GB782889A - Improvements in or relating to centrifugal governor-controlled electric switches - Google Patents

Abstract

782,889. Speed-responsive switches; switch cases. GENERAL MOTORS CORPORATION. June 1, 1956, No. 16975/56. Class 38 (5). A centrifugal-governor controlled switch device wherein a sleeve mounted coaxially on a rotatable shaft is moved axially by flyweights on the shaft, has first and second resilient members arranged to oppose initial and further motion, respectively, of the sleeve, and at least two switches operable sequentially by the initial and further movements of the sleeve. A shaft 17 adapted to be driven from its squared end 18 or counter-bored end 19, is supported at its former end in a bearing, the outer race 22 of which is received in a bushing 30 secured, together with a housing 76, by screws 36 to the casing. The bushing 30 has stepped portions 34, 35 serving as supports for, respectively, a low-rate spring 70 and a high-rate spring 72, the latter being pre-stressed and bearing against a thrust-washer 78 in the housing 76. The other end of shaft 17 carries a flange 48 on which are three pairs of spaced arms 50, each pair having a bearing pin 54 and ball-race supporting a governor flyweight 52. Surrounding shaft 17 and fitting lightly frictionally over sleeve 33 of bushing 30 is an axially-movable sleeve 60 with a flange 74 engaging the springs 70, 72 at low and high speeds, respectively, and a flange 61 on which is threaded an annular switch operating member 62. The other end of the sleeve 60 supports a ball-bearing, the outer race 65 of which is supported within and by the inwardlyfacing edges of arms 50 so as to rotate with the latter and move axially under the action of projections 69 on the flyweights 52. Two microswitches (only one being shown at S-2, Fig. 1) are mounted on one side of the operating member 62 so as to be operated at low speed by the member 62 moving away from their actuating members, and two further ones S-3, S-4 are mounted on the opposite side for operation at high speeds, all being of identical construction. Thus, a bracket 83 fixed on the base 82 is apertured to pass an operating member 84 which engages and supports one end of a contact arm 85 that straddles the bracket 83. An integral leaf-spring 86 on the contact arm engages the bracket 83 and causes the switch to operate with a snap-action as the upper end of arm 85 moves from one side to the other of the fulcrum. The bases 82 of the switches are adjustable by rotation of their fastening screws 102, and springs 106 take the thrust of the sleeve 60 during operation. In order to prevent undue rotation of sleeve 60 due to friction drag at the bearings, the member 62 thereon carries a pin 110 which engages a torque arm 112 pivotable about a pin 114 in the casing as the sleeve 60 moves axially.