<div class="htmlview paragraph">This paper is a preliminary evaluation of theoretical models and a report of an initial series of experiments investigating the scraping effect and film-reducing capabilities of edges and sliders with cross sections similar to those of piston rings.</div> <div class="htmlview paragraph">Three basic types of scrapers or sliders are described: the hydrodynamic wedge between inclined, straight, or curved surfaces; a parallel slider that also produces lift; and a blade without a nominal bearing width.</div> <div class="htmlview paragraph">The theoretical treatment of an oil ring with two geometrically equal rails indicates that it will only scrape with its leading rail, while the trailing ran will ride a velocity wave without a scraping effect. The validity of this theory and its amplification has been experimentally supported.</div>