Pneumatics Part # restrictions [Archive]

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Mike8519

18-01-2008, 10:11

Given that we are limited the Bores and Strokes listed on the bimba form are we also limited to DP for 3/4 and 1.5 and DXP for 2" cylinders? Nose mount (D mount) cylinders are illegal?

Tristan Lall

18-01-2008, 10:14

Given that we are limited the Bores and Strokes listed on the bimba form are we also limited to DP for 3/4 and 1.5 and DXP for 2" cylinders? Nose mount (D mount) cylinders are illegal?Technically not legal, but ask the Q&A: this is often an issue at inspection, and they may be willing to broaden the interpretation. The cylinders are functionally equivalent, as long as you don't take advantage of the different back end of the cylinder on the D models (they have no clevis, and the port is centred on the axis of the body).

MrForbes

18-01-2008, 10:17

It might be unfair to those teams who use the specified cylinders, since they weigh more than the same size D model, to use that example.

Chris Fultz

18-01-2008, 11:50

Given that we are limited the Bores and Strokes listed on the bimba form are we also limited to DP for 3/4 and 1.5 and DXP for 2" cylinders? Nose mount (D mount) cylinders are illegal?

You have to use the exact PN as indicated, including the mounting end.
All you can modify is to remove the pin in the clevis if you want to bolt the cylinder in place, and you can choose how to mount the extending end (clevis, but and bolt, etc.).

We proposed to use the front mount versions for transmission shifters a few years ago, because they are shorter, but we told we could not, via an official Q+A.

While the function of the cylinders is the same, the rule is there to assure that all teams have the same aprts and the same issues with mounting them,

Peter Matteson

18-01-2008, 14:16

This question comes up every year and the answer has always been the same as Chris mentions above. Use only what is listed on the cylinder order sheet as anything else will probably not pass inspection.

nighthawk0501

19-01-2008, 20:05

does anyone know if we have to use a clevis? or can we have on built in to our robot?

Chris Fultz

19-01-2008, 22:59

You do not have to use the clevis, but you cannot alter the actual cylinder as it comes out of the package, except to remove the pin.

Kat Kononov

20-01-2008, 01:08

does anyone know if we have to use a clevis? or can we have on built in to our robot?

<R92> Pneumatic components supplied in the Kit Of Parts (compressor, regulators, pressure switches, cylinders, valves, fittings, tubing, etc.) can not be modified except as follows:
• The tubing may be cut.
• The wiring for the valves and pressure switch may be modified as necessary to interface with the control system.
• Mounting and connecting pneumatics components using the pre-existing threads, mounting brackets, etc., is not considered a modification of the components. Removing the pin from the rear of an air cylinder is allowed as long as the cylinder itself is not modified.
Do not, for example, file, machine, or abrasively remove any part of an air cylinder. Consider pneumatic components sacred. They must remain in “out of the shipping box” condition.

I think this is the rule associated with your question. It doesn't say that you have to use the clevis. You can mount the cylinders using the threads that are on them, or example.

Andrew Schuetze

28-01-2008, 23:09

We have a 24" stroke cylinder in our supply which is the 1.5 inch bore. It was on the free cylinder form a few years back. The only 24" stroke cylinder on the free cylinder form this year is the 2 inch bore. So if cylinders from previous years are legal is this cylinder legal? I am leaning towards no citing the identical to free parts quote.

<R89>
In addition to the pneumatic cylinders provided in the Kit Of Parts and the “free” pneumatic

cylinders available for order through the Free Pneumatic Components Order Form,
additional air cylinders or rotary actuators may be used. All cylinders, regardless of source,
must be identical to those listed on the Free Pneumatic Components Order Form (e.g. same
part numbers). Any additional air cylinders must source from Bimba or Parker Hannifin, or
be recovered from prior year FIRST Kit Of Parts.

EricH

28-01-2008, 23:26

jgannon

28-01-2008, 23:36

By the rule you posted, it is not. Also see Q&A. It must be identical to the free ones from this year's order sheet.
What is the purpose of the last sentence of <R89>? Just to legalize the 1.5x8 Parker cylinder from KoPs past? Or does that one even count?

MrForbes

28-01-2008, 23:39

I think it is just to legalize that one cylinder...good thing too...we're using it in our design so far...

Jim E

28-01-2008, 23:44

Having read the Q&A tonight on pneumatic cylinder restrictions, The GDC response is kind of funny. There were 5 teams requesting variances to the allowed cylinders. The one answer the GDC recommended was exactly what is being said here by the CD community. If it's not on the approved 2008 list, it's not allowed.

Karthik

29-01-2008, 00:12

What is the purpose of the last sentence of <R89>? Just to legalize the 1.5x8 Parker cylinder from KoPs past? Or does that one even count?

The wording of <R89> had me confused for a while. This answer clears things up for me.

http://forums.usfirst.org/showthread.php?t=8447 (http://forums.usfirst.org/showthread.php?t=8447)

Tristan Lall

29-01-2008, 00:48

The wording of <R89> had me confused for a while. This answer clears things up for me.

http://forums.usfirst.org/showthread.php?t=8447 (http://forums.usfirst.org/showthread.php?t=8447)I'm a little surprised by that response (http://forums.usfirst.org/showthread.php?t=8447), because without some creative interpretation (which we might call "lawyering"*), it's hard to reconcile with the rule, which states:
All cylinders, regardless of source, must be identical to those listed on the Free Pneumatic Components Order Form (e.g. same part numbers).

Parker cylinders do not have the same part numbers as Bimba cylinders, so what are we to conclude? Hypothetically, I suppose the "e.g." clause could be a non-binding clarifying example like the one previously provided for the 80-inch rule (as opposed to "i.e.", which would be an unambiguous pronouncement), and "identical" could be short for "functionally identical". Even if that might be the case, I'd have to say the most obvious interpretation of the rule is that every cylinder's part number must match one provided on the form—why else would you give the example of matching numbers? Either way, that's worth clarifying once and for all in an update (if a rule is to be changed), or an unambiguous Q&A response.

Also (if we accept the permissive interpretation given above), why does the response state that these Parker cylinders must be from an old kit? If functionally identical (as opposed to matching-numbers identical) Parker cylinders are permitted under the 2nd sentence of <R89>, then according to the 3rd sentence, if they come from Parker, it's not necessary that they be from an old kit. (It must be either from Parker, from Bimba, or from an old kit; no combination of those things is required.)

*Not this again! :(

nvanderlugt

02-02-2008, 15:20

What about 3 position Bimba cylinders, custom ordered?
There is no mention of not using 3 position cylinders.
R89 states: Any additional air cyl must source from Bimba or Parker, or recovered from prior year First Kit of Parts. Any!!
Ours are 2" Bore 12" stroke, 9" then 3" more for three positions....

Anyone?

Thanks,

Nick v.

EricH

02-02-2008, 17:30

jgannon

02-02-2008, 18:09

What about 3 position Bimba cylinders, custom ordered?
Eric is right. Take a look at the sentence immediately before the one you quoted.
All cylinders, regardless of source, must be identical to those listed on the Free Pneumatic Components Order Form (e.g. same part numbers)
This is completely unambiguous, and has been reinforced by countless Q&A responses.