Hydraulic steering for heavy vehicle - has auxiliary servo for automatic change to higher gearing on loss of servo force

摘要

The hydraulic steering for the heavy vehicle has an additional servo cotrol which operates when the servo pressure across the steering motor exceeds a set valves. A failsafe valve switches the steering action to a manual gearing if the servo fails. The failsafe control enables the heavy vehicle to be steered manually on servo failure, using the manually driven servo pump in lower gearing link to the steering controls. The failsafe valve is operated by a solenoid.