BENDIX TU-FLO 700 COMPRESSOR Manual page 9

be rebored or honed oversize. Oversized pistons and piston
rings are available in .010 in., .020 in. and .030 in. oversizes.
Cylinder bores must be smooth, straight, and round.
Clearance between the cast iron pistons and cylinder bores
should be between .002 in. minimum and .004 in. maximum.
FIGURE 9 - MEASURING CYLINDER BORES
PISTONS
Check the pistons for scores, cracks, or enlarged ring
grooves; replace the pistons if any of these conditions are
found. Measure each piston with a micrometer in relation to
the cylinder bore diameter to be sure the diametral clearance
is between .002 in. minimum and .004 in. maximum.
Check the fit of the wrist pins to the pistons and connecting
rod bushings. The wrist pin should be a light press fit in the
piston. If the wrist pin is a loose fit, the piston and pin
assembly should be replaced. Check the fit of the wrist pin
in the connecting rod bushing by rocking the piston. This
clearance should not exceed .0007 in. Replace the wrist pin
bushings if excessive clearance is found. Wrist pin bushings
should be reamed to between .5314 in. and .5317 in. after
being pressed into the connecting rods.
Check the fit of the piston rings in the piston ring grooves.
Check the ring gap with the rings installed in the cylinder
bores. Refer to Figure 10 for correct gap and groove
clearances.
PISTON
RINGS
OIL RING
PISTON
RING
OIL RING
FIGURE 10 - CORRECT GROOVE CLEARANCE
CRANKSHAFT
Check the crankshaft threads, keyways, tapered ends and
all machined and ground surfaces for wear, scores, or
damage. Standard crankshaft journals are 1.1250 in.- 1.1242
in. in diameter. If the crankshaft journals are excessively
scored or worn or out of round and cannot be reground, the
crankshaft must be replaced. Connecting rod bearing inserts
are available in .010 in., .020 in. and .030 in. undersizes for
compressors with reground crankshafts. Main bearing
journals must be maintained so the ball bearings are a snug
fit or so that no more than .0065 in. clearance exists between
the precision sleeve main bearing and the main bearing
journals on the crankshaft. In crankshafts fitted with oil seal
rings, the oil seal ring groove or grooves must not be worn.
The ring groove walls must have a good finish and they must
be square. Check to be sure the oil passages are open
through the crankshaft.
CONNECTING ROD BEARINGS
Used bearing inserts must be replaced. Connecting rod caps
are not interchangeable. The locking slots of the connecting
rod and cap should be positioned adjacent to each other.
Clearance between the connecting journal and the
connecting rod bearing must not be less than .0003 in. or
more than .0021 in. after rebuilding.
STANDARD
PISTON
RING
EXPANDER
RING
OIL RING
END GAP
.002
.004
.000
.006
.002"
.010"
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