CYLINDER BLOCK GP 2398504 - Caterpillar

Illustration 1 g00821751
Modulation (Raise)
Illustration 1 represents the interpretation by the implement ECM of the signal from the lift lever when the control lever is in the RAISE position. As the control lever is moved from the HOLD position, no current is supplied to the raise solenoid for the lift linkage until the sensor is about three degrees from the center. At about three degrees of lever travel, the ECM supplies the Start of Modulation Current (1) to the raise solenoid. As the control lever is moved toward the detent, the current that is supplied to the raise solenoid increases. The increase is linear up to the Raise Maximum Modulation Current (2). The maximum modulation current is reached just before the control lever enters the detent position. Entering the detent position will not cause a further increase in the current.
Illustration 2 g00821755
Modulation (Lower)
Illustration 2 represents the interpretation by the implement ECM of the signal from the lift lever when the control lever is in the LOWER position. As the control lever is moved away from the center, no current is supplied to the solenoid valve until the control lever is about three degrees from the center. At about three degrees of travel by the lever, the implement ECM supplies the Start of Modulation Current (3) to the lower solenoid. As the control lever is moved toward the detent, the current that is supplied to the lower solenoid increases. The increase is linear up to the Lower Maximum Modulation Current (4). The maximum modulation current is reached just before the control lever enters the detent position. As the position sensor is moved into the detent position, the implement ECM will increase the current. The current will increase until pilot pressure shifts the main valve into the FLOAT position.Note: The Start of Modulation Current provides pilot pressure in order to shift the main valve spool. When the main spool is shifted, hydraulic oil will flow to the cylinders. The Start of Modulation Current varies for each valve. The Start of Modulation Current must be adjusted for each valve. The modulation current must be calibrated on each individual machine.Note: The Maximum Modulation Current provides enough pilot pressure in order to fully shift the main valve spool. When the main valve spool is shifted fully, the cylinder will reach maximum velocity. The Maximum Modulation Current must be adjusted for each valve. The currents must be calibrated on each machine. Reference: For additional information about using Caterpillar Electronic Technician in order to calibrate the modulation currents, refer to the Service Manual module Testing and Adjusting, "Main Control Valve - Electronic Technician" for the machine that is being serviced.Reference: For additional information about using the Caterpillar Monitoring System in order to calibrate the modulation currents, refer to the Service Manual module Testing and Adjusting, "Main Control Valve - Caterpillar Monitoring System" for the machine that is being serviced.