PLATE 8X0489 - Caterpillar

Illustration 7 g00916884
Boom I control valve (BOOM LOWER position) (17) Load check valve (21) Parallel feeder passage (22) Return passage (33) Port (34) Port (36) Spool (53) Port (59) Orifice (60) Orifice (61) Spring (62) PassageThe pilot oil flow from port (53) shifts spool (36) in boom I control valve (15) against the force of spring (61). The oil delivery from the right pump in parallel feeder passage (21) flows through load check valve (17), passage (62) and port (34). The oil delivery from the right pump then flows through line (5) to the rod end of boom cylinders (2) .The return oil from the head end of boom cylinders (2) flows through line (1) into boom lowering control valves (3). Pilot pressure in pilot line (48) shifts valves (47) open. The return oil pressure in line (1) shifts valves (45) open. The return oil in line (1) flows through valves (45), passages (46), and valves (47) to line (6). The return oil then flows through line (6) and valve block (10) to passage (54) .A portion of the return oil flows into port (33) of boom I control valve (15). The return oil flow is restricted by orifice (60). The return oil pressure in passage (54) increases. Most of the return oil flows through boom regeneration valve (56). The return oil is combined with the oil delivery from the right pump. The combined oil flow is supplied to the rod end of the boom cylinders through line (5) .Boom Regeneration Valve
Illustration 8 g00916919
Boom regeneration valve (slow boom down) (9) Main control valve (63) Pilot port (64) Passage (65) Check valve (66) Spool (boom regeneration valve) (67) Passage
Illustration 9 g00916921
Boom regeneration valve (slow boom down) (9) Main control valve (63) Pilot port (64) Passage (65) Check valve (66) Spool (boom regeneration valve) (67) PassageThe boom hydraulic circuit contains a regeneration circuit. This regeneration circuit allows the return oil from the head end of the boom cylinders to be supplied to the rod end of the boom cylinders during the BOOM LOWER operation.When the joystick for the boom is moved to the BOOM LOWER position, pilot oil flow from pilot control valve (18) enters pilot port (63). Spool (66) in the boom regeneration valve shifts downward. The return oil from the head end of the boom cylinders flows through passage (67) and through the throttling slots on the spool for the boom regeneration valve to check valve (65). Check valve (65) opens and the return oil flows through passage (64). The return oil from the head end of the boom cylinders in passage (64) combines with the oil delivery from the right pump. This combined oil now flows to the rod end of the boom cylinders.The oil delivery from only the right pump is used for the BOOM LOWER operation. Since the boom regeneration valve supplies return oil from the head end to the rod end of the boom cylinders, more efficient use of the oil delivery from the right pump is