GB1455826A - Valve devices for use in liquid pressure braking systems - Google Patents

Abstract

1455826 Valves; fluid-pressure brakes AUTOMOTIVE PRODUCTS Ltd 12 Dec 1973 [13 Dec 1972 9 July 1973] 57508/72 and 32678/73 Headings F2V and F2F A valve device comprises an inlet C and straight-through outlet D connected in the hydraulic circuit of the front brakes (12) of a vehicle (Fig. 1, not shown) such that fluid pressure acts on a piston component 45; an inlet A and an outlet B controlled by a valve member 39 and seat 38 connected in the hydraulic circuit of the rear brakes (13), the seat forming part of a stepped piston 28 which is connected to the piston component by a bolt 51; and biasing means 52 which tends to open the valve member by facing a stem 43 against a stop 42, and opposed by the pressure in the cavity 57 of the front brake circuit. The biasing means overcomes the resultant fluid pressure exerted by the rear brake circuit on the stepped piston 28 and front brake circuit up to a predetermined value so that the front and rear pressures generated by the tandem master cylinder (18, 17) are equal. Thereafter the valve member seats and opens proportionately with increasing master cylinder pressure. If the sub-system operating the front brakes fails, the effective thrust of spring 52 is increased and the predetermined value at which the valve device acts proportionately is automatically increased. The piston component may be made slidable on a stem of the stopped piston (Fig. 3, not shown) or may be made separable and abutting it (Fig. 4, not shown). The biasing means may be a spring varying with the vehicle load (Figs. 5, 6, not shown) or fluid loading varying with vehicle load (Figs. 7, 8, not shown).