LOCKNUT 2F4159 - Caterpillar

The piston is a two-piece, articulated design. The piston consists of a forged, steel crown and a cast, aluminum skirt. The two pieces of the piston assembly are connected to the piston pin. The two pieces of the piston assembly pivot about the piston pin. The steel crown carries all three piston rings. Engine oil from the piston cooling jets flows through a chamber which is located directly behind the rings. The engine 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. The oil ring is a standard ring. Engine oil returns to the crankcase through holes in the oil ring groove. The top two rings are the Keystone rings, which are tapered.The connecting rod has a taper on the pin bore end. This taper gives the connecting rod and the piston more strength in the areas with the most load. Four bolts, which are set at a small angle, hold the connecting rod cap to the connecting rod. This design keeps the connecting rod width to a minimum, so that a larger connecting rod bearing can be used and the connecting rod can still be removed through the cylinder liner.