GEAR AS 1329633 - Caterpillar

Illustration 1 g03869098
Location of the Modulating Valve for the Impeller Clutch
(1) Modulating valve for the lockup clutch
(2) Modulating valve for the impeller clutch
(3) Output side of the torque converter The modulating valve for the impeller clutch (2) is located on the output side of the torque converter. The valve is positioned just in front of the modulating valve for the torque converter lockup clutch.
Illustration 2 g00670987
Modulating Valve for the Torque Converter Impeller Clutch
The modulating valve for the impeller clutch modulates the torque converter impeller clutch pressure in response to the position of the torque converter pedal and the various operating conditions.The modulating valve for the impeller clutch solenoid is an output of the power train electronic control module (ECM). The modulating valve for the impeller clutch solenoid is a proportional solenoid valve. The valve is used by the power train ECM to directly modulate the oil pressure that is sent to the impeller clutch. The current to the clutch solenoid varies as the operator changes the position of the torque converter pedal. The distance that is traveled by the solenoid plunger (valve) is proportional to the electrical current of the solenoid. The position of the solenoid plunger (valve) controls the oil pressure of the impeller clutch. The amount of current that is sent to the clutch solenoid modulating valve regulates the amount of oil pressure that is supplied to the impeller clutch. When the power train ECM sends the maximum current to the clutch solenoid modulating valve, the oil pressure in the clutch is at the minimum. If current is not sent to the modulating valve for the impeller clutch, the oil pressure in the clutch is at the maximum.The modulating valve for the impeller clutch is also affected by the following items: the transmission speed switch, the transmission direction switch, the torque converter output speed and direction, the transmission output speed and reduced rimpull select switch.
Illustration 3 g00670988
Relationship between the Current and Pressure
(X) Current to the impeller clutch solenoid (Y) pressure at the impeller clutch.
The necessary amount of pressure that is required to adjust the impeller clutch is determined. A valve map then determines the proper amount of electrical current that will be sent to the solenoid. During normal operation, the control for the impeller clutch consists of several possible strategies. During each software control loop, each strategy produces a command for the desired pressure. A priority signal that consists of two levels determines the amount of pressure that is sent to the solenoid valve. This oil pressure will adjust the impeller clutch.Reference: For information on troubleshooting the transmission, refer to the Service Manual module for Troubleshooting, Testing and Adjusting, UENR0751, "Transmission" of the machine that is being serviced.Reference: For information on calibrating the clutch solenoid modulating valves, refer to the Service Manual module for Troubleshooting, Testing and Adjusting, UENR0751, "Fill Pressures For The Impeller Clutch of the Torque Converter (Electronic Technician) - Calibrate" of the machine that is being serviced.Reference: For more information on the power train electronic control