Hydraulic control system for excavator machine - in which steering control and brake control circuit are separate from main hydraulic circuit

摘要

The hydraulic system controls the operating functions of the machine. The arm and bucket movements are operated by means of a main pump, with a parallel pump controlling the steering and an auxiliary pump operating the braking system. The main (10), steering (12) and auxiliary (14) pumps are connected in parallel to the hydraulic circuit, driven by a motor (16), and supply hydraulic fluid from a reservoir (18) to the arm and bucket control valves (26) and control lever unit (28), the steering control valves (34) and steering wheel (36) and the braking system divider valve (70) and brake pedal (62). The auxiliary pump output is fed through a three-way branch (40) to the front and rear brake cylinders (44,46), to the control unit (28) and to a parking brake cylinder (56). Additional reservoirs (64) are in the brake circuit for emergency use. The flow divider valve (70) splits the fluid between the steering circuit (32) and a main shut-off valve (72) to the three-way junction (40).