Function
 | |
| Illustration 1 | g02161993 |
Pump compartment (1) Load signal reducing manifold (2) Pressure sensor (3) Solenoid valve (load signal diverter) (4) Orifice (5) Solenoid valve (load signal reduction) | |
 | |
| Illustration 2 | g02161996 |
Pump compartment (1) Load signal reducing manifold (3) Solenoid valve (load signal diverter) (4) Orifice (5) Solenoid valve (load signal reduction) | |
The function of the load signal reducing manifold is to provide a reduced load signal pressure to the pump regulators during boom down regeneration. When the boom is lowered with no load, the mass of the implements is sufficient to lower the boom without upstroking the pumps. The engine speed will be maintained at low idle during boom regeneration as well.
When boom regeneration conditions are present, manifold (1) is utilized. Once the work tool encounters resistance, the boom regeneration condition ends. Manifold (1) is no longer used. Boom regeneration can still function when other implements are operated. However, if other implements are operated during a boom regeneration condition, manifold (1) is not used. The full load signal pressure must be sent to the pump regulators in order to provide the proper pump flow to operate the other implements
During operations when boom regeneration is inactive, the machine ECM does not send an electrical signal to solenoid valve (3) or solenoid valve (5). The load signal pressure from the main control valve flows through load signal reducing manifold (1) to the pump regulators.
During boom regeneration, the machine ECM energizes solenoid valve (3) and solenoid valve (5). The load signal pressure is reduced so that the pump is destroked. Once the work tool encounters resistance, regeneration conditions are no longer present. The machine ECM de-energizes solenoid valve (3) and solenoid valve (5). The load signal pressure then increases and causes the pumps to upstroke.
Note: Any combined implement function or travel with boom down function will stop the boom load signal reduction condition.
Boom Regeneration With Implement and/or Travel Operation
 | |
| Illustration 3 | g02161988 |
No reduction of the load signal pressure (1) Load signal reducing manifold (2) Pressure sensor (3) Solenoid valve (load signal diverter) (4) Orifice (5) Solenoid valve (load signal reduction) (6) Passage (load signal from main control valve) (7) Passage (pressure sensor) (8) Spool (9) Passage (10) Passage (load signal to pump regulators) (11) Seat (12) Spool (13) Passage (drain) | |
When an implement or travel operation is performed during a boom regeneration condition, solenoid valve (3) and solenoid valve (5) are de-energized. The load signal pressure from the main control valve flows into manifold (1) at passage (6). The load signal pressure also flows into passage (7) to pressure sensor (2). Load signal pressure then flows to spool (8) and to passage (9). From passage (9), load signal pressure flows to passage (10). The load signal pressure in passage (10) flows directly to the pump regulators.
No reduction of the load signal pressure is performed. The pump regulators maintain the proper flow for implement and/or travel operations.
Spool (8) is shifted to the left when solenoid (3) is de-energized. Spool (12) is shifted to the left against seat (11) when solenoid (5) is de-energized. Load signal pressure is not reduced. No load signal pressure flows to the drain passages.
Load Signal Reduction During A Boom Regeneration Operation
 | |
| Illustration 4 | g02161991 |
Reduction of the load signal pressure (1) Load signal reducing manifold (2) Pressure sensor (3) Solenoid valve (load signal diverter) (4) Orifice (5) Solenoid valve (load signal reduction) (6) Passage (load signal from main control valve) (7) Passage (pressure sensor) (8) Spool (9) Passage (10) Passage (load signal to pump regulators) (11) Seat (12) Spool (13) Passage (drain) | |
Note: An electrical signal is sent from pressure sensor (2) to the machine ECM as an input. The pressure sensor in the head end of the boom cylinder lines is an input to the machine ECM. The machine ECM uses the inputs of pressure sensor (2) and the pressure sensor in the head end of the boom cylinders to control boom regeneration and load signal reduction.
When boom regeneration is active and no other implement or travel function is performed, manifold (1) is used. Solenoid valve (3) and solenoid valve (5) are energized by the machine ECM. The load signal pressure from the main control valve flows into manifold (1) at passage (6). The load signal pressure also flows into passage (7) to pressure sensor (2). Load signal pressure then flows to spool (8). Spool (8) is shifted to the right and blocks the flow of oil to passage (9). Load signal pressure flows to orifice (4). Orifice (4) creates back pressure in passage (6) and passage (7). The back pressure is sensed by pressure sensor (2) .
Spool (12) is shifted to the right when solenoid (5) is energized. The load signal pressure in passage (9) flows past seat (11) and then to passage (13). The load signal pressure in passage (9) drains to the hydraulic tank. The load signal pressure is reduced. No load signal pressure flows to the pump regulators. The main pumps are destroked.
During load signal reduction, pressure sensor (2) sends an electrical signal to the machine ECM. The electrical signal from the pressure sensor in the head end of the boom cylinders sends an electrical signal to the machine ECM as well. The load signal reduction is performed as long as the pressure in the head end of the boom cylinders is higher than the pressure that is in passage (7) .
During boom regeneration and load signal reduction, the pressure sensor in the head end of the boom cylinders senses higher pressure than pressure sensor (2). Once the work tool encounters resistance, the pressure in the head end of the boom cylinders lowers. The pressure in passage (7) becomes higher than the pressure in the head end of the boom cylinders. The machine ECM de-energizes solenoid (3) and solenoid (5). Boom regeneration ends as well. Load signal pressure is no longer reduced and is now sent to the pump regulators. The main pumps upstroke.