Abstract: A steering brake and clutch control for a crawler vehicle includes a pair of primary control levers, each of which, when operated by itself, acts through a spring to first effect disengagement of normally pressure-engaged clutch and then through a linkage to effect engagement of a brake. The clutch control levers are interconnected so that simultaneous actuation of the primary control levers results in both brakes being engaged without the clutches being disengaged. A pair of brake control levers have respective one-way connections with the pair of primary control levers and are spring-biased for simultaneously actuating the primary control levers to effect brake engagement. A pressure-operated plunger assembly is operative to maintain the brake control levers away from the primary control levers so long as sufficient hydraulic system pressure exists for normal operation.

Abstract: Right- and left-hand steering clutch and brake control valves each include a valve plunger, brake control spool and clutch control spool arranged in serial order in a valve bore with coil compression springs being interposed between the plunger and brake control spool, between the brake and clutch control spools and between the clutch control spool and an end of the bore. The reacting force on the control spools is a spring and constant hydraulic force while the applied force is by way of springs and hydraulic function pressure.