GB1403149A - Tandem mastercylinder - Google Patents

Abstract

1403149 Pressure failure indicating in tandem master cylinders SOC ANON DBA 5 Oct 1973 [25 Oct 1972] 46636/73 Headings F2E and F2F A single piston 16, defining respective chambers 22, 24 for independent brake circuits, has a blind bore containing a floating piston 46, exposed on opposite surfaces to pressure of these chambers, and in use the piston moves an extension 50 between two limit positions, defined by abutments 72, 82, as a function of pressure imbalance between the chambers to operate electrical contacts to indicate the imbalance. The chambers 22, 24 are in constant communication with the respective brake lines shown notionally as F, F<SP>1</SP> and piston shoulders 34, 36 operate tilt valves 30, 32 to open communication to reservoirs R, R<SP>1</SP> when the piston 16 is not actuated. In one limit position, a head 70 of the extension 50 abuts the abutment 72 in the form of a plate insulated from the cylinder housing but electrically connected to an indicator. In the other limit position, a shoulder 56 of the head 70 abuts a washer 60 insulated from the housing by a washer 62 but connected to the plate 72 via a spring 78; here, the washer 60 is held via a ring 58 against the abutment 82, whereas in the first limit position the washers 60, 62 and the ring 58 are moved against the spring 78 away from the abutment 82 by a shoulder 54 of the extension 50.