GB1470764A - Servo motor operated friction brakes - Google Patents

Abstract

1470764 Multi-disc brakes; cooling; lubricating; change-speed control; hydrodynamic torque converters SRM HYDROMEKANIK AB 8 March 1974 [21 March 1973] 13599/73 Headings F2E F2D and F2W A multi-disc brake 32 provided for releasing a planet gear carrier from a stationary casing connected with a hydraulic torque converter 10 is actuated by a servo-motor 34 having a space 36 supplied with pressure oil when the brake 32 is to be actuated; when the brake 32 is actuated pressure oil is for a limited period fed to a space containing the discs of brake 32 by a pump cylinder 42 to build up a counter pressure to the servo-motor 34 and to lubricate and cool the discs and to thereby reduce the torque absorption capacity of brake 32 during the limited period. As shown, the space 36 communicates via a pipe 40 with an oil pressure source and one side of a piston 44 of the pump cylinder 42 is connected to the pipe 40 whilst the other side of piston 44 communicates through a maximum pressure valve and pipes 48, 50 to the space containing the discs. This space is also fed from a reference pressure oil source through a pipe 52 having a restriction 54. The maximum pressure valve comprises a spring 56 and a valve member 58 and a servo cylinder 60 is provided to block the maximum pressure valve and disconnect pipes 48, 50 when desired. When pressure oil is fed into pipe 40, the piston 44, provided valve member 58 is open, is displaced leftwards, forcing oil into the space containing the discs, thus building up a counter pressure to the servo-motor 34 and lubricating and cooling the discs which include grooves to increase resistance therebetween. The discs are alternatively attached to a brake housing 26 which is fixed to the stationary casing of the torque converter 10 and to ring 24 engaged by arms 23 which are mounted on the shaft of planet gears 22. A hub 21 engages teeth on the planet gears 22 and the hub 21 and a hub 17 are associated for rotation with a guide ring shaft 15. The shaft 15 is connected to a guide ring 14 supporting a ring of guide blades 13 in the torque converter 10. The torque converter 10 also includes a ring of pump blades 11 and two rings of interconnected turbine blades 12 connected to a turbine output shaft 16. The guide ring 13 may be locked to hold it stationary relative to the housing by the action of a piston 19 pressurized by fluid in a space 20 on an annular disc 18 movable on the hub 17. For hydraulic braking the brake 32 and the lock-up clutch are operated simultaneously-for driving purposes they function independently.