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 (d) Start gears on shaft by hand, to align
4. Tap the bearing cup (outer race)
with the keyway, then use driver (table 4-1) to install the
from the idler gear with a brass drift, alternately at the four
gears.
notches provided around the shoulder of the gear.
(e) Lubricate the camshaft intermediate
(3) Cleaning, inspection, and repair.
bearing journals (13). Then place the two halves of the
(a) Wash all parts in clean fuel oil and blow
bearing (14) on a journal and secure the halves together with
dry with compressed air. Be sure that all foreign matter has
the two lockrings (15). Install each lockring with the gap over
been removed from oil passage in camshaft.
the upper half, with the ends an equal distance above the split
(b) Examine the cams and journals. If the
line of the bearing.
surfaces are badly scored or worn, replace the shaft.
(f) Assemble and preload the idler gear, as
(c) Check the runout at center intermediate
follows:
bearing with camshaft mounted on the end bearing surfaces.
1. Support the idler gear, shoulder
The runout should not exceed 0.002 inch.
down, on the bed of an arbor press and start the bearing cup
(d) Inspect the thrust washers for scoring
or wear. Measure clearance between thrust washer and thrust
cup tight against the shoulder of the gear, using a steel plate
shoulder. With used (removed) parts, the clearance must not
between the ram of the press and the bearing cup.
exceed 0.018 inch.
2. Support one bearing cone,
(e) Examine the faces of the shaft end
numbered side down, on bed of arbor press and lower the
bearings and any other surface which comes into contact with
gear and bearing cup down over the bearing cone.
the thrust washers. Replace badly marred parts. Slight
3. Lay spacer ring on face of
scratches may be cleaned up with an oil stone.
bearing cone.
(f) Inspect the bushings in the shaft end
4. Place the second bearing cone,
bearings. When bushings are worn, or if they have turned in
numbered side up, in gear and bearing cup against the spacer
the bearing, replace the end bearings.
ring.
(g) Check clearance between shaft end
5. Position the idler gear hub over
journals end bearings. Replace end bearings when clearance
o
the bearing cones so that the oil hole in the hub is 180 from
is 0.006 inch or more.
the gap in the spacer ring.
(h) Inspect, the intermediate bearings for
6. Press the hub into idler gear
scoring or wear. Replace the intermediate bearings when
bearing cones while rotating the gear (to seat the rollers
badly scored, or clearance is 0.009 inch. Discard lockscrews
properly between cones), until the face of the hub which will
with damaged threads. Damaged holes in the cylinder head
be adjacent to the cylinder block end plate is flush with the
may be plugged, redrilled and tapped.
corresponding face of the bearing cone. The bearing cones
(i) Wash the idler gear and bearing
should be supported so as not to load the bearing rollers
components in clean fuel oil and dry with compressed air.
during this operation.
Inspect as follows:
7. To check pre-load, mount the
1. Inspect bearing carefully. When
idler gear on the engine, after lubricating the bearing with light
pitting, scoring, or flat spots are noticed, replace the bearing.
engine oil. Secure with special washer and bolt to the end
2. Check hub and spacer for
plate and the cylinder block. Torque bolt to 80-90 ft. lb.
damaged or defective threads.
8. Place a steel plate, with
3. Examine gear teeth for wear,
matching holes to those in hub, over the idler gear hub and
pitting, or breaks. Also inspect other gears of the train.
secure to hub with 3 capscrews. Tighten to a torque of 25-40
Replace a defective gear.
ft. lb.
(4) Reassembly.
9. Tie one end of a piece of lintless
(a) Lubricate the rear cam and balance
1/8 inch cord around a 1/8 inch round piece of wood (or soft
shaft journals and slide the rear bearings (17 and 32, fig. 5-
metal stock). Place the wood between the teeth of the gear,
then wrap the cord around the periphery of the gear several
toward the gear end of shaft.
times. Attach the other end of the cord to a spring scale.
(b) If removed, install balance weights (23
Maintain a straight, steady pull on the scale, 90o to the axis of
and 38) on gears and secure with capscrews (24 and 39).
the hub, and note the pull, in pounds and ounces required to
(c) Install machine key (11), if removed.
start the gear turning. Make several checks to obtain an
average reading. If the pull is within 1 1/4 lb minimum to 6
NOTE
lbs 12 ounces maximum and does not fluctuate more than 2
The left hand helix gear belongs on the
lbs
camshaft. Right hand helix gear belongs
on the balance shaft.
5-33
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