TRUCK SERVICE MANUAL
TRANSMISSION
DESCRIPTION AND OPERATION
Para 2-1212-13
2-12. FOURTH CLUTCH (B, foldout 11)
(3) Since center sun gear and shaft assembly
23 (B, foldout 12 or A and B, foldout 13) is splined to the
a. Function
clutch housing, it will also rotate at input speed.
2-13. SECOND, THIRD CLUTCHES, AND CENTER
(2) The fourth clutch has a dual function.
SUPPORT (A, foldout 12)
Engaged with the forward clutch, it produces fifth gear.
Engaged with the low clutch, it produces reverse gear.
a. Function Differs Among Models
b. Description. The fourth clutch contain ten clutch
(2) The second and third clutches perform
plates, a clutch piston housing and a piston. Five plates
only one function. When engaged with forward clutch,
are internally splined and five are externally tanged. The
the second clutch produces third gear, while the third
piston is positioned inside the clutch housing in its bore
clutch produces fourth gear.
and retained by twenty piston return springs, a spring
retainer and a snapring.
b. Description (1) The second and third clutches
are composed of two identical pistons, twenty-one clutch
c. Operation (B, foldout 11)
plates (13 in second clutch; 8 in third clutch) and a center
(All models)
support.
(1) Internal-splined clutch plates 4, driven by
(2) Two pistons 10 and 21 are positioned
the fourth-clutch driving hub, rotate any time the input
back-to-back in the bores of center support housing
shaft and the forward clutch housing assembly rotates.
assembly 16. Each piston is retained in its bore by
twenty piston return springs 9 or 22, a return spring
(2) When hydraulic pressure is directed to the
retainer 8 or 23, four self-locking retainer rings 7 or 24
back side of fourth-clutch piston 9, the piston
and snap-rings 5 or 25.
compresses clutch plates 4 and 5 together. This locks
internal-splined plates 4 to external-tanged plates 5, and,
(3) Eight clutch plates are required for the
in turn, to clutch housing 14.
third clutch (four internal-splined and four external-
tanged plates). The internal-splined plates are attached
to the outside diameter of the fourth clutch housing and
are free to rotate. The external-tanged plates are
anchored to the transmission housing and cannot rotate.
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