Ejector Control in the HOLD Position
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| Illustration 1 | g03531457 |
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(1) Main Control Valve
(1a) Shuttle Valve (1b) Orifice (1f) Pressure Reducing Valve (1g) Check Valve (1j) Diverter Valve (1k) Diverter Valve (1n) Check Valve (1o) Diverter Valve (1p) Screen (1q) Orifice (1r) Check Valve (1t) Check Valve (1u) Orifice (1v) Screen (1cc) Shuttle Valve (1gg) Shuttle Valve (2) Ejector Manifold (2a) Sequence Valve (2b) Check Valve (2c) Flow Control Valve (2d) Load Control Valve (3) Ejector Control Valve (3a) Pilot Control Actuator (3b) Pilot Control Actuator (3c) Valve Spool (3d) Relief Valve (Eject) (3e) Relief Valve (Retract) (8) Piston Pump (Steering and Ejector) (9) Piston Pump (Brake, Ejector, and Fan) (34) Tailgate Cylinders (35) Ejector Cylinder (35a) Position Sensor | |
Piston pump (8) and piston pump (9) supply oil to the ejector system. Each piston pump is a variable displacement pump.
When the ejector control lever is in theHOLD position, the ECM sends no signal or current to pilot control actuators (3a) and (3b).
Oil flow from the P1 port flows through screen (1v), orifice (1u) and check valve (1t) to pressure reducing valve (1f).
The oil flows from pressure reducing valve (1f) out of the J port to pilot control actuators (3a) and (3b) at ejector control valve (3). The oil is then blocked by the pilot control actuators.
The internal springs within the ejector control valve keep valve spool (3c) in theHOLD position.
The oil from piston pump (8) flows to the P2 port in main control valve (1). With the ejector control valve in the HOLD position, oil flows through diverter valve (1j) which is then divided between the steering system and the ejector system.
Oil flow out of diverter valve (1j) to the steering system is blocked at the hand metering unit.
Oil flow out of diverter valve (1j) to the ejector system flows through check valve (1g), out of port P, and then to ejector control valve (3). The oil flow is blocked at the ejector control valve.
At the same time, oil flow from piston pump (9) flows to the P1 port in main control valve (1). If the braking system is fully charged, oil flows through diverter valve (1o) and check valve (1n). The oil then combines with the oil flow from piston pump (8) and the oil is blocked at the ejector control valve.
Since all the flow paths to the ejector cylinder and to the tailgate cylinder are blocked, the ejector blade and the tailgate are resistant to motion by external forces. Oil in the ejector cylinder is blocked at the ejector control valve which prevents the blade from moving during acceleration of the machine. The oil in the piston sides of the tailgate cylinders is blocked by check valve (2b) and control valve (2d). This action ensures that the tailgate does not open under the force due to gravity.
Oil flow from piston pump (8) is directed through diverter valve (1j). The oil flows through screen (1p), orifice (1q) and check valve (1r) into the load sensing system. Oil in the load sensing system flows through orifice (1b) and out of port LSST to the hand metering unit. The oil then flows through the hand metering unit to the hydraulic tank. At the same time, oil in the load sensing system flows through shuttle valve (1a) and out of port LS2 to piston pump (8).
With no demand on the ejector system and the load sensing line is directed to the hydraulic tank at the hand metering pump, piston pump (8) will maintain the minimum swashplate angle.
A check valve in the return line to the hydraulic tank maintains pressure in the tank line. The check valve also maintains the same pressure in the load sensing system. The pressure ensures a rapid response.
Oil flow from the P1 port flows through screen (1v), orifice (1u) and check valve (1t) to diverter valve (1k). The oil flow out of diverter valve (1k) is directed to the hydraulic tank.
With no demand on the ejector system and the load sensing line is directed to the hydraulic tank at the diverter valve, piston pump (9) will maintain the minimum swashplate angle.
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| Illustration 2 | g01169488 |
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The position sensor (A) is on the head end of the ejector cylinder. | |
Under normal operating conditions, the ECM will control the ejector forward and reverse solenoids according to the commands from the operator. A proximity switch is installed on the machine that allows the control system to detect the blade in the fully retracted position. The retract solenoid is switched off once the blade is fully retracted. When the blade is in the fully retracted position, the proximity switch will be CLOSED and the ejector system will be forced into HOLD. This action will only happen when the ejector lever is placed in any position except EJECT. Moving the ejector Lever to EJECT will override HOLD. The proximity switch will indicate the blade is not fully retracted. The switch will change to the open state and the ejector system will operate according to the lever request.
The "Blade Not Fully Retracted" lamp will illuminate when the proximity switch indicates that the blade is not fully retracted. The lamp will turn off when the proximity switch indicates that the blade is fully retracted. The "Blade Not Fully Retracted" lamp will operate independently of the "engine running" state. In other words, the lamp will not always be illuminated when the engine is not running, although the ejector system is actually in hold.
If the ejector lever remains in RETRACT longer than one minute without a change in the "Position Sensor" status, the ejector system will be forced into HOLD. This is causing the ejector system to sense a problem that prevents the blade from retracting or being detected as RETRACTED.
The system will be forced out of HOLD only if any of the following conditions are true:
- The proximity switch indicates that the blade is retracted.
- The shift lever has passed through the hold position.
The timer is reset when the hold override is cleared in this way. If the position sensor fails to close within one minute, the system will again be placed in HOLD.
During operation, the position sensor makes sure that the ejector cylinder remains fully retracted. Any cylinder drift in the ejector cylinder is detected by the position sensor and the ejector cylinder is retracted automatically.
Ejector Control in the EJECT Position
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| Illustration 3 | g03531459 |
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(1) Main Control Valve
(1a) Shuttle Valve (1b) Orifice (1f) Pressure Reducing Valve (1g) Check Valve (1j) Diverter Valve (1k) Diverter Valve (1n) Check Valve (1o) Diverter Valve (1p) Screen (1q) Orifice (1r) Check Valve (1t) Check Valve (1u) Orifice (1v) Screen (1cc) Shuttle Valve (1gg) Shuttle Valve (2) Ejector Manifold (2a) Sequence Valve (2b) Check Valve (2c) Flow Control Valve (2d) Load Control Valve (3) Ejector Control Valve (3a) Pilot Control Actuator (3b) Pilot Control Actuator (3c) Valve Spool (3d) Relief Valve (Eject) (3e) Relief Valve (Retract) (8) Piston Pump (Steering and Ejector) (9) Piston Pump (Brake, Ejector, and Fan) (34) Tailgate Cylinders (35) Ejector Cylinder (35a) Position Sensor | |
When the ejector control lever is moved to the EJECT position, a pulse width modulated signal is sent to the ECM. The ECM sends a current to pilot control actuator (3a). The current is proportional to the displacement of the ejector control lever in the cab.
Oil flow from the P1 port flows through screen (1v), orifice (1u) and check valve (1t) to pressure reducing valve (1f).
The oil flows from pressure reducing valve (1f) out of the J port to pilot control actuators (3a) and (3b) at ejector control valve (3).
When the pilot control actuator (3a) is activated, pilot oil is allowed to flow through the pilot control actuator in order to move valve spool (3c) to the EJECT position.
The oil from piston pump (8) flows to the P2 port in main control valve (1). When the ejector control valve is in the EJECT position, a pressure differential across diverter valve (1j) causes the spool to shift. The diverter valve directs oil into the ejector system.
Oil flow out of diverter valve (1j) to the ejector system flows through check valve (1g), out of port P, and then to ejector control valve (3).
At the same time, oil flow from piston pump (9) flows to the P1 port in main control valve (1). Oil flows through diverter valve (1o) and check valve (1n). The oil then combines with the oil flow from piston pump (8).
When valve spool (3c) is in the EJECT position, Oil flow is directed to the piston side of ejector cylinder (35). At the same time, return oil flow is directed through valve spool (3c) back to the hydraulic tank. The ejector cylinder extends and the blade moves toward the rear of the machine. Sequence valve (2a) maintains back pressure in order to ensure that the ejector cylinder is extended in the proper sequence.
An Internal passage within valve spool (3c) allows oil from the main oil supply to enter the load sensing system.
Load sensing pressure enters main control valve (1) at the LS port. The sensing pressure then moves shuttle valve (1a). This action allows sensing pressure out of the LS2 port to piston pump (8). At the same time, the sensing pressure then moves shuttle valve (1gg). This action allows sensing pressure out of the LS1 port to piston pump (9).
The load sensing pressure to piston pumps (8) and (9) causes the output of the piston pumps to increase in order to match the requirements of the ejector system.
The piston pump control valves that are located on piston pumps (8) and (9) control the angle of the swashplates. When the ejector cylinder is fully extended and stalled, the piston pumps will deliver the minimum flow but the maximum system pressure will be maintained.
Ejector Control in the RETRACT Position
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| Illustration 4 | g03531461 |
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(1) Main Control Valve
(1a) Shuttle Valve (1b) Orifice (1f) Pressure Reducing Valve (1g) Check Valve (1j) Diverter Valve (1k) Diverter Valve (1n) Check Valve (1o) Diverter Valve (1p) Screen (1q) Orifice (1r) Check Valve (1t) Check Valve (1u) Orifice (1v) Screen (1cc) Shuttle Valve (1gg) Shuttle Valve (2) Ejector Manifold (2a) Sequence Valve (2b) Check Valve (2c) Flow Control Valve (2d) Load Control Valve (3) Ejector Control Valve (3a) Pilot Control Actuator (3b) Pilot Control Actuator (3c) Valve Spool (3d) Relief Valve (Eject) (3e) Relief Valve (Retract) (8) Piston Pump (Steering and Ejector) (9) Piston Pump (Brake, Ejector, and Fan) (34) Tailgate Cylinders (35) Ejector Cylinder (35a) Position Sensor | |
When the ejector control lever is moved to the RETRACT position, a pulse width modulated signal is sent to the ECM. The ECM sends a current to pilot control actuator (3b). The current is proportional to the displacement of the ejector control lever in the cab.
Oil flow from the P1 port flows through screen (1v), orifice (1u) and check valve (1t) to pressure reducing valve (1f).
The oil flows from pressure reducing valve (1f) out of the J port to pilot control actuators (3a) and (3b) at ejector control valve (3).
When the pilot control actuator (3b) is activated, pilot oil is allowed to flow through the pilot control actuator in order to move valve spool (3c) to the RETRACT position.
The oil from piston pump (8) flows to the P2 port in main control valve (1). When the ejector control valve is in the RETRACT position, a pressure differential across diverter valve (1j) causes the spool to shift. The diverter valve directs oil into the ejector system.
Oil flow out of diverter valve (1j) to the ejector system flows through check valve (1g), out of port P, and then to ejector control valve (3).
At the same time, oil flow from piston pump (9) flows to the P1 port in main control valve (1). Oil flows through diverter valve (1o) and check valve (1n). The oil then combines with the oil flow from piston pump (8).
When valve spool (3c) is in the RETRACT position, Oil flow is directed to the rod side of ejector cylinder (35) and to the piston sides of tailgate cylinders (34). At the same time, return oil flow is directed through valve spool (3c) back to the hydraulic tank. The ejector cylinder retracts and the tailgate cylinders extend. The ejector blade moves toward the front of the machine, and the tailgate closes.
Relief valve (3d) controls the maximum system pressure in order to lower the dump body.
An Internal passage within valve spool (3c) allows oil from the main supply to enter the load sensing system.
Load sensing pressure enters main control valve (1) at the LS port. The sensing pressure then moves shuttle valve (1a). This action allows sensing pressure out of the LS2 port to piston pump (8). At the same time, the sensing pressure then moves shuttle valve (1gg). This action allows sensing pressure out of the LS1 port to piston pump (9).
The load sensing pressure that is sent to piston pump (8) and (9) will cause the output of the piston pumps to increase in order to match the requirements of the ejector system.
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| Illustration 5 | g01173128 |
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Main control valve 1 is located beneath the cab on the top of the chassis on the left side. | |
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| Illustration 6 | g01173394 |
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The ejector control valve (3) is located on the left side rear of the tractor. (3) Ejector Control Valve (3a) Pilot Control Actuator (3b) Pilot Control Actuator (3d) Relief Valve (3e) Relief Valve (3h) Check Valve (A) Eject Port (B) Load Sensing Port (C) Retract Port (D) Tank Port (E) Pump Port | |
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| Illustration 7 | g01173132 |
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The ejector manifold (2) is located on the right side of the machine above the articulated hitch. (2) Ejector Manifold (2a) Sequence Valve (2c) Flow Regulator (2d) Load Control Valve | |
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| Illustration 8 | g01173133 |
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Piston pump (8) for the steering and ejector systems is located beneath the cab toward the left side of the machine in front of main control valve (1). Piston pump (9) for the fan, the brake, and ejector systems is located on the right side of piston pump (8). | |