TM 5-3810-289-34
Figure 3-226. Crankshaft dimension points.
inch long (subsurface).
3/16 inch of a crankpin hole are acceptable if 12 inch
2. Light open indications on crankpin and
long or less and do not enter the oil hole chamfer or
main journal walls or bearing surface that extend closer
interest the 450 100 diagonal. Only those subsurface
than 1/8 inch to fillets, but do not enter fillets are
indications that lie closer than 1/16 inch to surface
acceptable if 3/16 inch long or less. Light subsurface
(measured at chamfer at a 45D 100 diagonal) are not
indications are acceptable.
acceptable.
All other subsurface indications are
(d) Indications located more than 1 inch
acceptable.
from major axis or centerline of adjacent web (measure
(e) Light open indications that enter the
circumferentially) must not exceed following limits:
chamfer of any main bearing oil hole are acceptable if
1. Light open indication in or entering fillet
they are 3/8 inch or less. Subsurface indications ending
are acceptable if 3/16 inch long or less. Light subsurface
in a main bearing oil hole are acceptable.
indications are acceptable.
(f) Fine subsurface, salt and pepper type
2. Light open indications on crankpin and
indications are permitted on upper and lower side of
main journal walls or bearing surfaces that extend closer
crankpins on trimming line.
than 1/8 inch to fillet, but do not enter fillet, are
(g)
Open longitudinal indications within
acceptable if /4 inch or less. Light subsurface indications
region "X" which are less than 1 1/8 inch on the main
are acceptable.
journals and 7/8 inch long on crankpins, are acceptable
a. Nicks on corners of webs are not accept able.
after sharp edges have been stoned 0.002/0.004 in.
The part will be acceptable if nick can be removed by
below the journal surface.
grinding a 1/8 inch radius on corner.
(h)
Longitudinal subsurface indications
within the area "X" are acceptable.
(i) Parallel open indications that meet the
requirements of (s) and other requirements on length
and frequency are acceptable.
(j)
Parallel subsurface indications are
acceptable.
(k) Indications that contain loose or foreign
particles or voids left by such particles are not
acceptable.
(l) Not more than three open indications are
to appear on any one journal or crankpin. Scattered
small, open, or subsurface indications, four per crankpin,
and six per main bearing 1/8 inch long or less, if not
Figure 3-227. Crankshaft magnetic inspection.
forming part of a long intermittent indication or entering
an oil hole or fillet, will not be counted as indications in
4. Imperfections on web periphery may be
arriving at total number permitted. However, if in addition
ground out to a depth of 1/8 inch maximum using a 1%
to showing maximum number of acceptable indications
inch minimum radius grinding wheel, provided balance
for the whole crank-
limits are maintained.
5. Light open indications that pass within
3-80
