GB682361A - Improvements in and relating to centrifugal electric switches applicable to speed governors - Google Patents

Abstract

682,361. Centrifugal switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 6, 1950 [Dec. 24, 1949], No. 29884/50. Class 38 (v) A centrifugal switch for use as a speed governor in an electric motor driven device, such as a food mixer, has a stationary contact assembly adjustable for position and a rotating element expansible by centrifugal force and embodying its own biasing means. The contact assembly comprises a rigid blade 27 carrying a contact 28 and a resilient spring blade 29 carrying a contact 30, the blades being carried by an L-shaped bracket 20 having a limb 21 slidable in an extension 24 of the motor housing. A spring 32 maintains the end of the limb 21 in contact with a cam 19 which may be turned by a knob 9 to adjust the position of the contact assembly relative to the rotary element to set the speed at which the switch operates. The rotary element comprises a cupshaped member 35 secured to the motor shaft 45 and containing balls 36 interposed between an internal dished face 37 of the member 35 and a corresponding face 39 of a longitudinally-slidable member 38 which has a finger 40 co-operating with the spring blade 29. As the shaft 45 rotates, the balls move outwardly and cause the member 38 to move to the left against the bias of a spring 42, the pin 40 opening the contacts 28, 30 at the desired speed. The spring 42 is interposed between the member 38 and a nut 43 rotatable in the member 35, the nut being adjusted and locked during manufacture of the switch- The member 38 is supported and located solely by the spring 42 and the balls 36 and has no frictional engagement with any other rotating part.