| 摘要 |
A fluid pressure braking system for an articulated vehicle having a towed unit and a towing unit includes a source of fluid pressure carried on the towing unit and a supply line (58) and a service line (62) which communicate the braking system on the towing unit with the braking system on the towed unit. A first proportioning valve (76) controls communication to the relay valve (84) which controls communication of braking pressure to the rear wheel service brakes on the towing unit. The proportioning valve (76) is controlled by an inversion valve (90) which is responsive to the pressure level in the supply line (58). When the pressure level in the supply line (58) is below a predetermined level indicating that the towing unit has been disconnected from the towed unit, the inversion valve (90) causes the proportioning valve (76) to proportion communication to the relay valve (84). A second proportioning valve (28) controls communication to the front wheel brakes of the towing unit and is responsive to the signal from the inversion valve (90) to proportion communication to the front wheel brakes when the towing unit is connected to the towed unit but which permits an uninhibited communication to the front wheel brakes when the towed unit is disconnected from the towing unit. A third proportioning valve (34) controls communication through the service line (62) and is responsive to an operator actuated control valve (68) to provide proportioned brake applications on the trailer service brakes when the trailer is lightly loaded. A synchronizing valve (40) is responsive to the magnitude of the brake application to reset the operator actuator valve (68) when higher pressures are generated, indicating that the towed and towing units have been recoupled. |
