GB385163A - Improvements in or relating to brake systems - Google Patents

Abstract

385,163. Fluid - pressure brakes. BOSCH AKT.-GES., R., 4, Militarstrasse, Stuttgart, Germany. April 1, 1932, No. 9368. Convention date, April 1, 1931. [Class 103 (i).] Fluid-pressure brakes comprise a cylinder 14, Fig. 1, on a tractor, operated by connection with a source of fluid-pressure by a manually operated valve 9 and a second cylinder 21 on a trailer, operated by connection to atmosphere and controlled by a valve 26 controlled by the pressure variation produced in the control pipe 27 of the first cylinder by the valve 9. The valve 26 comprises two controlling cylinders, the working space of the primary controlling cylinder 42, Fig. 3, being connected to the pipe 27 and the working space of the secondary controlling cylinder 19 being connected by a pipe 20 to the second brake cylinder 21. The secondary controlling cylinder is adapted to be connected by valves 49, 51 actuated by the. primary piston 41, to the atmosphere or to the source of pressure medium. The secondary piston 43 is loaded by a spring 53 and has a smaller effective surface than the piston 41 so that the braking effect on the trailer rises more quickly than on the tractor, and these pistons are subject on the left-hand side to atmospheric pressure. The trailer brake is spring applied and held off by vacuum produced through the valve 51 and pipe 17 from a vacuum reservoir 18, the vacuum in which is produced by the inlet manifold 11 of the vehicle engine. Vacuum produced by the manual valve 9 in the pipe 27 to operate the brake cylinder 14 produces operation of the valve 26 to close the valve 51 and open the valve 49 to connect the cylinder 21 to the atmosphere and apply the trailer brake. The consequent increase of pressure on the right of the piston 43 recloses the valves to give a lap position. In order that the movements of the piston 43 are unhindered by the piston 41 the pistons may be connected only in one direction loosely or by a weak spring. Piston 41 may be substituted by a diaphragm in a conical cylinder so that as the diaphragm moves to the right it bears more and more on the conical surface, thus reducing its surface as the pressure difference on it increases. The driver's valve 9, Fig. 2, comprises two valves 33, 34 adapted to be pressed on their seats by a spring 36 and operated by and displaceable on a rod 35 which is connected to the brake pedal by a lever 5 and a rod 4. On brake operation the lever 5 pivots about the end of a connection 6 to the brake shaft 8 and allows the atmospheric air valve 34 to close and opens the vacuum valve 33. The consequent movement of the brake shaft 8 recloses the valve 33 to give a lap position.