Dodge Nitro. Manual — part 350

Fig. 272: Identifying Torque Converter Components
Courtesy of CHRYSLER LLC

The TCC (9) was installed to improve the efficiency of the torque converter that is lost to the slippage of the
fluid coupling. Although the fluid coupling 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 turbine assembly to provide this
mechanical lock-up. See Fig. 272.

In order to reduce heat build-up in the transmission and buffer the powertrain against torsional vibrations, the
TCM can duty cycle the torque converter lock-up solenoid to achieve a smooth application 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:

Shift lever position

Current gear range

Transmission fluid temperature

Engine coolant temperature

Input speed

Throttle angle

Engine speed

OPERATION

TORQUE CONVERTER

1 - TURBINE
2 - IMPELLER
3 - STATOR
4 - INPUT SHAFT
5 - STATOR SHAFT
6 - PISTON
7 - COVER SHELL
8 - INTERNALLY TOOTHED DISC CARRIER
9 - CLUTCH PLATE SET
10 - EXTERNALLY TOOTHED DISC CARRIER
11 - TURBINE DAMPER

2007 Dodge Nitro R/T

2007 AUTOMATIC TRANSMISSION NAG1 - Service Information - Nitro

Fig. 273: Cutaway View Of Torque Converter
Courtesy of CHRYSLER LLC

1 - TURBINE
2 - IMPELLER
3 - STATOR
4 - INPUT SHAFT
5 - STATOR SHAFT
6 - TURBINE DAMPER

2007 Dodge Nitro R/T

2007 AUTOMATIC TRANSMISSION NAG1 - Service Information - Nitro

The converter impeller (driving member) (2), which is integral to the converter housing and bolted to the engine
drive plate, rotates at engine speed. The converter turbine (driven member) (1), which reacts from fluid pressure
generated by the impeller, rotates and turns the transmission input shaft (4). See Fig. 273.

TURBINE

As the fluid that was put into motion by the impeller blades strikes the blades of the turbine, some of the energy
and rotational force is transferred into the turbine and the input shaft. This causes both of them (turbine and
input shaft) to rotate in a clockwise direction following the impeller. As the fluid is leaving the trailing edges of
the turbine's blades it continues in a "hindering" direction back toward the impeller. If the fluid is not redirected
before it strikes the impeller, it will strike the impeller in such a direction that it would tend to slow it down.

STATOR

Fig. 274: Stator Operation
Courtesy of CHRYSLER LLC

1 - DIRECTION STATOR WILL FREE WHEEL DUE TO OIL PUSHING ON BACKSIDE OF

2007 Dodge Nitro R/T

2007 AUTOMATIC TRANSMISSION NAG1 - Service Information - Nitro

Torque multiplication is achieved by locking the stator's over-running clutch to its shaft Under stall conditions
(the turbine is stationary), the oil leaving the turbine blades strikes the face of the stator blades and tries to rotate
them in a counterclockwise direction. When this happens the over-running clutch of the stator locks and holds
the stator from rotating. With the stator locked, the oil strikes the stator blades and is redirected into a "helping"
direction before it enters the impeller. This circulation of oil from impeller to turbine, turbine to stator, and
stator to impeller, can produce a maximum torque multiplication of about 2.0:1. As the turbine begins to match
the speed of the impeller, the fluid that was hitting the stator in such as way as to cause it to lock-up is no longer
doing so. In this condition of operation, the stator begins to free wheel and the converter acts as a fluid
coupling. See Fig. 274.

TORQUE CONVERTER CLUTCH (TCC)

VANES
2 - FRONT OF ENGINE
3 - INCREASED ANGLE AS OIL STRIKES VANES
4 - DIRECTION STATOR IS LOCKED UP DUE TO OIL PUSHING AGAINST STATOR VANES

2007 Dodge Nitro R/T

2007 AUTOMATIC TRANSMISSION NAG1 - Service Information - Nitro