f. The Pistons and Connecting Rod (Fig. 8).
The crosshead
pistons used in this engine are of a two piece construction.
They
consist of a crown, oil seal (between the crown and the skirt),
skirt, and the piston pin holding the crown and skirt together.
There are six piston rings on the piston. The top three pistons are
compression rings, and the lower or bottom rings are oil rings.
Engine oil, under pressure, fed up through drilled passages in the
connecting rod provides lubrication and cooling for the crosshead
piston. When the oil reaches the piston pin, it goes through the oil
tube in the piston pin and the center hole in the bushing to the
underside of the piston crown.
Steel forge the connecting rods (Fig. 8) to an I-section, with a
closed hub at the upper end, and a cap at the lower end. Drilling of
the connecting rod provides a lubrication passage and an oil spray
nozzle for cooling the underside of the piston head at the upper end.
The connecting rod bearing shells consist of an upper shell seated in
the connecting rod, and a lower shell seated in the connecting rod
cap. Locate the tangs at the parting line at one end of the shell.
A relief groove in each end of the shell provides a clearance for the
connecting rod bolts.
The connecting rod caps are numbered 1R, 1R, 1L, 2L, etc., with
matching numbers stamped on the connecting rod. The upper and lower
connecting rod bearing shells are not the same and therefore cannot
be interchanged.
The upper bearing shell has two short oil grooves
and oil holes. Each groove starts at the edge of the shell and ends
at an oil hole.
The lower bearing shell has one continuous oil
groove, from one end of shell to the other, that maintains alignment
with the oil holes in the crankshaft. This ensures that a constant
supply of lubricating oil to the connecting rod bearings, piston pin
bushing, and spray nozzle through the oil passage in the connecting
rod.
g. The Oil Pump. The rotary oil pump mounts to the inside lower
engine front cover.
A gear, pressed on the crankshaft, drives the
inner rotor of the oil pump.
The pump draws oil from the sump
through the oil inlet screen.
The oil pump feeds oil, under
pressure, through oil passages in the front cover to the filter and
oil cooler.
From there it is fed through the various engine oil
passages for lubrication of the engine parts.
h. The Front Cover. The front cover mounts to the cylinder block
on the lower front of the engine, and serves as a housing for the
front oil seal, oil pump, oil pressure regulator valve, and oil
cooler bypass valve. The oil pressure regulator valve is located on
the right and the oil cooler bypass valve on the left side of the
front cover (as viewed from the front of the engine).
12
OD1713
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