TM 5-3810-289-34
correct thrust rings will be installed in their proper
position. Refer to figure 3-225.
(a) The marking should be stamped on the
rear crankshaft web.
(b) Both the thrust ring size and ring location
must be included in the stamping as shown in figure 3-
(c) Measure for flange wear by checking K
dimension (fig. 3-226).
(d) If wear does not exceed 0.003 in. at any
one point, flange condition is acceptable.
(e) If wear is 0.003 in. or more, regrind
flange to restore flatness. If total wear and regrinding
does not exceed 0.005 in., standard thrust rings may be
used.
Figure 3-223. Crank pin journal measurement.
(f) If worn more than 0.007 in., flange
should be ground for 0.010 or 0.020 in. oversize thrust
rings or built up by electric arc welding and reground to
specifications. Mark as noted in (a), (b), and (c) above.
(g) Regrind must clean up a minimum of 90
percent of the thrust surface.
(h) The regrind or resurfacing must result in
maintaining installed crankshaft end clearance below
0.015 in.
j. Magnetic Inspection
(1) Wet complete surface with magnetic
particle suspension before applying current.
(2) Table 2-2 lists magnetizing currents that
should be used.
(3) Flow magnetic particle suspension over
part in advance' of placing part through coil. Turn current
on coil and move coil full length of part.
(4) If shaft parts are within 2 or 3 inches of
coil I.D., ample magnetism will be obtained if 3 shots of
current are passed through coil while it is at each end
and center of part length.
(5) Limits of acceptability.
(a)
Unless otherwise stated, limits of
Figure 3-224. Cleaning drilled oil passages.
acceptability apply only to light slag or oxide stringers
usually defined as inherent inclusions. Obvious cracks
and Circumferential or transverse defects are not
acceptable.
(b) Limits listed in following steps must be
maintained within region "C" (Critical Region) shown in
Dimensional value of "C' is vertical
distance measured downward from crankpin centerline
and extending longitudinally for all crank webs between
region "X" on crankpin and region "X" on main journal.
(c) Indications located less than 1 in. from
major axis or centerline of adjacent web (measured
circumferentially) must not exceed the following limits:
1. Light indications in or entering fillets are
acceptable if not more than 1/8 inch long (open) or 1/4
Figure 3-225. Oversize thrust bearing size mark on
crankshaft.
3-79
