(c) Grinding the crankshaft
The crankshaft journals and crankpins must
be
refinished
to
a dimension smaller by 0.100 to
0.120 mm (0.00394 to 0.00472 in.) than the
undersize
of
bearings to
be
used.
Example: If
0.50-mm (0.01969-in.) undersize
bearings
are
to be used:
The journals must be refinished to
65
- 0.5 - (0.100 - 0.120)
[2.55905
- 0.01969 -
(0.00394-
0.00472 in.)]
The crankpins must be refinished
to
58 - 0.5 - (0.100 - 0.120)
[2.28346 - 0.01969 -
(0.00394-
0.00472 in.)]
When
grinding the crankpins and journals,
be
sure to produce the same filler radius (shoulder
radiUS)
as
the original one. Too small a radius
of
fillet will result
in
fatigue failure
of
crankshaft
while too large a fillet radius
is
sure to cause the
bearing to ride on the radius and thereby to
result in a bearing failure.
Be
extremely careful
not to grind
off
the radius part beyond the
desired dimension.
An
over-ground radius part
can be corrected only by grinding
off
the
shoulder
face
and this,
if
effected, will present
problems in obtaining a proper end clearance.
Also check the crankpins and journals for
hard-
ness. They should have a hardness
of
620 or
more in terms
of
Vickers Hardness Number.
If
necessary, re-harden the crankpins and journals,
and check them for cracks by conducting a
magnaflux (magnetic particle) test.
Specifications
Unit:
mm
(in.)
Undersize
Journals to
be
refinished to
0.25
!
64
75
-0.015
(25
92 -0.00059)
(0.0098)
. . -0.035 . 4 1-0.00138
0.50
6450-
0
.
015
(2
5393To.00059)
(0.0197)
.
-0.035'
-0.00138
0.75
6425
-0.015
(2 52952
-0.00059
)
(0.0295)
.
-0.035'
-0.00138
-30-
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