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Split main breaker design in Pushmatic electrical panel (C) InspectApedia DB Bulldog & ITE Pushmatic Circuit Breaker Design & Patent History

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Bulldog Pushmatic Circuit Breaker patent disclosure history & design features:

This article provides key patents describing the design of the Bulldog & Pushmatic circuit breaker & panel and the features of those components

The article series discusses the history of Pushmatic breakes, gives advice to homeowners whose building is served by a Pushmatic electrical panel, and we discuss both compatability of and concerns when using replacement circuit breakers or used Pushmatic circuit breakers sold by salvage operatoers. We solicit field failure and field inspection reports of questionable or possibly problematic electrical equipment in buildings such as the Bulldog™ and ITE-Pushmatic® brands described here.



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Bulldog & Pushmatic Patent Disclosure & Design Features

Pushmatic panel label (C) Daniel FriedmanMessing, Joseph. "Circuit breaker." U.S. Patent 2,035,743, issued March 31, 1936.
Patent information: Publication number US2035743 A Publication type Grant Publication date 31 Mar 1936 Filing date 29 Mar 1934 Priority date 29 Mar 1934, original text (with some OCR scan errors) is reproduced below:


March 31, 1936. w. H. FRANK ET AL CIRCUIT BREAKER Filed March 29, 1934 INVENTORS wwwajmif BY t W A TORNEY, Patented Mar. 31, 1936 PATENT OFFICE CIRCUIT BREAKER William 1!. Frank and Joseph Messing, Detroit, Mich, assignors to Bulldog Electric Products Company, Detroit, Mich, a. corporation of West Virginia Application March 29, 1934, Serial No. 717,989 12 Claims.
This application relates to circuit breakers, and discloses a novel holding means forv breaker trip pawls or levers, useful as a substitute for holding means of the character disclosed in Pat- 5 cut No. 1,982,289, November 27, 1934, Figs. 3-4.

Details of the constructions shown will be understood upon reference to the following detailed descriptive matter which relates to the appended drawing. In this drawing,

Figures 1 and 2 show holding means for a breaker pawl, in elevation and top plan view.

Figures 1 and 2 show novel holding means for breaker trip pawls or levers, useful as a substitute for a holding means like the one shown at 200-209, 2ll--2l3 of Patent No. 1,982,289, November 27, 1934, Figs. 3-4, to hold the end of a trip pawl or lever, like the end 88 of the pawl 81, pivotally mounted in the frame at 86.
On the base 66 is pivotally mounted at 2M a thermal warping element 282 urged toward the base by a coiled tension spring 283 connected in circuit through the pivot hinge at 28 l, or through a flexible jumper, and adapted to warp on overload to the right. Secured to and disposed transversely across and preferably insulated from the warping element is an E-shaped magnetic material piece 284 which, together with the magnetic material plate 285 mounted upon the pedestal 286, forms a magnetic circuit with the ther- 30 mal element 282 forming a single turn coil to provide the magnetomotive force.

A bracket 2M is rigidly secured to warping element 282 by rivets 262, there preferably being insulation 203 between the element and the brackets. An arm 204 is pivotally connected to bracket 2M by a pin ZOB-and is provided with a lock washer 206 which maintains arm 20; in any desired preset position, relative to the element. A pin 20! on the outer or free end of arm 204 rides freely in a circular slot 208 of a lever-latch 209 pivotally secured to a foot 2| l bya rivet M2 and thus mounted on the base 50. A hook M3 on the upper end of latch 209 holds the breaker pawl 81 firmly when the breaker is in the on position, or in its normal 0 position.

When an overload occurs, the warping element 282 moves to the right, due to thermal forces, or magnetic forces, or a combination of both forces. This motion is magnified by the leverage ratio 50 provided by the lever latch 209 moving the hook end 213 thereof to release the pawl 81.

Now having described an embodiment of the 5 invention. mounted that it may move bodily in accordance with stresses exerted thereon by the magnet.

2. For use in a circuit protective breaker having means normally tending to move parts into release condition when they are in reset condition and a pawl which when held prevents such action of the means, a holding means for said pawl including a circuit current controlled thermally responsive element which deflects by warping on overload into pawl releasing position and is mounted to move bodily regardless of deflection, and a circuit current controlled magnet for moving the element bodily and instantaneously 25 I into pawl releasing position on an overload of suficient magnitude to operate the magnet.

3. For use in a. circuit protective breaker having means normally tending to move parts into release condition when they are in reset condi- 30 tion and a pawl which when held prevents such actionof the means, a. holding means for said pawl including a circuit current controlled thermally responsive element which deflects by warping on overload into pawl releasing position and 35 is mounted to move bodily regardless of deflection, and a circuit current controlled magnet for moving the element bodily and instantaneously into pawl releasing position on an overload of sufficient magnitude to operate the magnet, the 40 holding means also including a holding latch connected to the element by a movement amplifying connection and operating directly on the pawl.

4. In a circuit protective device, a circuit ourrent controlled delayed action holding element, and a magnet carried by and forming part of the element for causing instantaneous movement of the element on overload, the element being so mounted that it may move bodily in accordance with stresses exerted. thereon by the magnet, the element being an energizing source for the magnet.

5. A holding and releasing means for a circuit breaker part comprising a thermally responsive element, movement amplifying means positively connecting the element to the breaker part whereby overload warping or return cooling of the element will cause amplifled movement of the breaker part, the current in said element providing a magnetic force auxiliary to the thermal force for releasing the breaker, the element being mounted to move bodily regardless of deflection in accordance with magnetic forces created by the current flowing through it.

6. A holding and releasing means for a circuit I breaker part comprising a thermally responsive bimetal element, movement amplifying means positively connecting the element to the breaker part whereby overload warping or return cooling of the element will cause amplified movement of the breaker part, and means responsive to the current flowing in said element for creating a magnetic force which assists the thermal warping force for causing release movement of said element and thereby releasing the breaker, the element being mounted to move bodily regardless of deflection in accordance with magnetic forces created by the current flowing through it.

7. A holding and releasing means for a circuit breaker part comprising a circuit current controlled element constructed to deflect itself with a delayed action to release position on a circuit fault and to deflect itself automatically to holding position thereafter, and mounted on a pivot hinge so as to be movable bodily to and from release and holding position regardless of deflection, and means operating on a circuit fault and against an adjustable resistance for, causing instantaneous movement of the element bodily to release position.

8. A holding and releasing means for a circuit breaker part comprising a circuit current controlled element constructed to deflect itself with a delayed action to release position on a circuit fault and to deflect itself automatically to holding position thereafter,.and mounted on a pivot hinge so as to be movable bodily to and from release and holding position regardless of deflection, and means operating on a circuit fault for causing instantaneous movement of the element bodily to release position.

9. A holding and releasing means for aicir-' cult breaker D811; comprising a circuit current controlled element constructed to deflect itself with a delayed action to release position on a circuit fault and to deflect itself automatically sheaves to holding position thereaften-and mounted on a pivot hinge so as to be. movable bodily to and from release and holding position regardless of deflection, and magnetically actuating means operating on a circuit fault and against an amustable resistance for causing instantaneous movement of the element bodily to release position.

10. A holdlngand releasing meansfor a circuit breaker part comprising a circuit current controlled element constructed to deflect itself with a delayed action to release position on a circuit fault and to deflect itself automatically to holding position thereafter, and mounted on a pivot hinge so as to be movable bodily to and from release and holding position regardless of deflection, and magnetically actuating means operating on a circuit fault for causing instantaneous movement of the element bodily to release position.

11. Means for moving a circuit breaker holding part comprising a circuit current controlled element constructed to deflect itself with a delayed action to move the part into release position on a circuit fault and to deflect itself automatically to move the part into holding position thereafter, and mounted so as to be movable bodily to and from release and holding position regardless of deflection, and means operating on a circuit fault for causing instantaneous movement of the element bodily to release position, the element being positively connected to the part through a movement amplifying connection so that minute movements of the element will positively cause amplied movements of the part.

12. Means for moving a circuit breaker holding part comprising a circuit current controlled element constructed to deflect itself with a delayed action to move the part into release position on a, circuit fault and to deflect itself automatically to move the part into holding position thereafter, and mounted so as to be movable bodily to and from release and holding position, - and circuit current controlled magnetically actuating means operating on a circuit fault for causing instantaneous movement of the element bodily to release position, the element being -positively connected to the part through a movement amplifying connection so that minute movements of the element will positively cause amplifled movements of the part. 1

Other Patents citing this invention

US2424909 * 30 Dec 1942 29 Jul 1947 Frank Adam Electric Co Circuit interrupting device
US2439511 * 10 Apr 1944 13 Apr 1948 Frank Adam Electric Co Latching or tripping mechanism of circuit breakers
US2447652 * 30 Oct 1942 24 Aug 1948 Westinghouse Electric Corp Circuit breaker
US2459427 * 24 May 1945 18 Jan 1949 Fed Electric Prod Co Circuit breaker
US2491088 * 29 Sep 1945 13 Dec 1949 Essex Wire Corp Thermal-magnetic circuit breaker
US2573306 * 11 Aug 1948 30 Oct 1951 Gen Electric Electric circuit breaker
US2579673 * 27 Sep 1947 25 Dec 1951 Square D Co Circuit breaker
US2588497 * 10 Dec 1949 11 Mar 1952 Westinghouse Electric Corp Circuit breaker
US2590663 * 3 Feb 1950 25 Mar 1952 Westinghouse Electric Corp Circuit breaker
US2624815 * 7 May 1945 6 Jan 1953 Westinghouse Electric Corp Circuit breaker
US2624816 * 9 May 1945 6 Jan 1953 Westinghouse Electric Corp Circuit breaker
US2631208 * 19 Apr 1951 10 Mar 1953 Gen Electric Electric circuit breaker
US2673263 * 18 May 1951 23 Mar 1954 Gen Electric Thermomagnetic electric relay
US2696540 * 27 Jan 1950 7 Dec 1954 Fed Electric Prod Co Automatic circuit breaker
US2696541 * 19 Feb 1953 7 Dec 1954 Bulldog Electric Products Co Circuit breaker
US2716679 * 11 May 1954 30 Aug 1955 Wadsworth Electric Mfg Co Circuit breaker
US2738393 * 12 Mar 1952 13 Mar 1956 Cutler Hammer Inc Circuit breakers and the like having power elements
US2824191 * 5 Feb 1953 18 Feb 1958 Fed Electric Prod Co Circuit breakers
US2866036 * 30 Nov 1955 23 Dec 1958 Crabtree & Co Ltd J A Electric circuit breakers
US3278707 * 22 Oct 1964 11 Oct 1966 Gen Electric Circuit breaker with ambient-temperature compensating means

Additional Bulldog & Pushmatic Circuit Breaker & Panel Patent Disclosures

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