Revision 6
Removal & Replacement
of
Main Bearings:
The two (2) main bearings are tapered roller type bearings. The Outer Crankshaft Roller
Bearing Races (cup-shaped) are a slip fit in the power frame. The Crankshaft Roller
Bearings (cone-shaped) are an interference fit on the crankshaft. (Refer to the assembly
drawings
of
the Power End in Section
9:
PARTS). New main bearings must be replaced as a
unit: a new race with a new tapered bearing.
11.
Remove the Outer Crankshaft Roller Bearing Races (Item #4) from the power frame by
tapping the races with a wood block and a soft-faced hammer.
12. Remove the Crankshaft Roller Bearings (Item #5) from the crankshaft by puller, press
or torch.
If
a torch is to be used, care must be exercised not to damage the crankshaft by
overheating.
13. Heat the new main bearing assembly
as
a unit to a temperature that is no hotter than
300° F (150 ° C). Slip the hot parts into position to install on the crankshaft.
Removal & Replacement
of
Connecting Rod Bearings and Wrist Pin Bushings:
The connecting rod and the matching cap assembly are bolted together and clamp the
connecting rod bearings into position around the crankshaft (Figure
8-40).
The connecting rod bearings are made in two (2) halves and are a matched set. The bearings
are steel with a layer
of
babbitt on the surface. Each bearing piece has a small
wedge-shaped alignment tab that fits into the groove on the rod or cap.
The Wrist
Pin Bushing is made of bronze. A hole in the middle of the bushing allows oil
to
flow into the hole in the connecting rod. The wrist pin bushing is pressed into the small end
of the connecting rod and is held in place by a set screw.
© Copyright October,
2001
NLB Corporation
8-32
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