GB1335916A - Pneumatic anti-skid devices - Google Patents

Abstract

1335916 Anti-skid device KNORR-BREMSE GmbH 19 April 1971 [7 Feb 1970] 21288/71 Heading F2F A pneumatic anti-skid device for use in a vehicle braking system which has a skid-sensing means connected to the device is, in use, connected in the braking line and allows braking pressure build up for normal braking applications until a skid is sensed whereby the device brings about a throttled reduction of braking pressure and then permits a subsequent increase in braking pressure at a rate less than the build up of braking pressure during normal brake applications. These steps are effected by a first valve 44, 46 and a second valve 13, 27. In the construction shown the device is in its rest position whence fluid pressure can pass through chambers 12, 14, 36 and 48 to normally apply a brake through an actuator 52. The skid sensing means 78 on sensing a skid activates the solenoid 80 of a solenoid actuated valve member 68, 73 so that the member moves to stop venting of a chamber 40 to atmosphere and apply to the chamber 40 reservoir pressure. This actuates a piston 39 with the resultant opening and closing respectively of a series of valves including valve 44, 46 so that pressure medium in the brake actuator may pass through a throttle 47 in the piston 39 to atmosphere to provide the throttled reduction of braking pressure. At the same time a chamber 5 is pressurized so that a piston 3 is actuated on extension 13 of the piston-rod 10 thereof throttling the passage between the chambers 12 and 14 so that, on deactivation of the solenoid and return of the parts at the right hand side of the device as seen in the drawing to their rest positions a throttled brake application is effected until such time that a chamber 24 which is connected to the chamber 48 reaches such a pressure that a piston 23 is actuated to bring about the cutting off of communication between the two chambers 12 and 14. A stable braking pressure lower than that originally applied is thus achieved. After a time pressure acting in chamber 5 will reach a value due to a throttle 61 which communicates with the atmosphere that the piston 3 will be urged by the spring 6 to its rest position and thus allow a further build up of braking pressure. The piston-rod 10 and extension 13 may be provided with a variably throttled passage 19, the throttling member being adjustable through an opening in the housing 2 of the device, the opening normally being closed by a screw 81. The pressure operating cycle is depicted in Fig. 2 (not shown).