Legality of Gas Spring?

Hello, my team and I would like to use a gas spring (a self-contained, hermetically-sealed hydropneumatic linear actuator containing pressurized nitrogen gas, which provides an output force). It is a SUSPA C16-23594, and provides 50 pounds of pressure. Is this allowed? Anything helps. Thank you!

Do you have any concerns with a specific rule? Component legality is generally pretty well defined in the season manual.

They are legal we used them last year on our arm last year to stop the cargo from bouncing

They have been technically illegal in the past (in the same way as pneumatic tyres), and some inspectors might erroneously give you a hard time around the pneumatics rules or even cite the cylinders as containing hydraulic fluid that could damage the field. We’ve used them in '16, '18, and '19 without issue.
The main reason a gas spring/shock might be ruled illegal is for safety concerns; they store quite a bit of energy and are often secured by a pneumatic pull-pin.

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Can you cite the year in which either of these things were true?

No competent inspector should “give you a hard time” about either item, which are plainly legal in the manual.

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I’m talking pre and early 2000s era with the stored energy and generally wack robot part rules.

You clearly have been inspected by only the finest and most fully qualified robot inspectors, the presence of which does not always grace us mere mortals (hence “some”). I remember an RI claiming the back of a pancake air cylinder couldn’t be on the plane of the frame perimeter…fun times.


@cvazq, I heartily believe R39D explicitly allows the devices you are asking about. When I was a mentor, these went on at least one robot I helped design and build that passed inspection, and as a robot inspector, I have passed several.

R39. Non-electrical sources of energy used by the ROBOT, (i.e., stored at the start of a MATCH), shall come only from the following sources:

  • A. compressed air stored in the pneumatic system that has been charged in compliance with R79 and R80,
  • B. a change in the altitude of the ROBOT center of gravity,
  • C. storage achieved by deformation of ROBOT parts,
  • D. closed-loop COTS pneumatic (gas) shocks, and
  • E. air-filled (pneumatic) wheels.

added: the gas shock/gas spring is my favorite non-battery way to store energy on the robot, especially when the energy is stored pre-match and/or will only be used once or a really small number of times during a match. Gas shocks inherently deliver their energy majestically (slowly), minimizing the chances of injury to people and damage to robots and other property during both practice and competitions.


From the rules:

:slight_smile: Of course the rule I go by is “Never believe what you read in a memo.” But then I am somewhat cynical.

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And with that, I’ll toss in a piece of recent history… Q695 in 2016:

Q. R35 allows for “closed-loop COTS pneumatic (gas) shocks” on the robot. Would a closed-loop “gas spring” that contains oil within its sealed housing meet the requirement of R35 and not violate the R9 ban on hydraulic fluid?
A. No, a shock containing oil, other than minuscule amounts for lubrication, is not considered a pneumatic shock.

Check out this CD thread for some more light reading on the topic :slight_smile:

Yes, you can use them.
We are using gas springs to extend our climber this year.
During Stronghold we used 2 - 250 lb gas springs for the actual climb.
I don’t remember them being illegal in the early 2000’s, but we did not use them until the 2005 year.

A bit more relevant and recent (2020):
Q 211 Gas Charged Lift Arm

We are looking into using a gas charged lift support arm, they are meant to be used to lift car hoods and hatches for mini vans. These are not controlled by pneumatics, are these legal to use? I can not see where it says it is or isn’t.
asked 20 days ago by FRC 6732



Yes, closed loop COTS pneumatic (gas) shocks are legal, as long as all other rules are satisfied (see final Blue Box of R77).

Right, the key being “as long as all other rules are satisfied”. The ones the OP asked about look legal to me, but some may not be, as the previous year’s Q&A indicated. This year, that would fall under R10 (Lubricants may be used only to reduce friction within the ROBOT. Lubricants must not
contaminate the FIELD or other ROBOTS.) or the blue box under R8 (. ROBOT parts shall not be made from hazardous materials… example: Hydraulic fluids or hydraulic items), and likely lead to a similar answer.

To me, that previous Q&A helped to shed some additional light on those “other rules” that this Q&A indirectly refers to :slight_smile:

Lets not forget the Logomotion minibot "light switch VS “limit switch” saga. For those of you who aren’t that old: If a package said “light switch” you could use it. If the package for the exact same switch did not have “light switch” on it, you could not use it.

Slightly more on subject. Every cots “air spring” I have seen uses oil for dampening. Air does not work for that because it is compressible. Considering how long they last, the amount of gas and oil they leak is small.

Edit: fixed that for ya Nessie

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What? You appear to be asserting the same thing twice. Perhaps you are missing a negative somewhere?

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