Boom lower position Boom lower position (3) B2 A2 b2 a2 P T B2 A2 6 Hydraulic circuit 76096WE53 When the pilot pressure is led to the port a2, the boom spool moved to lower position. Oil from the pump flows to the cylinder port A2 and oil from the cylinder flows into the tank passage through the cylinder port B2. When the lowering speed of boom is faster, the return oil from the large chamber of boom cylinder combines with the oil from the pump through regeneration check valve (6), and flows into the small chamber of the cylinder. This prevents cylinder cavitation by the negative pressure when the pump flow cannot match the boom down speed.
6-28 a2 T P a1 A1 B1 LS A2 B2 pst ump t Down m 6 D Roll back Bucke Up Boo b1 A2 B2 b2