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Newsletter 11.19.2014

Special Rings, Special Service!

Daros, Federal-Mogul's brand, designs and manufactures rings for all 2-stroke engines being nowadays used and produced, both in marine application as well as in power plants.
Small, Medium and Large Bore piston rings for 2-stroke engines: Zephyr, appointed as Daros'official Worldwide distributor, offers you the possibility to purchase these components at the most convenient price!

Contact us for the full ring pack list!

Piston rings seal the combustion chamber from the cylinder crankcase in order to prevent combustion gases (or blow-by) penetrating the crankcase and to prevent the lubricating oil being sprayed around in the crankcase from penetrating the combustion chamber. In addition, the piston rings dissipate the heat from the piston to the cylinder and ensure the lubricating film is evenly distributed. Therefore the main requirements for piston rings are high resistance to wear and corrosion and a low drop in elasticity at high temperatures.

Perfect base materials, correct geometry and highly specialized coatings require a modern production facility. In order to satisfy the high requirements for piston rings, the basic material used in Federal-Mogul piston rings comprises high-quality lamellar or spherolithic cast materials. The basic material is selected from a wide range according to application and fuel quality. We are able to assist your choice of the correct material for your specific application: click HERE to know more.


For small bore MAN engines (26 to 50), a new type of piston ring has been introduced into the market which supersedes the CL grooves version.
The Port on Plane (POP) version grants a constant pressure drop across the top ring even if worn out. This effect is obtained by the replacement of CL grooves made by a number of ports milled on the lower side of the piston ring (see picture) which increase the bypass area as the ring wears, instead of reducing it.
The new version has been developed after the observation of premature wear out of the controlled leakage (CL) grooves causing increased wear on the top ring and on the liner.

Thermally induced stress leading to hard ring-liner contact and/or unintended blow-by in large-bore engines has been a well-known problem for many years. An effective way to avoid such problems is to use a gas-tight (GT) lock on the piston ring, while controlling the blow-by leakage through grooves (CPR Controlled Pressure Relief grooves) on the ring's periphery, as shown in the picture.
Normally CPR grooves are introduced together with Cermet coating, in order to reduce the wear and ensure that CL grooves are not prematurely worn out.

In order to improve the wear resistance and tribological properties of the rings, different coatings are used on running surfaces: click HERE to know more about Piston Ring Coatings (Cermet, Alucoat and Hard Cromium).