Ford COUGAR 1968 Shop Manual page 253

PART 7-3
-
C 6 Automatic Transmission 7 - 6 5
5. Spring end of the 2-3 backout
valve.
6. Intermediate servo accumulator
valve.
Fig. 10 shows how primary throttle
pressure varies with engine vacuum.
Main Oil Pressure Booster Valve
Forward Driving Ranges (D, 2,
1).
TV pressure is delivered to the lower
valley of the pressure booster valve
and to the end of the pressure booster
valve. Force created on the booster
valve by TV pressures in these two
areas is added to the main regulator
valve spring force transmitted to the
main regulator valve. This will pro-
vide increased control pressure re-
quired to compensate for increased
throttle openings and engine torque
output. Fig. I I shows how control
pressure varies with engine vacuum
at zero output shaft rpm.
Reverse (R). Additional fluid
pressure is required in reverse to pre-
vent clutch and/or band slippage
under stall or partial stall conditions.
This additional pressure is provided
by directing line pressure to the
upper valley of the pressure booster
valve when reverse range is selected.
The differential in area between the
lands of this valve provides a force
which is added to the TV pressure
forces present in the lower valley
and on the end of the valve, to
boost line pressure to a higher value
than is available in the forward driv-
ing ranges.
Governor
At Rest (0 MPH). Control pres-
sure (line) is fed to the secondary
governor valve through the center
passage in the valve body. Because
of the differential in area of the inner
and outer lands of the valve, the
valve will be forced inward, shutting
off line pressure feed to the gover-
nor passage and allowing this pas-
sage to be opened to exhaust, a t the
inner end of the valve. At the same
time, line pressure
will
pass by two
flats on the outer end of the valve,
pressurizing the line leakage pas-
sage leading to the primary governor.
valve. At rest, the spring on the out-
er end of the primary governor
valve holds the primary governor
valve inward, blocking further flow
of the fluid in the line leakage pas-
sage. This causes pressure in the
line leakage passage to build to the
same value as line pressure. As a
consequence, the secondary gover-
nor valve is held in and there is no
pressure in the governor circuit.
20 18
16
14 12 10 8 6 4 2 0
MANIFOLD VACUUM I N INCHES HG.
D 1640- A
FIG. 10-Primary Throttle Pressure, Throttle Boost Pressure and Control
Pressure Versus Engine Manifold Vacuum
-
-
g
100
W
OL
80
LlNE PRESSURE AT 10 INCHESENGINE VACUUM1
2
Y)
W
Or
60
P
LlNE PRESSURE AT 17 INCHES ENGINE VACUUM
40
20
120
OUTPUT SHAFT RPM
x
100
0 1641 - A
LINE PRESSURE AT 1 INCH ENGINE VACUUM
FIG.
I
I-Control Line Pressure and Governor Pressure Versus Output
Shaft rpm
and t h ~ valve moves outward, open-
ing the line leakage passage to ex-
, haust. This action reduces the pres-
LlNE PRESSURE
VS.
OUTPUT
: :
SHAFT R.P.M. AT 0 PSI TV.
IN I AND 2 RANGES
E l 1 0
a
-100
K
90
5
80
K
70
a 60
, w
50
3
40
30
0 2 4 6 8 1012 14 16 18 20 22 24 26 28 30 9
OUTPUT SHAFT R P M
x
100
0 1763-A
FIG.
12-Line Pressure Versus Output
Shaft rpm
Above 10 MPH. When speed
reaches approximately 10 mph, cen-
trifugal force on the primary gover-
nor valve overcome spring force,
sure on the end of the secondary
governor valve to zero (0). allowing
the secondary valve to also move
outward, due to spring force and
centrifugal force. When the secon-
dary valve moves outward, it closes
the governor exhaust passage, and
allows line pressure to enter the gov-
ernor passage. As pressure builds in
the governor passage, it will create a
force on the secondary governor
valve due to the differential in areas
of the inner and outer lands of the
valve. This force tends io move the
valve inward. When the force on
the valve created by pressure in the
governor passage exceed the cen-
trifugal force plus spring force, the
valve will move inward, allowing
governor pressure to exhaust, and
close the passage between line pres-
sure and governor pressure. When
governor pressure is reduced, the