Mitsubishi Eclipse. Technical Information Manual (1994) — part 39
POWER TRAIN
Automatic Transaxle
CLUTCH
All flve clutches in the
transaxle are applied
hydraulically. Four of the clutches are released with
springs, and one is released with a coil
spring. Three of the clutches supply input power
to the planetary geartrain and are called input
clutches. The other two clutches hold components
of the planetary geartrain and are called holding
clutches. With the exception of direct gear, one input
clutch and one holding clutch must be applied to
obtain a gear range. In direct gear, two input clutches
are applied and basically connect the input and
output shafts together. This causes the entire
set to rotate as one with no relative motion between
planetary
components.
C
Overdrive/Reverse
hub
Underdrive hub
rdrive
thrust washer
thrust
plate
Overdrive
Overdrive
Input Clutch Assemblies
The input clutch assembly is located directly behind the oil
pump housing, and rides on the reaction shaft support journal.
The assembly consists of an input shaft, input hub, clutch
retainer, clutch pistons, an overdrive hub, an underdrive hub
and three input clutches. The clutches are the underdrive clutch,
overdrive clutch and reverse clutch. When the torque converter
turbine (which is splined to the input shaft) turns, the input
shaft, hub, and clutch retainer also turn.
Underdrive Clutch Hub
The underdrive clutch is splined to the underdrive hub assembly.
The underdrive hub and shaft assembly is splined to the rear
sun gear. When the underdrive clutch is applied the rear sun
gear is driven (rotated).
Overdrive Hub
The overdrive clutch is splined to the overdrive hub assembly
and the overdrive hub is splined to the front carrier assembly.
The reverse clutch is splined to the front sun gear assembly
and rotates it when applied.
Input Clutches
Each of the three clutches, in the input clutch assembly, have
the job of supplying input power to a particular component
in the planetary
when they are hydraulically applied.
They are connected to the planetary
through the over-
drive hub and shaft assembly, the underdrive hub and
assembly, and the front sun gear assembly. When any of these
clutches are applied, they turn or drive a component in the
planetary
POWER TRAIN
Automatic Transaxle
2-43
Underdrive Clutch
Underdrive
clutch
Rear sun
gear
Hub
Underdrive clutch
hub shaft
Input clutch
reiainer
The underdrive clutch is located in the front of the
input clutch retainer. Line pressure is supplied to
the clutch from the valve body, through passages
in the case, oil pump and reaction shaft support.
The pressure then passes through a drilled passage
in the input clutch hub and to the front side of the
underdrive piston. The piston moves toward the
rear of the transaxle, compressing the clutch and
connecting it to the underdrive hub. The underdrive
hub is splined to the rear sun gear and turns it
when the clutch is engaged.
line pressure is released, the clutch piston
returns with tension from the coil spring between
the piston and spring retainer. The piston has a
vent in it, and the spring retainer has a seal on
it. Both the vent and retainer seal are used to keep
oil on the back side of the piston. They counteract
the centrifugal pressure that develops when the
clutch is spinning. Centrifugal pressure can cause
the piston to move slightly and the clutch to drag
when the clutch is not actually being applied.
Overdrive Clutch
Overdrive clutch
Front planetary
carrier
Clutch retainer
Overdrive
clutch hub
2-44
POWER TRAIN Automatic Transaxle
The overdrive clutch is the center clutch in the input
clutch assembly. The clutch pack is held on the
retainer, and the piston that applies the clutch is
located around the outside of the retainer. A pressure
plate in the rear of the clutch pack is used to com-
press the overdrive clutch when needed. Line pres-
sure from the valve body is directed through pas-
sages in the case, oil pump housing and reaction
shaft support. It is then directed through the input
hub and input clutch retainer to the back side of
Reverse Clutch
Hub
the
clutch piston. The pressure pushes
the piston forward and applies the overdrive clutch.
The clutch pack is compressed against the same
reaction plate that the underdrive clutch uses.
When applied, the overdrive clutch engages and
turns the overdrive hub, which is splined to the front
planetary carrier. When line pressure to the clutch
is released, the belleville spring on the front side
of the
piston returns the piston to its re-
leased position.
Reverse
clutch
Front sun
gear hub
The reverse clutch is located in the back of the
input clutch assembly. The reverse clutch is oper-
ated by the same piston, pressure plate and belleville
spring that operates the overdrive clutch. Line pres-
sure that applies the reverse clutch comes from
the valve body, directed through passages in the
case, oil pump and reaction shaft support. The line
pressure then goes through the input hub to the
front side of the
piston. The pressure
moves the piston to the back and compresses the
reverse clutch pack. When the clutch is applied,
it turns the front sun gear and hub assembly.
When line pressure to the reverse clutch is removed,
the belleville spring will pull the piston forward to
its released position. The
clutch piston
belleville spring is positioned so it will counter the
piston to prevent either the overdrive or reverse
clutches from dragging when they are not applied.
POWER TRAIN
Automatic Transaxle
2-45
Holding Clutches
2-4 Clutch
Front sun
gear hub
2-4 clutch
I
Transaxle case
Piston
retainer
Snao .
spring
Separator
plates
Piston
discs
The 2-4 clutch is one of two clutches located in
the rear portion of the transaxle case. This clutch
sits behind the input clutch assembly. The 2-4 clutch/
piston retainer is in the front and held in place by
a snap ring. The 2-4 piston is located inside the
2-4 clutch/piston retainer. A belleville spring is used
to return the piston after releasing the clutch. The
clutch pack comes next in the case. The reaction
plate is secured to the case using two snap rings.
The reaction plate for the 2-4 clutch is shared with
the Low Reverse clutch. When the 2-4 clutch is
applied hydraulically, it locks or secures the front
sun gear/hub assembly to the case so it does not
turn.
To apply the 2-4 clutch, line pressure is sent from
the valve body straight into the piston retainer. The
valve body has a rubber seal located on the top
of it that seals the valve body to the piston retainer.
When line pressure is removed and vented, th
belleville spring returns the
to release th
clutch.
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