Bendix Westinghouse Limited

David John Knight

Sidney A Lippiatt

A tractor/trailer vehicle fluid pressure braking control system enabling two line control of trailer service and secondary braking includes for tractor braking a service brake control valve for controlling the fluid pressure applied both to service brake actuators and to a trailer service brake control line, a secondary control valve which controls the magnitude of a counteracting pressure applied to tractor spring brakes and also to a relay valve which controls a pressure in a trailer secondary spring brake control line.

Fluid pressure operable tractor and trailer vehicle braking systems

A load dependent control arrangement wherein an electrical load sensor such as a strain gauge controls the mark-to-space ratio of a pulse train output from a pulse generator. The pulse train operates a solenoid valve to control a pneumatic output pressure in proportion to the ratio of marks to spaces. The output pressure may be amplified in a self-lapping pneumatic relay valve. The final output pressure may be utilized in any suitable manner, for example, in operating the pneumatic brakes of a vehicle whose load is being measured by the sensor.

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Bath, United Kingdom

David John Knight