Patent GB-1488119-A (GB)
Title: Hydraulic braking systems for vehicles
IPC: B60T13/12
Filed: 1973-10-02
Abstract: 1488119 Hydraulic braking systems GIRLING Ltd 23 Sept 1974 [2 Oct 1973] 46033/73 Heading F2F An hydraulic braking system comprises two separate independent and unconnected supplies of hydraulic fluid under pressure 4, 5, and a pedal-operated dual booster valve assembly 6 for controlling the supplies separately to at least one booster operated master cylinder which is connected to at least one brake actuator. In the embodiment of Fig. 1 there are provided three booster-operated master cylinders 1, 2, 3 having respective boosters 10, 11, 14. The booster valve assembly 6 has independent valve assemblies 7, 8, and the supply 4 is controlled by assembly 7 to actuate the boosters 10, 11 and the supply 5 is controlled by the assembly 8 to actuate the booster 14. Each master cylinder is of the single pressure space hydrostatic type-the pressure space of master cylinder 1 is connected to a brake actuator 16 on the front wheel 17, the pressure space of master cylinder 2 to a brake actuator 19 on the other front wheel 20, and the pressure space of master cylinder 3 is connected to brake actuators 22, 23 on the rear wheels 24, 25. The pressure spaces of the master cylinders 1, 2 form one brake circuit and the pressure space of the master cylinder 3 forms a second brake circuitrespective reservoirs 66 are provided for the two circuits. In the modification of Fig. 2 the master cylinder 1 is of tandem construction with pressure spaces 27, 28 connected respectively to rear brake actuators 22, 23 and master cylinders 2, 3 are connected respectively to actuators 16, 19. The valve assembly 7 controls the supply 4 to boosters 10, 14 through a connection 33. The valve assembly 8 controls the supply 5 to booster 11 and to booster 10 independently of the supply 4 via connections 34, 35 respectively. In the modification of Fig. 3 (not shown) the master cylinder 3 is also of tandem construction with two pressure spaces (36, 37). Each front wheel has two actuators (38, 39; 40, 41) and the pressure spaces (27, 28) of master cylinder 1 are respectively connected to the actuators (38, 39) of one front wheel (17) and the pressure spaces (36, 37) are connected to the actuators (40, 41) of the other front wheel (20). The pressure space of the master cylinder (2) is connected to the rear wheel brake actuators (22, 23). All three boosters (10, 11, 14) are operable from the supply 5 while the boosters (10, 14) are also operable independently by the supply (4). In the modification of Fig. 4 (not shown) the master cylinder 2 is also of tandem construction and its pressure spaces (49, 50) are connected to brake actuators (40, 41) on the front wheel (20). The pressure spaces (36, 37) of tandem master cylinder 2 are each connected to pairs of brake actuators (53, 54) on the rear wheels (24, 25). The booster (11) is also supplied with fluid from supply 4 and, independently, from supply 5. In the embodiment of Fig. 5 (not shown) the pressure spaces (27, 28) of master cylinder 1 are connected respectively to brake actuators (58, 59) on the rear wheels (25, 24) respectively, the pressure spaces (49, 50) of master cylinder 2 are connected to the brake actuators (38, 39) on the front wheel (17), and the pressure spaces (36, 37) of master cylinder 3 are connected to the brake actuators (40, 41) on the front wheel (20). Any or all of the systems may include antiskid control means, e.g. the master cylinder assemblies may include modulator pistons as described in cognate Patent Application 57887/72, 15597/73 and 35393/73 Serial No. 1,451,314 or in Patent Application 1,488,118.