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VA
TORQUE CONVERTER (Continued)
1 - ENGINE FLEXPLATE
2 - OIL FLOW FROM IMPELLER SECTION INTO TURBINE
SECTION
3 - IMPELLER VANES AND COVER ARE INTEGRAL
TORQUE CONVERTER CLUTCH (TCC)
The TCC (Fig. 229) was installed to improve the
efficiency of the torque converter that is lost to the
slippage of the fluid coupling. Although the fluid cou-
pling provides smooth, shock-free power transfer, it is
natural for all fluid couplings to slip. If the impeller
and turbine were mechanically locked together, a
zero slippage condition could be obtained. A hydraulic
piston with friction material was added to the tur-
bine assembly to provide this mechanical lock-up.
In order to reduce heat build-up in the transmis-
sion and buffer the powertrain against torsional
vibrations, the TCM can duty cycle the torque con-
verter lock-up solenoid to achieve a smooth applica-
tion of the torque converter clutch. This function,
referred to as Electronically Modulated Converter
Clutch (EMCC) can occur at various times depending
on the following variables:
AUTOMATIC TRANSMISSION - NAG1 21 - 143
Fig. 225 Impeller
4 - ENGINE ROTATION
5 - ENGINE ROTATION
• Shift lever position
• Current gear range
• Transmission fluid temperature
• Engine coolant temperature
• Input speed
• Throttle angle
• Engine speed
OPERATION
The converter impeller (driving member), which is
integral to the converter housing and bolted to the
engine drive plate, rotates at engine speed. The con-
verter turbine (driven member), which reacts from
fluid pressure generated by the impeller, rotates and
turns the transmission input shaft.
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