Hold Position
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| Illustration 1 | g01053950 |
Electrohydraulic System (1) Tilt cylinder (2) Lift cylinder (left) (3) Lift cylinder (right) (4) Main control valve (left) (5) Switch (hydraulic lockout) (6) Kickout set switch (7) Shuttle valve (8) Main control (right) (9) Tilt linkage position sensor (10) Pressure reducing valve (11) Implement electronic control module (12) Cat Data Link (13) Lift linkage position sensor (14) Solenoid valve (hydraulic lockout) (15) Check valve (16) Detent coil (tilt back) (17) Detent coil (raise) (18) Detent coil (lower) (19) Relief valve (20) Pilot relief valve (21) Relief valve (22) Fixed displacement piston pump (23) Tilt lever position sensor (24) Lift lever position sensor (25) Solenoid valve (variable displacement piston pump) (26) Variable displacement piston pump (27) Pilot pump (28) Hydraulic tank | |
The implements are controlled by movement of the lift control lever and the tilt control lever. As one of the control levers are moved, a change in the duty cycle from one of the lever position sensors is sent to the implement electronic control module (ECM) (11). From the ECM (11), a current that is proportional to the movement of the control lever is sent to the respective pilot control actuators. In the HOLD position, the signals from the lever position sensors are balanced and no current is sent to the pilot control actuators.
In the pilot control, pilot pump (27) draws oil from hydraulic tank (28). Pilot oil flows to pilot relief valve (20) and the pressure of the pilot oil increases until the pressure setting of pilot relief valve (20) is reached. Then, pilot relief valve (20) regulates the pilot pressure and a constant pressure is maintained. The pilot oil flow is sent through the solenoid valve (hydraulic lockout) (14). When the switch (hydraulic lockout) (5) is in the UNLOCKED position and the engine start switch is in the ON position, implement electronic control module (11) will energize the solenoid valve (hydraulic lockout) (14). Then, the pilot oil flows to the pilot control actuators at both ends of each stem on the main control valve. The pressure on both ends of the stems are equalized and the stems in the main control valves are hydraulically locked in the HOLD position.
When the main control valve is in the HOLD position, the stems in the main control valve block oil flow to both tilt cylinder (1) and to lift cylinders (2, 3). In the HOLD position, hydraulic oil that is provided by the implement pumps flow around the stems to hydraulic tank (28) .
Slow TILT BACK Position
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| Illustration 2 | g01053952 |
Electrohydraulic System (1) Tilt cylinder (2) Lift cylinder (left) (3) Lift cylinder (right) (4) Main control valve (left) (5) Switch (hydraulic lockout) (6) Kickout set switch (7) Shuttle valve (8) Main control (right) (9) Tilt linkage position sensor (10) Pressure reducing valve (11) Implement electronic control module (12) Cat Data Link (13) Lift linkage position sensor (14) Solenoid valve (hydraulic lockout) (15) Check valve (16) Detent coil (tilt back) (17) Detent coil (raise) (18) Detent coil (lower) (19) Relief valve (20) Pilot relief valve (21) Relief valve (22) Fixed displacement piston pump (23) Tilt lever position sensor (24) Lift lever position sensor (25) Solenoid valve (variable displacement piston pump) (26) Variable displacement piston pump (27) Pilot pump (28) Hydraulic tank | |
When the tilt control lever is moved to the SLOW TILT BACK position, tilt lever position sensor (23) sends a signal to the implement (ECM) (11). The signal is a pulse width modulated signal. Implement ECM (11) analyzes this signal and the signals from tilt lever position sensor (23) and from lift lever position sensor (24). Then, implement ECM (11) then sends a proportional current that energizes the tilt back solenoid. The tilt back solenoid is located on the pilot control actuator for the main control valve (left) (4) .
The solenoid valve drains oil that is between the pilot control actuator (tilt back) and the tilt back stem in the main control valve. The oil will drain to hydraulic tank (28). This reduces the pilot pressure at the tilt back stem. The pilot oil pressure on the dump stem shifts the tilt back stem. The tilt stem shifts and the oil that is demanded will flow to the rod end of tilt cylinder (1) .
The oil from fixed displacement piston pump (22) that was flowing through the valve to the hydraulic tank is blocked and the hydraulic oil flows around the tilt stem to the rod end of tilt cylinder (1). The bucket will move toward the TILT BACK position. The oil at the head end of tilt cylinder (1) flows around the tilt stem to hydraulic tank (28) .
The oil from variable displacement piston pump (28) is not needed for slow tilt back operation. Implement ECM (11) will not energize the solenoid valve (variable displacement piston pump) (25). The oil that is supplied by the variable displacement piston pump flows through the main control valve (right) (8). Then, the oil flows to hydraulic tank (28) .
Fast TILT BACK Position
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| Illustration 3 | g01053953 |
Electrohydraulic System (1) Tilt cylinder (2) Lift cylinder (left) (3) Lift cylinder (right) (4) Main control valve (left) (5) Switch (hydraulic lockout) (6) Kickout set switch (7) Shuttle valve (8) Main control (right) (9) Tilt linkage position sensor (10) Pressure reducing valve (11) Implement electronic control module (12) Cat Data Link (13) Lift linkage position sensor (14) Solenoid valve (hydraulic lockout) (15) Check valve (16) Detent coil (tilt back) (17) Detent coil (raise) (18) Detent coil (lower) (19) Relief valve (20) Pilot relief valve (21) Relief valve (22) Fixed displacement piston pump (23) Tilt lever position sensor (24) Lift lever position sensor (25) Solenoid valve (variable displacement piston pump) (26) Variable displacement piston pump (27) Pilot pump (28) Hydraulic tank | |
When the tilt control lever is moved to the full TILT BACK position, tilt lever position sensor (23) sends a signal to the implement (ECM) (11). The implement (ECM) (11) analyzes this signal and the signals from both tilt linkage position sensor (9) and from lift linkage position sensor (13). Then, implement ECM (11) sends a current that is proportional to the movement of the tilt control lever to the tilt back solenoid valve. The increase in current to the tilt back solenoid valve will increase the amount of pilot oil that is between the pilot control actuator and the tilt back stem. This will increase the movement of the tilt stem. The increased movement of the tilt back stem allows a larger flow of oil through main control valve to the rod end of the tilt cylinder.
The solenoid valve drains oil that is between the pilot control actuator for the TILT BACK position and the tilt back stem in the main control valve. The oil will drain to hydraulic tank (28). This reduces the pilot pressure at the end of the tilt back stem. The pilot oil pressure on the dump stem shifts the tilt back stem. The tilt stem shifts and the oil that is demanded will flow to the rod end of tilt cylinder (1) .
The hydraulic oil that was flowing through the main control valve to the hydraulic tank is blocked. The oil from fixed displacement piston pump (22) flows around the tilt stem in the main control valve (left) (4) to the rod end of tilt cylinder (1). The oil that is provided by the variable displacement piston pump (26) flows around the control valve spool in the main control valve (right) (8) to the rod end of tilt cylinder (1) .
The oil from the head end of tilt cylinder (1) flows around the tilt stem in the main control valve (left) and the main control valve (right). The flow of return oil around each tilt stem is proportional to the flow of supply oil around the tilt stems.
As the demand for implement oil increases, the solenoid valve (variable displacement piston pump) (26) becomes energized. The variable displacement piston pump will increase the flow as the demand increases. The hydraulic oil from variable displacement piston pump (26) flows through the main control valve (right) (8) to the rod end of tilt cylinder (1) .
Slow RAISE Position
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| Illustration 4 | g01053954 |
Electrohydraulic System (1) Tilt cylinder (2) Lift cylinder (left) (3) Lift cylinder (right) (4) Main control valve (left) (5) Switch (hydraulic lockout) (6) Kickout set switch (7) Shuttle valve (8) Main control (right) (9) Tilt linkage position sensor (10) Pressure reducing valve (11) Implement electronic control module (12) Cat Data Link (13) Lift linkage position sensor (14) Solenoid valve (hydraulic lockout) (15) Check valve (16) Detent coil (tilt back) (17) Detent coil (raise) (18) Detent coil (lower) (19) Relief valve (20) Pilot relief valve (21) Relief valve (22) Fixed displacement piston pump (23) Tilt lever position sensor (24) Lift lever position sensor (25) Solenoid valve (variable displacement piston pump) (26) Variable displacement piston pump (27) Pilot pump (28) Hydraulic tank | |
When the lift control lever is moved to the slow RAISE position, lift lever position sensor (24) sends a signal to the implement (ECM) (11). The implement (ECM) (11) analyzes this signal and the signals from both tilt linkage position sensor (9) and lift linkage position sensor (13). Then, implement ECM (11) sends a current that is proportional to the movement of the lift control lever to the raise solenoid valve. The increase in current to the raise solenoid valve will increase the amount of pilot oil that is drained between the pilot control actuator and the lift stem. The increased movement of the tilt back stem allows a larger flow of oil through main control valve to the head end of the lift cylinders.
When the oil is drained between the pilot control actuator for the RAISE position and the raise stem in the main control valve, the pilot pressure at the lift stem is reduced. The pilot oil pressure on the raise stem shifts the lift stem. The lift stem shifts to the RAISE position. The oil that is demanded will flow to the head end of lift cylinders (2, 3) .
The hydraulic oil that was flowing through the main control valve to the hydraulic tank is blocked. The oil from fixed displacement piston pump (22) flows around the control valve spool to the head end of lift cylinders (2) and (3). The oil at the rod end of the lift cylinders flows around the control valve spool to hydraulic tank (28) .
The oil from variable displacement piston pump (26) is not required for slow raise operation. Implement ECM (11) will not energize the solenoid valve (variable displacement piston pump) (25). The hydraulic oil from variable displacement piston pump (26) flows through the main control valve (right) (8) to hydraulic tank (11) .
Fast RAISE Position
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| Illustration 5 | g01053956 |
Electrohydraulic System (1) Tilt cylinder (2) Lift cylinder (left) (3) Lift cylinder (right) (4) Main control valve (left) (5) Switch (hydraulic lockout) (6) Kickout set switch (7) Shuttle valve (8) Main control (right) (9) Tilt linkage position sensor (10) Pressure reducing valve (11) Implement electronic control module (12) Cat Data Link (13) Lift linkage position sensor (14) Solenoid valve (hydraulic lockout) (15) Check valve (16) Detent coil (tilt back) (17) Detent coil (raise) (18) Detent coil (lower) (19) Relief valve (20) Pilot relief valve (21) Relief valve (22) Fixed displacement piston pump (23) Tilt lever position sensor (24) Lift lever position sensor (25) Solenoid valve (variable displacement piston pump) (26) Variable displacement piston pump (27) Pilot pump (28) Hydraulic tank | |
When the lift control lever is moved to the fast RAISE position, lift lever position sensor (24) sends a signal to the implement (ECM). Implement ECM (11) analyzes this signal and the signals from both tilt linkage position sensor (9) and lift linkage position sensor (13). Then, implement ECM (11) sends a current that is proportional to the movement of the lift control lever to the raise solenoid valve on the pilot control actuator. The increase in current to the raise solenoid valve will increase the amount of pilot oil that is drained between the pilot control actuator and the lift stem. The increased movement of the lift stem allows a larger flow of oil through main control valve to the head end of lift cylinders (2, 3).
The hydraulic oil that was flowing through the main control valve to the hydraulic tank is blocked. The oil from fixed displacement piston pump (22) flows around the lift stem in the main control valve (left) (4) to the head end of lift cylinders (2, 3). The oil that is provided by the variable displacement piston pump (26) flows around the lift stem in the main control valve (right) (8) and combines with the hydraulic oil from the main control valve (left) (4) to the head end of lift cylinders (2, 3) .
As the demand for implement oil increases, the solenoid valve (variable displacement piston pump) (26) becomes energized. Variable displacement piston pump (26) will increase the flow as the demand increases. The hydraulic oil from variable displacement piston pump (26) flows through the main control valve (right) (8) to the head end of lift cylinder (2, 3). The oil in the rod end of the lift cylinders flow around the lift spool to hydraulic tank (28) .