5. BUCKET ROLL IN OPERATION R/G R/G Ps Ps Pm1 Pm2 Pm2 Pm1 P2 P1 T1,T2 T1,T2 P2 P1 P Rs CK1 Pn2 Pn1 D B A C DR BC COMP.
NRV2 NRV1 S/Motor DB Pk 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 DR2 Pc3 Pb3 GB GA Pa2 1 V3 BOOM2 ARM2 Pd4 B2 1 B(CW) Mu A(CCW) Pd2 Pc2 C2 D2 Pb2 1 A2 DR1 Pa2 Pb2 0 C1 SWING BOOM1 P02 Patt B1 0 Pc1 D1 Pd1 TRAVEL (LEFT) TRAVEL (RIGHT) A1 Pb1 Pa1 P01 DR0 Ptr STRAIGHT TRAVEL T1 P2 P1 Pu MRV SWING ARM BUCKET BOOM TRAVEL (2) (4) (3) (1) SH (3) (1) (2) (4) (1) (2) A1 A2 Psv a4 A B D E G F H J Pd2 Pc2 Pc4 0 Pa2 0 Pb2 0 T P Pa5 Pb5 Pd1 Pc1 Pb1 Pa1 (3) (4) Dr#,dr#,R# a2 a1 Pm1 (Pump) Pm2 (Pump) Pd4 0 Pk (T/Joint) Pm1 Pm2 A1 A2 A1 A2 ACC P4 PG(S/Motor) Pi1 (Fl,MCV) Pi2 (Fr,MCV) M T P2 P3 P1 Po1(MCV) Dr B1 B3 A3 a3 T(dr2) T D21073HS13 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 rear 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 boom spool in the main control valve. When this happens, the bucket rolls in. The cavitation which will happen to the bottom of the bucket cylinder is also prevented by the make- up valve in the main control valve. 3-16