ENGINE AR 7N2740 - Caterpillar

Illustration 1 g01084288
(1) Top ring
(2) Intermediate ring
(3) Oil control ring
(4) Piston pin bore
(5) Piston pin
(6) Piston pin retainer The piston is a one-piece piston that is made of forged steel. A large circumferential slot separates the crown and the skirt. The crown and the skirt remain attached by the strut for the pin bore. The crown carries all three piston rings. Oil from the piston cooling jets flows through a chamber which is located directly behind the rings. The oil cools the piston which improves the life of the rings. The pistons have three rings which include two compression rings and one oil ring. All the rings are located above the piston pin bore. Oil returns to the crankcase through holes in the oil ring groove.The connecting rod has a taper on the pin bore end. This taper gives the rod and the piston more strength in the areas with the most load. Four bolts, which are set at a small angle, hold the rod cap to the rod. This design keeps the rod width to a minimum, so that a larger rod bearing can be used and the rod can still be removed through the liner.