GB860516A - Improvements in or relating to air pressure braking systems - Google Patents

Abstract

860,516. Fluid-pressure brakes. CLAYTON DEWANDRE CO. Ltd. Nov. 13, 1959 [Aug. 13, 1958], No. 26032/58. Class 103 (1). An air-pressure braking system comprises a compressed air reservoir having one end of annular form enclosing a servomotor and control valve, the thrust of the servo-piston being transmitted to a master cylinder supported coaxially of the servomotor-reservoir assembly, and the valve being actuated by a lever mechanism from a pedal. The end wall 2 of reservoir 1 forms the servomotor cylinder 3 containing a piston 6 connected via yoke 7 and rod 8 to the piston 9 of a master cylinder 5 attached to the servomotor cover-plate 4. The piston 6 has a chamber 15 containing a diaphragm 16 connected via rod 17 and pin 27 to a lever 24 pivoted at 25 to plate 4 and connected to a foot-pedal via rod 26. A sleeve 20 fixed to diaphragm 16 slides in a housing 18 on piston 6 and includes a valve disc 21 normally biased against a seat 23 formed on an extension 19 of housing 18 and spaced from a seat 23 formed on sleeve 20. In the release position, as shown, atmosphere is communicated through rod 17 to chamber 15, pass seat 23 and ports 30 to the rear servomotor chamber and via port 31 to the front of diaphragm 16. On brake application, rod 26 rotates lever 24 to shift rod 17 and diaphragm 16 to the left to first engage seat 23 on disc 21 and then raise disc 21 from seat 22 to admit compressed air to the rear chamber via extension 19 and port 30 to move piston 6 and operate master-cylinder 5. Compressed air passes through port 31 to act on diaphragm 16 against movement of rod 17 to transmit " feel " to the pedal. A lap position is eventually reached wherein disc 21 engages both seats 22, 23. On failure of the servomotor the master cylinder can be operated manually when rod 17 abuts yoke 7.