Figure 3-89. Ridging of crankshaft.

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).

procedure. IN-

but

one

the

step

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.