GB850809A - Improvements in or relating to dynamo-electric machines incorporating brakes - Google Patents

Abstract

850,809. Electromagnetic brakes. CLEVELAND ELECTRIC MOTOR CO. July 29, 1957 [Aug. 17, 1957], No. 24013/57. Class 103 (1). [Also in Group XXXV] In a dynamo-electric machine having a stator 9 surrounding a rotor 8 on a shaft 7 rotatably mounted within a supporting structure 1, 2, 5, 51, a plunger 12 mounted on the shaft for movement into and out of a position in which the plunger adjoins the rotor, and stationary and movable brake. friction surfaces on the structure and plunger respectively, a permanent magnet assembly 21, 23 is incorporated in the plunger itself to urge the plunger towards the stationary braking surface. As shown applied to a squirrel cage type motor, the plunger preferably of cast iron is caused to rotate with the rotor 8 by rotor pins 18 on which plunger bores 19 are slidable and its frusto-conical end surface 12b engages when the motor is at rest a complementary brake lining 15 comprising four trapezoidal segments disposed in mutually reversed relation and cemented by an epoxy resin adhesive to a flange 4 of a housing extension 2. When the motor is energised its stator flux disengages the brake plunger to the position shown, but when it is de-energised a compression spring 14 effects initial movement to the left, whereupon the magnet 21 becomes effective with respect to a pole piece 26 and quickly engages the braking surfaces. Magnet 21 is either annular or comprises a plurality of equi-spaced permanent magnets and the plunger 12 itself also may be magnetised, the magnetisation of both being effected after the annulus 21 is cemented into the plunger 12 by a jacket 23 preferably of a cured epoxide resin. The position of the pole piece 26 is adjustable by screws 31 and others not shown. Specification 850,810 is referred to.