four wheel drive MITSUBISHI ECLIPSE 1990 Service Manual

GENERAL
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O-l
CONTENTS
GENERAL DATA AND SPECIFICATIONS . . . . . . . ..._..................._........_ 9
TECHNICAL FEATURES
4WD (Four-wheel Drive)........................................710
PJT Safety-lock Syste m........................................7
..__............................... 3
Theft-alarm System (Option for 4WD
Vehicles) . . . . . . . . . . . . . . . . . . . . . . . . . .._._........_..................... 8

GENERAL -Technical Featureso-74WD
(Four-wheel drive)The full time 4WD system adopts viscous coupling
unit (VCU) as the differential limiting device for thecenter differential of 4WD vehicle to achieve auto-
matic and ideal distribution of engine torque to the
front and rear wheels.
r_
Engine
00P0031Viscous coupling
Viscous coupling
(VCU) VP?limited slip differential (OptIOn)
A/TSAFETY-LOCK SYSTEMinterlock device) has been adopted to improve
JT safety-lock system (shift lock device and keysafety*FNKey interlock device
Ignition key cylinder
Shift lock device
Selector handle
AIT control cableShift lock cable
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21-10MANUAL TRANSAXLE <4WD> - General Information4WD SYSTEM OPERATION
Conventional 4WD systems (direct-coupled
4WD,or center differential type 4WDl have their own
merits and demerits; they rely on manual operation
(switching between 4WD and 2WD modes, center
differential locking) to cope with their demerits.
With this new 4WD system, the viscous coupling
built in the center differential automatically performssuch operations used to be made manually. The
driver can participate with the merits of 4WD at alltimes.The operation of the differential and the
viscous
coupling under representative conditions
are described in the following section.
I
Reardifferential
Center
differential
U differential
Viscous AuDk?TFNOO5’difference
ce271010i
TFMMYTFMMY
0
Turningdirection
ITFMOO!X
-.During normal driving
During normal driving (traveling straight on a level road at a
constant speed), the four wheels rotate at nearly the same
speed. Since there is no rotating speed difference among the
four wheels, the viscous coupling does not apply differential
limiting torque and the three differentials distribute drive power
equally to all of the wheels.
During a sharp turn
During a sharp turn, in addition to the rotating speed difference
between the left and right wheels, a small difference in rotati
speeds between the front and rear wheels also occurs.
Such rotational speed difference is absorbed by the differential
action of the three differentials, thereby allowing smooth
driving.The rotational speed difference is also transmitted to the
viscous coupling but the difference is so small that the coupling
makes almost no differential limiting torque application conse-
quently it does not affect the differential action of the center
differential.
When starting out and accelerating
When starting out and accelerating, the center of gravity of the
vehicle shifts towards the rear increasing the rear wheel load
and decreasing the front wheel load. The center
differenti”causes less drive power to be transmitted to the rear whee.
resulting in a lower driving torque. At the same time, however,
the rotational speed difference between the front and rear
wheels increases and the viscous coupling operates to limit the
differential action of the center differential. securing a supply of
drive power to the rear wheels. In this way, performance when
starting out and accelerating is secured.