GB1245542A - Improvements in mastercylinders for hydraulic brakes of motor vehicles - Google Patents

Abstract

1,245,542. Master cylinders. J. WODESLAVSKY. 11 April, 1969 [12 April, 1968], No. 18781/69. Heading F2F. A master cylinder 1 for the hydraulic brakes of a motor vehicle comprises chambers E, D for hydraulic liquid for the supply of liquid to the braking systems of the front and rear wheels of the vehicle, and two pistons 2, 3 positioned one behind the other and working in the bore of the master cylinder. The piston 2 at the front end of the master cylinder is adapted to open and close the liquid supply from the chamber D to one of the braking systems B and the other piston 3 opens and closes the liquid supply from chamber E to the other braking system A. The chamber D is connected directly to the braking system B and the other chamber E is connected to the other braking system A through a bore M in the wall of the body of the master cylinder and a bore K in the body of the piston 2, each of the pistons being adapted to interrupt the flow of liquid from one of the chambers when a defect occurs in the mastercylinder or a leakage occurs in the conduit to one of the braking systems, while permitting the other braking system to operate normally. As shown, the piston 2, 3 have recesses 2<SP>111</SP>, 3<SP>11</SP> in which are slidable rods 2<SP>11</SP>, 8, which may be of equal length, carrying piston heads 4<SP>1</SP>, 4 in housings 4<SP>11</SP>, 5 biased relative to the heads by springs 4<SP>111</SP>, 6. The spaces G, F communicate with outlets B, A connected to braking systems for the front and rear wheels respectively of a vehicle. In operation, when pressure is applied by a brake pedal and piston 3 moves in direction of arrow 3<SP>111</SP>, the head 4 of the piston closes the bore K to prevent flow of liquid from chamber E into space F, further movement of the pedal causing the head 4<SP>1</SP> of piston 2 to close the bore H between the chamber D and space G so that pressure is generated in the brake systems connected to outlets A, B. In the event of leakage occurring in, e.g. the system connected to outlet A the pressure exerted by the brake pedal pushes the piston 3 against bore K and piston 2 when the latter closes the bore H, so the pressure is maintained in the system connected to outlet B whereby the front wheel brakes are operated. Similarly, pressure is maintained in the braking system A to operate the rear wheel brakes when leakage occurs in the system B, the piston head 4<SP>1</SP> closing the bore H. In a modification, separate fluid chambers E, D communicate directly with the spaces G, F.