Hyundai HL955 Manual page 56

When the turbine speed is reaching about 80% of the pump speed, the torque multiplication becomes
1.0 i.e. the turbine torque becomes equal to that of the pump torque.
From this point on, the converter is working similar to a fluid clutch.
A stator freewheel serves to improve the efficiency in the upper driving range, in the torque
multiplication range it is backing-up the torque upon the housing, and is released in the clutch range.
In this way, the stator can rotate freely.
Function of a hydrodynamic torque converter (schematic view)
From the engine
T
P
Starting
condition
Intermediate
condition
Condition in the
coupling point
Pump wheel
1
1
1
T = Torque of the pump wheel
P
T = Torque of the turbine wheel
T
T = Torque of the reaction member (stator)
R
T
R
Reaction member
1.5
(stator)
<1.5
0
3-5
Turbine wheel
T
T
To the gearbox
n = 0
T
2.5
Machine standing
still
n < n engine
T
<2.5
n = 0.8n engine
1 T
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