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 TM 55-1905-219-14-5
3-91.3. IDLER GEAR AND BEARING ASSEMBLY - MAINTENANCE
INSTRUCTIONS (Cont).
LOCATION
ITEM
ACTION
REMARKS
PRE-LOAD CHECK OF BEARING (Cont)
b. Any time an idler gear assembly has been removed from an engine for servicing or inspection, while
performing engine overhaul or other repairs, the pre-load should be measured as part of the operation.
c. After the idler gear, hub and bearing are assembled together, the bearing should be checked to
ascertain that the gear may be rotated on its bearing without exceeding the maximum torque specifications, nor
be so loose as to permit the gear to be moved in relation to the hub by tilting, wobbling or shaking the gear.
d. If the mating crankshaft and camshaft or balance shaft gears are not already mounted on the engine,
the torque required to rotate the idler gear may be checked by mounting the idler gear in position on the engine,
using a steel plate 4" square and 3/8" thick against the hub and cone as outlined below.
e. However, If the crankshaft and camshaft gears are on the engine, a suitable fixture, which may be
held in a vise, may be made.
f. Three plates, a 1/2"-13 x 2 3/4" bolt and a plain washer are used with a 1/2"-13 nut and plain washer
for mounting. One of the plates is used to take the place of the flywheel housing, and the other two plates, the
cylinder block. "Engine-mounted" conditions are simulated by tightening the nut to 80-90 lb-ft torque and
tightening the three plate-to-hub attaching bolts to 25-40 lb-ft torque. The components of the fixture may be
made from steel stock in accordance with the dimensions.
g. The idler gear bearing should be clean and lubricated with clean light engine oil prior to the preload
test. Idler gear assemblies which include new bearings should be "worked in" by grasping the gear firmly by
hand and rotating the gear back and forth several times.
h. To check the pre-load by the first method:
(1) Mount the idler gear assembly on the engine.
(2) Install the center bolt and washer through the gear hub and thread into the cylinder block a 1/2"-13 x
2 1/2" bolt replaced the 1/2"-13 x 2" bolt). Tighten the bolt to 80-90 lb-ft torque.
3-1580
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