GB423954A - Hydraulic brake system - Google Patents

Abstract

423,954. Fluid - pressure brakes; pistons. WHITE, J. W., 18965, Muirland Avenue, Detroit, Michigan, U.S.A. Aug. 21, 1933, No. 23244. [Class 103 (i)] [See also Group XXVI] A hydraulic brakeoperating device comprises a flexible cup secured to a cylinder and having a dome-shaped portion which engages a piston and which is curved to a greater radius than its cylindrical wall. As shown, a pair of cylinders 15 are screwed into a member 14 secured, for example, to the back plate of an internal expanding brake. A pair of cups 22 of rubber or other flexible material have their edges 23 clamped between the cylinders 15 and an annular flange 24 on the member 14 and bear upon pistons 19 sliding in the cylinders 15. The pistons have projections 20 which pass through the ends of the cylinders 15 and abut on the heads 10<1> of adjusting screws 10 mounted in the upper ends of a pair of operating levers 5 pivoted at their lower ends on the back plate. These levers each carry a brake shoe. The member 14 has lugs 16, 17 projecting through the back plate 6 and one of these carries a fixing nut 18. Supply and bleed passages 25, 30 pass through these lugs and connect with an annular groove 27 in the member 14. To reduce the fluid capacity of the device a filler 28 of, for example, sheet steel is provided. The central portions of the cups 22 is of a flattened dome shape so that during the initial stage of an application, due to the tendency of the cups to assume a hemispherical form, the cups draw away from the cylinder walls and from the peripheral part of the pistons and then as the pressure increases stretch and again contact with the whole surface of the piston. A cushioning action is thus obtained.