Patent GB-313079-A (GB)
Title: Improvement in brake system for automotive vehicles
IPC: B60T13/24
Filed: 1929-05-27
Abstract: 313,079. Bragg, C. S., and Kliesrath, V. W. June 6, 1928, [Convention date]. Fluid - pressure. - Fluid-pressure brake mechanism for automobiles comprises a valve casing containing valves exposed to substantially the same pressure differences as the brake cylinder, connections from the valve casing and the valves, one to a part of the vehicle and the other to the foot pedal and yielding means, as a spring in a connection to the casing, the arrangement being such that the tension of the spring, increased by operation of the valve, is overcome by the pressure differences produced in the valve in order to re-close the valve. In an arrangement in which the brake piston is normally submerged in atmospheric air the valve comprises a casing 6, Fig. 2, connected to a single-acting brake cylinder by a pipe 14. Longitudinal movement of the handle 80 by the operator to apply the brakes closes a disc valve 10 against a diaphragm 8 to close the brake cylinder from the atmospheric ports 18, 19 and raises the diaphragm from a seat 11 to connect the brake cylinder to the suction chamber 12 and pipe 32 leading to the induction pipe of an internal-combustion engine. The valve casing is mounted in a pivoted yoke 530, Fig. 15, having an adjustable stop 535 and is connected to a fixed part by a spring 50, Fig. 2, which is tensioned on valve operation. The partial vacuum introduced into the chamber 13 of the valve causes the diaphragm to reseat and maintain the brakes applied at a desired pressure and also produces a reactionary effect on the operating-handle. Brake application may thus be graduated as may brake release and leakage of air to or from the brake cylinder is automatically compensated. A locking means for the handle 80 is shown comprising a mutilated thread 85 on the stem 82 and in the collar 86, which threads can be engaged by turning the handle 80, which is connected to the diaphragm by a ball joint 83. In a modification, the spring may be arranged between a foot-operated pedal and the valve casing and the valve operating part is fixed to the vehicle, a rod also loosely connects the pedal and the valve casing, which forces the valve into release position. In an arrangement using this modification on a trailer the valve-operating part is directly connected to the brakes of the tractor and the foot pedal is also connected to the valve casing by a pin and slot to allow these brakes to be applied manually when the tractor brakes, which are controlled by the valve, have been fully applied. In further modifications the brake pistons are submerged in vacuum and a valve is used in which the chamber 206, Fig. 10, is permanently connected to vacuum through apertures 207, 219 and the interior 210<b> of the disc valve 210 is permanently connected to atmosphere by means of apertures 218 in the hollow valve stem 220. The brake cylinder is double acting and one side of the piston is connected permanently to vacuum, the other side being connected to vacuum through the valve in release position, air being admitted to apply the brake. The valve is operated by a hand lever and Bowden wire, which in the case of a trailer having a valve operated from the tractor is allowed the necessary slack. In a further modification the front wheel brakes of a vehicle are connected to the brake cylinder and the rear wheel brakes to the piston, the cylinder being suspended by pivoted arms to allow it to move lengthwise. Also a bell-crank lever is pivoted on the foot-pedal shaft having a projection on one arm for engagement by the pedal, the other arm being connected to the rear wheel brake rod in order that the rear brakes may be applied manually. In the modification shown in Fig. 15, the brake piston is connected by a rod 505 to the front-wheel brakes and this rod is connected by a lever 590 to the rear-wheel brakes. The lever 590 is pivoted on the foot pedal shaft and is provided with an arm 591 having a projection 592 adapted to be engaged by the foot pedal for direct manual operation. In a further modification three brake valves for controlling three brake cylinders are arranged in tandem, the casing of each being connected to the valve actuating part of the one in front except the casing of the front valve which is connected by a spring to the brake pedal and the valve actuating part of the rear valve which is connected directly to one set of brakes. The valves are operated simultaneously by the foot pedal. Pipe connections may be arranged from a brake cylinder to other brake cylinders so that the latter may simultaneously be operated.