4. TRAVEL SPEED CONTROL SYSTEM R/G R/G Ps Ps Pm1 Pm2 Pm2 Pm1 P2 P1 T1,T2 T1,T2 P2 P1 D B A C DR P Rs CK1 Pn2 Pn1 Pk BC COMP.
NRV2 NRV1 S/Motor DB D5 C5 A5 B5 Pc5 Pd5 OPTION-B BUCKET CK2 Pb5 Pa5 (RG) SGo Dr SRG ARG SH DR3 C4 D4 B4 Au PG Pd4 0 Pc4 Pc4 1 ARM1 REGENERATIION CUT OPTION-A BREAKER Pc4 2 Pa4 Pb4 Dr(R7) 0 Pc3 Pb3 GB GA DR2 Pa2 1 V3 BOOM2 ARM2 Pd4 B2 1 B(CW) Mu A(CCW) Pd2 Pc2 C2 D2 Pb2 1 A2 DR1 Pa2 Pb2 0 SWING BOOM1 P02 Patt B1 0 Pc1 D1 Pd1 C1 TRAVEL (LEFT) A1 Pb1 Pa1 P01 DR0 TRAVEL (RIGHT) Ptr STRAIGHT TRAVEL T1 P2 P1 Pu MRV SWING ARM BUCKET BOOM TRAVEL (2) (4) (3) (1) (3) (1) (2) (4) Psv A B D E G F H J SH Pd1 Pc1 Pb1 Pa1 (1) (2) (3) (4) a2 a1 A1 A2 a4 Pd2 Pc2 Pc4 0 Pa2 0 Pb2 0 T P Pd4 0 Pa5 Pb5 Dr#,dr#,R# Pm1 (Pump) Pm2 (Pump) A1 Pk (T/Joint) A1 A2 ACC Pi1 (Fl,MCV) Pi2 (Fr,MCV) Pm1 Pm2 A2 P2 P3 P4 PG(S/Motor) Po1(MCV) 19 M a3 T(dr2) T T P1 Dr B1 B3 A3 D21073HS05 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 Pk 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 Pk 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