Buick LeSabre 1965 Service Manual page 303

SUPER TURBINE "400'
DESCRIPTION & OPERATION 5 - 8 9
Figure 5-222
also allows the detent regulator
v a l v e to regulate. See Figure
5-222.
12. Detent Regulator Valve
When the detent valve shifts, the
detent regulator is freed to allow
drive oil to enter the detent pass-
age and thus becomes regulated
to a value of 70 psi. Detent pres-
sure will also flow into the modu-
lator passage which flows to the
shift valves. Lo oil moves the
detent regulator open to drive oil
allowing drive oil to enter the
modulator and detent passages.
See Figure 5-223.
13. Stator Valve
Shifts when line oil is exhausted
at end of the valve when the stator
control solenoid is energized.
TKis exhausts oil from the vari-
able stator piston and the.stator
blades change from low angle to
high angle. When the solenoid is
not energized, converter oil is
directed to the stator piston and
low angle is obtained. See Figure
5-224.
14. Front Servo
The front servo applies the 2nd
overrun band to provide engine
braking in 2nd gear in L
2
and L
1
Ranges. It is also used as an
accumulator for the apply of the
direct or 3rd clutch and in con-
Figure 5-223
junction with a series of check
balls controlling orifices is a part
of the timing for the release of
the direct or 3rd clutch.
To prevent the apply of the 2nd
overrun band in Neutral, Drive
and Reverse ranges, oil is di-
rected from the manual valve to
the release side of the servo
piston.
In Drive Range the servo release
oil from the manual valve is used
to charge the servo in preparation
for the apply of the direct clutch.
Direct clutch oil is directed to the
front servo accumulator piston
where spring force plus 3rd
clutch pressure stroke the piston
up against the force of servo re-
lease oil. This lowers the clutch
" C O N V E R T E R "
ILINE
Figure 5-224
Figure 5-225
apply p r e s s u r e for a smooth
engagement.
The release of the direct clutch
and the exhausting of the front
servo accumulator is slowed down
by three check balls and three
orifices which permits a soft re-
turn of the drive load to the in-
termediate sprag and also allows
engine RPM to increase during a
detent 3-2 downshift in prepara-
tion for the lower gear ratio,
which results in a smooth shift
and better acceleration.
a. Front Servo Operation in
Reverse—Neutral—Drive -
1st Speed
Servo oil from the manual drive
valve in Drive Range charges the
accumulator by stroking the servo
and accumulator pistons against
the accumulator s p r i n g . This
prepares the accumulator for the
controlled apply of the direct
clutch on a 2-3 shift. The charg-
ing of the accumulator in Drive
Range, 1st gear, also makes it
possible to have a controlled 1-3
"let up" shift as the accumulator
is prepared for direct clutch ap-
ply in 1st gear. See Figure 5-225.
Servo oil and the servo release
spring prevents the apply of the
band in 2nd gear Drive Range
when intermediate clutch apply oil
is directed between the servo and
accumulator pistons.