GB1124650A - Motor vehicle brake system - Google Patents

Abstract

1,124,650. Anti-skid braking system; drum brakes. FORD MOTOR CO. Ltd. 8 Sept., 1966, No. 40215/66. Headings F2E and F2F. A motor vehicle anti-skid braking system includes a sensor device acted upon by a force which varies with the limiting friction between a friction member and a part rigid with the vehicle wheel and a force dependent upon the actual frictional force between those parts, the arrangement being such that when the limiting friction dependent force overcomes the force dependent on the actual friction force the sensor reduces the pressure in the brake application line. The sensor 9 is disposed between a master cylinder 1 and the drum brake actuator 17 and is further supplied with fluid under pressure from the leading shoe abutment piston and cylinder device 25. While the wheel is rotating the pressure generated in cylinder 25 increases with increase of pressure supplied to the actuator 17. When the wheel locks the frictional force between shoe and drum remains constant but the rising force as an increased pressure is applied to actuator 17 causes sensor plunger 35 to move leftwards, cutting off communication between the master cylinder and the line 52 leading to the brake actuator, the increase in volume to the right of the plunger causing a fall in the pressure in line 52. To prevent the device operating when the vehicle is moving in reverse a rod 45 co-operates with a passage 43 in the plunger to block that passage when the vehicle is moving in a forward direction but to open the passage when the vehicle reverses and no pressure is experienced in line 57 and allow the master cylinder pressure to pass to line 52 despite the leftward movement of plunger 35. In another embodiment (Fig. 6, not shown), both wheels of an axle are provided with cylinders 25; these are connected to the sensor 9 through a valve which operates to connect the cylinder delivering the lesser pressure to the sensor.