3.
TRAVEL SPEED CONTROL SYSTEM TRAVEL MOTOR-LH TRAVEL MOTOR-RH L/H R E D R/H SWING MOTOR R E D PP DR R E D 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 SOLENOID SELECTOR 3WAY VALVE BUCKET CYL BOOM CYL D B C A G H F E T P TURNING JOINT C2 C3 C1 C4 P2 P1 B/SWING CYL Pa10 Pb8' DR2 Pa8 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 7 Pa6 Pb7 Pa7 SAFETY 2-SPEED ACC A1 A2 B/SWING LH 1 2 RH 2WAY OPT LH 1 2 RH P4 P2 K3 K1 K2 T P1 SOLENOID VALVE K4 TR Pb2 Pb3 Pa2 Pb4 Pa4 MAIN PUMP 189AK3HC05 When the travel speed switch is pushed, the travel speed solenoid valve is actuated and the discharged oil from the pilot pump flows to the PP port of pilot valve in the travel motors.
As a result, the control piston is pushed by the main oil flow, thus the displacement is minimized. When the travel speed switch is pushed once more, the travel speed solenoid valve is return to original position by the force of spring, the hydraulic oil of PP port returns to the hydraulic tank. As a result, the control piston is returned by the main oil flow, thus the displacement is maximized. 3-9 10 A10 BUCKET A9 B8 BOOM B7 A7 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 MRV-P2 MRV-P1 MRV-P3 DOZER DOWN UP 4 1 2 Pb6 Pb1 Pa1 ING ARM BUCKET BOOM H RH OUT IN IN OUT UP DOWN 1 3 2 4 3 1 2 4 Pa3 Pb5 Pb10 Pa10 Pb8 Pa5 Pa8