Komatsu 170-3 Series, Руководство по ремонту, Страница: 443 / 454

170-3 SERIES
15-37
REPAIR AND REPLACEMENT OF PARTS
• The surface roughness of the pin journal and
main journal must not exceed 0.6 S.
a
Equipment and jigs necessary for repair by
grinding
1) Magnaflux inspection equipment
2) Shore hardness tester
3) Etching kid
4) Crankshaft grinder
5) Crankshaft polisher
6) Roughness gauge
7) Fillet radius ball gauge
For min. value: 795-500-1140
For max. value: 795-500-1150
1. Inspection before repair by grinding
1) Visual inspection
Check the journals for cracking, damage,
discoloration by seizure, wear, etc. to see if
they can be repaired by grinding.
2) Testing hardness of journal surface
Permissible range: 74
–
81 HS
Lower limit: 74 HS
When using with output below 750 PS
Permissible range: 60
–
67 HS
Lower limit: 60 HS
* The hardness of the spare crankshaft is
74
–
81 HS. On the other hand, the
hardness of the crankshaft of an engine
of 551.6 kW (750 PS) or less is 60
–
67
HS. The crankshaft of this class must be
used for an engine of 551.6 kW (750 PS)
or less. The crankshaft having hardness
of 7 4
–
81 HS can be used for a ny
engine.
a
If the hardness of a crankshaft is below
the lower limit, discard it.
3) Check for torsion
Permissible range of throw a: 85 mm
Permissible range of horizontal displacement
(Difference between 1st cylinder and last cyl-
inder): 0.94 mm
Dispersion of throw a of each cylinder:
Max. 0.20
If any of the above item of a is out of the per-
missible range, discard the crankshaft.
•
Dimension b is the stroke.
0
- 0.15
(7)
REPAIRING CRANKSHAFT
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