CHRYSLER SERVICE MANUAL
TORQUE-FLUE TRANSMISSION—27
is being fed oil only through the hole in the
servo pressure bleed valve, pressure on this area
drops to a low value while oil from the 2-3 shift
valve builds up pressure on the rear clutch and
the "off" area of the kickdown servo. The
kickdown band load is then reduced sufficiently
to allow a smooth band release. In the mean-
time,
pressure in the rear clutch has built up
sufficiently to complete a smooth engagement.
The second function of the shuttle valve is
to regulate the application of the kickdown pis-
ton when making high speed (above approxi-
mately 30 mph.) kickdowns. Kickdowns made
at low vehicle speeds require very little time in
which to complete the shift due to the compara-
tively small change in engine speed between
direct and kickdown gear. The higher the vehi-
cle speed at which the kickdown is made, the
longer is the time required to make a smooth
shift.
The force of the shuttle valve spring is great
enough so that the force of governor pressure
(at vehicle speeds under approximately 30
mph.) on the governor pressure area cannot
move the shuttle valve toward the shuttle valve
plug. Thus, for kickdowns below 30 mph. oil
is fed to the line pressure area of the kickdown
servo through both the hole in the servo pres-
sure bleed valve and the line pressure and servo
pressure ports of the shuttle valve. Speed of
kickdown piston application is then at its maxi-
mum.
As further insurance against the engine
"running away" during low speed kickdowns,
rear clutch disengagement is delayed while the
kickdown piston is applying the band. This is
accomplished by the introduction of a restric-
tion (metering hole "E") placed such that oil
is "backed up" into the clutch chamber as the
kickdown piston moves on. This "back up"
pressure is greatest on low speed kickdowns
when the kickdown piston applies rapidly and
is sufficient to hold the clutch applied until the
kickdown band is applied. At this time, the
kickdown piston can no longer force oil into
the clutch and the pressure is allowed to fall
to zero.
For kickdowns at higher vehicle speeds, gov-
ernor pressure attains a sufficient value to move
the shuttle valve toward the shuttle valve plug,
cutting off the feed of line pressure to the shut-
tle valve. Oil must then flow to the apply pres-
sure area of the kickdown servo only through
the hole in the servo pressure bleed valve. Kick-
down piston application is, therefore, retarded.
9. OPERATIONAL SUMMARY
With the
D
(drive) button pushed in, the manual
valve is positioned to give the full range of
operation of the transmission. With the manual
valve in the drive position, the front clutch is
engaged and the transmission will transmit
drive torque in breakaway.
At a speed which is dependent on throttle
position, the transmission automatically up-
shifts to second gear. The change is initiated
by movement of the 1-2 shift valve to the up-
shifted position so that pressure is directed to
the apply side of the kickdown servo. When
the kickdown band develops sufficient capacity
to slow the rear clutch retainer, the overrun-
ning clutch starts to over-run, so release of
the previous reaction member is automatic. The
band application during the shift is controlled
by action of the accumulator.
At a speed which is again dependent on
throttle position, the transmission makes an
upshift to direct. This action is initiated by
movement of the 2-3 shift valve. The upshift
is accomplished by simultaneous disengagement
of the kickdown band and engagement of the
rear clutch.
Forced 3-2 shift is obtained below speeds
shown in Shift Pattern Summary Chart, and
forced 3-1 shift is obtainable below speeds
shown in Shift Pattern Summary Chart. Nor-
mal downshifts are not throttle sensitive and
above half-throttle, they occur in sequence 3-2,
and 2-1. At throttle openings less than
half-
throttle the two shift valves are interlocked by
means of the 3-1 relay valve and the two shift
valves downshift together. The shift occurs as
a 3-1 relay sequence at the normal 2-1 down-
shift speed. This action provides a smooth
downshift since the overrunning clutch is over-
running in breakaway.
Pushing in the 2 (second) button of the con-
trol unit moves the manual valve so that line
pressure is directed to the kickdown circuit of
the 2-3 shift valve. When in direct, this results
in a downshift to second speed only if the vehi-
cle speed is below 3-2 kickdown limit. If the
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