5.
BUCKET ROLL IN 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 DR2 Pa8 Pa10 Pb8' Pa8 Pa6 Pa7 Pa4 Pa5 AC Pa3 Pa1 Pa2 DOZER Pb10 T2 Pb6 Pb7 Pb4 Dr1 T1 Pb3 Pb1 Pb2 MAIN CONTROL VALVE Pb8 BU Pp1 TRAVEL L/H 2 1 Pb7 Pa7 SAFETY 2-SPEED ACC A1 A2 7 B/SWING 2WAY OPT K1 K2 LH 1 2 RH LH 1 2 RH P4 P2 P1 K3 TR T Pb2 Pa2 Pb4 Pa4 SOLENOID VALVE K4 MAIN PUMP 189AK3HC14 When the right control lever is pulled left, the bucket spool in the main control valve is moved to the roll in 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 large chamber of bucket cylinder. At the same time, the oil from the small 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 in. The cavitation and excessive pressure in the bottom of the bucket cylinder is also prevented by the make-up valve and relief valve in the main control valve.
3-15 B10 A10 A9 B8 B7 BUCKET BOOM Relief Make up valve 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