On close inspection, piston rings which have been run display minimum wear, from which one can derive information concerning ring movement in the groove. The wear induced side shape of rings and piston grooves characteristic of a large number of engines of different construction. The movement of rings in their grooves changes in turn as a result of the changed side shapes. This has a significant influence on performance, oil consumption and blow-by, as well as on bearing surface wear.
The sealing behavior of a compression ring under static gas pressure and simulated inertial load can be studied in a simple test apparatus.
By comparing ring sealing behavior determined in this way with blow-by curves measured in a running engine, further information is obtained about side contact and movement characteristics of the piston ring in its groove.
The relationship established permits the analysis of ring behavior in the engine and of wear-induced changes, thus providing the basis for optimization research.