Patent GB-1174246-A (GB)
Title: Fluid-Pressure Operated Braking Apparatus for Tractor-Trailer Vehicles
Inventor: SHATTOCK CHARLES FREDERICK BAY
IPC: B60T15/36
Filed: 1965-12-21
Abstract: 1,174,246. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. 6 Dec., 1966 [21 Dec., 1965; 29 April, 1966; 27 May, 1966; 8 July, 1966], Nos. 10034/69, 10035/69, 10036/69 and 10037/69. Divided out of 1,174,243. Heading F2F. In a fluid-pressure braking apparatus for a tractor/trailer vehicle, controlling means, in the form of a supplementary loading member A disclosed in the valve described and claimed in copending application No. 54066/65, operates upon a "break-away" of the trailer from the tractor to control the braking apparatus on the trailer to secure a degree of braking of the trailer which will not result in excessive braking of the trailer. As shown in Fig. 1, the tractor vehicle braking system is connected via a flexible coupling 54 to a trailer reservoir 51 arranged to be charged through a one-way valve 52. Leading from the trailer reservoir 51 is a pipe 56 leading to a relay valve 57, the output of which is connected to the brake cylinder 58 of the trailer vehicle. The pipe 56 has a branch connection 59 connected to the inlet port 30 of the fluid-pressure control valve 50, the outlet 10 thereof being connected via a pipe 60 to the relay valve 57. Suitable conductors 61 and 64 connect the wires 62 and 65 respectively on the tractor vehicle with the wires E and 63 respectively on the trailer vehicle so that the coil 18 of the valve 50 is arranged to be energized by the wire 63, the coil 18 being paralleled by a shunt 67 which incorporates a variable resistor 68, the resistance of which can be varied in dependence upon the weight of the trailer. The wire E when energized, results in the energization of the coil D of the supplementary loading means A and the armature C will be held out of engagement with the cantilever-mounted leaf spring 14 of the valve 50. During normal operation, the reservoir 51 is kept fully charged and the trailer brakes are operated by energization of the tractor wire 65 which, through the connection 64 and the wire 63 energizes the coil 18. The pressure of the output 10 of the valve 15 will be dependent upon the degree of energization of the coil 18 and the pressure at the output 10 is applied over the pipe 16 to the relay valve 57 to permit air under pressure to flow from the reservoir 51 to the brake cylinder 58 such that the pressure is dependent upon the pressure at the output. During this operation the coil D is energized and the armature C is held out of engagement with the cantilevermounted leaf spring 14 of the valve 15. Should the trailer break away from the tractor, the two connections 64 and 65 will be broken, as will the flexible coupling 54. Since the coil 18 and the supplementary loading means A are no longer energized the armature C will be caused by a spring to exert a resilient loading on the leaf spring 14 so that the brakes of the trailer will be operated by fluid pressure applied to the port 30 of the valve 50 to apply to the outlet port 10 a pressure which will be supplied through the pipe 60 to the relay valve 57 such that the degree of pressurization of the brake cylinder 58 will be less than that to which the brake cylinder 58 will be pressurized to, obtain a maximum degree of braking. In an alternative embodiment (Fig. 2, not shown) the variable load shunt 67 is omitted and the relay valve 57 is replaced by a variable load valve 70 which alters the degree of braking according to the loading on the vehicle.