Subaru LEGACY 2002 Quick Reference Index page 280

Automatic Transmission
B: FEATURES
1. MPT MODELS
! The transmission uses both structural and control means to reduce gearshift and engagement
shocks; a one-way clutch and three accumulators effectively absorb shock loads, while fully elec-
tronic gear-shift control (1st through 4th), hydraulic pressure (line pressure) control and lock-up
clutch control minimize chances of shock occurring.
! Both power transmission efficiency and fuel economy are improved by the use of a torque con-
verter with hydraulically operated lock-up clutch and a gear train creating four forward and one re-
verse speeds with two sets of simple planetary gears.
! Apart from a highly rigid transmission case, the use of a push-pull cable for the selector lever
mechanism improves quietness as the cable conveys vibration only slightly to the driver's control
mechanism.
! The TCM has an on-board diagnosis function to facilitate servicing and a fail-safe control func-
tion to ensure minimum level of operation should an important problem occur in the system.
! The degree of engagement of the transfer clutch is accurately controlled by the TCM. This is
especially effective to prevent undesirable tight corner braking which would occur when making a
sharp turn at a low speed.
! Distribution of torque to the rear wheels is optimally controlled according to the engine output
torque and selected gear. This improves fuel efficiency and directional stability.
! When the ABS is in operation, the TCM performs special control for the most effective braking
by properly adjusting the degree of engagement of the transfer clutch and fixing the speed to a
certain gear.
! The manual range feature enables the driver to hold the transmission in a desired gear. If used
properly, it can improve driveability and ride comfort.
2. VTD MODELS
! The gearshift feeling is improved by optimally controlling the gearshift timing and the engine
torque during gearshifts.
! Both power transmission efficiency and fuel economy are improved by the use of a torque con-
verter with hydraulically operated lock-up clutch and a gear train creating four forward and one re-
verse speeds with two sets of simple planetary gears.
The center differential combining compound planetary gears with an electronically controlled
!
and hydraulically operated multi-plate differential action limiting device (limited slip differential) is
a vehicle controllability enhancement feature that enables the vehicle to be handled easily even in
a marginal condition.
! When the ABS is in operation, the TCM controls the differential action limiting device in such a
way that the ABS can be controlled most appropriately in accordance with signals from the ABS
system.
The manual range feature enables the driver to hold the transmission in a desired gear. If used
!
properly, it can improve driveability and ride comfort.
The TCM has an on-board diagnosis function to facilitate servicing and a fail-safe control func-
!
tion to ensure minimum level of operation should an important problem occur in the system.
GENERAL
AT-4