TM 5-3810-300-24&P-3
1.7.4
IDLER GEAR AND BEARING ASSEMBLY
The idler gear mounts on a double row, tapered roller
2. Remove the idler gear hole spacer (23), Fig. 1 of
bearing which, in turn, is supported on a stationary hub
Section 1.7.2, in the same manner if the engine is
(Fig. 1). A hollow pin serves a two-fold purpose; first, as
being completely reconditioned.
a locating dowel it prevents the idler gear hub from
rotating and, second, the hollow pin conducts oil under
Disassemble Idler Gear, Hub and Bearing Assembly
pressure from an oil gallery in the cylinder block through
a passage in the gear hub to the roller bearing inner
While removing or installing an idler gear bearing, the
races.
bearing MUST be rotated to avoid the possibility of
damaging the bearing by brinelling the bearing races.
The inner races of the idler gear bearing are pressed
Brinelling refers to the marking of the races by applying a
onto the gear hub and, therefore, do not rotate since the
heavy load through the rollers of a non-rotating bearing
hub is doweled to the end plate and bolted to the cylinder
in such a way that the rollers leave impressions on the
block and also bolted to the flywheel housing. A spacer
contact surfaces of the races. These impressions may
separates the two bearing inner races.
not be easily discerned during normal inspection. For
example, a bearing may be brinelled if a load were
The bearing outer race has a light press fit in the idler
applied to the inner race of the bearing assembly in order
gear and is held against a flanged lip inside the idler gear
to force the outer race into the idler gear bore, thus
on one side and by a retainer se-cured tightly with six
transmitting the force through the bearing rollers. A
bolts on the other side.
brinelled bearing may have a very short life.
An idler gear hole spacer (dummy hub) is used on the
Refer to Fig. 1 and disassemble the bearing as follows:
side opposite the idler gear. NO gasket is used between
the idler gear hub or dummy hub and the flywheel
1. Remove the six bolts and three bolt locks which
housing. The flywheel housing bears against the inner
secure the bearing retainer to the idler gear.
races of the idler gear bearing and also against the
dummy hub. Three self-locking bolts and steel washers
are used to attach the fly-wheel housing at the idler gear
and dummy hub locations. The washers seat in 7/8"
spot faces at the flywheel housing attaching bolt holes,
thus preventing oil leakage at these locations.
Remove Idler Gear, Hub and Bearing Assembly
and Idler Gear Hole Spacer (Flywheel Housing
Previously Removed)
1. Remove the hub to cylinder block bolt and washer
(Fig. 1) and withdraw the assembly from the cylinder
block rear end plate.
NOTE: Before removing the idler gear check
the idler gear, hub and bearing assembly for
any perceptible wobble or shake when pressure
is applied; by firmly grasping the rim of the gear
with both hands and rocking in relation to the
bearing. The bearing must be replaced if the
gear wobbles or shakes. If the gear assembly
is satisfactory, it is only necessary to check the
Fig. 1 - Idler Gear Mounting
pre-load before reinstallation.
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