When the left control lever is pushed left or right, the swing spool in the main control valve is moved to the left or right swing 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 swing motor. At the same time, the return oil from the swing motor returns to the hydraulic oil tank through the swing spool in the main control valve. When this happens, the superstructure swings to the left or right. The swing parking brake, make up valve and the overload relief valve are provided in the swing motors.
The cavitation which will happen to the swing motor is also prevented by the make up valve in the swing motor itself. 3-18 7. SWING OPERATION R/G R/G Ps Ps Pm1 Pm2 Pm2 Pm1 T1,T2 T1,T2 P1 P2 P2 P1 Pn2 Pn1 CK1 Rs CA P DR BD NRV1 BC COMP.
NRV2 Pk B5 S/Motor DB C5 A5 D5 Pc5 Pb5 Pd5 OPTION-B BUCKET CK2 Pa5 (RG)DS rR SG ARGSH PC c4 D 4 PbB 44 Go DR3 41 REGENERATIION CUT PG Pa4 Pd40 ARM1 OPTION-A BREAKER Au Pc40 Pc4 2 Dr(R7) Pc3 Pb3 DR2 Pd41 Pa2 1 BOOM2 ARM2 GB GA V3 B2 B(CW) Mu A(CCW) C2 A2 D2 Pb21 P Pc d2 DR1 Pb20 2 Pa20 SWING BOOM1 P02 Patt C1 B1 Pc1 D1 A1 Pb1 Pd1 TRAVEL Pa1 P01 DR0 (LEFT) T (RR IA GV HE TL ) Ptr S TRTR AA VI EG LHT MRV P1 P2 T1 Pu SWING ARM BUCKET BOOM TRAVEL Psv (1) (3) (2) (4) (3) (1) (2) (4) SH a4 A1 A2 (2) (1) (4) (3) A B D E G F H J Pa1 Pb1 Pd1 Pc1 a1 a2 Pc2 Pd2 Pc4 0 Pa5 Pb5 Pa2 0 Pb2 0 P T Dr#,dr#,R# Pd4 0 (P Pm um1 p) (P Pm um2 p) ( T /P Jok int) A1 A2 ACC A1 (Fl,MCV) Pi1 Pm1 (Fr,MCV) Pi2 Pm2 A2 P4 PG(S/Motor) M P3 Po1(MCV) P2 a3 Dr T T P1 B1 B3 A3 T(dr2) D21073HS15