Patent GB-909176-A (GB)
Title: Improvements in or relating to electro-mechanical brakes
Inventor: ROLAND KOEHLI
IPC: F16D65/28
Filed: 1960-09-01
Abstract: 909,176. Electromagnetic brakes. INVENTIO A.G. Sept. 1, 1960 [Sept. 2, 1959], No. 30175/60. Class 103 (1). [Also in Groups XXIV and XXXVII] In a spring-applied brake comprising brake shoes mounted on brake levers which are released by an electric motor, the speed of release and brake applying movements are adjustable, a gear arrangement being provided between the brake applying levers and the motor, the gear arrangement being operable in one sense of rotation for a release movement and in the opposite sense of rotation for a brake applying movement, contact control means being provided for interrupting current to the electric motor when the brake is in its fully released position. In the diagrammatic representation in Fig. 1, the external shoe-drum brake 1, 2 is applied by springs 7 acting on brake levers 4 pivoted at 5 and is released by an electric motor 8 acting through gearing 9, and an electromagnet dog clutch 10, a rotatably mounted lever 11 and two rods 13 so that the brake levers 4 are released through adjustable rings 14 and spring 15. A cam disc 16, forming the contact control means, is connected to the secondary side of the clutch 10 for co-operation with two double pole switches 17, 18. The electrical control arrangement is shown in Fig. 2, wherein a three-phase main supply RST serves for energizing the brake release motor 8 and D.C. terminals plus and minus serve for energizing electromagnets 20, 19. In operation, when the brake is to be released, the control switch 21 is closed to close auxiliary contact 20.2 and energize clutch 10 and switch-over contacts 20.1 (switch 17 being closed), the motor being energized to release the brake. When switch 17 is interrupted by cam disc 16 the motor 8 is de-energized. When the brake is to be applied, the control switch 21 is opened to open auxiliary contact 20.2 and a magnetic field is maintained in the clutch by unilateral conductor 22 and closed contact 19.1. Switch 18 is closed and the motor is energized in an opposite direction to apply the brakes at a predetermined speed through brake applying springs 7. Fig. 4 shows an alternative embody ment of the brake in which brake shoes 34, pivoted at 35, are urged into contact with the brake drum by means of springs 37 and provided at the ends of a rod 36. Mounted on the rod 36 is a displaceable casing 38 provided with a worm 40 driven by an electric motor 58 a toothed segment 41 meshing with the worm 40. Rotation of the segment in a clockwise direction causes a plunger 44 to be displaced towards the right and move brake lever 34 carrying a resilient arm 46 away from the brake drum 31. Also in the casing 38 is an electromagnet 51 which is energized simultaneously with the motor 58 to attract armature plate 52 which has a shaft 53 attached to it ; the other end of the shaft 53 engaging an adjustment screw 57 attached to the other brake lever 34. Rotation of the motor shaft 59 causes a nut 61 to be displaced in one or other sense along the spring 60 and operates a number of contacts 63 by means of a projection 62. The contacts 63 stop the motor in both end positions. An additional magnetic brake 64 is provided for braking the motor 58 and is released by the motor.