4) WHEN THE RCV LEVER IS IN THE DUMP POSITION WHEN THE RCV LEVER IS IN THE DUMP POSITION 40 S1 S2 760F6WE06 В If the RCV lever (4, bucket) is pushed right, the bucket spool is moved to dump position by pilot oil pressure from EH control block (40). The oil from main pump (1) flows into main control valve (3) and then goes to the small chamber of bucket cylinder (13). The oil at the large chamber of bucket cylinder (13) returns to hydraulic tank (21). When this happens, the bucket is dumped. When the dumping speed of bucket is faster, the oil returned from the large chamber of bucket cylinder combines with the oil from the pump, and flows into the small chamber of the cylinder.
This prevents cylinder cavitation by the negative pressure when the pump flow cannot match the bucket dump speed. В В В В 6-7 13 12 28 PS RH 28 PS a2 a3 LS 3 T P a1 A1 B1 A2 B2 pst A3 B3 Floating Aux Bucket Boom Dump 4 Joystick Down 5 9 Control unit Bucket Boom Aux back (Electro-Hydraulic & Joysick steering) Roll Up EH18 EH17 EH20 EH19 EH22 EH21 T P 4 1 6(4) 3(2) 5(3) 2(1) ( ) :
2 Spool b1 A2 B2 Regeneration To MCV check valve b2 LH b3 12 a3 b3 a1 b1 a2 b2 41 A1 Steering valve 27 27 10 (EHPS) EF port Steering valve (EHPS) LS port S1 X1 X2 P1 T 11 X3 Return line 28PS1 X1 X2 22 Return line ring system 23 B1 B2 24 25 21 S1 L2 L1 S2 L4L3 Fan & brake pump 12 28 PS RH 28 PS a3 LS A3 B3 A1 B a2 1 A2 B2 pst Dump Down Floating Bucket back Roll Up Boom Aux