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

[ShaneKent253]

Originally Posted by nicholsjj

Did you take the internal safety lock pins out?

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

[nicholsjj]

Originally Posted by ShaneKent253

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

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.

[Chris is me]

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.

[jimwick]

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.

[JamesCH95]

Originally Posted by luckof13

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.

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.

Originally Posted by Chris is me

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.

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.

[donkehote]

Originally Posted by nicholsjj

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.

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.

[droswell]

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.

[Ladiesman217]

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.

[Alan Anderson]

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.

[geomapguy]

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

[waialua359]

Originally Posted by Alan Anderson

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.

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.

[ToddF]

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.

[Al Skierkiewicz]

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.

[Lil' Lavery]

Originally Posted by ToddF

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.

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.

Originally Posted by ToddF

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.

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....

[mathking]

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.