Komatsu 170-3 Series, Руководство по ремонту, Страница: 431 / 454

170-3 SERIES
15-25
REPAIR AND REPLACEMENT OF PARTS
REPLACING MAIN BEARING CAP
a
When replacing the main bearing cap, machine
the semi-finished part according to the following
procedure.
•
No. 1,2,3,4,5,7 Main cap 6240-29-1210
• No. 6 Main cap 6240-29-1250
1. Machining the bore of main bearing cap
1) Remove the cylinder liner
2) Install the replacement bearing cap to the
cylinder block and tighten it to specification.
a
Align the notches on the cylinder block
and cap.
a
Coat the thread and seat with engine oil
SAE30
a
Tighten the bolts at the 3rd time by angle
tightening method.
3
Main bearing cap mounting bolt:
3) Set the jig for mounting the cylinder block to
the table of a horizontal boring machine.
Install the cylinder block by mounting its hole
for the liner to the datum plug of the jig.
4) Center the arbor of the boring machine by
applying a dial gauge to the inside wall of the
two bearing caps which have the largest
pitch in the caps to be used again.
5) Cut the inside of bearing cap (1) little by little
while checking its inside diameter.
a
Cut until the cutting tool contacts the
inside wall of cylinder block (2).
a
Inside diameter of main cap:
Tolerance: 148 mm
a
Surface roughness: Max. 12.5S
a
Never cut the inside wall of the cylinder
block.
Step Target Range
1st 284Nm {29kgm}
269 – 299Nm
{27.5 – 30.5kgm}
2nd 578Nm {58kgm} 568 – 588Nm {57 – 59kgm}
3rd 105° 120° – 90°
+ 0.025
0
(7)
REPLACING MAIN BEARING CAP
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