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 51 of 323
PAR 23-25
DESCRIPTION AND OPERATION OF
CHAP 2, SEC II
MAIN TRANSMISSION ASSEMBLY
is the driving member. It meshes with and
drives gear 14. Gear 14 rotates on a needle
bearing 13, and is supported by shaft 10.
Gear 11 rotates on needle bearings 7 and
17, supported by body 8 and cover 19. Ball
9 anchors shaft 10 against rotation. Pins
18 and screws 15 aline and retain cover 19.
(2) The pump assembly mounts in
the converter housing near the transmis-
sion left-output coupling. Four self-locking
bolts 1 retain it. The pump is driven by a
gear splined to the transmission output
shaft and in mesh with gear 5, which is
keyed to gear 11.
b . Operation (fig. 384, fold-out 13)
(1) This pump assembly is a con-
ventional spur gear type. It supplies oil to
the hydraulic system when the vehicle is
moving forward.
In reverse, a spring-
loaded check valve 63 (fig. 374, fold-out
3) prevents oil from returning to the in-
take side of the pump.
(2) The oil pumped augments that
supplied by the input-driven pump. It is
the only source of oil pressure if the ve-
hicle is towed or pushed while the engine
is not operating.
24. BRAKE COOLANT OIL PUMP
ASSEMBLY AND MANIFOLD
a . Components (fig. 384, fold-out 13)
(1) The pump assembly includes
drive gear 49, shaft 40, two gears 21 and
26, two gears 33 and 43, shaft 22, separa-
tor plate assemblies 23 and 36, cover
assembly 44, body 32 and cover assembly
28. The gears and shafts are steel. The
body and covers are cast iron.
(2) The pump consists of two se-
parate pumping sections — one for each
of the brakes. Each pump has a separate
pair of gears.
A common housing and
common shafts serve both pump sections.
The pairs of gears are separated by two
plate assemblies 23 and 36. Driving gears
33 and 43 are keyed to shaft 40. Idler
gears 21 and 26 are not keyed. Shafts 22
and 40 each rotate on three needle bear-
ing assemblies.
(3) Manifold 56 serves as a base
and mounting pad for the pump assembly.
The manifold includes passages for separ-
ate intake ports for each pump section
and provides m cans for two intake check
valves.
b. Operation (fig. 384, fold-out 13)
—
(1) The pump is driven by a gear
splined to the low-range carrier shaft and
in mesh with gear 53 (fig. 379, fold-out 8),
which, in turn, drives gear 49 (fig. 384,
fold-out 13). The pump rotates any time
the vehicle moves. During forward move-
ment, when brakes are released, air is
drawn into the pump through open air
valves (refer to par. 18b(2), above). During
reverse movement (brakes released), air is
expelled through the air valves.
(2) When brakes are applied, the
air valves are closed.
The pump then
draws oil through check valve washer
assembly 67. Each section of the pump
then delivers oil to a brake. The right
section supplies the right brake; the left
section supplies the left brake.
25. OIL FILTER AND SCREENS
a. Components (fig. 373 and 374,
—
Told-outs 2 and 3)
(1) All oil in the system must
pass through screens before it is directed
into its various circuits. The scavenge
pump must draw oil through screen 107
(fig. 373, fold-out 2) before returning it to
the transmission sump. The input- and
output-driven pressure pumps draw oil
through screen assembly 23 (fig. 374,
fold-out 3) before sending it into the
system. The brake coolant pump must
draw oil through the same screen. These
two screens are simple, cylindrical wire
mesh screens.
(2) Oil filter assembly (fig. 153),
capable of screening finer particles from
the oil, is located in the circuit which di-
rects the output of the pressure oil pumps
into the hydraulic system. The assembly
includes a filter head assembly and filter
element.
Change 2 23
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