The torque converter hydraulically connects the engine to the transmission. There is no direct mechanical connection between the engine and the transmission.
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| Illustration 1 | g00807730 |
(1) Torque converter (2) Pump pressure regulator (3) Torque converter inlet relief valve | |
When the machine works against a load, the torque converter can multiply the torque from the engine, and the converter can send a higher torque to the transmission. The oil for the operation of the torque converter (1) comes from the transmission oil pump. Oil is directed to the transmission circuit and to the torque converter circuit. The torque converter inlet oil pressure is controlled by relief valve (3). The relief valve limits the pressure to torque converter (1) to 1000 kPa (145 psi). Outlet oil from the converter flows through the transmission oil cooler and into the lubrication and the cooling system.
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| Illustration 2 | g00807665 |
(4) Flex plate (5) Housing (6) Turbine (7) Impeller (8) Stator (9) Stator clutch | |
The torque converter consists of the following four main parts: housing (5), impeller (7), turbine (6) and stator (8). The housing is connected to the engine flywheel through flex plate (4). Impeller (7) and housing (5) are connected. The impeller and the housing turn with the engine flywheel at engine speed. Turbine (6) turns the transmission input shaft. Stator (8) is installed on the stator support. Impeller (7), which turns with housing (5) at engine speed, directs the oil toward the outside of the impeller and against the blades of turbine (6). The force of the oil that is hitting the turbine blades causes the turbine (6) and the transmission input shaft to rotate. The rotation of the transmission input shaft provides power to the transmission.
Oil returns through the stator vanes to the impeller. The stator vanes direct the oil back to the impeller. This causes a torque increase. When the speed of the turbine (6) and the speed of the impeller (7) are equal, the stator clutch (9) permits the stator to turn freely with the rotation of the engine for more efficiency.
When turbine torque is greater than impeller torque the stator is locked in place. Torque is multiplied only when the stator is held in place.