When is a "motor" a "motor"?

Hi, this is my first year as an electrical mentor with an FRC team. I have been and still am involved with Jr FLL and FLL teams for 5 years so I am a little dazzled by the bright lights and rules of FRC.

My question when is a motor not a motor relates to “window motors”. One of the students has found an off the shelf linear actuator that appears to powered by a window motor. I say appears as I have not been able to get a data sheet for it yet, but looking at the photographs it appears to have the same metal motor housing and connector as a window motor.

Rule R18 says “window motor” various - does this define a window motor as the whole assembly with the “end effector / gear chain” that’s primary / designed use is for opening and closing windows?

Or is it the actual electrical motor component that could be integrated in to an alternative off the shelf part that is not primarily designed to open and close windows?

I guess the underlying question is - If the electrical specification is the same as the electrical specification of a window motor, would this actuator be legal?


(By searching this forum, you have already answered many of my questions, please keep up the great work)

If, when you purchased it, it was labelled as a window motor, then it is a window motor.

I don’t suppose you could share the part number and source of that wonderful product with us?

or it could be a Door Motor, Windshield Wiper Motor, or Seat Motor. I like how wide open the rule is, but I’m sure it’ll get mucked up because someone will ask “is this motor legal?” on Q&A, and get it ruled illegal.

Since the original intent of the rules restricting motor use seems to have been to make things “fair”, by not allowing extra powerful motors, or motors that were not COTS, it appears to me that the nifty little linear actuator motor assembly you found fits the intent of the rules. But you might want to see if there’s a way to call it one of the names of motors used in automobiles, listed above. There was a thing a few years ago where FIRST got the auto salvage industry involved, by letting us get free automotive motors from salvage yards (voucher system), and I think it’s related somehow.

also, in past years the window motors were treated as an assembly with the gearbox, and could not be modified significantly, and still be legal to use.

For a new mentor, you sure picked a challenging question! :eek:

Oh gosh is this another “how its sold” fiascos where depending on marketing a part is legal… How did the last one go I only heard about it I didn’t actuallly participate in the shenanigans.

Here is the link to the web site.

It would be truly wonderful if it is legal to use.

My fear is that it is not.


I am looking to see if we can replace the existing motor with an off the shelf window motor. I guess I need to read the rules again to check the impact.

Thanks for the help so far.

It went pretty chaotically. As I recall, the last time this happened, “light switches” were allowed for use on the 2011 Minibots, but certain switches were not sold as “light switches,” but as “120 Volt Switches,” or something like that, thus making them pointlessly illegal.

As-is, this product isn’t a motor but an entire actuation system. There is no vagueness in how this particular part is sold - as a kit of motor + rack/pinion.

With that said, there are plenty of examples where COTS items have their motors replaced by FRC-legal motors for legal use in a competition - Vaccuum pumps, acme screw-based linear actuators and multi-speed Dewalt drills are three that immediately come to mind.

As pedantic as it sounds, even if the motor in that link were around the same power rating as a typical Van Door or Window motor, I don’t know for sure that it would be legal to use since it came with a kit for a specific type of actuation. In the 3 examples above, some of the motors are identical but have the wrong part # on the motor and that makes the COTS setup illegal to use as-is (thus the replacement FRC-legal motor). In this actuator’s case, it’s a gray area given the wording of the rules. Personally I wouldn’t take the risk, and would replace the actuator’s motor with a Window motor from prior years’ KOP - though that’s easy for me since we have so many sitting around.

I’d ask this in the official Q&A

My guess is that it’s probably not legal to use.

Which means you get to do some more brainstorming and design work, to figure out a way to do it more simply. We’ve always shied away from linear things, and used hinged things instead. It’s so easy to make a hinged mechanism…drill a hole, insert a bolt.

Thanks for all the quick responses, I’m discovering that that is what FRC is all about!

I have just managed to speak to a tech rep for the actuator and it is indeed an automotive motor. The motor manufactures web site states " These motors are commonly used for RV and truck step lift assemblies, window lift, awning extension, and many other applications". Its listed under wiper systems.

This is the motor -


The motor and actuator are available separately or as an assembled unit.

With that said should we buy them separately and self assemble or does having a data sheet for the motor assembly stating its automotive heritage suffice to meet the rules? This is were experience wins the day!

Thanks again for all your input.

Just to be safe, you could buy them separately…but it looks like you found a good answer. Have the documentation with you during robot inspection (the first day of the regional competition), just in case you need to show the inspector.

Also keep in mind that we are not the Q&A, so our answers are not official.

It’s a fun game, having engineers play lawyer.

After going through LRI training this weekend, without any other information besides that data sheet, I’d probably pass it at my event. But it is a bit of a grey area so it can vary from event to event, to be sure you’ll need a Q&A response.

With a little engineering and some lost-motion springs that will make a nice electronic shifter.

Thank you all, you have been a great help.

We will play it safe and have the correct documentation and if possible replace the motor with an existing KoP motor.

Like I said, please keep up the great work you do on this forum its invaluable to people like me.:slight_smile:

Can you explain what a lost motion spring is? When I search for it, I see results about a recall for lost motion springs used in cars, but not about what it actually is or how it works.

I would agree with Allen… It’s a gray area, and I would probably pass it (pending any relevant Q&A or rule changes). The rules on automotive motors are rather vague this year. Bring a datasheet that specifies the automotive use for the motor, which I think you already found.

Congrats on finding a really cool off the shelf assembly!

It’s a pretty nifty solution, but for that price tag I personally would use something else.

However each team has their own priorities, and two LRIs have weighed in, so good on you.

Where you ever able to get the motor part number from the supplier? Then you could look it up and see if there is a datasheet or documentation to show it is used as a window motor.