7. SWING OPERATION 7.
SWING OPERATION ARM CYLINDER BUCKET CYLINDER BOOM CYLINDER PG AU AU PG DR DR MB MA MB MA MU MU ps1 ps2 T3 T1 T2 T4 VA(CCW) VB(CW) VA(CCW) VB(CW) (Td#) TRAVEL MOTOR A SWING PARKING SOLENOID VALVE P T [Td#] TRAVEL P T pb6 pa1 pb1 pa6 (2) (1) (4) (3) BOOM P T BUCKET ARM P T SWING T1 T2 T3 PUMP A1 PUMP A2 PILOT PUMP (2) (1) (3) (4) (2) (3) (1) (4) P T dr# A D E F G H J B PH (MCV) F (T/JOINT) a b d e f g h j pa2 pb2 PS c h1 j1 PS PS d1 f1 g1 PS PS PS e2 PS A1 A2 A5 P3 P4 Pi(D/C VALVE) P(2-EPPR) PP(MCV) Td# P pb9 pb5 T A B C (Td#) P2 P1 HYDRAULIC TANK pa9 pc1 pa5 pa8 pa11 pb8 pc6 pb3 pb7 pc2 pa7 pa3 LINE FILTER 480A3HC16 When the LH 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 (pa2, pb2) from the remote control valve.
The oil from the A1 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 upper structure swings to the left or right. The swing parking brake, make up valve and the motor brake valve are provided in the swing motor. The cavitation which will happen to the swing motor is also prevented by the make up valve in the swing motor itself. 3-20 3-20 A5 pb5 ARM 1 pa5 B4 A4 pb4 pa4 OPTION A3 B3 pb3 B2 pa3 BOOM 2 A2 TRAVEL(LH TRAVEL STRAIGHT A6 pb6 pa6 ) P3 P2 CROSS ASS P1 P2 P3