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| Illustration 1 | g01453925 |
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 Transmission
The three basic systems have a hydraulic connection, an electrical connection, a magnetic connection, or a mechanical connection.
Power is supplied from the engine flywheel to the torque converter through a flexible coupling. Power goes from the torque converter to the 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 mechanical 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 mechanical 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 transmission.
The Power Train ECM will activate the appropriate ECPC valves when shifts are needed. These valves hydraulically engage the correct transmission clutches. The transmission clutches mechanically connect the transmission input shaft to the output shaft.
The planetary transmission has six forward speeds and one reverse speed. The selection of the desired speed is done automatically. REVERSE, NEUTRAL, and FIRST use only torque converter drive.
At lower ground speeds, SECOND speed uses torque converter drive. As the ground speed increases in SECOND speed, the lockup clutch of the torque converter engages. This provides SECOND speed with direct drive.
The torque converter is always in direct drive for speeds THIRD through SIXTH. This provides smooth, automatic upshifting from THIRD through SIXTH and smooth, automatic downshifting from SIXTH through THIRD.
The torque converter hydraulic system uses oil that is also common with the transmission hydraulic system.
Some of the components in the torque converter hydraulic system include a torque converter inlet relief valve, a crescent gear pump, a torque converter bypass valve, a torque converter outlet relief valve and a torque converter lockup clutch.
Pressurized oil that will engage the lockup clutch comes from the gear pump to the transmission oil filter. Oil flows through the transmission oil filter. All of the oil goes to the ECPC supply. When the torque converter lockup clutch gets a pressure signal from the lockup solenoid, pump oil from the gear pump will be sent through the ECPC valve to the torque converter lockup clutch. This oil engages the torque converter lockup clutch.
Pressurized oil from the gear pump, oil filter, and ECPC supply also goes into the torque converter. Oil exits the torque converter and flows through the torque converter outlet relief valve. Oil from the outlet relief valve goes through the cooler circuit and then the planetary lubrication circuit and then to the sump. A lubrication relief valve is activated when clutch two is pressurized for gears "4", "5", and "6". The lubrication relief valve bypasses some lubrication oil to the pump inlet to improve efficiency.