Distinction and Installation Method of Three Piston Rings for Diesel Generator Set

Piston rings are small yet vital components of diesel generator sets. They are elastic split metal rings. A diesel engine is fitted with three piston rings. The top ring close to the combustion chamber is the compression ring, the middle one is the gas ring, and the bottom one is the oil ring. The three rings are arranged with a 120-degree stagger angle.

Then how the users to distinguish them? Dingbo Power advise you to distinguish by those methods as following:

1. Check its thickness and color: check the thickness and color. Generally, the first ring is brighter, whiter and thicker than the second one, while the second ring is darker, blacker and thinner.

2. Check the cross-section: The cross-section of the first ring is cylindrical or trapezoidal, while that of the second ring is generally rectangular.

3. Check the smoothness: The edge of the first ring is smoother, whereas the edge of the second ring is rougher (and feels sharper to the touch).

Generally, the compression rings of a diesel generator set are installed in the compression ring grooves on the piston crown. Their primary function is to prevent high-pressure gas from leaking from the cylinder into the crankcase, providing an effective seal. Most of the heat absorbed by the piston crown is transferred outward through the compression rings to the cylinder wall, where it is then carried away by the cooling water in the water jacket. Therefore, compression rings also play a role in heat transfer.

The oil control rings are installed in the oil ring grooves below the compression rings. They distribute lubricating oil on the cylinder wall to reduce wear between the piston and the cylinder wall, while scraping excess oil from the cylinder wall back into the crankcase to prevent oil from entering the combustion chamber. The specific installation steps for the piston rings of a diesel generator set are as follows:

1. When installing the spiral expander oil ring, first insert the spiral expander into the oil ring groove and connect the joint with the lock pin. Then install the oil ring body into the groove. The joint of the expander lock pin must be located opposite the gap of the ring body.

2. Pay attention to the mounting direction when fitting compression rings. Reversed installation will cause oil burning and gas blow-by. The marked side on both ends of the piston ring shall face the combustion chamber of the piston.

3. If the structure of the second and third compression rings differs, follow the installation steps below:

①Compression rings marked with "T" or "TOP" on the end face are tapered rings, which shall be fitted into the third ring groove.

②After placing the piston ring into the groove, it shall rotate freely without jamming when pushed toward the groove bottom.

③Stagger piston ring gaps by 120 degrees before installing into cylinder liner.

The above is the piston ring knowledge of diesel generator sets compiled by Dingbo Power for your reference. Founded 20 years ago, Dingbo Power is a professional manufacturer of diesel generator sets. We own modern production facilities, professional R&D team, advanced manufacturing technology, strict quality management system and comprehensive after-sales service. We can customize units ranging from 30KW to 3000KW as required. Please feel free to consult us.