Patent GB-275172-A (GB)
IPC: B60T7/04
Filed: 1927-05-23
Abstract: 275,172. Bragg, C. S., and Kliesrath, V. W. July 29, 1926, [Convention date]. Fluid-pressure.-Brake mechanism for motor vehicles comprises a pedal lever having operative connections to one set of brake mechanisms and a rocking pedal mounted on the pedal lever and connected to another set of brake mechanisms, whereby these brake mechanisms may be independently or simultaneously controlled by an operator placing his foot on the pedal. In a brake arrangement for a tractor and trailer the pedal lever 8, Fig. 1, is connected by a link 10 to the tractor brakes C and the trailer brakes D are operated by a single-acting brake cylinder 1 actuated bv suction from the intake manifold of the tractor engine and controlled by the rocking pedal 18 of the lever 8. The pedal 18 is pivoted at 19 and connected by a link 20 to a rotary valve mounted in a housing rigid with the pedal lever. The valve is provided with a recess adapted to provide communication between a port in the housing connected to the brake cylinder pipe 14 and a port connected to a pipe leading to the engine manifold or an atmospheric port according to whether the brake is applied or released. In the release position the pedal is normally held against a stop by means of a spring. The pedal is so arranged that the placing of the foot in the normal position on the pedal to operate the brakes tilts the pedal so as to move the valve mechanism and operate the brake cylinder, and the pedal lever is so pivoted that the depression of the pedal rocks it rearwardly in the normal position of the operator's foot to disconnect the suction port from the cylinder port. In an arrangement for a single vehicle the rear brakes are operated by a double-acting brake cylinder controlled by the link 10 and the front brakes or the intermediate brakes of a six-wheeled vehicle are operated by a single-acting brake cylinder controlled by the rocking pedal. The double-acting brake cylinder, Fig. 5, is controlled by reversing valve mechanism 40 - - 43 operated by a valve-actuating sleeve 27 connected to the link 10 and extending through the piston hub and the oppositely disposed piston rods 28, 29 through which atmospheric air is admitted to the cylinder under the control of the valve mechanism. The valve mechanism is connected to the engine manifold by a flexible pipe 62, the interior of the sleeve 27 and a suction chamber 30. The suction valves 41, 42 are normally held open by means of an adjustable collar 31 on the sleeve 27 in order to maintain a vacuum on each side of the piston 26. The sleeve 27 may directly operate the piston 26 by means of a collar 32 adapted to engage the piston-rod 28. In a further modification of the invention the brakes of a tractor are operated by a double-acting cylinder controlled by the link 10 and the brakes of a trailer are operated by a double-acting cylinder controlled by valve mechanism actuated by the rocking pedal. The valve mechanism comprises a stationary plate 211, Figs. 7 and 8, attached to the lever 208 and containing ports leading to pipes 214, 214a connected to each end of the cylinder, a port leading to the pipe 217 connected to the engine manifold and ports 213, 215<a> connected to atmosphere. A valve member 212 is pivoted to the plate 211 and contains two recesses adapted normally to connect pipes 214. 214a to the atmospheric connections 215, 215a and on rocking of the pedal to the suction pipe 217. The valve is held in normal position by a spring. In a modified construction a single recess normally connects pipes 214, 214a to suction to maintain a state of rarification in the cylinder and atmospheric ports are provided in the movable valve member adapted, on operation of the brakes, to register with the cylinder port not connected to suction. A stop rod and adjusting nut 218 maintain the valve in normal position. The pipes leading to the rocking pedal are flexible to allow of movement of the brake lever. An adjustable restricting valve 17a, Fig. 1, and a check valve 17<b> are provided in the suction pipe. Specifications 250,193: and 259,189, [Class 135, Valves &c.], are referred to.