| |
| Illustration 1 | g03788186 |
|
Hydraulic schematic for BOOM RAISE (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (4) Main control valve (5) Passage (6) Flow combiner spool (7) Flow combiner PHMV (8) Drive pump bypass PHMV (9) Idler pump bypass PHMV (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (14) Boom independent metering valve (IMV) (15) Return passage (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (23) Boom cylinder-to-tank rod end spool (24) Boom pump-to-cylinder rod end spool (25) Boom pump-to-cylinder head end spool (26) Boom cylinder-to-tank head end spool (27) Pilot pump (28) Drive pump (29) Idler pump | |
A BOOM RAISE operation is accomplished when the oil delivery from both drive pump (28) and idler pump (29) is supplied to the head end of boom cylinders (1). Flow combiner PHMV (7) is activated by the machine ECM. Flow combiner spool (6) then shifts to the open section allowing drive pump oil in passage (5) to combine with idler pump oil in passage (10). The combined oil from idler pump (29) and drive pump (28) then flows to boom IMV section (14).
| |
| Illustration 2 | g03788188 |
|
Main control valve (12) Port (boom DOWN) (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (21) Port (boom UP) | |
When the joystick for the boom is moved to the full BOOM RAISE position, the ACS valve ECM activates pump-to-cylinder PHMV (18) and cylinder-to-tank PHMV (16). Pilot oil then shifts spool (23) and spool (25) upward. Simultaneously, the machine ECM activates drive pump bypass PHMV (8) and idler pump bypass PHMV (9). Bypass PHMV's (8) and (9) are modulated according to the joystick position. Pump oil is then supplied to passages (5) and passage (10) in main control valve (4).
The oil delivery from idler pump (29) flows through passage (10) in main control valve (4) to boom IMV (14). The oil delivery from drive pump (28) flows through passage (5), flow combiner spool (6), and passage (10) to boom IMV (14).
| |
| Illustration 3 | g03788193 |
|
Boom independent metering valve (BOOM RAISE position) (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (23) Boom cylinder-to-tank rod end spool (25) Boom pump-to-cylinder head end spool | |
Pump delivery oil in passage (10) flows through flow compensator (13). Load check valve (20) opens and allows the pump oil to flow to boom pump-to-cylinder spool (25). The pump oil then flows through port (21) and line (3) to the head end of boom cylinders (1).
Return oil from the rod end of boom cylinders (1) flows through line (2) to port (12). Return oil flows through cylinder-to-tank spool (23) and to the hydraulic tank.
Note: For more information on the boom drift reduction valve, refer to Systems Operation, "Boom Drift Reduction Valve".
| |
| Illustration 4 | g03788196 |
|
Hydraulic schematic for BOOM RAISE and STICK IN (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (4) Main control valve (5) Passage (6) Flow combiner spool (7) Flow combiner PHMV (8) Drive pump bypass PHMV (9) Idler pump bypass PHMV (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (14) Boom independent metering valve (IMV) (15) Return passage (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (23) Boom cylinder-to-tank rod end spool (24) Boom pump-to-cylinder rod end spool (25) Boom pump-to-cylinder head end spool (26) Boom cylinder-to-tank head end spool (27) Pilot pump (28) Drive pump (29) Idler pump (30) Stick cylinder (31) Stick pump-to-cylinder PHMV (32) Stick pump-to-cylinder head end spool | |
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 (31). Stick pump-to-cylinder spool (32) restricts the amount of pump oil that can flow to the head end of stick cylinder (30). An increased amount of oil flow is then sent to the head end of boom cylinders (1) 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 (1).
Boom Lower (With Regeneration)
| |
| Illustration 5 | g03788216 |
|
Hydraulic schematic for BOOM LOWER with regeneration (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (4) Main control valve (5) Passage (6) Flow combiner spool (7) Flow combiner PHMV (8) Drive pump bypass PHMV (9) Idler pump bypass PHMV (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (14) Boom independent metering valve (IMV) (15) Return passage (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (23) Boom cylinder-to-tank rod end spool (24) Boom pump-to-cylinder rod end spool (25) Boom pump-to-cylinder head end spool (26) Boom cylinder-to-tank head end spool (27) Pilot pump (28) Drive pump (29) Idler pump | |
The boom hydraulic circuit contains a regeneration function. This regeneration function allows the return oil from the head end of boom cylinders (1) 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 (14).
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 (17) and cylinder-to-tank PHMV (19). The ACS valve ECM also activates pump-to-cylinder PHMV (18). Spool (25) shifts upward allowing return oil from the head end of boom cylinders (1) to combines with the oil delivery from idler pump (29). This combined oil now flows to the rod end of boom cylinders (1).
The oil delivery from only idler pump (29) is used for the BOOM LOWER operation. Since the boom regeneration function supplies return oil from the head end to the rod end of boom cylinders (1), more efficient use of the oil delivery from drive pump (28) is achieved during a BOOM LOWER operation.
| |
| Illustration 6 | g03788256 |
|
Boom independent metering valve (BOOM LOWER position) (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (23) Boom cylinder-to-tank rod end spool (24) Boom pump-to-cylinder rod end spool (25) Boom pump-to-cylinder head end spool (26) Boom cylinder-to-tank head end spool | |
Pump delivery oil in passage (10) flows through flow compensator (13). Load check valve (20) opens and allows the pump oil to flow to boom pump-to-cylinder spool (24). The pump oil then flows through port (12) and line (2) to the rod end of boom cylinders (1).
Return oil from the head end of boom cylinders (1) flows through line (3) to port (21). Part of the return oil flows through cylinder-to-tank spool (26) and to the hydraulic tank. Since boom head end pump-to-cylinder PHMV (18) is activated, spool (25) is shifted upward. The other part of the return oil flows through spool (25) and combines with the oil delivery from drive pump (28). The regeneration oil from the head end of the cylinder is then returned to the rod end of boom cylinders (1).
Boom Lower (Without Regeneration)
| |
| Illustration 7 | g03788277 |
|
Hydraulic schematic for BOOM LOWER without regeneration (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (4) Main control valve (5) Passage (6) Flow combiner spool (7) Flow combiner PHMV (8) Drive pump bypass PHMV (9) Idler pump bypass PHMV (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (14) Boom independent metering valve (IMV) (15) Return passage (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (23) Boom cylinder-to-tank rod end spool (24) Boom pump-to-cylinder rod end spool (25) Boom pump-to-cylinder head end spool (26) Boom cylinder-to-tank head end spool (27) Pilot pump (28) Drive pump (29) Idler pump | |
The ACS valve ECM uses pressure sensor information to determine the position of the boom. When the boom cylinder head end pressure is low and the joystick position sensor detects a boom down operation, the ACS valve ECM recognizes that the work tool is on the ground and regeneration is not necessary.
| |
| Illustration 8 | g03788279 |
|
Boom independent metering valve (BOOM LOWER position) (1) Boom cylinders (2) Line (oil flow from boom cylinder rod end) (3) Line (oil flow to boom cylinder head end) (10) Passage (11) Pressure sensor (boom cylinder rod end) (12) Port (boom DOWN) (13) Flow compensator (16) Boom rod end cylinder-to-tank PHMV (17) Boom rod end pump-to-cylinder PHMV (18) Boom head end pump-to-cylinder PHMV (19) Boom head end cylinder-to-tank PHMV (20) Load check valve (21) Port (boom UP) (22) Pressure sensor (boom cylinder head end) (24) Boom pump-to-cylinder rod end spool (26) Boom cylinder-to-tank head end spool | |
When the joystick for the boom is moved to the BOOM LOWER position, the ACS valve ECM activates pump-to-cylinder PHMV (17) and cylinder-to-tank PHMV (19). Front pump delivery oil in passage (10) flows through flow compensator (13). Load check valve (20) opens and allows the pump oil to flow to boom pump-to-cylinder spool (24). The pump oil then flows through port (12) and line (2) to the rod end of boom cylinders (1).
Return oil from the head end of boom cylinders (2) flows through line (4) to port (61). The return oil flows through cylinder-to-tank spool (24) and to the hydraulic tank. The boom then lowers without regeneration oil.