GB1035138A - Hydraulic braking system incorporating a booster - Google Patents

Abstract

1,035,138. Fluid-pressure brakes. GIRLING Ltd. June 4, 1965 [July 1, 1964], No. 27075/64 Heading F2F. In an hydraulic braking system employing a tandem auxiliary cylinder 21 the primary piston 22 of which is operated by a vacuum booster 26 controlled by hydraulic pressure produced by a tandem master cylinder 10, the arrangement is such that the booster control valve is sensitive to the pressure of fluid in either or both pressure spaces 14, 17 of the master cylinder. These pressure spaces, which are respectively supplied by separate reservoirs 15, 18 via a tiltable replenishing valve 16 and a valve 19 which is controlled by the secondary piston 13, are respectively connected via pipes 31, 48 to the secondary chamber 29 and to the space behind the primary piston 22 of the auxiliary cylinder, and also to chambers on opposite sides of a floating piston 51, whereby the pressure in either or both of the spaces 14, 17 acts on a differential control piston 45 whose other, smaller diameter, end is acted on by the corresponding output pressures in chambers 29, 32 which act on opposite sides of a second floating piston 54, via passages 33, 36. Pipes 35, 37 connect the outputs of the auxiliary cylinder respectively to the front and rear brakes of a vehicle, or alternatively to separate cylinders acting on the same brakes. The control piston 45 acts on the stem of a T-shaped member 44 carrying poppet valves 39, 41 controlling respectively a vacuum supply line 42 from the front chamber of the booster and an atmospheric air supply pipe 43, whereby either vacuum, in the unboosted condition, or air, when the booster is to be actuated, is communicated via pipe 38 with the rear chamber of the booster. When the booster is actuated it causes piston rod 25 to close recuperation port 24 in the primary piston 22, while subsequent movement of secondary piston 23 causes recuperation valve 27 to close.