Subaru XT 1988 Service Manual page 440

MANUAL TRANSMISSION AND DIFFERENTIAL
Power transmission when front wheel or rear wheel is
locked (when driving in 5th gear)
Power is transmitted as follows:
With front wheel locked
Th is does not rotate because
the front wheels are locked.
With rear wheel locked
This does not rotate because
the rear wheels are locked.
In either case, the output shaft is driven at a speed twice that of the hollow input shaft.
Fig. 10
5) When the center differential lock switch is operated and
the center differential lock is activated, the differential gear
coupled to the front and rear drive shafts does not function.
If the front or the rear wheel slips, torque is transmitted to the
remaining wheel by the center differential lock, so that the
car can maneuver off the slippery surface, or get out of mud.
The suction vacuum of the engine is utilized to activate the
vacuum actuator to changeover the locking mechanism.
7
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