FRC shifting gears

[Lil' Lavery]

Originally Posted by IndySam

"It's a cylinder, not a piston"

Brought to you by the IACNAP campaign.

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.

[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.

[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... :/

[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.

[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.

[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.

[GeeTwo]

Most commonly pneumatics, though a few use servos, especially if the robot will not have any other pneumatic systems. AndyMark and VexPro shifters have pneumatic parts or kits referenced from their web pages, and AM also has servo kits. Due to the limits of servos allowed by recent FRC rules, servos do not provide as much force or speed in shifting, making pneumatics the favored method.

[frcguy]

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

[cbale2000]

Has anyone ever attempted to use multiple servos to actuate a single shifter? Seems like it would be the logical thing to try given the option to use unlimited numbers of servos and their relative low weight (especially when considering the weight of adding an entire pneumatics system for a single function).

That said, that door lock actuator is intriguing as well. My team is planing on using pneumatics for actuating our ball shifters this year, but those actuators might be something worth trying out too.