GB645085A - Improvements in or relating to a brush lifting mechanism - Google Patents

Abstract

645,085. Brush-gear for dynamo-electric machines. LELAND ELECTRIC CO. March 12, 1948, No. 7577. Convention date, Oct. 1, 1947. [Class 35] In a brush-lifting mechanism for a commutator motor, the brushes are carried on pivoted arms moved into or out of engagement with the commutator by over-centre springs, the ends of which are attached to a member guided by the pivot-pin and moving radially under the influence of the motor speed. Mounted around the shaft 11 are a series of centrifugal weights 12 which move outwardly against a band-spring 15 to short-circuit the commutator 13 at the desired speed. In the rest position, Fig. 4, the band-spring interlocks with a shoulder on a retaining-plate 18. A series of hinged weights 16 are connected to the short-circuiting weights 12 so as to move radially with them. Flanges 17 on weights 16 are arranged to form a substantially continuous annular flange engaging a slot 47 in an adjustable insulating member 46 connected to the brush-lifting mechanism. The brush supporting arms 25 are both pivoted on a stud 22 and each one is in the form of a bell-crank having a lever 32 on the opposite side of the stud, on which the over-centre spring 50 acts to raise or lower the brush with a snap-action under the influence of a link 40. The motion of the arms is limited by pins 35 engaging holes 36 in the arms. The link 40 slides vertically on the stud 22 and is pivoted at 42 to a lever 44 pivoted at 45 and carrying the insulating operating arm 46 which is moved by the weights 16.