1) WHEN THE RCV LEVER IS IN THE RAISE POSITION 14 13 4 Aux Bucket 5 Control unit 6 EH18 EH17 EH20 EH19 4 1 6(4) 3(2) a3 b3 a1 b1 a2 b2 Steering valve (EHPS) EF port Steering valve (EHPS) LS port Return line Steering system 757F6WE03 В When the RCV lever (4, boom) is pulled back, the boom spool is moved to raise position by pilot oil pressure from EH control block (6). The oil from main pump (1) flows into main control valve (3) and then goes to the large chamber of boom cylinder (13) by pushing the load check valve of the boom spool. The oil from the small chamber of boom cylinder (13) returns to hydraulic oil tank (22) through the boom spool at the same time.
When this happens, the boom goes up. В В В 6-5 LH RH 29 PS PS 29 40 a1 a2 a3 P A1 B1 A2 B2 A3 B3 3 Floating LS Boom Bucket Boom Aux Dump Down Joystick 4' Pst back Roll Up ick steering) T H22 EH21 T P 5(3) 2(1) ( ) : 2 Spool To MCV b1 b2 b3 A1 28 28 11 12 S1 X1 X2 P1 T X3 9PS1 X1 X2 23 Return line B1 B2 24 25 26 22 S1 L2 L1 S2 L4L3 Fan & brake pump LH 40 a1 a2 A1 B1 A2 LH RH 29 PS PS 29 a3 B2 A3 B3 Dump Bucket Floating Down Boom Aux Roll back Up Up