Trailer brake for hydrostatic transmission vehicle - with force multiplier to operate trailer brakes w.r.t. servo pressure

摘要

Automatic transmission vehicle has the hydrostatic transmission controlled by a hydraulic servo pump of variable output. When the brake pedal is operated the pump output is set to zero and the transmission ratio altered to provided a transmission drag for braking. An interlock to the trailer brakes enhances the trailer braking effect to prevent the trailer from overrunning the towing unit. A monitor for the hydraulic pressure in the transmission is linked to the trailer brakes by a mechanical servo driven by the hydraulic system. A multiplier ensures that sufficient force is available to operate the trailer brakes.