GB992928A - Improvements in and relating to fluid pressure operated valves controlling the operation of servomotors - Google Patents

Abstract

992,928. Fluid operated brakes. AUTOMOTIVE PRODUCTS CO. Ltd. March 31, 1964 [April 4, 1963], No. 13422/63. Heading F2F. A valve controlling operation of a servomotor of an air or vacuum-suspended type comprises an actuating rod 6 associated with a piston 11 operable by fluid pressure in the master cylinder and a lever 13 operable by the master cylinder piston 18 in event of a fluid pressure breakdown therein to effect mechanical operation of the actuating rod 6. Two servomotors (not shown) are independently controlled by two valves 52, 61 arranged in tandem in a casing 7 which is attached off-set to the line of the master cylinder bore 9 so that the motor 11 intrudes beyond the end chamber 8 thereof. The lever 13 is a metal plate held at the end of the bore 9 by the reverse side of an end-cup 14 supporting the return spring 17 and has its end bent at 15 so that it pivots on the cylinder wall. In event of a pressure break-down the piston 18 travels beyond its normal stopping point and a projection 19 on its end causes the lever 13 to actuate the rod 6. The casing 7 is divided into two chambers 38 and 39 by an annular flexible diaphragm 35 supporting a tubular bush 36 with a central rubber disc 37. The chambers 38 and 39 each contain a sleeve 41, 42 supported on a flexible diaphragm 43 and slidable through a lip-seal 45 retained by a washer 46 to form two further chambers 47 and 48. Blocks 47a and 48a slide in bores in the sleeves 41 and 42 and limit axial movement of the latter by engagement between shoulders 49 and 50. The outer ends of the blocks 47a and 48a form seatings for disc valves 52 and 61 which are normally closed by springs 54 and 63 so that the chambers 48 and 49 are isolated from the chambers 38 and 39. The chambers 38 and 39 connect with the two servomotors and are themselves interconnected and the chambers 47 and 48 are open to atmosphere (Fig. 1, not shown). The rod 6 and another rod 57 have ball ends 58 which engage in recesses in the blocks 47a and 48a, the end of the rod 57 being supported against the wall of the casing 7. When the rod 6 is moved axially it opens the valve 61 to admit air to the chambers 38 and 48, thereby operating the servomotors. The rubber disc 37, compressed between the blocks 47a and 48a, provides " feel " when the rod 6 is being manually operated to apply the brakes. The master cylinder is pedaloperated. To provide power operation to assist the hand-brake a bell-crank lever 20 is pivoted to a bracket on the casing 7 at 21 engaging one end behind a shoulder 25 on the rod 6 and can be operated by a Bowden cable 30 to move the rod 6 independently of the master cylinder.