BANDS
KICKDOWN (FRONT) BAND
DESCRIPTION
The kickdown, or “front”, band (Fig. 83) holds the
common sun gear of the planetary gear sets. The
front (kickdown) band is made of steel, and faced on
its inner circumference with a friction-type lining.
One end of the band is anchored to the transmission
case, and the other is acted on with a pushing force
by a servo piston. The front band is a single-wrap
design (the band does not completely encompass/
wrap the drum that it holds).
OPERATION
The kickdown band holds the common sun gear of
the planetary gear sets by applying and holding the
front clutch retainer, which is splined to the sun gear
driving shell, and in turn splined directly to the sun
gear. The application of the band by the servo is typ-
ically done by an apply lever and link bar.
LOW/REVERSE (REAR) BAND
DESCRIPTION
The low/reverse band, or “rear”, band (Fig. 84) is
similar in appearance and operation to the front
band. The rear band is also a single-wrap design (
the band does not completely encompass/wrap the
drum that it holds).
OPERATION
The rear band holds the rear planet carrier sta-
tionary by being mounted around and applied to the
low/reverse drum.
ACCUMULATOR
DESCRIPTION
The accumulator (Fig. 85) is a hydraulic device
that has the sole purpose of cushioning the applica-
tion of a band or clutch. The accumulator consists of
a dual-land piston and a spring located in a bore in
the transmission case.
OPERATION
Line pressure is directed between the lands of the
piston (Fig. 86), bottoming it against the accumulator
plate. The accumulator stays in this position after
the transmission is placed into a Drive position.
When the 1-2 upshift occurs (Fig. 87), line pressure
is directed to the large end of the piston and then to
the kickdown servo. As the line pressure reaches the
Fig. 83 Front Band—Typical
1 - FRONT BAND
2 - TRANSMISSION HOUSING
Fig. 84 Rear Band
1 - PLANETARY GEARTRAIN
2 - REAR BAND
3 - LEVER
4 - SERVO
5 - ADJUSTER
Fig. 85 Accumulator
1 - ACCUMULATOR PISTON
2 - PISTON SPRING
21s - 60 31TH AUTOMATIC TRANSAXLE PL
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