TM-9-2520-234-35
POWER TRAIN ASSEMBLY; ALLISON MODEL XTG411-2A
TECHNICAL MANUAL; FIELD AND DEPOT MAINTENANCE MANUAL
JULY 1962
TM-9-2520-234-35 - Page 41 of 323
PAR 9-11
DESCRIPTION AND OPERATION OF
CHAP 2, SEC II
MAIN TRANSMISSION ASSEMBLY
is inherent with fluid drives and torque
converters without lockup.
10. INPUT PRESSURE AND SCAVENGE
OIL PUMP ASSEMBLY
a . Components (fig. 373, fold-out 2)
(1) A 2-section, gear-type pres-
sure and scavenge oil pump 45 is located
on the input transfer housing. It is driven
by the input transfer gears and rotates at
any time the vehicle engine rotates. One
section is the input pressure pump. The
other (smaller) section is the scavenge
pump. The assembly includes a pump drive
gear 57, pump idler gear 58, two scavenge
pump gears 55 and 56, pressure pump body
61, scavenge pump body 47, four needle
bearings 53, 54, 59 and 60, and separator
plate 50.
(2) Pump drive gear 57 and idler
gear 58 are the input pressure pump ele-
ments. Scavenge pump gear 56 is keyed
to the shaft of the drive gear 57 by key 51.
Gear 55 is mounted on shaft of gear 58.
The drive and driven gears are supported
in the pump bodies 47 and 61. Separator
plate 50 divides the pump sections.
b . Operation
(1) The input pressure section of
the pump supplies oil under pressure to the
power train for control, lubrication and
converter charging. This oil is picked up
from the sump of the main transmission
section and pumped into the hydraulic
system, passing first through the main oil
screen assembly.
(2) The scavenge section of the
pump picks up oil which collects in the
input transfer gear housing and converter
housing, and returns it to the sump of the
main transmission section. The source of
this oil is lubrication of the input transfer
gears and bearings.
(3) The pump assembly rotates
at approximately 1.62 times engine speed
and in the same direction as the engine.
Section II. DESCRIPTION AND OPERATION OF MAIN TRANSMISSION ASSEMBLY
11. HIGH-RANGE CLUTCH AND
GOVERNOR
a . High-range Clutch and Governor
Components (fig. 375, fold-out 4)
(1) The high-range clutch in -
cludes a housing assembly 73, a piston as-
sembly 67, four (XTG 411-2A) or five
(XTG 411-4) plates 57, five plates 56, re-
action plate 59, return springs 66 and re-
tainer 65. The high-range clutch hub is
integral with the intermediate-range car-
rier assembly 16 (fig. 376, fold-out 5). A
governor ring is riveted or welded to the
clutch housing assembly 73 (fig. 375, fold-
out 4).
(2) Pitot tube 76 is a governor
component. It is mounted by two bolts 14
to transmission housing 17. The high-range
clutch and governor ring rotate.
b . Operation of High-range Clutch
and Governor (fig. 375, fold-out 4)
(1) The high-range clutch trans-
mits torque at 1:1 ratio from the conver-
ter turbine shaft to the high-range clutch
hub and, in turn, through the low- and
intermediate-range planetaries, which are
locked together, to the transmission out-
put shaft. When hydraulic pressure is di-
rected to the cavity between piston as-
sembly 67 and housing assembly 73, the
piston compresses internal-splined 56 and
external-splined 57 plates against reaction
plate 59. This locks the high-range clutch
hub (located on the intermediate-range
planetary carrier) to the clutch housing,
and transmits converter output torque
directly to the transmission range output
shaft.
(2) When hydraulic pressure is
exhausted from the clutch cavity, springs
Change 2 13
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