Manufacturers and users of piston rings classify them based on their function and use.
A piston ring seals the gap between a piston and a cylinder wall. Regular maintenance of the rings is crucial for maintaining the unit’s functionality. As you do this over an extended period, the piston rings will last much longer, preventing periodic replacement. This, in the long term, guarantees savings.
Having trouble determining how to maintain piston rings? Here’s how to do it.
Piston Rings: Types and Functions
- Compression rings or pressure rings
A compression ring seals above a piston and prevents combustion gas leakage. The piston’s first grooves contain compression rings.
The engine design may have an impact on this. Rings serve primarily as seals for gases entering the combustion chamber and as heat transfer components.
To provide enough lubrication for the top compression rings, the oil ring is sliced to remove the layer left by it. Furthermore, it provides sealing and heat transfer assistance to the compression ring at the top.
- Wiper ring
The wiper ring is also known as the backup compression ring or Napier ring. It is installed under the compression ring.
These rings are mainly responsible for cleaning the liner surface free of excess oil and preventing any gas leaks on the way down from the top compression ring.
Generally, wiper rings have a tapered angle face positioned toward the bottom, creating a wiping action as the piston moves toward the crankshaft.
When the piston moves toward the crankshaft, it creates a wiping action as the piston moves toward the crankshaft.
Having the tapered angle of the wiper ring closest to the compression ring results in excessive oil usage. Oil is wiped away from the combustion chamber by the wiper ring.
- Oil control or scraper rings
Lubricating oil passes up or down the cylinder walls with the help of oil control rings. In addition, these rings ensure that oil is distributed evenly around the liner’s circumference.
The oil splashes onto the cylinder walls. In this case, the scraper rings scrape the oil away and put it back in the crankcase.
By blocking the space between a ring’s face and its cylinder, these rings prevent oil from passing through.
What Causes the Piston Rings to Fail?
The piston rings need to be protected from the high pressure exerted by the combustion chamber. A higher combustion pressure inside the chamber can affect a ring’s performance if it produces a lot of gas.
The cause could be a leak in the injector that ignites the fuel or a combination of dirty air.
The performance of the cylinder ring is also affected by the quality of the cylinder oil and whether it is contaminated with fuel oil. As the ring starts to wear down and become less effective at sealing the combustion gases, its ability to do so will diminish.
The regular causes of piston rings wearing out are bad fuel or cylinder oil quality, improper combustion, incorrect fuel timing, worn liner, etc. In most cases, blowby, or gases flowing into the crankcase or under the piston area, indicates a worn ring.
What Are the Circumstances in Which Replacement is Necessary?
Check the grooves on your piston after removing the rings; if they are too worn, you may have to replace them. Ensure that your piston is clean and in good condition. If the engine continues to perform poorly, it may be necessary to replace the rings.
Is it Necessary to Maintain Piston Rings Regularly?
Here are a few situations where piston rings require maintenance:
Performance at the low level
Your engine’s piston rings may need maintenance if they degrade in performance even after the best maintenance.
If the piston rings of the machine have to be replaced, then the quality performance will be restored to the machine with a simple replacement.
Deterioration of piston quality
To improve their durability, piston rings often include an additional layer of chrome or a coating.
However, this protective layer might wear off earlier than expected, indicating that your engine should be inspected as soon as possible.
Overconsumption of oil
Changing your engine’s piston rings may be necessary if you need more oil than usual. A high level of smoke may also result from excessive oil consumption.
Things to Be Checked During the Inspection of Piston Ring
Piston rings must be inspected to ensure proper operation and then either cleaned or replaced (if broken or worn).
There is a higher position for the top ring groove in 2-stroke engines than in 4-stroke engines.
Care during inspection
A screwdriver is used for pressing piston rings during normal scavenge space inspections.
The purpose of doing this is to check whether or not the rings have a spring action or are tensioned.
Additionally, this will tell us whether the ring is broken. A broken ring will result in a lack of spring action because the ring is not functioning.
You need a thorough review of the rings to ensure they do not stick in the grooves due to carbon deposits. This could lead to the rings getting stuck and finally breaking, causing a lot of damage to the lining in the process.
While in a major overhaul
A new piston ring set is usually installed during significant overhauls. If the rings need to be scrapped, the following steps should be considered:
- Firstly; the piston ring must be removed from the groove if it is stuck there.
- When the rings have a reduced axial height and ample clearance between the rings and groove.
- There is peeling or damage to the chrome layer. During the overhaul, carbon deposits must be removed from the grooves, and damage must be checked.
Conclusion
Understanding piston rings’ different types and functions are essential to proper maintenance.
A piston ring can only function properly if it is in good condition. When performance declines, maintaining them becomes necessary.
Considering the tips outlined above, you can ensure your piston rings and engine will endure for many years.
B.E (Mechanical) Mumbai, MBA – ISB, Hyderabad (2011)
Managing Director at Atrac Engineering Co (manufacturers and exporters of aftermarket engine parts)
Member of EO Navi Mumbai.
Hobbies include avid fitness enthusiast – crossfit, golf and trekking.
