Generator diesel engine piston connecting rod, piston ring and piston pin

The piston connecting rod is one of the main force-moving parts in a diesel engine. When attaching and detaching the piston rod, it must be careful and correct. When transposing each part, attention should be paid to the structural difference of each model, otherwise it will cause adverse consequences.
1. The piston piston is made of eutectic silicon aluminum alloy. There are three air ring grooves and one oil ring groove above the pin hole of the piston; the top is a large-diameter, shallow w-type combustion chamber. Some models of pistons are fitted with wear-resistant inserts at the first ring groove, and the piston is anodized at the top. When replacing the piston, special attention should be paid to the depth of the valve pit and the distance between the piston pin hole and the top surface of the piston. Otherwise, the piston will collide with the cylinder head or the valve, causing a serious accident or reducing the compression ratio and failing to work properly.
The piston skirt is a precision machined surface that prevents bumping during assembly and disassembly. There are 4 small holes of 05mm on the piston pin seat for oil splash lubrication of the piston pin and pin hole mating surfaces. The inner circle of the lower end of the piston can also be reused to adjust the weight of the piston group, and a weight grouping number mark is also made on the top surface of the piston for the user to select when installing or replacing the new piston. The difference in weight of each piston in the same diesel engine should be no more than 10g.
During inspection and repair, there is a small area of ​​scratches, burn marks, or slight scratches on the skirt of the piston top. It can be used after shading with a scraper and oil stone, otherwise it should be replaced.
2. The piston ring and the piston pin are non-supercharged diesel engines. The first ring groove is equipped with a chrome plated gas ring; the second and third ring grooves are equipped with an inner circle chamfered gas ring, and the chamfering side of the assembly should face upward; Four rings are fitted with spring-plated chrome rings. Turbocharged diesel engines are equipped with chrome-plated gas rings in the first and second ring grooves; a third ring groove is equipped with a circular chamfered gas ring; and a fourth ring groove is fitted with spring-plated chrome rings. 138 series, NT, NK series and other new diesel engine piston ring, usually the first barrel surface trapezoidal ring, the second installed on the side of the inner chamfered barrel surface rectangular ring, the third install cone surface ring, assembly time " The TOP side is facing up, and the fourth lane is fitted with spring-plated chrome rings. At the same time, the closed clearance and axial clearance of the end faces of all piston rings should be measured as required. If the closing gap is too small, it can be corrected with a file.
When inspecting the piston, if the piston ring bites, it can be immersed in diesel (kerosene or gasoline) for a period of time, and then it can be removed and shaken gently. The piston ring can be loosened without scraping.
The engagement of the piston pin with the piston and the small hole of the connecting rod is a full-float type, that is, a transitional fit with the piston pin hole and a clearance fit with the connecting rod small head.