PLUG 1230173 - Caterpillar

The piston is a two-piece unit. A steel crown is held to a forged aluminum body by four studs and nuts. An inner cooling chamber is formed and a piston outer cooling chamber is formed inside the crown. The cooling jet oil flow enters the outer chamber through a drilled passage in the piston body. After entering the outer shaker chamber, the oil flows to the inner shaker chamber. The oil then returns to the sump through a centrally located drain hole. The drain hole is located above the small end of the connecting rod.Three piston rings are used on the piston assembly for sealing combustion gas. The top two piston rings are located in a hardened steel groove in the piston crown. The third piston ring is located in the aluminum body.The oil control ring is located in the lower groove in the aluminum body. Four holes are drilled from the bottom edge of the oil groove to the interior of the piston. The four holes drain excess oil from the oil ring. The piston has two 1/2 -13 NC threaded holes in the crown for lifting the piston and connecting rod assembly.The connecting rod has a taper on the pin bore end. This gives the connecting rod and the piston more strength in the areas with the most load. Four bolts and nuts hold the connecting rod cap to the connecting rod.