Window Motor locking up

[nitneylion452]

I found a similar thread, but the solution seemed to be using a Black Jag instead of the original one, or using a Victor to control the window motor.

We are using a black jag to control a window motor which powers our elevator/ladder. Every now and again, the motor just stops working. We checked the Jag and it is sending the signal, but the motor does not respond. We felt the motor and it was quite hot. Even after cycling the robot, the motor does not respond, then after a few minutes, it finally begins to work again, but generally only for one command.

The motor is being used to turn a spool which is connected to our ladder via pulleys and steel cable. I know the window motor is supposed to have very high torque, so I don't think we're over loading it, but I'm open to the possibility if it's explained well enough. Does anyone have any idea why we may be experiencing this issue?

If you need any more info to help, feel free to request it and I will get back to you ASAP.

Thanks!

[Nick Lawrence]

Originally Posted by nitneylion452

I found a similar thread, but the solution seemed to be using a Black Jag instead of the original one, or using a Victor to control the window motor.

We are using a black jag to control a window motor which powers our elevator/ladder. Every now and again, the motor just stops working. We checked the Jag and it is sending the signal, but the motor does not respond. We felt the motor and it was quite hot. Even after cycling the robot, the motor does not respond, then after a few minutes, it finally begins to work again, but generally only for one command.

The motor is being used to turn a spool which is connected to our ladder via pulleys and steel cable. I know the window motor is supposed to have very high torque, so I don't think we're over loading it, but I'm open to the possibility if it's explained well enough. Does anyone have any idea why we may be experiencing this issue?

If you need any more info to help, feel free to request it and I will get back to you ASAP.

Thanks!

Window motors and variable speed controllers don't get along. If you can, I'd recommend switching to a spike to control it. If you need to vary the speed, switch to a different motor.

-Nick

[548swimmer]

Window motors have a thermal cut-off. If the motor gets too hot, you'll have to wait for it to cool before you can continue working with it.

You might want to use an IR thermometer (if one is available) to check if this is happening.

[nitneylion452]

Originally Posted by Nick Lawrence

Window motors and variable speed controllers don't get along. If you can, I'd recommend switching to a spike to control it. If you need to vary the speed, switch to a different motor.

-Nick

Would a spike be programmed similarly to a Jag?

[Nick Lawrence]

If you're assigning a button to the Jaguar, then it will behave the same. However, the programming is different. Remember that the spike does not offer variable speed control, it's just a relay.

-Nick

[Chris Fultz]

We had this problem on our 2010 robot, using window motors to rotate the swerve modules (1 window motor for two wheels).

We found the issue was the thermal break, and the motors would stop until they cooled down.

Try to find ways to reduce the friction in the system, or add some other assists to reduce the work load on the motors. Also, be sure they are well ventilated, and maybe even add some cooling (fans) to help.

My understanding is that the thermal break is a safety feature - these are really window motors, and if part of someone was caught in the window as it was being rolled up, this thermal break would cause the motor to stop to avoid a worse injury.

[meaubry]

Yes, Power Window Motors have a safety component included inside of it that is called a PTC. It essentially, acts like a resettable fuse. When the motor has to work too hard, the PTC trips and you have to wait until it resets before it functions properly again.
It is a safety feature on many motors used in vehicles, to avoid having a fire, in case the motor is stalled for long peruiods of time.
In your case, the problem is that it will "act funny", or seem like it isn't functioning at all - once the PTC trips and tries to reset. Which is never a good thing.
As Chris indicated, the solution is to reduce or eliminate the friction causing the current draw to increase. If that can't be accomplished, you may have to use a different motor.

Mike

[nitneylion452]

What would be another good motor to use? Our whole reasoning for using the window motor was that it can't be back driven. Are there worm gearboxes available for purchase?

[548swimmer]

Originally Posted by nitneylion452

What would be another good motor to use? Our whole reasoning for using the window motor was that it can't be back driven. Are there worm gearboxes available for purchase?

http://www.directindustry.com/indust...cer-72868.html

They all look really heavy though. Another thing you guys could do (this is what we're doing) is use a FP and a Barbie trans with a sprocket reduction, and/or find some way (surgical tubing or gas strut) to reduce the load on your arm.

[Ankit S.]

Instead of using a whole new gearbox/motor, just figure out how to program a spike, as we are using spikes for our elevator and it works fine.

Using a spike would probably be easier as well.

[apalrd]

Originally Posted by Chris Fultz

My understanding is that the thermal break is a safety feature - these are really window motors, and if part of someone was caught in the window as it was being rolled up, this thermal break would cause the motor to stop to avoid a worse injury.

Cars don't stop providing power to the motors when they hit their end stops. They just stall the motor. So, if you hold the button long enough, you will trip the PTC and won't be able to move the window for a little while. Try it. It's fun (not really...).


We are running 2 window motors on the wrist joint of our elevator. On our practice bot they share a Victor (to save $), and we run the practice robot for about 2 hours per day (about 1 hour of actual driving, the rest is changing batteries, programming, and talking about fixes and additions).

No issues from us, however if we do manage to trip the PTC, then the two window motors will jam each other. We learned our lesson, and wrote code to prevent stalls.

As for a more powerful motor, you could use a Dewalt drill trans (see the Nothing But Dewalts whitepaper here). A Banebots RS550 motor has exactly the same mounting as a Fisher-Price.

[yarden.saa]

We had the same problem. You must use victors with the window motors, we did it and the problem stopped.

[Navid Shafa]

Before competing, we switched our 2 window motor's controllers to victors. Then we got tired of putting up with them in general, we thought about switching to an FP, but with an additional banebot left, we swapped to an RS-550. Since then, our arm hasn't had any issues.

Sounds like some great advice has been given. If time permits or all else fails, a quick redesign may be the trick. It worked for us!

[Al Skierkiewicz]

Guys,
There are several threads related to this issue. Window motors have a set of locking pins that seem to interact with the higher switching frequency in the Jags. Once locked, the motor has to be reversed to release the pins and allow forward motion. The rules this year allow you to remove the pins if your design does not need them. If the pins are locked and you continue to push the motor, it will over heat and the PTC will limit the current through the motor. For info on removing the pins, search window motors and John Novak. You will find a procedure for removing the pins.

[Brian C]

As Al stated above removing the locking pins is the way to go. This is a great link from team 1640 that shows in great detail how to do it.


http://wiki.team1640.com/index.php?t...r_Locking_Pins

Team 1468 is using Jaguars to control them and with the locking pins removed we have had no problems with the window motors.

However, as also stated above you need to see how much load you're putting on the motor as the thermal cutoff will give you fits as well/