Piston Ring Types - Oil Control Rings
Oil control rings are located in the bottom piston groove and their function is to control the supply of oil to cylinder wall to lubricate the piston skirt– and keep excess oil out of the combustion chamber. There are a variety of oil control ring designs as detailed below that are suitable for different applications.
Drainage holes or slots are provided to prevent oil from accumulating between the two outer lands.
Single-Piece Oil Control Rings
Designed to prevent oil passing from the space between the face of the ring and the cylinder.
Slotted Oil Control Ring:
The slot in the radial centre of the ring allows the excess oil to flow back to the reservoir and control the amount of lubricating oil up or down the cylinder walls. The parallel lands width is smaller than the overall width creating a higher unit pressure.
Bevelled Edge Oil Control Ring:
The outer lands are bevelled (or chamfered) on this style of ring which increases the contact pressure between the ring and liner to a higher degree than the slotted oil control ring.
Double Bevelled Edge Oil Control Ring:
The lands on the edge connecting to the combustion champion are both bevelled on this type of ring. This reduces oil consumption due to improved scraping from the chamfered edge.
Two-Piece Oil Control Rings:
In modern engines multi-piece oil control rings are more frequently used than single piece control rings as the meet today’s higher performance requirements of ring flexibility. Two-piece oil control rings are produced with a heat-resistant spring steel around the ring circumference to maintaining greater pressure and contact with the liner whilst maintaining oil economy. The coil spring is positioned in semi-circular or V-shaped groove which reduces the moment of inertia.
Coil Spring Loaded Slotted Oil Control Ring:
As the slotted oil ring control – the coil spring loaded oil control ring has two parallel outer lands. This ring also has a grove running inside the diameter to house the coil spring. There a number of variations to the coil spring loaded oil control ring:
- Coil Spring Loaded Slotted Oil Control Ring
- Coil Spring Loaded Bevelled Edge Oil Control Ring
- Coil Spring Loaded Double Bevelled Oil Control Ring
- Coil Spring Loaded Bevelled Edge Oil Control Ring with Chromed, Profile Ground Lands
- Nitrided Profiled Steel Ring
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