SEAL 8J2414 - Caterpillar

Illustration 1 g01219210
Basic diagram for the power train systems
The power train is made up of three basic systems. The following systems are the three 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 upshift solenoid or the downshift solenoid when shifts are needed. The upshift solenoid and the downshift solenoid hydraulically activate the rotary actuator of the transmission. Movement of the rotary actuator mechanically selects the position of the rotary selector spool. The flow through the rotary selector spool hydraulically activates the correct valves in the pressure control valve. These valves engage the correct transmission clutches. The transmission clutches mechanically connect the transmission input shaft to the output shaft.When the rotary selector spool is in the position to engage the correct transmission clutches, the transmission gear switch will electronically signal the Power Train ECM that the shift is complete. The Power Train ECM will stop energizing the upshift solenoid or the downshift solenoid.When the output shaft of the transmission is rotating, the transmission output speed sensor will provide an electrical signal to the Power Train ECM. The signal is proportional to the transmission output shaft speed. The transmission will not drive the output shaft unless power is flowing through the torque converter.The transmission has eight forward speeds. If the transmission is equipped with the warm-up mode feature, the transmission will have seven forward speeds. The selection of the desired speed is done manually.When the transmission is in any forward gear, the