BEARING-ROLLER 1118919 - Caterpillar

During combined operations of BOOM RAISE and STICK IN, the ACS control algorithm determines the amount of flow that is required for circuit. Flow distribution is based off inputs such as joystick position and cylinder pressure sensors. Output signals sent to the pump-to-cylinder and cylinder-to-tank spools vary in order to provide the optimum flow to the circuit which requires the most demand.When the joystick is moved to the BOOM RAISE position during a STICK IN, the ACS valve ECM limits the signal to stick pump-to-cylinder PHMV (17). Stick pump-to-cylinder spool (18) restricts the amount of pump oil that can flow to the head end of stick cylinder (20). An increased amount of oil flow is then sent to the head end of boom cylinders (2) during this combined hydraulic operation.The amount of oil flow from the main pumps to the stick hydraulic circuit decreases. This action causes a greater portion of the oil flow from the main pumps to flow to the head end of the boom cylinders (2).Boom Lower (With Regeneration)
Illustration 5 g03650477
Hydraulic schematic for BOOM LOWER with regeneration
(1) Flow combiner PHMV
(2) Boom cylinders
(3) Line (oil flow from boom cylinder rod end)
(4) Line (oil flow to boom cylinder head end)
(5) Main control valve
(6) Flow combiner spool
(7) Passage
(8) Boom independent metering valve (IMV)
(9) Passage
(10) Boom cylinder-to-tank rod end spool
(11) Boom pump-to-cylinder head end spool
(12) Flow compensator
(13) Valve
(14) Boom drift reduction valve
(15) Front pump bypass PHMV
(16) Rear pump bypass PHMV
(19) Return passage
(27) Load check valve
(29) Front pump
(30) Pilot pump
(31) Rear pump
(60) Boom drift reduction solenoid valve
(62) Boom head end cylinder-to-tank PHMV
(63) Boom head end pump-to-cylinder PHMV
(64) Boom rod end pump-to-cylinder PHMV
(65) Boom rod end cylinder-to-tank PHMV The boom hydraulic circuit contains a regeneration function. This regeneration function 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. The regeneration function is accomplished within the boom independent metering valve section (8). The ACS valve ECM uses rod end and head end pressure sensor information to determine when a regeneration function can be accomplished. When the boom cylinder head end pressure is high and the joystick position sensor detects a boom down operation, the boom regeneration function is activated.When the joystick for the boom is moved to the BOOM LOWER position, the ACS valve ECM activates pump-to-cylinder PHMV (64) and cylinder-to-tank PHMV (62). The ACS valve ECM also activates pump-to-cylinder PHMV (63). Spool (11) shifts upward allowing return oil from the head end of the boom cylinders to combines with the oil delivery from the front pump. This combined oil now flows to the rod end of the boom cylinders.The oil delivery from only the front pump is used for the BOOM LOWER operation. Since the boom regeneration function supplies return oil from the head end to the rod end of the boom cylinders, more efficient use of the oil delivery from the rear pump is achieved during a BOOM LOWER operation.
Illustration 6 g02968736
Boom independent