GB874968A - Improvements in vehicle braking - Google Patents

Abstract

874,968. Hydraulic braking systems. REGIE NATIONALE DES USINES RENAULT. Sept. 18, 1958 [Sept. 19, 1957], No. 29941/58. Class 103 (1). An hydraulic braking system for a vehicle comprises a pressure source, such as master cylinder 2 controlled by a driver's brake pedal 1, first and second ducts 5 and 23 leading from the source and respectively serving for feeding pressure fluid to the front and rear brakes of the vehicle for braking purposes, a valve in one of said ducts and hydraulic means connected to vary operation of the valve in accordance with the loading of one end of the vehicle thereby to establish a variable ratio between the front braking and rear braking of the vehicle in accordance with the loading conditions of the vehicle. When, with the rear of the vehicle lightly loaded so that the thrust from spring 20 is low, the force exerted by the driver exceeds a particular value, the pressure of the liquid will be sufficient to force down valve 19, which progressively closes the duct 5. The differential piston 24/25 is displaced to the right and the initial pressure existing in cylinder portion 22<SP>1</SP> will be reduced in the cylinder portion 222 in proportion to the ratio of cross-section of the differential piston 24, 25 so that the braking action on the rear wheels will be less vigorous under small loads than under heavy loads. In accordance with the load on the rear wheels, as determined by movement of the vehicle chassis, the right-hand end of lever 10 is moved so that its other end by operation of piston slide valve 7 causes a corresponding displacement of the piston 11 which alters the compression of spring 20. As the load on the rear wheels increases, it therefore requires an increased pressure in chamber 22<SP>2</SP> to depress the valve 19 sufficiently to obstruct the conduit 5 and with high rear wheel loading the pressure in conduit 23 becomes substantially equal to that in conduit 4 leading to the front wheels.