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TM 5-4320-305-24
4-12. REPLACE/REPAIR CRANKSHAFT ASSEMBLY (Continued)
c.
However, if the crankpins are evenly worn, not
out-of-round, and the crankshaft journal
diameters are within specified limits, the
condition may be rectified by replacing
connecting rod bearing shells. Replace in
accordance with paragraph 4-11. Check the
radial clearance of the bearing shells. If it
exceeds the tolerance limits of 0.0016 to 0.0118
inch (0.04 to 0.3 mm), the crankshaft must be
replaced.
d.
If the measurements at points 1 and 2 differ by
more than 0.0028 inch (0.07 mm) and/or any
one set is outside the tolerance limits, the
crankpin is worn into a conical shape and the
crankshaft must be replaced. If the
measurements along axes A and B differ by
more than 0.0028 inch (0.07 mm) and/ or one
set is outside the tolerance limits, the crankpin
is worn into an oval shape and the crankshaft
must be replaced. For both these out-of round
conditions, also check connecting rods, pistons;
and cylinders for unusual wear.
e. The crankpin width at point 3 should be 1.4173 to 1.4189 inches (36.0 to 36.039 mm). The fillet radius measurement
should be 0.1693 to 0.1772 inch (4.30 to 4.50 mm). If either measurement is outside the specified limits, the crankshaft
must be replaced.
7
Inspect crankshaft main bearing journals.
a.
Measure diameter of each crankshaft main
bearing journal (1) at points 1 and 2 and along
axes A and B with micrometer. Measure width
of journal at point 3. Measure radius of fillets (2)
between main bearing journal and crank cheek
(3).
b.
Normal main bearing journal diameter should
be 2.8728 to 2.8736 inches (72.97 to 72.99
mm). If any measurement is outside the
specified limits, the crankshaft must be
replaced. However, if journals are evenly worn,
not out-of-round, and crankpin diameters are
within specified limits, only main bearing
bushings need be replaced.
c.
Replace bearing bushings in accordance with
paragraph 4-13. Make sure that main bearing
bushing radial clearance does not exceed
0.0020 to 0.0118 inch (0.052 to 0.3 mm). If
specified limits are exceeded, the crankshaft
must be replaced.
d.
If measurements at points 1 and 2 differ by more than 0.0028 inch (0.07 mm) and/or one set is outside the
specified limits, the journal is worn into a conical shape and crankshaft must be replaced. If
measurements along
axes A and B differ by more than 0.0028 inch (0.07 mm) and/or one set is outside the specified limits, the journal is
worn into an oval shape and crankshaft must be replaced.
4-97
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