CARRIER-PLANETARY 6I9785 - Caterpillar

Illustration 1 g03204505
Basic diagram for the power train systems
The power train is made up of three basic systems:
Power Train Electronic Control Module
Torque Converter
Planetary and TransmissionThe three basic systems have a hydraulic connection, an electrical connection, a magnetic connection, or a mechanical connection.Power is supplied from the engine to the torque converter. Power goes from the torque converter to the speed increaser and then to the planetary transmission. If the transmission is in gear, power flows from the transmission to the output shaft.The operation of the power train begins at the Power Train Electronic Control Module (Power Train ECM). The Power Train ECM receives information from the selected speed of operation through sensors in the electrical system. The Power Train ECM uses the information from sensors in the electrical system to control the torque converter and the transmission hydraulic system.The rotating housing of the torque converter is fastened directly to the engine flywheel. The torque converter has a lockup clutch for direct drive and a one-way clutch for torque converter drive. During torque converter drive, the torque converter drives the transmission hydraulically. During direct drive, there is a direct connection between the engine flywheel and the transmission.The Power Train ECM will activate the lockup clutch solenoid when direct drive is necessary. When the lockup clutch solenoid is activated, the lockup clutch is hydraulically engaged. The lockup clutch becomes a direct connection between the rotating housing and the output shaft of the torque converter. The full power from the engine flywheel is transmitted through the torque converter when the torque converter is in direct drive.The output shaft of the torque converter is connected to the speed increaser and planetary transmission.The Power Train ECM will activate the appropriate ECPC valves when shifts are needed. These valves engage the correct transmission clutches. The transmission clutches mechanically connect the transmission input shaft to the output shaft.The transmission has eight forward speeds. The selection of the desired speed is done manually.When the transmission is in first gear, the torque converter will be in either torque converter drive or direct drive. Converter state is dependent on load factors, output speed of the torque converter and output speed of the transmission.When the transmission is in any of the gears between the second gear and the eighth gear, the operator can choose to run the transmission in torque converter drive or in direct drive. The torque converter will be in torque converter drive for a short time during transmission shifts providing smoother engagement of the transmission clutches.The torque converter hydraulic system uses oil that is also common with the transmission hydraulic system. These systems use the same section of the transmission case.Some components in the torque converter hydraulic system include the torque converter inlet relief valve and the torque converter lockup clutch.Pressurized oil that will engage the lockup clutch comes from the internal gear pump through the transmission oil filters. Some of the oil is