GB640542A - Improvements in servo-brakes - Google Patents

Abstract

640,542. Fluid-pressure, brakes. SERVOFREIN DEWANDRE SOC. ANON. Jan. 9, 1948, No. 709. Convention date, Oct. 18, 1947. [Class 103 (i)] A fluid-pressure-operated servo-brake device, particularly for heavy vehicles, of the type operating by means of a system of floating levers similar to that described in Specification 256,560, [Class 103 (i)], is characterized in that a reaction or valve-operating piston 18, subjected to the pressure of fluid in the brakeoperating cylinder 4, transmits to the brake control member 35 a force opposite in direction to that applied to the member 35 by the operator, thus providing " feel ". The device comprises a balance lever 33 connected by one of its ends 30 to the brake-operating piston 3 and by its other end 34 to the control member 35, the lever 33 being pivoted with limited radial clearance about a fixed pivot 28, so that when the brakes are actuated, the dis, placement of the lever 33 in relation to the pivot 28, through the medium of the piston 18, operate pressure fluid supply and exhaust valves 11 and 13, the piston 18 being connected to the balance lever 33 at the level of its pivot 28. The exhaust valve 13, which controls the escape of fluid by passages 23 and 24 in the piston 18, is mounted on a spring-loaded member. The end 13<SP>1</SP> of which operates to open the supply valve 11. Compressed air, hydraulic or any other fluid may be used for operation of the device.