HYDRAULIC CONTROL VALVE FOR OPERATING STEERING AND BRAKING MEANS FOR LER TRACTOR

摘要

A hydraulic control valve for operating steering and braking means for crawler tractor. The control valve comprises a housing and a pair of independently actuatable valve spools in the housing, each spool being biased into a neutral position and selectively movable therefrom to other positions. A pair of main inlet ports and a main outlet port are provided in the housing. A pair of pressure ports are associated with each valve spool. A pair of passages each communicate with one main inlet port and one pressure port. Each valve spool, when in neutral, enables full communication through a passage between one main inlet port and one of its associated pressure ports but prevent communication between the other main inlet port and the other of its associated pressure ports. Each valve spool when moved from neutral to another position decreases communication between the one main inlet port and the said one of its associated pressure ports and enables communication between the other main inlet port and the said other of its associated pressure port.