should FP gearboxes work in both forward and reverse?

[smcmahon]

Good morning Chief Delphi,

Last night we had mounted a 2012 KOP Fisher Price gearbox and motor on the side of our elevator. We wanted to use it to power down the bridge lowering rail. It went down just fine. However it stutters, for lack of a better term, coming back up. The motor appears to run for a second, stop, run, stop, etc. But only in reverse.

I wasn't sure if the gearboxes were meant to only go one way, or if we're having some other problem. The gearbox seems to me that it would spin fine in both directions, especially because of it's real-life application. Though, I guess it's possible 'power wheels' only go forward? Been years since I rode one.

I'm starting to think it's a programming issue, but I wanted to double check in this forum that there is no mechanical reason for our FP motor/gearbox to work fine in one direction and stutter along in the other.

[Al Skierkiewicz]

SMC,
The gearboxes can be run in either direction. However, the FP motors have a thermal breaker internal to the motor. When driving up, you may be over taxing the motor and it is tripping the thermal device which gives you the stutter you describe.

[FrankJ]

Last year we had a FP on our arm. We could get the FP motor smoking hot with no stutter. We were using a jag & a big breaker. We eventual limited the output command to the jag to keep the current to a reasonable level, but that is a different story. Maybe it is the self resetting circuit breaker doing its thing?

Different years gear boxes come with different tooth pinions. It might be that you managed to get a smaller pinion installed. It will work on low load, but skip on high load.

The FP gear box is used on an electric kiddie car. It will run forward & backward. They are as close to indestructible as anything in First.

[Ether]

Originally Posted by smcmahon

2012 KOP Fisher Price gearbox and motor

Originally Posted by Al Skierkiewicz

the FP motors have a thermal breaker internal to the motor

Al,

I couldn't find documentation anywhere that says the FP 00968-9013 motor has an internal thermal breaker.

Did you guys take an FP 00968-9013 motor apart and find a breaker inside? Or perhaps run some tests?

[Al Skierkiewicz]

If your FP has the breaker it is visible from the end of the motor. It is connected directly to one of the power input tabs. Use a flashlight.

[MrForbes]

If you want to isolate the problem as to programming or hardware, just reverse the motor wires where they connect to the speed controller. The motor will run backwards when commanded to run forwards.

DO NOT switch the power wires to the speed controller! only the motor wires

[Ether]

Originally Posted by Al Skierkiewicz

If your FP has the breaker it is visible from the end of the motor. It is connected directly to one of the power input tabs. Use a flashlight.

Are you saying that some FP 00968-9013's have a breaker, and some do not???

[Al Skierkiewicz]

I am saying that some FP motors have a breaker and some do not. I do not have a cross reference as to all FP motors that are available for FRC use this year.

[Ether]

Originally Posted by Al Skierkiewicz

I am saying that some FP motors have a breaker and some do not. I do not have a cross reference as to all FP motors that are available for FRC use this year.

The OP said he was using a 2012 KOP Fisher Price motor, which would be the FP 00968-9013. I am told that model does not have an internal breaker.

[AlexD744]

As a programmer (who has seen motors behave this way many times), I would typically relate this to a software problem. Typically motion like this is described when in one part of the code the motor is being set to a certain speed, while in another part of the code it is being set to a speed of 0.

Admittedly, it could be other things, and as stated above, switching the leads to the motor end of the speed controller could tell you a lot about the root of the problem being in hardware or software.

[Joe Johnson]

Originally Posted by Ether

The OP said he was using a 2012 KOP Fisher Price motor, which would be the FP 00968-9013. I am told that model does not have an internal breaker.

How about the 00801-0673 F-P (the 2011 KOP FP motor)? does it have an internal breaker? I remember the 2010 KOP FP motor did because we had some problems with our winch tripping the breaker (I was with 2849 that year). But I have no idea about the 2011 one. I only have two by accident and when the I got scared about using the BB motors in my drive, I switched over to these that happened to buy on a lark from AM in the fall.

Joe J

[Ether]

I'm not sure about the 9013 breaker either. I was hoping someone could take a look like Al said and verify.

[Joe Johnson]

Originally Posted by Ether

I'm not sure about the 9013 breaker either. I was hoping someone could take a look like Al said and verify.

My only two are in the bag!

[slijin]

Originally Posted by smcmahon

Last night we had mounted a 2012 KOP Fisher Price gearbox and motor on the side of our elevator. We wanted to use it to power down the bridge lowering rail. It went down just fine. However it stutters, for lack of a better term, coming back up. The motor appears to run for a second, stop, run, stop, etc. But only in reverse.

Have you counterbalanced your elevator?

Don't forget that when pushing a lift down, gravity works with the motor, but against you when pulling it back up. The same applies to any mechanism that works with gravity one way, and fights it the other way. Sort of like how going down stairs is easier than going up

If you haven't counterbalanced your elevator, then that would produce exactly the type of behavior you describe.

[smcmahon]

Sorry, just realized I never stopped back in this thread to let you know the end result. It was indeed a programming issue. We had been telling the motor "If this button is pressed, you're ON. Otherwise you're OFF." But then, with a whole different button, we were telling it to go the other direction when pressed, otherwise off. This confused the motor in case two, and it was trying to be both OFF and REVERSE at the same time. We fixed it with some nested select statements in LabVIEW.

Thanks for the insight everyone!