TRUCK SERVICE MANUAL
TRANSMISSION
DESCRIPTION AND OPERATION
piston. Six are internal-splined clutch plates and seven
(4) The low planetary gear set is located
are external-tanged clutch plates. The external-tanged
behind the gear unit and main shaft assembly. Re f e r
plates are held stationary by the adapter housing, while
to figure 2-9. It contains a sun gear, a carrier assembly,
the internal splined plates are free to rotate. The piston
and a ring gear. The sun gear is splined to the main
for each model is positioned in its respective bore and
shaft, and the rear carrier is splined to the low ring gear,
retained there by 28 piston return springs, the return
thereby interconnecting the four planetary systems.
spring retainer, four retainer rings and a snapring.
(5) This interconnection of the planetary input,
c. Operation (A, foldout 15)
reaction, and output elements and connections with the
forward and fourth clutches produces five forward
(1) When the low clutch is released, internal-
speeds and one reverse speed.
splined clutch plates 15 are free to rotate. Since low
b. Operation (A, foldout 13)
planetary ring gear 14 is splined to internal plates 15, it
will also rotate freely.
(1) The front planetary assembly 5, used in
conjunction with the center planetary assembly 16,
(2) When hydraulic pressure is directed to the
produces third gear when the forward and second
back side of low piston 6 (A, foldout 15), the piston c o m
clutches are applied (fig. 2-11).
presses clutch plates 15 and 16 together. This locks
rotating internal-splined plate 15 to stationary external-
(2) The center planetary is active in third,
tanged plate 16, preventing ring gear 14 from rotating.
fourth, fifth and reverse gears.
(3) With the application of the forward or
(3) The rear planetary carrier assembly 38, is
fourth clutch in conjunction wit h the low clutch, a
required in second, third, fourth and fifth gears. In
reaction within the planetary gearing will produce either
second gear, with the application of forward and first
forward or reverse rotation, respectively, at the output
clutches, it singularly transmits torque, at a reduction,
shaft.
through the low carrier to the output shaft (fig. 2-10). In
third, fourth and fifth gears its only function is in the
2-17. PLANETARY GEARING
transmitting of torque through the low carrier to the
output shaft.
a. Description (A, foldout 13)
(4) The low planetary carrier assembly 18 (A,
(1) The planetary gearing i s composed of a
gear unit and main shaft assembly (A, foldout 13), the
transmitted through the main shaft to low sun gear and
low planetary carrier assembly 18 (A, foldout 15) and its
then to the low carrier assembly. With the application of
sun gear and ring gear.
transmitted by the carrier, at a reduction, to the output
(2) The gear unit and main shaft assembly (A,
shaft. In reverse gear, torque is transmitted through the
foldout 13) contains three planetaries called front, center
fourth clutch housing, sun gear shaft assembly 23 (A,
and rear, so designated because of their location i n
foldout 13), center carrier assembly 16 and main shaft
relation to each other in the gear unit.
assembly 34 to the low sun gear and carrier. With the
(3) Each of the three planetaries has a sun
transmitted by the carrier, at a reduction, to the output
gear and a ring gear, which are interconnected by the
shaft (fig. 2-14).
main transmission shaft and a connecting drum.
NOTE
In fifth gear, because both the forward
and fourth clutches are engaged, all four
planetaries rotate as a unit. This gives
direct drive through the transmission.
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