CHAP 2, SEC IV
DESCRIPTION AND OPERATION OF
PAR 30
RIGHT- AND LEFT-OUTPUT DRIVE ASSEMBLIES
TV pressure at this time is at maximum
and can flow into the T pressure line. T
pressure is connected to the area below
the lockup shift valve, as is TV pressure.
The effect of T pressure is to delay the
downward movement of the lockup shift
v a l v e . T h u s , a t f u l l t h r o t t l e , g o v e r n or
(pitot) pressure must be higher to cause
lockup. Higher governor pressure requires
higher turbine shaft speed.
i . T h e m a i n p r e s s u r e l i n e e n t e r i ng
the throttle valve bore at the right has no
function.
j . A t t h e s t e e r p r e s s u r e r e g u l a t or
valve, main pressure is reduced and regu-
lated, and produces steer pressure.
N o t e : The pressure which applies
the output clutches, geared steer
clutches and brakes — whether for
steer operation or straight travel
— i s a l w a y s d e s i g n a t e d " s t e e r
pressure ."
Steer pressure is constant, regardless of
fluctuations in main pressure.
k . Steer pressure is directed to the
steer valves. In neutral, it simply flows
through passages surrounding the steer
valves, and is directed by two drive clutch
feed lines to the drive clutch relay valve.
The drive clutch relay valve, held upward
by signal pressure, directs steer pressure
t o t h e r i g h t -
a n d l e f t - g e a r e d s t e er
clutches,
T h e s e c l u t c h e s a r e t h e d r i ve
clutches in first gear. Thus, in neutral,
they are engaged and ready to transmit
drive when a shift is made to first gear.
1 . Governor (pitot) pressure is pro-
duced in a fluid velocity-type governor.
T h i s c o n s i s t s o f o n l y t w o m a i n c o m p o-
nents: a governor ring and a pitot tube.
The ring is a rotating channel, open at its
inner circumference. It is attached to the
high-range clutch housing and rotates with
the turbine output shaft. Oil is constantly
fed to it from the lubrication system and
centrifugal force retains the oil. Tine pitot
tube is L-shaped and its open end is im-
mersed in the oil in the governor ring.
The open end of the tube faces against the
rotation of the ring. The oil, moving at
virtually the same speed as the ring, is
thrown into the pitot tube and is directed
to the top of the lockup shift valve, the
left end of the shift inhibitor valve, and to
the area between the lands of the lock-up
c u t o f f v a l v e . G o v e r n o r p r e s s u r e v a r i e s
with the speed of the turbine output shaft.
m . A t t h e t o p o f t h e l o c k u p s h i ft
valve, governor pressure pushes downward
on the valve. At closed throttle condition,
pressure sufficient to overcome only the
lockup shift valve spring will force the
valve downward. At part throttle condi-
t i o n , s p r i n g p r e s s u r e p l u s T V p r e s s u re
( i n i t i a l l y ) m u s t b e o v e r c o m e . A t f u ll
throttle condition,
spring pressure plus
maximum TV pressure and T pressure must
be overcome.
n . At the shift inhibitor valve, gov-
ernor pressure pushes the valve toward the
right.
A spring resists this movement.
When governor pressure is sufficient, the
right end of the inhibitor plunger will be
pushed against the longest projection on
the manual selector valve lever. In neu-
tral, this is not significant.
o . At the lockup cutoff valve, gover-
nor pressure is blocked except for brief
intervals during shifting. When shifts are
m a d e , t h e l o c k u p c u t o f f v a l v e m o v es
rapidly to the left and exhausts governor
pressure to the sump. This destroys gover-
nor pressure and allows the lockup shift
valve, if downward, to move upward and
r e l e a s e t h e l o c k u p c l u t c h . T h i s f e a t u re
ensures that the lockup clutch will be re-
leased every time a range clutch engages.
p . Oil returning from the torque con-
verter passes through an (external) oil
cooler and flows into the area above the
28 Change 2
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