Buick LeSabre 1965 Service Manual page 243

SUPER TURBINE "300"
HYDRAULIC CONTROLS 5 - 2 9
of the valve keeping it at the bot-
tom of its bore as long as the
solenoid is energized.
Energization of the detent sole-
noid allows oil from the center of
the valve to flow to exhaust. Drive
oil applying force to the area be-
tween the valve body and the first
land of the valve moves the valve
against its spring pressure to the
bottom of its bore.
D u r i n g a full-throttle acceler-
ation main line oil is directed to
the modulator valve and manual
shift control valve. Main line oil
entering the manual shift control
valve is routed into the drive oil
passage and then directed to the
governor valve, shift valve, de-
tent valve, high speed down shift
timing valve, and modulator limit
valve, and low servo.
Main line oil directed to the mod-
ulator valve enters between the
first and second lands. At low
engine vacuum the vacuum modu-
lator tends to keep the valve to-
ward the bottom of its bore. In
this position oil is delivered
through a drilled passage in the
valve to the space between the
first land of the valve and the
valve body. Oil pressure in this
area plus governor pressure on
the second land of the second
modulator valve tend to move the
valve against the force of its
spring to regulate oil pressure
leaving the valve.
Modulator pressure applies force
to the left end of the boost valve
causing it to move to the right.
As the boost valve moves to the
right it contacts the pressure
regulator valve. This hydraulic
force combined with n o r m a l
spring force on the pressure reg-
ulator valve results in a higher
main line pressure. With the de-
tent valve solenoid energized,
drive oil pressure will enter into
the limited feed line. When limited
feed pressure reaches a high
enough value and exerts enough
force to overcome spring pres-
sure on the modulator limit valve,
the valve will regulate governing
the limited modulator and detent
pressure behind the shift regula-
tor valve.
As higher governor pressure is
reached it acts on in the area be-
tween the valve body and the first
land of the high speed down shift
timing valve until governor pres-
sure overcomes spring pressure
and moves the valve to the right.
This movement blocks the non-
restricted line, routing the servo
apply oil through the restricted
orifice. On a down shift this re-
striction of flow causes, the band
apply to be delayed slightly and is
thus timed to the forward clutch
release for a smooth down shift.
m. Operation of Hydraulic
Controls in Low Range
(Closed Throttle Coast)
During operation in Low range,
the manual shift control valve is
positioned as shown in Figure
5-35. During a closed throttle
coast in low range, main line oil
is directed to the modulator valve
and manual shift control valve.
Main line oil entering the manual
shift control valve is routed into
drive oil passage and modulator
boost passage. Oil routed in the
drive oil passage is directed to
the governor valve, shift valve,
and detent valve, high speed down
shift timing valve and low servo.
Oil routed in the modulator boost
passage is directed to the shift
valve and vacuum m o d u l a t o r
valve.
Modulator boost oil enters the
shift valve between the shift valve
and the shift control valve, mov-
ing the shift valve to the left and
holding it in the bottom of its
bore thus exhausting the forward
clutch. Drive oil directed from
the manual shift control valve will
apply the low servo.
n. Operation of Hydraulic
Controls in Reverse
Range (Light Throttle)
During operation in R e v e r s e
range the manual shift control
valve is positioned as shown in
Figure 5-36. During light throttle
in reverse, main line oil is di-
rected to the manual shift control
valve. Main line oil entering the
manual shift control valve is di-
rected to the reverse clutch and
between the 1st and 2nd land of
the boost valve. Main line pres-
sure applies a force to the 2nd
land of the boost valve causing
it to move to the right. As the
boost valve moves to the right
it contacts the pressure regulator
valve. This hydraulic force com-
bined with normal spring force
on the pressure regulator valve
results in a higher main line
pressure needed for reverse op-
eration. When the manual shift
control valve is in reverse the
forward clutch and low servo are
exhausted.
o. Operation of Hydraulic
Controls in Neutral
Range(Closed Throttle)
During operation in N e u t r a l
range, the manual shift control
valve is positioned as shown in
Figure 5-37. In neutral operation
main line oil entering the manual
shift control valve is routed to
the vacuum modulator only. In
neutral operation the stator con-
trol solenoid is energized switch-
ing the pitch to high angle.
NOTE: At any c l o s e d throttle
condition a switch on the carbu-
retor w i l l energize the stator
control solenoid switching the
pitch to high angle. By switching
the pitch to high angle it will
allow higher engine RPM in re-
lation to turbine speed. With the
solenoid energized the valve will
bottom in its bore allowing the
stator to exhaust switching the
pitch to high angle.