THEORY OF OPERATION - CONTINUED
TRANSMISSION - CONTINUED
Torque converter connects engine to transmission hydraulically. There is no direct mechanical connection between
engine and transmission.
Torque converter is welded into one piece and cannot be opened. These components are inside torque converter:
Torque converter uses oil to send torque from engine to transmission. When machine is working against a load,
torque converter multiplies torque from engine and sends a higher torque to transmission.
Oil for torque converter operation comes from transmission oil pump. Oil pump is driven by gear. Oil flows to a
flow control valve in transmission case and is divided. Oil is directed to transmission circuit and torque converter
circuit. Torque converter inlet oil pressure is controlled by torque converter inlet relief valve. Converter inlet relief
valve is mounted in transmission case below transmission control valve. Relief valve limits maximum pressure to
torque converter to 130 psi (895 kPa). Torque converter inlet relief valve protects torque converter from high pres-
sure due to cold oil or some other restriction in torque converter or cooler circuit.
Flex plate is mounted to engine flywheel and torque converter. Impeller is connected to inside of torque converter.
Stator support slides over input shaft. Turbine connects to input shaft.
Stator connects to stator support. Stator support is mounted to transmission case and stator does not turn.
Teeth on gear mesh with splines on torque converter. Gear meshes with oil pump gear.
Oil from transmission hydraulic controls flows into torque converter. Impeller rotation gives force to oil.
Impeller turns with rotating torque converter housing at engine speed. Impeller causes oil to go to outside of impel-
ler. Oil goes around inside of housing and against turbine blades. Force of oil that hits turbine blades causes turbine
to turn. This sends torque to transmission input shaft.
After oil hits turbine blades, it flows to inside of turbine. Oil from turbine moves in a direction opposite rotation of
impeller. Stator causes oil to change direction, going back into impeller in direction of rotation.
Force of oil from stator can now add to torque output. This extra force can increase engine torque output to turbine.
Amount of oil force from stator is larger difference between impeller speed and turbine speed.
Difference in impeller speed and turbine speed is caused by machine load. When torque converter is at stall condi-
tion, torque multiplication of torque converter is at maximum. Oil from outlet passage flows to converter outlet
relief valve, then flows to oil cooler and transmission lubrication system.