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TRANSMISSION-TORQUEFLITE
21 -47
HYDRAULIC CONTROL SYSTEM
The hydraulic control circuits on pages 37 through
44 show the position of the various valves with color
coded passages to indicate those under hydraulic pres-
sure for all operations of the transmission.
The hydraulic control system makes the transmis-
sion fully automatic, and has four important functions
to perform. In a general way, the components of any
automatic control system may be grouped into the
following basic groups:
The pressure supply system, the clutches and band
servos, the pressure regulating valves and the flow
control valves.
Taking each of these basic groups or systems in
turn, the control system may be described as follows:
Pressure Supply System
The pressure supply system consists of a front
pump driven by the engine through the torque con-
verter, and a rear pump driven by the transmission
output shaft.
Pressure Regulating Valves
The pressure regulating valves consist of a regu-
lator valve which controls line pressure at a value
dependent on throttle opening.
The torque converter control valve maintains
torque converter operating pressure and transmission
lubricating pressure.
The governor valve transmits regulated pressure
to the transmission (in conjunction with throttle pres-
sure) to control u
The throttle v
the transmission
sure) to control u
The 2-3 shift valve automatically shifts the trans-
mission from second to direct or from direct to sec-
ond depending on the vehicle operation.
The kickdown valve makes possible a forced down-
shift from direct to second-second to breakaway or
direct to breakaway (depending on vehicle speed )by
depressing the accelerator pedal past the detent "feel"
near wide open throttle.
The shuttle valve has two separate functions and
performs each independently of each other. The first
is
that of providing fast release of the kickdown band,
and smooth front clutch engagement when the driver
makes a "lift-foot" upshift from second to direct. The
second function of the shuttle valve is to regulate the
application of the kickdown servo and band when
making direct to second kickdowns.
Clutches, Band Servos and Accumulator
The front and rear clutch pistons, and both servo'
pistons are moved hydraulically to engage the clutches
and apply the bands. The pistons are released by
spring tension when hydraulic pressure is released.
On the 2-3 upshift, the kickdown servo piston is re-
leased by spring tension and hydraulic pressure.
The accumulator controls the hydraulic pressure on
the apply side of the kickdown servo during the 1-2
shift; thereby, cushioning the kickdown band appli-
cation at any throttle position.
GEARSHIFT AND PARKING LOCK
CONTROLS
pshift and downshift speeds.
alve transmits regulated pressure to
(in conjunction with governor pres-
pshift and downshift speeds.
The transmission is controlled
1:
gearshift incorporated within the
The control has six selector lever p
R (reverse), N (neutral), D (drive),
(low). Some vehicles are equipped w
console gearshift which has -the sa
positions.
'alves
P check
prevents loss
Of
front
Mechanical connection between
1
hrough the rear pump circuit during
trol and the transmission manual
The
front pump
check
pre-
the parking lock is obtained throuj
h
v
n . 3 - n
nvnc.c..ivn
t h v n - r n h
tho f m n t
Flow Control V
The rear pum]
pump pressure tl
reverse operatioi
vents loss of rehL
puiiip
p i c n n u i c
L l l l u u ~ l l
LilG
L I u l l L
pump circuit when the front pump flc-w is recirculat-
ing.
A check valve is incorporated in the rear oil pump
cover to prevent air from entering the system during
reverse operation.
The manual valve obtains the different transmis-
sion drive ranges as selected by the vehicle operator.
The reverse blocker valve mechanically blocks the
manual valve from moving into reverse position above
approximately 20 mph.
The 1-2 shift valve automatically shifts the trans-
mission from low to second or from second to low
depending on the vehicle operation.
)y a "lever type"
steering column.
ositions: P (park),
2 (second) and 1
ith a "lever type"
me selector lever
:he gearshift con-
:ontrol valve, and
: h two cables en-
closed in weatherproof housings. The parking lock
is
applied by moving the selector lever past a gate to
the P position.
CAUTION: Never apply the parking lock until the
vehicle has stopped; otherwise, a severe ratcheting
noise will occur.
OPERATING INSTRUCTIONS
The transmission will automatically upshift and
downshift at approximately the speeds shown, in the
"Shift Pattern Summary Chart."
NOTE: All shift speeds given in the "Shift Pattern
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