Patent GB-300174-A (GB)
Title: Improvement in power actuator
IPC: B60T13/24
Filed: 1928-10-29
Abstract: 300,174. Bragg, C. S., and Kliesrath, V. W. Nov. 7, 1927, [Convention date]. Fluid-pressure. - A control valve particularly for vehicle brake mechanism arranged to give a resistance to the foot to indicate the braking pressure and in which a force corresponding to that required to overcome this resistance is transmitted by the valve casing to the brakes, comprises a diaphragm valve 8 dividing the valve casing into a chamber 17 connected to the atmosphere and a chamber containing a valve seat 11 dividing this chamber into an annular part 12 connected to the vehicle engine induction pipe and a central part 13 connected to the brake cylinder, and to the atmosphere by apertures 19 in the diaphragm when the brakes are released. Depression of the brake pedal which is connected by means of a rod 82 to the diaphragm presses an annular part 10<a> of a disc valve 10, which is also mounted on the rod 82, against the diaphragm and closes the atmospheric connection; further movement raises the diaphragm from the seat 11 and connects the chamber 13 and the brake cylinder to the chamber 12 and the vacuum of the induction pipe, thus applying the brakes and establishing differential pressures on the sides of the diaphragm to provide a resistance to movement of the foot pedal. The valve casing is connected by a rod 74a to the brake rigging movement of which recloses the diaphragm valve and maintains the brakes applied and also transfers a part of the fluid pressure on the diaphragm to the valve seat 11. A force corresponding to that exerted by the operator to overcome the pressure difference on the valves is transmitted to the brakes by the valve casing. The brakes may be applied directly by means of the rod 74<a>. In a modification the valve casing is mounted directly upon the brake piston rod which is hollow whereby it provides communication between the brake cylinder and the valve casing. In a further arrangement the brake piston is connected permanently on one side to the vacuum and the chamber 213, Fig. 6, of the valve is connected to the other side of the piston by a pipe 214 which in brake release position is connected to the vacuum chamber 212. The chamber 206<d> is also connected to vacuum by means of apertures 219, 206<c>. The disc valve 210 is provided with annular sealing means 210<a> adapted to hold the diaphragm 208 against an annular abutment 206<b>. The space within the disc valve is connected to atmospheres by means of apertures 218, 218a in the hollow valve rod, movement of which brings the diaphragm into engagement with the seat 211 and moves the disc valve away from the diaphragm, thus connecting the chamber 213 and one side of the brake piston to atmosphere. This arrangement is also shown with the valve casing mounted directly on the piston rod. In this case the vacuum chambers 212, 206d are connected to vacuum through the hollow piston rod which is connected by apertures to the side of the piston permanently connected to vacuum. In another valve for a brake in which one side of the brakes piston is permanently connected to suction the chamber 413, Fig. 9, is connected by a pipe 432 to the induction pipe and in brake release position is connected to the other side of the brake piston by a pipe 414. On brake operation this latter connection is cut off by the disc valve 410, the diaphragm is raised from the seat 411 so that the suction takes effect on the whole area of the diaphragm and valves 418<a> are raised by the diaphragm to admit air ' to the pipe 414 and the brake cylinder. The brake cylinders may be connected by piping to other brake cylinders so that the latter are also controlled by the control valve.