International Harvester Company Cub Lo-Boy C-60 Service Manual page 30

and, therefore, an allover lubricating and
cooling action for the piston and crankcase
sleeve. Excess oil is wiped by the rings,
back down to the crankcase. The remaining
rings are compression rings. Rings shouldbe
installed on a piston so that the gaps are
90 degrees from the thrust side of the piston
and 180 degrees from one gap to another.
Pistons
The piston is one of the most important
units in the engine, and its condition has
much to do with the perforn1ance of the
engine. Its function is to receive the force
of the combustion pressure and transmit it
to the connecting rod and crankshaft. The
escape of combustion pressure past the
piston is prevented by the piston rings.
The fit of the piston and rings in the sleeve
must be close enough to prevent the escape
of combustion gases but must be free
enough to keep friction to its working
minimum.
Piston Pins
The piston pin is made of steel and is cy-
lindrical in shape. Its purpose is to anchor
the piston to the connecting rod. The pin is
retained in the piston by retainer rings that
lock into grooves of the piston pin bore.
The pin is allowed to float in its bushing in
the upper end of the rod. The aluminum of
the piston is an excellent bearing material
and, therefore, no bushing is provided be-
tween the pin and the piston. The bearing
of the steel pin in the aluminum piston is
the reason for the tight fit of the pin when
the piston is cold. It is usually necessary
to heat the piston in order to remove the pin.
Piston Rings
The pistons are fitted with three piston
rings. One oil regulating ring is fitted to
each piston. The oil regulating ring pro-
vides an even circulation of lubricating oil
Cylinder
ridge
Removal
1. Remove the cylinder head. (Refer to
page
1-13.)
2. Remove the drain plug and drain the
engine lubricating oil from the crankcase
oil pan. Replace the drain plug.
Worn rings
fit ridge
3. Remove the cap screws securing the
oil pan, and remove the oil pan and gasket.
CAUTION: Before proceeding with
piston and connecting rod removal, the
ridge, existing on the cylinder wall at the
upper end of the ring travel, must be re-
moved by using a ridge reamer. This pre-
vents damage to the piston ring lands dur-
ing removal of pistons, and prevents dam-
age to new top piston rings after the in-
stallation of new rings.
New ring
interference
FESM-3257
1-26