Patent GB-250193-A (GB)
Title: Improvement in valve control mechanism for fluid pressure actuators for brakes
IPC: B60T13/24
Filed: 1926-03-03
Abstract: 250,193. Bragg, C. S., and Kliesrath, V. W. April 3, 1925, [Convention date]. Fluid-pressure. - Control of a pressure or vacuum brake for motor vehicles is effected by movement of a pedal member with respect to the lever which carries it, the lever being connected to the brake piston so that direct actuation of the brakes can be effected thereby. The pedal may form one of the control valve members or it may operate the valve by mechanical or electromagnetic means. The suction or pressure may be provided by a connection to the intake manifold or to the cylinder of the engine. Figs. 5 and 6 show a construction for a single-acting vacuum system comprising a pedal lever 108 connected by a link 110 to the brake piston and having fixed relatively thereto, between bifurcated ends 108<a>, a valve member 111 upon which is rotatably mounted a co-operating valve member 119 provided with a pedal 118. The member 111 is provided with ports 113, 116 connected respectively to the brake-cylinder pipe 114 and to the suction pipe 117 and also with a vent port. The pedal member 119 has a cavity 112<a> cooperating with the ports in the member 111 which is normally held by the engagement of a spring 121 with a flat on the member 119 so that the brake cylinder is vented to atmosphere. By rocking the pedal on the lever 108, the cylinder can be connected to the suction pipe 117 to apply the brakes and can then be partly returned to neutral position to hold the brakes applied. The brakes can however be directly applied at any time by rocking the lever 108 about the pivot 109. In another construction, the pedal member has a link connection with an inner rotary valve member. Figs. 10 and 17 show a double-acting system in which suction can be applied at both sides of the brake piston 302. The control valve comprises a disc 811 fixed to the pedal lever 308 and provided with ports 313, 313a, vent ports 315, 315<a>, and a port 316 connected to the suction pipe 317. The pedal member 318 is provided with a rotary disc valve member having cavities, shown in broken lines in Fig. 12, and in the normal position shown connecting both ends of the cylinder to atmosphere. By rocking the pedal on the lever 308, the cylinder pipe 314 may be connected to the suction pipe 317 to apply the brakes, or this pipe may be vented to atmosphere and the pipe 314<a> be simultaneously connected to the suction pipe to effect release of the brakes. A stop rod 318<c> may however be provided on the pedal having a nut 318<d> which engages a fixed part when the pedal lever 308 is in the normal position so as to hold the pedal in position with the suction port 316 closed; or if the stop rod is not provided, the pipe 314a may be so located as to be closed by the piston in the off position. The valve mechanism just described may be adapted for a system in which suction is normally maintained or both sides of the piston by arranging the vent ports 315<b>, 315<c>, cylinder ports 313<e>, 313c and suction ports 316b in the valve member 311, and a single cavity in the pedal member 318. Air - mav thus be admitted to one side of the piston to apply the brakes, be again exhausted therefrom to reduce the braking pressure, and be admitted to the other side of the piston to return the mechanism to the off position. The stop rod 318<c> in this case returns the pedal valve member to the position shown in Fig. 13 when the lever 308 reaches the off position. Fig. 14 shows an arrangement for electromagnetic control. Spring-closed vent and suction valves 415a 417a are adapted to be opened by magnets 425. 422, either of which can be energized by pairs of contacts 426, 422 on the pivoted pedal 418 and lever 408 to open the valves. To avoid waste of current when the brakes have been completely released, a switch 434 on the lever 408 and in the circuit of the vent valve is opened by engagement with a stop 435, or a stop rod such as 318<c>, Fig. 10, may be provided adapted to hold the pedal in position with both pairs of contacts disengaged. The Specification as open to inspection under Sect. 91 (3) (a) describes a further construction in which the pedal is in the form of a tubulat valve which slides within a cylinder fixed to the pedal lever and to which are connected the suction and cylinder pipes. This subject-matter does not appear in the Specification as accepted.