Piston Skirts

Majority of two stroke piston skirts have one or more bronze bearing bands in the cast iron body to provide a compatible running surface against the cylinder liner wall and to prevent contact between the cylinder liner and piston skirt.

In operation, these bands will eventually wear down with the skirt body and can damage both the piston skirt and the cylinder liner which could result in severe seizure or cracking.

DMI Dubai’s reconditioning process starts with cleaning the skirt and inspecting for the presence of any cracks that may cause rejection of the piston skirt. If the piston skirt is crack free then the following steps are followed:

• Removal of old bearing bands by machining
• New extruded bronze material is pressed in and locked in to the dovetail form of the groove.
• Machining to the correct diameter as specified by the OEM.
• A series of vertical grooves are then formed in each band to allow for radial expansion.
• Machining of seating faces to provide a true surface. In some of the engine types, cross hatching is also done on the piston skirts for oil grooves.