Dodge Durango (DN). Manual — part 119
assembly (Fig. 21) and (Fig. 22). The input clutch
assembly also contains:
• Input shaft
• Input hub
• Clutch retainer
• Underdrive piston
• Overdrive/reverse piston
• Overdrive hub
• Underdrive hub
OPERATION
The three input clutches are responsible for driving
different components of the planetary geartrain.
UNDERDRIVE CLUTCH
The underdrive clutch is hydraulically applied in
first, second, and third (direct) gears by pressurized
fluid against the underdrive piston. When the under-
drive clutch is applied, the underdrive hub drives the
input sun gear.
OVERDRIVE CLUTCH
The overdrive clutch is hydraulically applied in
third (direct) and overdrive gears by pressurized fluid
against the overdrive/reverse piston. When the over-
drive clutch is applied, the overdrive hub drives the
reverse carrier/input annulus assembly.
REVERSE CLUTCH
The reverse clutch is hydraulically applied in
reverse gear by pressurized fluid against the over-
drive/reverse piston. When the reverse clutch is
applied, the reaction annulus gear is driven.
HOLDING CLUTCHES
DESCRIPTION
Three hydraulically applied multi-disc clutches are
used to hold planetary geartrain components station-
ary while the input clutches drive others. The 2C,
4C, and Low/Reverse clutches are considered holding
clutches. The 2C and 4C clutches are located in the
4C retainer/bulkhead (Fig. 23), while the Low/Re-
verse clutch is located at the rear of the transmission
case (Fig. 24).
Fig. 21 Input Clutch Assembly-Part 1
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DESCRIPTION AND OPERATION (Continued)
OPERATION
2C CLUTCH
The 2C clutch is hydraulically applied in second
gear by pressurized fluid against the 2C piston.
When the 2C clutch is applied, the reverse sun gear
assembly is held or grounded to the transmission
case by holding the reaction planetary carrier.
4C CLUTCH
The 4C clutch is hydraulically applied in fourth
gear by pressurized fluid against the 4C clutch pis-
ton. When the 4C clutch is applied, the reaction
annulus gear is held or grounded to the transmission
case.
LOW/REVERSE CLUTCH
The Low/Reverse clutch is hydraulically applied in
park, reverse, neutral, and first gears by pressurized
fluid against the Low/Reverse clutch piston. When
the Low/Reverse clutch is applied, the input annulus
assembly is held or grounded to the transmission
case.
PLANETARY GEARTRAIN
DESCRIPTION
The planetary geartrain is located behind the 4C
retainer/bulkhead, toward the rear of the transmis-
sion. The planetary geartrain consists of three pri-
mary assemblies:
• Reaction (Fig. 25).
• Reverse (Fig. 26).
• Input (Fig. 26).
Fig. 22 Input Clutch Assembly-Part 2
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21 - 343
DESCRIPTION AND OPERATION (Continued)
OPERATION
REACTION PLANETARY GEARTRAIN
The reaction planetary carrier and reverse sun
gear of the reaction planetary geartrain are a single
component which is held by the 2C clutch when
required. The reaction annulus gear is a stand alone
component that can be driven by the reverse clutch
or held by the 4C clutch. The reaction sun gear is
driven by the overdrive clutch.
REVERSE PLANETARY GEARTRAIN
The reverse planetary geartrain is the middle of
the three planetary sets. The reverse planetary car-
rier can be driven by the overdrive clutch as
required. The reverse planetary carrier is also
splined to the input annulus gear, which can be held
by the low/reverse clutch. The reverse planetary
annulus, input planetary carrier, and output shaft
are all one piece.
INPUT PLANETARY GEARTRAIN
The
input
sun
gear
of
the
input
planetary
geartrain is driven by the underdrive clutch.
GEARSHIFT MECHANISM
DESCRIPTION
The gear shift mechanism provides six shift posi-
tions which are:
• Park (P)
• Reverse (R)
• Neutral (N)
• Drive (D)
• Manual second (2)
• Manual low (1)
OPERATION
Manual low (1) range provides first gear only.
Overrun braking is also provided in this range. Man-
ual second (2) range provides first and second gear
only.
Drive range provides first, second third and over-
drive fourth gear ranges. The shift into overdrive
fourth gear range occurs only after the transmission
has completed the shift into D third gear range. No
further movement of the shift mechanism is required
to complete the 3-4 shift.
Fig. 23 2C and 4C Clutches
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DESCRIPTION AND OPERATION (Continued)
The fourth gear upshift occurs automatically when
the overdrive selector switch is in the ON position.
No upshift to fourth gear will occur if any of the fol-
lowing are true:
• The transmission fluid temperature is below 10°
C (50° F) or above 121° C (250° F).
• The shift to third is not yet complete.
• Vehicle speed is too low for the 3–4 shift to
occur.
• Battery temperature is below –5° C (23° F).
OVERDRIVE OFF SWITCH
DESCRIPTION
The overdrive OFF (control) switch is located in
the shift lever arm.
OPERATION
The switch is a momentary contact device that sig-
nals the PCM to toggle current status of the over-
drive function. At key-on, overdrive operation is
allowed. Pressing the switch once causes the over-
drive OFF mode to be entered and the overdrive OFF
switch lamp to be illuminated. Pressing the switch a
second time causes normal overdrive operation to be
restored and the overdrive lamp to be turned off. The
overdrive OFF mode defaults to ON after the ignition
switch is cycled OFF and ON. The normal position
for the control switch is the ON position. The switch
must be in this position to energize the solenoid and
allow a 3-4 upshift. The control switch indicator light
illuminates only when the overdrive switch is turned
to the OFF position, or when illuminated by the
transmission control module.
Fig. 24 Low/Reverse Clutch
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DESCRIPTION AND OPERATION (Continued)
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