c r a n k s h a f t in service; a b e n d i n g f o r c e a n d a
(6) Most of the indications revealed by the
twisting force. The design of the shaft is such that
above inspection methods are normal and harmless
the forces produce practically no stress over most of
and only in a small percentage of cases is reliability
t h e surface. Certain small areas, designated as
of the part impaired when indications are found.
critical areas, however, sustain most of the load. See
Since inspection reveals harmless indication with
figure 3-90. Crankshaft failures are usually at the
the same intensity as the harmful ones, detection is
fillet at 45° to the axis of the shaft (fig. 3-91).
Cracks of this nature should result in the
TERPRETATION OF the indications is the most
replacement of the crankshaft.
i m p o r t a n t step.
(7) There are two types of loads imposed on a
Figure 3-89. Ridging of crankshaft.