GB403668A - Improvements in brake mechanism for vehicles and the like - Google Patents

Abstract

403,668. Fluid-pressure brakes. JOHNSON, M. E., and FEENY & JOHNSON, Ltd., 134, Ealing Road, Wembley, Middlesex. June 27, 1932, No. 18097. [Class 103 (i).] The pressure in a fluid-pressure brake system for vehicles of the kind in which fluid is expelled from a pedal &c. operated cylinder to brake operating cylinders actuates a valve that renders operative a vacuum or pneumatic pressure power cylinder that acts to increase the pressure in the system or to apply other brakes. In Fig. 1, the master piston g of a hydraulic system is operated by the pedal a and levers c, e and the conduit leading to the brake cylinders is connected also by pipe k to a valve device l comprising a piston p, carrying valves q, r that control the connections n, m, t leading respectively to a servocylinder o, a vacuum source, and the atmosphere. The valves q, r are normally held in the position shown by a spring a acting on a plunger s. When in applying the brakes, the pressure in the pipes j, k is sufficient to overcome the spring u, the valves q,r are operated, vacuum being established in the cylinder o dependent upon the degree of opening and closing of the valves q, r respectively. The cylinder applies additional pressure to the piston g, by the lever c<1>. The servo-cylinder may act upon a piston in a separate cylinder communicating with the hydraulic system. The pressure in the hydraulic system of a tractor vehicle may in a similar manner bring into operation a servo-cylinder that is provided on and operates the brakes on a trailer vehicle. Specification 354,842 is referred to. According to the Provisional Specification, the servomotor may be connected to the pedal through a floating lever and the servo-motor may be in the form of an engine-driven pump adapted to force oil into the system under the control of a valve operated by the pressure of the oil in the system.