DESCRIPTION
The piston assembly. Fig. 3-1, consists of a cast iron alloy piston, four compression rings. and two oil control rings. A "trunnion" type piston carrier, Fig. 3-2, is used with the piston assembly to allow the piston to rotate or "float" during engine operation. The carrier supports the piston at the internal piston platform. A thrust washer, Fig. 3-2, is used between the platforn and the carrier. The carrier is held in position in the piston by a snap ring inside the piston. Oil taken up by the two oil control rings passes through the oil holes at the bottom of the piston A bearing insert, Fig. 3-3, is applied in a broached slot in the carrier. Tangs at each end of the bearing insert are bent into a counterbore on the carrier to prevent endwise movement. The highly polished piston pin, Fig. 3-3, is applied in the carrier in contact with the bearing insert, and the assembly is bolted to the upper end of the connecting rod.
Internal parts of the piston are lubricated and cooled by the piston cooling oil. Cooling oil is directed through a drilled passage in the piston carrier, circulates about the underside of the piston crown area, and then drains through two holes in the carrier located at the taper as shown in Fig. 3-3.

DESCRIPTION
The "trunnion type" connecting rods. Fig. 3-12. are interlocking, blade and fork construction. The blade rod moves back and forth on the back of the upper crankpin bearing and is held in place by a counterbore in the fork rod.
One end of the blade rod slipper foot is longer than the other and is known as the "long toe." The blade rods are installed in the right bank with the long toe toward the center of the engine.
The fork rods are installed in the left bank. Serrations on tile sides of the rod at the bottom thatch similar serrations on the fork rod basket, Fig. 3-12. 'The rod basket consists of two halves.  held together at the bottom by three bolts and self-locking nuts. The fork rod and basket are bolted together at the serrations. Fork rods and baskets are not interchangeable since they are line bored as an assembly. Both the fork rod and basket are stamped with an identical assembly serial number for matching and identification purposes.

The connecting rod bearings should be checked whenever the piston and rod assembly is removed from the engine. To make this check, apply bearings to fork rod and basket in which they are to be used. Torque upper basket bolts to 258 N-m (190 ft-lbs), and torque lower basket (split line) bolts to 102 N-m (75 ft-lbs). Measure bearing bore at three points 60° apart. This is similar to the procedure used when checking fork rod basket bore, Fig. 3-14. The average of these three readings must not be less than is necessary to ensure a clearance between crankpin journal and bearing within the specified limits. After oper ation, rod bearings may give indication of being tight across the split line when
23E379 3 - 12
Section 3
loose on the crankpin. However, rod bearings intended for use should be mounted in the fork rod and then checked.
NOTE: After bearings have once been used, they should not be used on any other journal.
Check upper bearing step thickness as shown in Fig. 3-15. This will indicate blade rod bearing surface wear. Step thickness should not be less than minimum limit.
Bearing shells will usually be dirt scratched to some degree, but unless condition is severe, the bearings can be reused.