2.
BOOM DOWN OPERATION TRAVEL MOTOR-LH TRAVEL MOTOR-RH L/H R E D R E D R/H SWING MOTOR R E D PP DR PP PP ARM CYL EXTENSION CYL DOZER CYL A(FW) B(BW) DR2 DR1 DR1 DR2 A(FW) B(BW) STOP VALVE B(CW) A(CCW) T D B C A G H F E T P TURNING JOINT SOLENOID SELECTOR 3WAY VALVE BUCKET CYL BOOM CYL C2 C3 C1 C4 P2 P1 B/SWING CYL Pa8 Pa10 Pb8' DR2 Pa8 Pa6 Pa7 Pa4 Pa5 AC Pa3 Pa1 Pa2 DOZER MAIN CONTROL VALVE Pb10 T2 Pb6 Pb7 Pb4 Pb8 Dr1 BU Pp1 T1 Pb3 Pb1 Pb2 TRAVEL R/H L/H 2 3 1 Pa6 Pb7 Pa7 B/SWING 2WAY OPT 2-SPEED A2 K2 LH 1 2 RH LH 1 2 RH P4 P2 P1 T Pb2 Pb3 Pa2 Pb4 Pa4 SOLENOID VALVE K4 TR MAIN PUMP 189AK3HC11 When the right control lever is pushed forward, the boom spool in the main control valve are moved to the down position by the pilot oil pressure from the remote control valve.
The oil from the P1 pump flows into the main control valve and then goes to the small chamber of boom cylinder. At the same time, the oil from the large chamber of boom cylinder returns to the hydraulic tank through the boom spool in the main control valve. The cavitation in the boom cylinder rod end circuit is prevented by the make-up valve. 3-12 B10 A7 B7 BOOM B8 A9 BUCKET A10 P1 P2 A6 B6 A5 B5 PTO A4 B4 P3 B3 A3 B2 ARM SWING CROWD A2 B1 A1 ARM TRAVEL(RH) TRAVEL(LH) BS Make up valve MRV-P2 MRV-P1 MRV-P3 DOZER DOWN UP 4 1 2 Pb6 Pb1 Pa1 ING ARM BUCKET BOOM LH RH OUT IN IN OUT UP DOWN 1 3 2 4 3 1 2 4 Pa3 Pb5 Pb10 Pa10 Pb8 Pa5 Pa8 7 ACC SAFETY A1 K1 K3 ACC K3 SAFETY A1 K1