Use of nitrogen gas in modern shock absorbers

In summary, nitrogen gas is used in shock absorbers to prevent oil aeration. It does this by acting as a piston, and by being compressible, it prevents the oil from boiling.
  • #1
vinay ks
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nitrogen gas is said to prevent cavitation in shock absorbers and thus provide a comfortable ride.. i want to know what actually happens in a shock absorber when nitogen gas is used. how does it prevent cavitation?
 
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  • #2
gas shock use nitrogen to prevent oil aeration. a plastic bag filled with nitrogen is placed in the oil reservoir space between the inner and outer tube of a single tube shock. Since it is compressible it permits oil volume change during shaft movement and since it is in its own separate bag, it does not mix with the shock oil. Shock oil is special oil for high temperature use.

without this the oil would become aerated – filed with air bubbles and performance would suffer.
 
  • #3
but what is the use of a floating or separating piston in a monotube shock absorber when u can use a plastic bag of nitrogen between the inner and outer tubes??
 
  • #4
I do not understand what you ask
 
  • #5
Nitrogen filled in a plastic bag will act as a spring as Nitrogen is compressible. Therefore it will act as a piston as well.
 
  • #6
vinay ks said:
nitrogen gas is said to prevent cavitation in shock absorbers and thus provide a comfortable ride.. i want to know what actually happens in a shock absorber when nitogen gas is used. how does it prevent cavitation?

In short, it doesn't prevent cavitation(Essentially boiling the shock oil due to low pressure behind piston). If it could then my job would be a lot easier. If anything it HELPS to prevent cavitation, but if the piston is moving fast enough you will always encounter cavitation(Race cars can see piston speeds upwards of 1m/s). Nitrogen is the gas of choice in motorsport for everything from shock absorbers to filling the tyres. It's inert and expands at a constant rate, compared to atmospheric air when its heated.
 
  • #7
I think the prevention of cavitation occurs because the entire assembly is at a MUCH higher pressure than atmospheric.. Any time you have an instantaneous, localized pressure of close 0 ATM, (especially at higher temperatures) the risk of cavitation increases greatly.. If you pressurize the entire assembly to 50ATM, it will be VERY much harder for any cavitation to occur.
 
  • #8
We find the cavitation point on a shock dyno. this attached PDF file should help explain a lot.
 

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  • SHOCK ADJUSTABILITY.pdf
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  • #9
Excellent article Mike!
 
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1. How does nitrogen gas improve shock absorbers?

Nitrogen gas is used in modern shock absorbers because it is less prone to expansion and compression than air. This results in a more consistent and stable performance, which improves the overall ride quality and handling of a vehicle. Nitrogen gas also has a lower moisture content, which helps prevent corrosion and extends the lifespan of the shock absorbers.

2. Can nitrogen gas be used in all types of shock absorbers?

Yes, nitrogen gas can be used in almost all types of shock absorbers, including hydraulic, gas-charged, and coilover shocks. However, it is most commonly used in gas-charged shocks, as they have a higher pressure threshold and are better able to maintain the gas charge over time.

3. How is nitrogen gas added to shock absorbers?

Nitrogen gas is typically added to shock absorbers through a process called recharging. This involves removing the old fluid and gas from the shock absorbers and replacing it with fresh nitrogen gas. This process should be performed by a trained professional, as it requires specialized equipment and knowledge.

4. What are the benefits of using nitrogen gas in shock absorbers?

In addition to improving ride quality and handling, using nitrogen gas in shock absorbers can also provide other benefits. These include better heat dissipation, reduced foaming and aeration of the shock fluid, and improved resistance to fading (loss of damping performance over extended use).

5. Are there any potential drawbacks to using nitrogen gas in shock absorbers?

One potential drawback of using nitrogen gas in shock absorbers is the cost. Recharging shock absorbers with nitrogen gas can be more expensive than using air or other fluids. Additionally, if the gas charge is not properly maintained, it can lead to decreased performance and potential damage to the shock absorbers. However, these potential drawbacks can be mitigated by regular maintenance and recharging by a professional.

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