Patent GB-628614-A (GB)
Title: Improvements in or relating to fluid-pressure braking systems for tractor trailer combinations
IPC: B60T13/52
Filed: 1946-12-18
Abstract: 628,614. Fluid-pressure brake systems. GUNDERSON, R. R. Dec. 18, 1946, No. 37254. Convention date, Dec. 28, 1945. [Class 103 (i)] A fluid-pressure brake system, of the kind in which a manually-operated master cylinder controls a booster motor actuating a second master cylinder coupled to the brake cylinders, is provided with a valve mechanism to control simultaneously or separately the pressure in said booster motor and the pressure in a pipe connected to the vacuum relieved brakes of a trailer. The valve mechanism comprises a closed cylinder 3 fitted with a hollow piston 8 and piston-rod 9 and secured to a booster motor casing 6 provided with a flexible diaphragm 12 clamped to the rod 9 and extended by a spring 16. A pipe 10 connects the cylinder 3 on one side of the piston 8 to a pedal-controlled master cylinder (not shown) and a pipe 11 connects the other side of the cylinder to the brake cylinders. The rod 9 is provided with an internal piston 30 yieldingly connected through a spring 31 with a rod 32 forked at its opposite end to connect with an annular member 25 attached by a spider 26 to a flexible diaphragm 19 mounted in a valve casing 17. A suction pipe 21 is extended to form a valve seat 22 engaged by a spring- urged valve member 23. The spider 26 is spaced at 28 from the valve 23 by a spring 27. When in the position shown, the mechanism to the left of a diaphragm 42 is open to atmosphere through an air filter 29. The space to the right of the diaphragm 42 is divided into two chambers 36, 37 by a flexible diaphragm 20 rigidly secured to a rod 39 which engages at one end a spring 43 bearing against the spider 26 and is hollowed out at the other end and provided with ports 45 and a valve seating 44. The outer end of the casing 17 is extended into an air filter 48 and provided with a valve seating 46 which engages a spring-urged valve 47, the screwed shank of which engages with the seat 44. A pipe 361 connects the chamber 36 to the trailer vacuum brake cylinder (not shown) and a pipe 38 connects the chamber 37 to suction. Fluid pressure from the pipe 10 moves the piston 30, rod 32, fitting 25 and diaphragm 19 to the right, thus closing the port 28 and unseating the valve 23, causing a pressure reduction in the casing 6. Atmospheric pressure, acting on the diaphragm 12 through ports 35 moves the piston 8 to the right to effect tractor brake actuation. Movement of the diaphragm 19 and the spider 26 will also cause the rod 39 and the diaphragm 20 to move to the right to engage the seating 44 with the shank of the valve 47 and unseat the valve, thus sealing the pipe 36<SP>1</SP> from suction and exposing it to atmosphere through the filter 48. Independent manual control of the rod 39 may be effected by a Bowden control 57 and a lever 52, pivoting at 51, and balanced by a spring 53, and a lost-motion connection may be provided between the rod 39 and the spider 26 (Fig. 2, not shown) to enable the tractor and trailer brakes to be operated by the control 57. Specification 550,450 is referred to.