the handle would extend upwards as shown by dotted lines in Figure 4.

The lost motion provided by these pins particularly adapt our up-fiow switch also for including a throw-over means associated with the crank for insuring a quick making and breaking of the contact between each switch blade and the corresponding blade clip. Illustrative of this, Figures 5 and 6 show such a throw-over including a spiral compression spring l5 operatively interposed between the left-hand U-shank of the crank and a slotted thrust lug Iii fastened to the left-hand side of the casing, with the spring housing a part of a sliding rod I! to keep the spring from buckling. With all of our heretofore described variations it will be obvious that our switches will fully meet the need for an up-flow type which can be easily and cheaply connected to the circuits, which will disconnect the load Wires, fuses, switch pivots and switch blades from the circuit when the switch is open; which will present the handle in the required depending position when the switch is turned off; and which will require no make-shift wiring around either half of the periphery of the switch panel, such as might increase the fire hazard.

Consequently, the introduction of our here disclosed up-flow switches in both fused and unfused types should enable the underwriters and electric inspectors to bar the further installing of make-shift and fire-risking interior wiring in switches designed for a down-flow, thereby reducing the hazards, decreasing the installation costs, and also reducing production time losses due to interruptions of motor service. However,

since an electrical contractor with spare switches of our up-flow type in his stock might be tempted to convert such switches into down-flow types by the already discussed make-shift wiring, we desirably also provide our switches with barriers for positively preventing this.

Thus Figure 4 shows two barriers 20 fastened to a casing bottom and sides, each of which barriers substantially spans the space between one casing side and the adjacent side edge of the insulating panel I, each of which barriers desirably reaches forwardly far beyond the front face of that panel. Each barrier then prevents a running of wires through the'space between one side edge of the panel and the adjacent casing side, not only for reducing the previously described fire risk but also to guard against having any thus run wire engage a part of either the rotation-reversing gearing or the throw-over mechanism.

However, while we have illustrated and described an embodiment of our invention including numerous typical details of construction and arrangement, it should be obvious that many changes might be made Without departing either from the spirit of our invention or from the appended claims.

We claim as our invention:

1. A multi-bladed safety switch in which pivoted blades mounted on the front of an insulating panel are moved downwardly to engage fixed terminals, a switch-throwing crank at the front of the panel pivoted at the sides thereof and engaging the blades to operate them, a handle mounted to swing at the side of the panel, and

meshing gears secured to the handle and to the end of the crank for reversing the applied movement so that the handle is swung upwardly to close the switch and downwardly to open it.

2. A safety switch of the reverse type having an upright insulating panel with power inlet terminals at the bottom and power outlet terminals at the top, a pivoted blade at the front of the panel and swinging downwardly to close a circuit with the power terminal, a crank engaging the blade at the front of the panel pivoted at the side thereof, a handle also pivoted at the side of the panel, a gear on the handle and a gear on the crank meshing together for reversing the movement imparted bythe handle and crank to the blade to insure that the handle is pulled down in opening the switch to simulate regular switch operation.

3. A reverse safety switch of the type set forth in claim 2 in which the panel is mounted in a casing having walls spaced at the sides therefrom in which the ends of the crank and the arm are pivoted, the meshing gears being located in the side space between the casing and panel, and the handle being located at the outer side of the casing and swinging from a depending position to an upright position in closing the switch blade.

4. In a safety switch of the reverse type having an upright insulating panel with power inlet terminals at the bottom, power outlet terminals at the top and pivoted blades mounted on the panel and movable downwardly to close a circuit with the power terminals, a crank engaging the blades at the front of the panel and the ends pivoted at the sides thereof, a handle pivoted at the side of the panel, a gear secured to the handle, a gear meshing therewith and loosely mounted on the adjacent pivoted end of the crank, and operating pins projecting from the crank gear in spaced apart relation with a portion of the crank arm extending loosely therebetween and engaged thereby for lost motion operation in either direction.

5. In a safety switch of the reverse type having a lost-motion reversing gear operating means for the crank, as in claim 4, and a spring actuated throw-over connected to the crank to insure a quick making and breaking of the blades and their respective contacts.

ARTHUR J. HARMON. WALTER G. COAKLEY.

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