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| Illustration 1 | g03745975 |
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(1) Housing
(2) Turbine (3) Impeller (4) Stator (5) Transmission Input Shaft (6) One-way clutch (7) Lockup Clutch (8) Hub | |
The torque converter is driven by the engine flywheel. The torque converter consists of the following:
- impeller (3)
- turbine (2)
- lockup clutch (7)
- stator (4)
- one-way clutch (6)
The one-way clutch (6) is incorporated into stator (4). The lockup clutch permits the machine to operate in direct drive to keep the power loss at a minimum. The one-way clutch holds the stator when torque converter drive is used. The one-way clutch allows the stator to turn freely when direct drive is used.
The torque converter housing is fastened to the flywheel housing for the engine. Shaft (5) connects the torque converter to the transmission planetary group.
The engine flywheel turns rotating housing (1) and impeller (3). The impeller directs oil onto the blades of turbine (2). This action causes the turbine to turn. The turbine directs the oil onto stator (4). This action causes the stator to try to turn in the opposite direction of the turbine. The movement of the stator causes the rollers of one-way clutch (6) to move between stator (4) and the carrier for the stator. The action of the one-way clutch keeps the stator from rotating in the opposite direction to the turbine. The stator now directs most of the oil back to the impeller. The remainder of the oil goes out of the torque converter. The oil, that goes back to the impeller from the stator, moves in the same direction as the rotation of the impeller. Since this oil is moving in the same direction as the impeller, the torque output from the torque converter is multiplied.
Turbine (2) turns hub (8). The hub turns shaft (5). Power is sent through the shaft to the transmission planetary group.
Lockup clutch (7) is part of the torque converter. The lockup clutch is located between the engine flywheel and the turbine. The lockup clutch is engaged under the following conditions:
- Sufficient input speed to the transmission planetary group
- Sufficient oil pressure in the transmission planetary group
- Sufficient engine rpm
When the lockup clutch is engaged, the impeller and the turbine turn at the same speed as the engine. There is no loss of power in the torque converter. The connection between the engine and the transmission planetary group is now direct.
Torque converter drive is available in first gear and second gear. Torque converter drive is also available when the transmission control is in the REVERSE position. The lockup clutch provides direct drive once the transmission speed and the engine speed are matched.
Direct drive is provided in all the higher gears.
The input speed of the torque converter is measured at the engine flywheel. This speed is the same speed as the engine output speed. The output speed of the torque converter is measured at the planetary transmission. This speed is the same speed as the transmission input speed.
Torque Converter and Lockup Clutch Operation
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| Illustration 2 | g03798547 |
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Torque converter and lock up clutch (1) External splined (meshes with the flywheel) (2) Pressure passage for lock up piston (3) Lock up clutch (4) Transmission input shaft | |
The torque converter is mechanically connected to the engine flywheel with external Splines (1). The torque converter provides a hydraulic connection between the engine and the transmission and is used to increase the torque as the torque load on the machine increases. This torque converter drive mode is employed when operating in lower gears and when climbing a grade.
When torque loads are low, the Transmission ECM will "ENERGIZE" the lockup clutch control valve solenoid, which provides high-pressure oil through the pressure passage (2) to "ENERGIZE" the lockup clutch (3), which then provides a mechanical connection between the engine and transmission. This Direct Drive Mode is more fuel efficient and reduces power loss to a minimum, when conditions allow. When "ENGAGED", the lockup clutch provides Direct Drive Mode once the transmission speed and the engine speed are matched. The lockup clutch remains "ENGAGED" during transmission shifts to ensure that torque is always supplied to the wheels during transmission shifting.
Transmission input shaft (4) transfers the rotational power to the transmission via a mechanical connection to the torque converter output.