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US 4,258,959 AGranted
Fluid pressure operable tractor and trailer vehicle braking systems
AssigneeBendix Westinghouse Limited
InventorsDavid J. Knight, Sidney A. Lippiatt
Life of this patent
Estimating the term…
Abstract
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.
Claims9
A tractor trailer fluid pressure brake control circuit comprising:
- tractor service and spring brakes;
- trailer service and spring brakes;
- a fluid pressure reservoir;
- a trailer service line for communicating fluid pressure to the trailer service brakes;
- a service brake control valve for generating a primary fluid pressure signal communicated to the tractor service brakes and to the trailer service line to control the application of the tractor and trailer service brakes;
- a trailer supply line for communicating fluid pressure to the trailer spring brakes;
- a manually operable auxiliary control valve for generating an inverted graduable auxiliary fluid pressure signal variable between minmum and maximum levels for communication to the tractor spring brakes and to the trailer supply line to control the application of the tractor and trailer spring brakes;
- and
- a manually operable pressure control valve for generating a maximum pressure signal communicated to the trailer service brakes to effect an application thereof and communicated to the trailer spring brakes to effect a release thereof and to effect a repressurization of the trailer supply line in response to an operator parking release input signal applied during a period when the tractor and trailer spring brakes are applied and when the tractor and trailer service brakes are released, the pressure control valve further comprising means responsive to a predetermined pressure in the trailer supply line for termination of the pressure signal communicated to the trailer service brakes to effect release thereof upon repressurization of the trailer supply line to said predetermined pressure.
6 more elements
Dependencies are inferred from the claim text.