Page 5 of JE Pro Seal Catalog by JE Pistons

Barrel Face Torsional Plasma Moly Inlay Barrel Face Torsional Chrome Barrel Face Chrome Nitride or Moly Dykes Flat Face Torsional Barrel Face Torsional HNS and Tool Steel 6 TOP RINGS The top compression ring is responsible for creating a seal with the cylinder wall to maintain combustion chamber pressure. The top ring also transfers up to 45% of the heat generated by the combustion process to the cylinder wall en route to the engine cooling system. JE Pro Seal top compression rings are available in a variety of shapes (see illustrations below), sizes and material types that allow you to choose the most efficient and economical ring to suit your application. Most JE Pro Seal top compression rings have a barrel face with a positive torsional twist. This twisted configuration takes up the axial clearance in the groove, providing a better cross sealing. During most of the intake stroke, the piston ring twists upward because of the chamfer while the barrel face utilizes its lower half to maintain contact with the cylinder wall (fig. 4). On the compression and exhaust strokes, the ring may sit fllat on the groove surface (fig. 6) or be twisted upwards (fig. 4) or downwards (fig. 5), depending on the size of the chamfer, inertia forces at top and bottom of stroke and combustion chamber pressures (most notable when piston is near top dead center. A third position is achieved during the power/combustion stroke. Although inertial forces direct the ring upward, combustion pressure forces the ring to the bottom of the ring groove and forward against the cylinder wall. FIGURE 1 FIGURE 2 COMPRESSION GAS 45% 20% 5% RINGS TRANSFER 70% OF COMBUSTION CHAMBER HEAT INTO THE CYLINDER WALL COMBUSTION CHAMBER HEAT FIGURE 3 GAS SEALING HEAT TRANSFER OIL CONTROL FIGURE 4 Illustrations are exagerated for demonstration purposes (All figures shown are close approximations) FIGURE 5 FIGURE 6 RING FUNCTIONS RING FUNCTIONS Piston rings serve three basic functions in an automotive engine, gas sealing, heat transfer, and oil control. The primary duty of the top compression ring is to provide a seal that prevents combustion gas or pressure from bypassing the piston. This is achieved by maintaining contact with the cylinder wall at all times. The second compression ring also assists the top ring in its sealing function, although its main purpose is to provide a secondary form of oil control for oil that has bypassed the oil ring (fig. 1). Secondly, both compression rings and the oil control ring transfer the heat of combustion from the piston to the cylinder wall where it is then transferred to the cooling system (fig. 2). Lastly, the second compression and oil ring also serve as an oil control system regulating the film of oil on the cylinder wall. As the piston moves downward, the sharp edges of the second ring and the two rails scrape the top layer of oil off the cylinder wall, leaving only a very thin layer behind. The excess oil is discharged by three methods. Most simply gets scraped by the lower oil ring rail back down into the oil pan. Some excess gets forced into drain back holes in the oil ring groove, to the interior of the piston and then back to the oil pan. If the piston has pressurized pin oilers , the remainder gets forced into holes in the oil ring groove through the pin bosses into the wrist pin reservoir, then directly onto the wrist pin. TOP RING SHAPES AND TYPES

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