GB1134032A - Improvements in vehicle brake systems - Google Patents

Abstract

1,134,032. Trailer braking system; warning devices. ROBERT BOSCH G.m.b.H. 29 Nov., 1965 [27 Nov., 1964], No. 50569/65. Headings F2E and F2F. A pneumatic two line brake system for the tractor vehicle of a lorry train comprises first and second reservoirs, a trailer reservoir feed line 26, first and second brake circuits adapted to apply respective sets of brakes, a trailer brake line 25 connected between the first brake circuit and a trailer brake coupling head, a multi-circuit main brake valve with a common brake actuator, an auxiliary brake valve with a valve actuator for causing application of rear wheel brakes by a storage spring actuator having a brake releasing cylinder, and a valve assembly having a stop valve 33 in the trailer brake line, a relay valve 34 controlling a line to the storage-spring cylinder responsively to operation of the auxiliary brake valve, and an emergency brake valve 35 for connecting the trailer reservoir feed line to the trailer brake line when the stop valve is closed, a lever 54 interconnecting movable members of the stop valve, the relay valve and the emergency brake valve to render their operation interdependent. In the Figure the valves are shown in the "normal travelling" position. Duet 22 is connected to a valve connecting two independent tractor reservoirs to a charging reservoir, duct 21 leads to the "hold off" cylinder of the storage spring brake actuator. Ducts 25 and 26 are connected to the trailer's relay valve and reservoir respectively, ducts 23, 24 to the tractor's front and rear brake circuits, respectively. Ducts 27 and 28 lead to and from, respectively the auxiliary hand brake actuator valve. The trailer reservoir is charged through ducts 22, 62, 76, 26 and the storage spring actuator brakes are held off by pressure in line 21 supplied when valve 61 was slightly off its seat 60. On application of the footbrake pressure appears in both lines 23, 24 and acts on both sides of the piston 68 of valve 34, consequently no movement of the valve occurs. Pressure from the front brakes passes through chamber 47 to duct 25 to cause actuation of the trailer brakes. Should a leak occur in the front brake circuit (23) piston 68 raises valve 34 and, through lever 54, the emergency brake valve 35 to apply full pressure to line 21 and maintain the storage spring brake off, while valve 40 seats to prevent air loss from the trailer reservoir through the damaged front brake circuit. Alternatively, failure of the rear brake circuit causes valve 34 to fall opening line 21 to atmosphere to allow the spring actuated brakes to be applied. When the hand brake valve is actuated during normal running line 27 feeds the valve from below restriction 67 and the pressure returning from line 28 depresses piston 46 of valve 33, rod 39 and lever 54 also lowering valve 34 to open line 21 to atmosphere and allow the storage spring actuated brakes to be applied. The hand brake valve may also control mechanically controlled brakes in addition. In a modification (Fig. 8, not shown) the valve member 55 controls a valve in an auxiliary circuit for holding off the spring applied brakes, which will then not operate directly on failure of the air pressure supplied thereto, but will operate only on attempted actuation of the brakes by the driver. Warning Devices.-A pressure gauge 96 (Fig. 1, not shown) and indicator 95 is provided.