2-12
O-200-D & X Series Engine Installation and Operation Manual
3 January 2017
Engine Description
2-3.2.1. Crankshaft
The crankshaft is an aircraft quality steel forging with three machined main journals
supported by precision-bearing inserts in each of the three bearing saddles machined in the
crankcase. Four machined rod journals provide attachment of the connecting rod
assemblies. The crankshaft gear is indexed on the crankshaft by a dowel and secured by
machined bolts. A solid neoprene oil seal over the crankshaft flange is seated between the
crankcase castings in the front shaft exit area, and is sealed to the crankshaft by a helical
spring inside the seal’s cavity.
Crankshafts are center bored for weight reduction. The front bore runs out at the front
crank cheek and the rear end bore at the rear crank cheek. Oil holes are drilled through
solid cheeks from the center journal to crankpins.
The flange type crankshaft has a propeller mount flange forged on the front end with six
tapped holes in the flange. Six bolts, screwed into the propeller flange, clamp the propeller
between a loose front flange and the propeller flange. The loose front flange and the six
bolts are not supplied as part of the engine.
The crankshaft gear is piloted on the small rear flange of the crankshaft and aligned by the
crankshaft dowel, retained by four screws. The space between two adjacent punch marked
gear teeth points to the camshaft when No. 1 crankpin is at TDC. A cluster gear is driven
by the starter pinion.
Figure 2-6. Crankshaft
2-3.2.2. Connecting Rods
The connecting rods halves are machined from a single forging of aircraft quality steel and
cut into two pieces, splitting the center of the larger opening of the connecting rod
assembly. The resulting pieces, called the rod and cap are fitted with a two piece bearing
and attach to the crankpin or rod journal with special bolts and nuts.
The portion of the rod between the rod and the crankpin and piston pin ends is called the
“I” beam. A split steel-backed bronze bushing is pressed into the piston pin end and
Summary of Contents for O-200-D
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