tolerance limits in Fig. 33. If piston shoe (18) does not
pistons may be refitted with two groove pistons again
fall within tolerance limits, discard reworked piston and
only as a nine piece set. Two groove and three groove
pistons must not be mixed in the same unit.
Model 45 and 60 pistons are easily
identified by characteristic piston
shoe running surface configurations.
Piston shoe rework tolerance
Check piston shoe for iron or steel particles imbedded in
the running surface. If present, discard the piston.
Often, large scratches on the piston shoe running
surface will "heal over" if placed back in service. It is
Piston shoe configuration
recommended, however, that all piston shoes with badly
11. Inspect steel piston body. If any galling is apparent
scratched running surfaces be either reworked within
or if any irregularities can be felt with the fingernail, the
tolerance limits or replaced.
piston must be discarded. See Fig. 35. If damage is
apparent, check the corresponding cylinder block bore
Dynapower units may be encountered
(12) for similar damage.
with either two groove or three
Inspecting piston body
Two groove and two groove pistons
Inspect piston return plate (19) for heat discoloration or
Units supplied from the factory with two groove pistons
cracks. Check for flatness. If discolored, cracked or
may be refitted with three groove pistons as a nine piece
distorted, replace with a new return plate. See Fig. 140.
12. Install piston assemblies (18) in piston return plate
In a like manner, units supplied with three groove
(19). Used pistons must be so positioned in