ENGINE AR-CORE 3454412 - Caterpillar

Illustration 1 g02923120
Front of the main control valve (12) Control Valve Spool for the Boom Drift Reduction ValveThe boom drift reduction valve in the boom circuit is located in the main control valve between the rod end and head end of the boom cylinder. When the joystick for the boom is in the NEUTRAL position, the boom drift reduction valve stops oil leakage. The boom drift reduction valve stops oil leakage from the head end of the boom cylinders. Stopping oil leakage prevents boom drift.Boom Raise
Illustration 2 g02920776
Boom drift reduction valve (BOOM RAISE) (1) Drain port (2) Pilot port (3) Passage (4) Valve (5) Port (6) Boom drift reduction valve (7) Spring (9) Drain port (10) Passage (11) Drain passage (12) Spool (13) Passage (14) Spring chamberDuring a BOOM RAISE operation, pilot oil is not sent from the pilot control valve to port (2) of boom drift reduction valve (6). Spool (12) does not shift.The oil flow from the boom I control valve enters through passage (3). Oil flow from the boom II control valve enters from passage (10) and combines with oil from the boom I control valve. As the oil pressure in passage (3) increases, valve (4) shifts against the force of spring (7). The oil in spring chamber (14) flows through passages (13) to port (5). The oil delivery in passage (3) now flows through valve (4) and port (5) to the head end of the boom cylinders.Boom Lower
Illustration 3 g02921396
Boom drift reduction valve (BOOM LOWER without regeneration) (1) Drain port (2) Pilot port (3) Passage (4) Valve (5) Port (6) Boom drift reduction valve (7) Spring (9) Drain port (10) Passage (11) Drain passage (12) Spool (13) Passage (14) Spring chamberDuring a BOOM LOWER operation, pilot oil is sent from the pilot control valve to port (2) of boom drift reduction valve (6). Spool (12) shifts. The oil in spring chamber (14) flows through passage (13), the orifice in spool (12), and spring chamber (15). The oil in spring chamber (14) now flows through drain passage (11) to the hydraulic tank.The return oil from the boom cylinder head end enters port (5). Since the pressure in spring chamber (14) is low, the oil in port (5) shifts valve (4) against the force of spring (7). The oil from the head end of the boom cylinders flows through port (5), valve (4) and passage (3) to the boom I control valve.