FRC shifting gears

[MrBasse]

Originally Posted by Lil' Lavery

While you're correct that devices like these are pneumatic cylinders, the portion of the cylinder applying a force to shift gears would be a piston. What he said is not incorrect.

Just because he isn't incorrect doesn't mean that he's right. This is a great opportunity to stress the proper terminology for the assembly, and not use the term for a single component within.

Just like I don't claim to drive my engine up to the store... truck is a lot more appropriate.

[IndySam]

Originally Posted by Lil' Lavery

While you're correct that devices like these are pneumatic cylinders, the portion of the cylinder applying a force to shift gears would be a piston. What he said is not incorrect.

Actually the part applying the force is a rod or shaft. The rod is attached to a piston.

[Bluman56]

With the update to the servo rules this season, is there any change in the viability of using a servo to shift? Thinking of using a SonicShifter as a winch with about 20 lbs of force from surgical tubing when retracted. Don't know if it would be possible to shift with a 10-12W servo in that case.

Would appreciate help. Thanks.

P.S. For those unaware, servos are now limited to the current put out by the 6V rail on the RoboRio instead of a strict Watt requirement as in previous years.

[pfreivald]

This "IACNAP Campaign" is pretty annoying.

Linguistically, language evolves and usage is king, so what you want words to mean (and/or what you were taught that they mean, and/or what they originally meant (assuming you can even chase down the etymology to verify)) has no bearing whatsoever on what they currently mean. There is value in specificity, but there's also value in not "correcting" people when they're using terminology understood by everyone in the conversation.

To whit, McMaster-Carr redirects searches for "pneumatic pistons" to their catalog page for "pneumatic cylinders."

[Dale]

I believe I saw in the Q&A that automotive motors like window motors but more importantly door lock actuators are legal. A door lock actuator could be a dandy device for shifting.

[FrankJ]

Originally Posted by IndySam

Actually the part applying the force is a rod or shaft. The rod is attached to a piston.

Couldn't be said the part applying the force is the air? Clearly you don't have a force until you start having a differential pressure.

[FrankJ]

Originally Posted by pfreivald

To whit, McMaster-Carr redirects searches for "pneumatic pistons" to their catalog page for "pneumatic cylinders."

That is because McMaster-Carr is more interested in selling stuff that what you call it. They should get an award for the best web based catalog ever.

Or the difference between an engineer and smart engineer.

[Lil' Lavery]

Originally Posted by IndySam

Actually the part applying the force is a rod or shaft. The rod is attached to a piston.

The piston rod is transferring force from the piston head to the shifting mechanism.

[Bluman56]

Originally Posted by Dale

I believe I saw in the Q&A that automotive motors like window motors but more importantly door lock actuators are legal. A door lock actuator could be a dandy device for shifting.

I like that the actuation is linear in door lock motors but from the specs that I've seen (hard to find specs on them for some reason) it looks like they won't be enough. Maybe I haven't looked hard enough but the most I've found was capable of 8lbs of force... :/

[Dale]

I like that the actuation is linear in door lock motors but from the specs that I've seen (hard to find specs on them for some reason) it looks like they won't be enough. Maybe I haven't looked hard enough but the most I've found was capable of 8lbs of force...

8 pounds is quite a bit of force. I'll bet it's good enough as long as you weren't shifting under full load. If your robot didn't have a pneumatics system for other things, it would be a shame to pay that pneumatics weight tax just for those little cylinders.

This one does 10 pounds.

[Dale]

By the way, here's the Q&A that makes door lock actuators legal for the first time ever:

642 Q. Does an actuator with an included motor sold as a "door lock actuator" meet the definition of "Select Automotive Motors" per R29 (sample: http://www.amazon.com/dp/B0088YE6YQ/)?

A. Yes. As per the answer to Q626 , the intent of "Select Automotive Motors" is to limit the selection criteria of automotive motors to those specifically listed in the parenthesis that immediately follows. "Door" motors are listed, and a motor sold as a "Door Lock Actuator" does fall under that category.

[REDBARON]

Our team chose to use servos with the Andymark sonic shifters however now we are looking into using pneumatic cylinders, however we'd also like to avoid adding another system if possible. Has anyone successfully or otherwise used door lock actuators such as this to shift?

[brianbond]

Hands down pneumatics, you can not beat the snappy action of a pneumatic cylinder in this application.

[Alan Anderson]

This might be the first year such automotive "door motor" devices are legal. You're breaking new ground here. I think it's a great idea, and if you make it work well you'll probably want to talk to AndyMark about how you mounted things.

[frcguy]

I second the pancake pneumatic cylinder from Vexpro. We use it with the 2 CIM ball shifter and it works great.