Pneumatics off board recharge packs

[mman1506]

Originally Posted by Joey1939

I am also very confused by the pictured recharge pack. Not only is it not legal (must be controlled and powered by robot), but having tanks onboard the pack makes no sense to me. I am going to assume that your goal is to fill the tanks on the robot and that you started with the tanks on the pack full before connecting it to the robot. The air stored on board the pack will spread equally through out the system and drop in overall pressure. Then you would have to leave it connected with the compressor running until not only the robot was full, but also the onboard tanks. I believe that it would take an equal amount of time as without tanks to fill the robot, therefore it is unnecessary to have the tanks.

It looks like they could turn a valve and disconnect the tanks after the pressure has been equalized. We used a similar setup controlled by the robot in 2014.

[MrBasse]

Having the tanks on the recharge pack makes it against r70 as pointed out in post 8. Hope that wasn't used during the season at a competition.

In the past, even when it wasn't against the rules we got a hassle for offboard storage. And having a valve to seperate the tanks from the system wasn't enough, trust wasn't very strong that day...

[GeeTwo]

Originally Posted by Lil' Lavery

My guess would be, since it's not controlled by the robot (once again, <R69>), and thus not limited by the pressure switch, they fill those tanks beyond 120psi. They probably use that final pressure regulator to ensure a 120psi fill into their on-board storage.

If it's not going to be used for competition, why not just get an A/C compressor that will charge much faster? Here is a 150 psi 6 gallon A/C compressor for under $130, much less than the components used for the the module shown. As I figure it, 6 gal of 150 psi air expands to about 7-1/4 gal of 120 psi air, so you can charge five quarts of on-board tank (that's eight of the largest plastic tanks currently on the AndyMark site) to 120 psi from a full charge of the on-board tank, no more electricity needed.

Addendum: After working with the air cannon for several years, I've come to realize that an FRC battery is a very inefficient way of getting compressed air (especially in terms of time, but also of electricity). Unless you have rules that specify that the air must come from a compressor powered by the robot's battery, there are several much better ways! On top of that, the regulator to get from 120 psi to 60 psi is inherently no more than 50% efficient when the tanks are full. Pneumatics are an elegant solution when you want to project a defined force, so I would be willing to put up with inefficiencies. Other than that, I'd try to find a way to use a motor more directly.

[MichaelBick]

Originally Posted by GeeTwo

You would not be able to use the pack pictured above for competition under either of these 2015 rules - no battery, no switch, and no air tanks can be off board. There may be some other nitnoids, but I stopped looking after these obvious ones.

True, but it is not illegal to use in your shop for refilling a robot during practice.

[GeeTwo]

Originally Posted by MichaelBick

True, but it is not illegal to use in your shop for refilling a robot during practice.

Not illegal, but silly. An AC compressor makes much more sense.

[346CADmen]

Originally Posted by GeeTwo

Not illegal, but silly. An AC compressor makes much more sense.

Unless of course you may want to go back to using the compressor on board a robot at some time. This unit is very portable, and with a simple modification, competition legal.

[Lil' Lavery]

Originally Posted by 346CADmen

Unless of course you may want to go back to using the compressor on board a robot at some time. This unit is very portable, and with a simple modification, competition legal.

What modification would that be? Almost all of this device would have to be redesigned to be competition legal (under 2015 rules). You'd have to both remove the air storage and change the electrical system to interface with the robot. At that point, you're basically starting over.

[staplemonx]

Originally Posted by 346CADmen

OK a few photo's as you mentioned missing the opportunity to take some.

Thanks for posting.

All, thanks for all of the comments. This was a way more useful question then we realized.

[Bob Steele]

I will just leave this here.

[Al Skierkiewicz]

Guys,
The dominant 2015 rule here is...
R69 The compressor (permitted per R68) may be located off-board, however the compressor must still be controlled and powered by the ROBOT.
The compressor may be mounted on the ROBOT, or it may be left off the ROBOT and used to pre-charge compressed air in storage tanks on the ROBOT. The intent of this rule is to permit teams to take advantage of the weight savings associated with keeping the compressor off-board. However, using the compressor off-board of the ROBOT does NOT permit non-compliance with any other applicable rules.

In the past the interpretation has changed from year to year. It has been sometimes allowed to have the pressure switch and regulator off board provided the stored air on the robot is at the 60 psi pressure. Any other parts of the pneumatic system must be on the robot and controlled by the robot. This includes the battery and storage tanks. While the team above may use this arrangement (see photos) for demos and post season events, it is likely to be ruled illegal at an FRC event. Sorry.