Buick LeSabre 1965 Service Manual page 311

SUPER TURBINE " 4 0 0 "
DESCRIPTION & OPERATION 5 - 9 7
Drive oil is also regulated to
another variable pressure at the
1-2 accumulator v a l v e . T h i s
pressure, called 1-2 accumulator
oil, is controlled by modulator
oil and is directed to the rear
servo. 1-2 Accumulator oil at
the rear servo acts on the ac-
cumulator piston.
Stator Blade Angle
When at idle, the stator blades
are at high angle. This is also
true under heavy throttle opera-
tion due to the stator solenoid
being activated.
At light or medium throttle (as
shown), the solenoid is not acti-
vated. Line pressure then moves
the s t a t o r valve against t h e
spring, allowing converter oil to
act on the stator piston, which
puts the blades at low angle.
SUMMARY
The converter is filled and the
stator blades are at high or low
angle, depending upon throttle po-
sition. The forward clutch is ap-
plied. The transmission is in
first gear.
c. Drive Range—Second Speed
As both vehicle speed and gover-
nor pressure increase, the force
of governor oil acting on the 1-2
shift v a l v e will overcome the
force of re-regulated modulator
oil pressure. This allows the 1-2
shift valve to open, permitting
drive oil to enter the intermediate
clutch passage. Oil in this pass-
age is called intermediate clutch
oil. See Figure 5-244.
Intermediate clutch oil from the
1-2 shift valve is directed to the:
1. Intermediate Clutch
2. Rear Servo
3. Front Servo and Accumulator
Pistons
4. 2-3 Shift Valve
Basic Control
Intermediate clutch oil from the
1-2 shift valve seats a one-way
check ball and flows through an
orifice to the intermediate clutch
piston to apply the intermediate
clutch. At the same time, inter-
mediate clutch oil moves the ac-
cumulator piston against the 1-2
accumulator oil and accumulator
spring to maintain lower pressure
in the clutch during a 1-2 shift
for a smooth clutch apply. Inter-
mediate clutch oil seats a second
one-way check ball and flows to
the front servo and accumulator
pistons. Intermediate clutch oil
is also directed to a land of the
2-3 shift valve.
SUMMARY
The f o r w a r d and intermediate
clutches are applied. The trans-
mission is in second gear.
d. Drive Range—Third Speed
As vehicle speed and governor
pressure increase, the force of
governor oil acting on the 2-3
shift valve overcomes the force
of the 2-3 shift valve spring and
modulator oil. This allows the
2-3 shift valve to move, feeding
intermediate clutch oil to the di-
rect clutch passage. This oil is
termed direct clutch oil. See Fig-
ure 5-245.
Direct clutch oil from the 2-3
shift valve is directed to the:
1. Direct Clutch
2. Front Accumulator Piston
3. 3-2 Valve
Basic Control
Direct clutch oil from the 2-3
shift valve flows past a one-way
check valve to the inner area of
the direct clutch piston to apply
the direct clutch. Simultaneously,
direct clutch oil is fed to the front
accumulator piston. The pressure
of the direct clutch oil, combined
with t h e accumulator s p r i n g ,
moves the accumulator and servo
pistons against servo oil. This
acts as an accumulator for a
smooth direct clutch apply.
Direct clutch oil is also supplied
to the 3-2 valve to move the valve
against modulator pressure. This
cuts off modulator oil to the 1-2
r e g u l a t o r and 2-3 modulator
valves and allows the transmis-
sion to utilize the torque multi-
plying c h a r a c t e r i s t i c s of the
variable pitch converter.
Stator Blade Angle
The degree of converter torque
multiplication is dependent upon
the angle of the stator blades
(high or low angle) which is con-
trolled by the stator solenoid.
When activated, the line oil acting
on the solenoid and stator valve
is exhausted at the solenoid. The
stator valve spring will move the
stator valve cutting off converter
oil to the stator piston. The con-
verter charge pressure will move
the stator piston, putting t h e
stator blades at high angle.
SUMMARY
The forward, intermediate and di-
rect clutches are applied. The
transmission is in third gear
(direct drive).
e. Detent Downshift—
Valves in Second Speed
Position
While operating at speeds below
approximately 70 MPH a forced