pic: Team 1158 Teaser

[wedellm]

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[Tom I]

This isn't much of a Teaser as much as a drive train design.

Even still, good design, I wonder how well those piston shock absorbers work. This should be very interesting if/when this design finishes production.

[Chris is me]

Originally Posted by Tom I

This isn't much of a Teaser as much as a drive train design.

I'm not complaining

I'm excited to see how you guys get this to turn on a dime. I think I can see how it will be done, and it would be really cool to see it work.

This is a lot like a drive I wanted to try this year.

[Abrakadabra]

If those are standard pneumatic cylinders acting as shocks, I think that Team Update #5 may have just made that particular use illegal, even if they are planned to be operated in a totally closed manner.

Our team was considering doing something similar, but now we are rethinking it. Team Update #5 modifies rule <R72-I> to add the word "COTS" between "closed-loop" and "pneumatic":

I. For the purposes of the FIRST competition, closed-loop COTS pneumatic (gas) shocks are not considered pneumatic devices, and are not subject to the pneumatic rules (although they must still satisfy all other appropriate rules).

Standard pneumatic cylinders cannot be be considered "COTS shocks" because that is not what they are really designed for. So now, even though they may be operated in a "closed-loop", they have to be considered part of the pneumatics system and are subject to the pneumatic rules, the primary one of which is that all "working" pressures must be no greater than 60psi.

Although you may pressurize the cylinders to much less than 60psi, there is no way to guarantee that a sudden drop or bump won't raise the pressure in one end of the cylinder to over 60psi due to simple mechanical force.

One possible way to satisfy this rule would be to have the top sections of all four cylinders connected to a pressure relief valve that would provide relief above 60psi (and probably add a pressure gauge as well to satisfy inspectors). However, there are still many grey areas in such a setup, and it could still be deemed an "out-of-spec" (i.e. illegal) use of the pneumatic components.

What does the community think?

[SpaceOsc]

i doubt a pneumatic piston ceases to be pneumatic just because its closed, seems like the spirit of the rule might discourage the use of gasses other than whats in air.

[Alan Anderson]

Originally Posted by Abrakadabra

Although you may pressurize the cylinders to much less than 60psi, there is no way to guarantee that a sudden drop or bump won't raise the pressure in one end of the cylinder to over 60psi due to simple mechanical force.

One possible way to satisfy this rule would be to have the top sections of all four cylinders connected to a pressure relief valve that would provide relief above 60psi (and probably add a pressure gauge as well to satisfy inspectors). However, there are still many grey areas in such a setup, and it could still be deemed an "out-of-spec" (i.e. illegal) use of the pneumatic components.

What does the community think?

The pressure regulators we've used in the past are "relieving regulators" and indeed prevent back-pressurization from mechanical force on the pistons. I don't see anything wrong here at all.