Mitsubishi Eclipse. Technical Information Manual (1994) - part 41

POWER TRAIN 

 Automatic Transaxle

Third Gear

 

 

(turns rear sun)

 

 

(turns front carrier/rear 

In third gear, two input clutches are applied to provide

torque input; the underdrive and overdrive clutches.
The underdrive clutch rotates the rear sun gear,
while the overdrive clutch rotates the front carrier/

rear 

 assembly. The result is two 

nents (rear sun gear and rear 

 gear) rotating

at the same speed and in the same direction. This
effectively “locks” the entire planetary 

 

 and is rotated as one unit. The gear ratio

in third is 

Fourth Gear

Overdrive clutch applied

(turns rear sun)

2-4 

clutch applied

(holds front sun)

In fourth gear input torque is through the overdrive

clutch which drives the front carrier. The 2-4 clutch
is applied to hold the front sun gear. As the overdrive

clutch rotates the front carrier, it causes the pinions
of the front carrier to “walk around” the stationary
front sun gear. This causes the front carrier pinions

to turn the front 

 carrier assembly which

provides output torque. In fourth gear, transaxle
output speed is more than engine input speed. This
situation is called overdrive. Fourth gear (overdrive)
ratio is 

POWER TRAIN 

 Automatic Transaxle

Reverse Gear

Reverse clutch applied
(turns front sun)

Low-reverse clutch applied

(holds rear 

 front carrier)

In reverse, input power is through the reverse clutch.

rotates the front carrier assembly pinions. The front

When applied, the reverse clutch drives the front

carrier is being held by the 

 clutch so the pinions

sun gear through the overdrive hub and shaft. The

are forced to rotate the 

 

 carrier

 clutch is applied to hold the front carrier/rear

assembly in the reverse direction. Output torque

 assembly stationary. The front sun gear

is provided, in reverse, with a gear ratio of 

Transfer System
The 

 transaxle uses a transfer gear system to transfer

power from the output shaft of the rear carrier to the transfer
shaft. The gear that is splined and bolted to the output shaft
of the rear carrier   called the output shaft transfer gear. It
supplies power to the transfer shaft transfer gear which is
splined and retained by a large nut to the transfer shaft. The
bolt and nut that retain the transfer gears to each shaft must
be tightened to the proper torque specification. Proper torque

is essential for two reasons; to keep the gears on the shafts
and to maintain the bearing settings that provide for long life
of the system.
Both gears have helical cut teeth designed for quiter operation.

The overall gear ratio of the transaxle is in part determined

by the transfer gear ratio.

POWER TRAIN   Automatic Transaxle

Differential

case

pinion

Final Drive Gears and Differential

The final drive gears include the transfer shaft which has a

pinion gear on one end and the differential ring gear which
is driven by the transfer shaft pinion gear. The ring gear is
bolted to the differential case and when rotated drives the
case. The case drives the differential 

 and in turn, the

front axle shafts. The axle shafts then drive the front wheels.
The differential gears are typical in design and include; a shaft,
two pinion gears, and two side gears. The final drive gears

and the differential case each are supported by tapered roller
bearings. The transfer shaft and its tapered roller bearings
are set-up with a specific amount of 

 The differential

ring gear and case assembly bearings are set-up with a specific
amount of preload. Follow the service manual procedures for

setting up these bearings to ensure long life of the bearings
and the components they support.

POWER TRAIN 

 Automatic Transaxle

The valve body and solenoid assembly work 
er to control five transaxle clutches and the torque
converter clutch. It also directs pressurized fluid
for lubrication. The oil pump is the source of 

ized fluid for the valve body and solenoid assembly.

The pump is a positive displacement, gear and 
cent type pump. It is driven by the engine through
the torque converter hub.

Fluid for the pump is drawn through the transaxle

filter, through the valve body housing, and into the

Pump
housing

 

Reaction 

support

Seal rings (4)

VALVE BODY AND SOLENOID ASSEMBLY

pump. The pump pressurizes the fluid and sends
it back through the valve body to the regulator valve.

The valve body uses only five valves along with
four solenoids in the solenoid assembly. They 
form all functions needed to operate the transaxle
for each of its gear ranges. A brief description on
the operation of each valve and solenoid follows.

Hydraulic Control System

OIL PUMP

The oil pump is located in the pump housing inside the bell

housing of the transaxle case. The 

 uses a crescent

type gear pump. The inner gear is driven by the torque converter

hub. Torque is supplied to the hub by the engine crankshaft

through the flex plate and torque converter housing.
As the gears rotate, the clearance between the gear teeth

increases in the crescent area and creates a suction at the
inlet side of the pump. Fluid is pulled through the pump inlet

from the oil pan. As the clearance between the gear teeth

in the crescent area decreases, it forces fluid into the pump

outlet. The pressurized oil from the outlet operates the torque
converter, clutches, and the lubrication system. The pump is
held in the housing by the reaction shaft support. The reaction
shaft is splined to and holds the inner race of the torque convert-
er 

 overrunning clutch.