GB1207264A - Brake systems - Google Patents

Abstract

1,207,264. Vehicle braking systems; valves. WESTINGHOUSE BREMSEN UND APPARATEBAU G.m.b.H. 7 Feb., 1968 [16 Feb., 1967], No. 6107/68. Headings F2F and F2V. In a vehicle fluid-pressure braking system the braking force is transmitted unchanged to the wheels of an axle other than the front axle, but the force to the front wheels is reduced by a regulator whose output/input ratio is less than unity for lower degrees of braking and greater than unity for higher degrees of braking. In the case of a multi-axle vehicle, e.g. a tractor/ trailer, the braking force is preferably unchanged to all the wheels other than the front wheels. Fig. 1 shows a suitable regulator for a compressed-air system. When the brake valve (not shown) is operated, compressed air enters via 2 into a chamber 6 and thence (a) through valve 17 and hole 14 into a chamber 13 and (b) through pipe 18 into chamber 19. The regulating element comprises a piston 7 carrying a diaphragm 8 abutting radial ribs 9 on the piston 7. The increase in pressure in chamber 13 forces the piston upwards until the diaphragm 8 touches the lower sloping surfaces of radial ribs 11 on the housing 3, these ribs being interleaved with the ribs 9 on the piston (Fig. 2, not shown). The valve 17 is now closed by the piston 7 abutting a valve member 15, and air can no longer flow from chamber 6 to chamber 13. The pressure in the latter is less than that in chamber 6 since the lower surface of the diaphragm 8 is of greater area than the upper surface of the piston. Each increase in inlet pressure opens the valve 17 for a short time until the given ratio of pressures in chambers 13 and 6 has been restored. At a higher level of inlet pressure a piston 20 is raised against a spring 21 by the pressure in chamber 19. The top of piston 20 raises the valve seat 15 so that the equilibrium position of piston 7 is higher. Increase of input pressure thus forces more and more of the diaphragm 8 against the ribs 11 and changes the ratio of pressures in chambers 6 and 13. Eventually the effective areas of both sides of the piston become equal and the pressure transmitted to the brakes via outlet 4 becomes equal to the input pressure. The spring 21 is located in a chamber 25 which is connected to the atmosphere via a release aperture 27 fitted with a cover 26. The chamber 28 above the diaphragm 8 is connected to the atmosphere via a filter 29. The maximum pressure may be limited by an adjustable stop which prevents the valve seat from rising beyond a predetermined position (Fig. 4, not shown).