Subaru SVX 1992 Manual page 457

AUTOMATIC TRANSMISSION AND DIFFERENTIAL [IV122B3] 3- 2
3. LOCK-UP CONTROL
The lock-up engaging and disengaging conditions are
set for each gear shift range, gear position and shift
pattern and correspond to the throttle opening and
vehicle speed, and the duty solenoid is electronically
controlled by TCU controls the lock-up clutch . The
lock-up clutch engagement and disengagement are
controlled by the lock-up control valve.
(When engaging and disengaging)
The shuttle duty shift valve is actuated by the hydraulic
pressure from the shift valve A. It controls the position
of the lock-up control valve for engaging or disengaging
the lock-up clutch .
(1) 1st gear, N, R, and P ranges
Since no operating pressure is generated from the shift
valve A, the shuttle duty shift valve sets the lock-up
control valve in the "disengaging" position .
The lock-up operating pressure (torque converter reg-
ulator pressure) acts on the lock-up clutch disengaging
circuit, while the engaging circuit communicates with
the oil cooler circuit. Accordingly, the lock-up clutch is
disengaged by the pressure difference .
(2) 2nd, 3rd, and MIN gear
The operating pressure generated by the shift valve A is
applied to the shuttle duty shift valve, which pushes the
lock-up control valve to the "engaging" position . Since
the lock-up operating pressure is applied to the engag-
ing side circuit while the disengaging circuit is drained,
the lock-up clutch is engaged by the pressure differ-
ence .
(Smooth control)
The duty solenoid B is controlled by the TCU and
controls the operation of the lock-up control valve .
Because the lock-up operating pressure is controlled by
the lock-up control valve, the force applied to the
lock-up clutch is controlled for smooth clutch operation .
When locking up, the clutch is set in the half-engaged
state beforehand . After this, the lock-up operating pres-
sure is gradually increased to achieve smooth locking
up .
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