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.
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.
The piston rod is transferring force from the piston head to the shifting mechanism.
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… 
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.
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.
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?
Hands down pneumatics, you can not beat the snappy action of a pneumatic cylinder in this application.
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.
I second the pancake pneumatic cylinder from Vexpro. We use it with the 2 CIM ball shifter and it works great.
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.