GROUP 5 COMBINED OPERATION 1. OUTLINE ARM CYLINDER BUCKET CYLINDER BOOM CYLINDER SWING MOTOR TRAVEL MOTOR pc1 pa9 pa5 (34,2) P2 pb8 (34,1) A7 pa11 pa8 TURNING JOINT pc7 B7 pc2 pb3 pb7 pa3 pa7 A6 B6 pc6 PT PS P1 P2 PH PA PP PS SH A1 A2 FRONT PUMP REAR PUMP PILOT PUMP HYDRAULIC TANK 900L3HC20 The oil from the A1 and A2 pump flows through the neutral oil passage, bypass oil passage and confluence oil passage in the main control valve. Then the oil goes to each actuator and operates them. Check valves and orifices are located on these oil passage in the main control valve.
These control the oil from the main pumps so as to correspond to the operation of each actuator and smooth the combined operation. STRAIGHT TRAVEL SPOOL This straight travel spool is provided in the main control valve. If any actuator is operated when traveling, the straight travel spool is pushed to the right by the pilot oil pressure from the pilot pump. Consequently, the left and right travel oil supply passage are connected, and equivalent amount of oil flows into the left and right travel motors. This keeps the straight travel. 3-22 ps1 pa11 DR1 pc1 B5 A5 pb9 pb5 ARM1 pa5 PO B4 A4 B B1 OPTION A A1 DR7 pc7 A3 B3 pb3 pb9 ARM2 B8 A8 BUCKET DR2 pc2 p