If we fix this, can/ should we still use it?

EDIT: Thanks everyone for the input. I has a good feeling that was gonna be the case but it doesn’t hurt to ask.

Just like the title says. If we repair this cylinder, is it
FIRST legal to use/ is it even safe to use? We’ve never had this problem before.

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Did that fail where the stainless steel tube crimps on to the aluminum end? If so, no you shouldn’t use it. It if broke elsewhere, also probably no you shouldn’t use it.

I don’t think that is within the abilities of any FRC team to repair, compressed air is no joke, and Nitra cylinders are cheap.

ETA: also will never be FIRST legal again, I believe that is pretty “modified”

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Unless the cylinder model says “repairable,” do not attempt to repair it.

AFAIK the pictured cylinder is not repairable.

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FRC is very clear about “don’t do anything to air components”!
Trash that sucker!

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Out of curiosity, how did this fail? It looks like you had a very high-inertia load and it just blew out the cap when it finished the travel, but I could be wrong.

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About 200 pounds of plywood fell on our robot while filming for the IR@H challenges. Fell right on the intake which pushed it down and then even further down.

The lesson learned here is don’t let your robot go into coast mode when you hit disable.

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But did it make a good noise? I’m surprised the tubing didn’t fail first. I’d expect a PTC fitting barb to let go before the body of the cylinder!

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It made a very loud crunchy sound. couldn’t tell if that was the plywood spitting, the robot crying or both lol. It was rather spectacular and also terrifying at the same time. We can laugh about it now but at the time it was a full on scramble to pick up the plywood.

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Hmmmm in my head I totally imagined the sound of pulling your finger out of your cheek. Oh well, crunching is entertaining too sometimes

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No.

Also no.

Pneumatics are intrinsically sketchy. If you ever have the opportunity to do so safely, try taking two identical tanks (or cylinders) and pressurizing them to failure, one with air, and the other with water. When hydraulic vessels fail, they tend to do so fairly calmly, with a leak forming and thus depressurizing the vessel. Air tanks fail in a far more bomb-like fashion; since air is compressible, you can squeeze way more energy in there.

I’ll happily play around with high voltages, radiation, and lasers, because things like that are pretty easygoing and predictable. It’s fast-draining energy reservoirs, like gas bottles and big capacitors, that scare me.

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Did it fail due to being bent sideways? or from pressure? My guess is you’d have to bend it to get it to fail like that.

I think it is worth quoting the manual. Something like this has been in the manual for years. As an LRI, I find myself quoting the bit about being “sacred” fairly often.

Do not, for example, paint, file, machine, or abrasively remove any part of a pneumatic
COMPONENT – this would cause the part to become a prohibited item. Consider
pneumatic COMPONENTS sacred.

I believe the weight and force of the plywood falling on the intake made the cylinders hyper extend. Our go pro was running at the time but the failure was just out of frame.

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I think the piston made it past it’s stop and made contact with the end cap. On most cylinders these days the end cap isn’t made to take an impact and the stops are less than adequate for what was described here. Usually whatever clevis or attachment was on the rod would make contact at the other end first, but this is a fun failure mode that is rare to see.

As to other statements on compressed air and safety, metal air storage and such is typically safer because rather than exploding they tend to peel open like a banana whereas plastic tanks have the easier ability to fail explosively. Not saying to take it lightly, but we are always happy to have the added weight in exchange for a little peace of mind.


Here is where that piston goes.

oh, it was just extended too far, because of a high load on it. Makes sense seeing that.

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Seems like you got a good and fairly inexpensive lesson in best practices.
Everyone’s out there complaining about rods in bending, but this looks like a solid argument against rods in tension as well…

I could totally see that happening on-field under heavy defense.

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And I was just about to ask if you had any video. That would have been both interesting and scary to watch.

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sooooo… there actually might be video of it breaking. We THINK our tripod camera that we’re using for the IR@H videos was still on. We’ll find out in a couple of days when we check the tapes.

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The only way I could see it happening on the field is if a climbed robot fell on us or another robot was yanking on it. I’ve been wrong before though.