6.
BUCKET ROLL OUT 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 A(FW) B(BW) DR2 DR1 DR1 DR2 A(FW) B(BW) ARM CYL EXTENSION CYL DOZER CYL 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 L/H 2 1 Pb7 Pa7 7 B/SWING 2WAY OPT SAFETY 2-SPEED ACC A1 A2 K1 K2 LH 1 2 RH LH 1 2 RH P4 P2 P1 K3 T Pb2 Pa2 Pb4 Pa4 SOLENOID VALVE K4 TR MAIN PUMP 189AK3HC15 When the right control lever is pushed right, the bucket spool in the main control valve is moved to the roll out 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 bucket cylinder. At the same time, the oil from the large chamber of bucket cylinder returns to the hydraulic oil tank through the bucket spool in the main control valve. When this happens, the bucket rolls out. The cavitation which will happen to the rod of the bucket cylinder is also prevented by the make-up valve in the main control valve.
3-16 B10 A10 A9 B8 B7 BUCKET BOOM Make up valve P1 P2 A7 A6 B6 A5 B5 PTO A4 B4 P3 B3 A3 B2 ARM SWING CROWD A2 B1 A1 ARM TRAVEL(RH) TRAVEL(LH) BS MRV-P2 MRV-P1 MRV-P3 DOZER H 3 4 DOWN UP 1 2 Pa6 Pb6 Pb1 Pa1 SWING ARM BUCKET BOOM LH RH OUT IN IN OUT UP DOWN 1 3 2 4 3 1 2 4 Pb3 Pa3 Pb5 Pb10 Pa10 Pb8 Pa5 Pa8