Window Motor will not lift ball anymore. It did, but it wont any more.
 

Hello from team 253!

We have a window motor lifting a claw that extends out of our frame roughly 19". Last week it worked fine running directly off of a spike and now we just cant get the claw to lift even though we haven't changed a single thing.

I don't know what to do and I am feeling a lot of stress about the situation. Any help would be appreciated.

Thank you!

Shane

Pictures coming.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Are you gearing the arm directly to the window motor? This is bad bad bad. You need at the very least a healthy sprocket reduction.

When we used window motors on our 2011 arm, even with a reduction and counterbalancing the motors would wear out about once per regional. Basically they would get very hot and then just stop working like yours seems to have. I would not do a window motor arm again unless it was very short and / or a ton of reduction was added to the motor.

With the high number of COTS gearboxes that are available to accomplish high reductions, you have a number of other options to consider that use a higher power motor more safely. You will likely need to combine products (e.g. a VersaPlanetary + a spur gearbox) but it's very doable.s

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Here is a picture of our motor. This motor is brand new and it still wont work again. Can you think if there is any reason that a brand new motor wont work any more?

Thanks.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Does the motor still spin in a no load application? (Not having to lift the entire arm assembly?)

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

from what you described it sounds like you stripped the main gear of the motor. The same happened to my team2395 in 2012 on our bridge manipulator. You either have to change out the gear or replace the entire window motor, but that will be a temporary fix because it will strip again if you don't change the way in which you rotate the shaft.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Does the motor make any noise at all? Did you burn out the 20A fuse in the Spike?

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

The fuse is brand new and so is the window motor.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

In a no load application where we are only lifting our arm assembly without the ball the motor works fine. Only when we try to lift with the ball does the window motor not work.

Any ideas?

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

The window motor has an internal thermal breaker in it which opens to prevent the motor from burning out. It appears that you have the motor attached directly to the pivot of the arm. This will place a large load on the motor. When the ball is added, the motor stalls, and the internal breaker trips.
Try using a different motor, and using a gear/chain/belt reduction before the arm.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Would it be plausible to use a pnuematic piston on a cam system. By my knowledge it wouldn't have to be a large piston, it would just have to apply enough force to lift the ball.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Did you take the internal safety lock pins out?

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

No, but I have heard about this. Can you explain what this would do for us?

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

That could be possible. It depends on what you are trying to do. A pneumatic cylinder only has two positions, in and out. If that is all you need, then it could work. You will have to do the calculations to determine how large a cylinder you need.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

http://www.chiefdelphi.com/media/papers/2685? This is a paper on how to take them out. From my limited understanding of what happens is that they will lock the system up if they are put under too much stress, such as lifting a heavy arm. This is added to them as a saftey feature so that children or adults do not break their fingers in a jamed car window I think. We had trouble at first with them last year as we used 4 windowmotor gearboxes for our climber. If you arm is lifiting and then all of a sudden stops then I would look into taking them out. It is legal to do still by R30 in the rules. If you are still having problems you can machine out another motors output shaft and attach it to the window motor gearbox leagly per Q&A 243.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

You definitely can't get away with directly driving an arm with a window motor. You need a reduction of some kind.

If you can make pneumatics work for you, I would suggest that simply because it's much easier to accomplish and simpler than a motor driven arm system.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

The breaker was added to stop the finger breakage, the locking pins mean a thief cant just force the window down. When its not powered, they are locked.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Also, is the indicator light on your Spike changing color when you attempt to move it?

Could be a loose/bad/wrong way PWM, program change, etc. If the indicator is turning red/green, then you know the relay is working.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Could you maybe reduce the stress by putting a window motor on both sides of the arms? I would think using 2 window motors would help a lot, but i might be mistaken.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Doubling up window motors might end up with a worse problem. If one of them runs just a little faster than the other, they'll start fighting each other, and the anti-backdrive feature is likely to lock one of them up. If you don't need the motors to actively hold their position against a force trying to move them, it might be best to open them up and remove the pins.

This application probably calls for a stronger motor, though. It's a good opportunity to do the math and find out what torque is required at what speed, then match that to an available motor and gearbox.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Try using a PG motor or a versa planetary.....Window motors are that good

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

I would agree that the single window motor isn't going to work. Looking here, the stall torque of your motor is 94 inch pounds. I'd conservatively estimate you are trying to move 4 pounds with a 2.5 foot arm. This will apply 120 inch pounds. You simply need more power.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

If you like this design, you could mount an additional window motor to the other side of the arm and wire "backwards" to the first one, so they are both working together. We used the same kind of system to push the bridge down in 2012.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

IN 2011, we used a double window motor setup, but had them coupled together via a shaft to ensure they ran at the same speed when moving our arm.
Given the amount of COTS options compared to several years ago, however, we will never use them again for a similar purpose because it doesnt backdrive after a match.

If OP is set on using a window motor, put a reduction AND use another window motor.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

No matter what motor you end up using, the first thing you can do to help yourselves is to add a spring to counter balance the weight of your arm. This could be as simple as a piece of surgical tubing wrapped around a pulley that's attached to your arm pivot axis. Attach the other end of the surgical tubing to your frame so that the weight of the arm is supported by the stretched tubing, not your motor. Then, the motor just has to handle arm motion, not carry the weight.

Properly counterbalanced, a window motor just MIGHT work. But, the teams at our last FRC summit concluded that window motors are supplied as object lessons for rookie teams to learn what NOT to use. Most of us just throw them in the trash. With their limited capabilities, there are much better options available. Not to mention that the thermal cutoff will kick in at the most inopportune moment, leaving you motionless until the motor cools down.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

To remind everyone, the locking pins in these motors are really only an issue when driven by Jaguars. There is a lot of discussion about this in the files. It was first brought to our attention by John Novak from Team 16.
I like Todd's suggestion, so you can check if the motor is defective or just being asked to do too much (which we all suspect now that we have seen the assembly). The motor does have a thermal cutout (a PTC as I remember) but that is usually backed up by a hot motor casing.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

A window motor is just not going to get the job done here. You are experiencing what happens when you try direct drive. But if you gear it down it will be too slow to shoot the ball.

If you look at the motor data sheet for this year you will find that the window motor is comparatively low power.

You need to find a different basic way to operate your arm using a more powerful motor.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

And the internal thermal breaker gets weaker over time it seems, at least in my/my team's experience with them. If they trip a few times you best be replacing that motor soon.

I agree, penumatics are a great way to do simple 2-position mechanism actuation.

The window motor's max output is 23W, with is quite a bummer considering there are only a few motors weaker than it, and most motors are a LOT more powerful: http://www.usfirst.org/sites/default...nformation.pdf

Like others have mentioned, it would be a really good idea to use a better/bigger motor.

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

Can't believe it took this long to suggest this. This is a great method to reduce the load on any motor, and the worm-drive mechanism in the window motor is a great way to sidestep any backdriving issues caused by changes in the spring force as your arm travels.

I disagree that they're useless. There are plenty of low-load applications where window motors work just fine, and their worm gear reduction offers a great deal of resistance to backdriving (which is often very useful). Rather than heavily reduce a high power 500-series motor for a low-speed, low-power application, we often use window motors. In 2012, we used a window motor to power our final stage roller, that would load the balls into our shooting wheels. Not much speed or power required, and with a tight compression, high CoF, and the worm gear combined, we prevented ourselves from "accidentally" shooting a ball early when the loader stacked up. In 2013, our original loading cam was powered by a window motor as well, but this entire loading mechanism was eventually replaced by a pneumatic system.
Don't take that to mean that the window motor is the correct choice for this application, though.

The throttle motors, on the other hand....

Re: Window Motor will not lift ball anymore. It did, but it wont any more.
 

I completely agree with Mr. Lavery about the window motors not being useless. We have certainly burned out our fair share of them when we were stretching their capabilities, but in the correct applications they can be very useful. The hubs alone can make them useful for some applications, as they are easy to mount things to without significant machining capabilities. Add the worm gear and they can be used in a variety of ways, as long as you aren't trying to put too much load on them. As Mr. Ferrante said, counterbalancing the load with a spring of some sort can help a lot. Here is an application of this sort of counterbalancing.