paper: Window Motor Lockups: Causes and Solutions

[Al Skierkiewicz]

Larry,
I could see that using a right and left motor with the pins in place could lead to some locking of one or the other of the motors when used with either controller. However, I have also seen a number of teams use this configuration for arms without any reported difficulty. In those cases the teams intended that the anti-back drive keep their arm in place. They seemed happy with the performance.
In talking with John Novak who did some testing with these motors, it really does appear that the very low mass of the pins (I believe they are phenolic) can easily be set in motion by the switching frequency of the Jags when the motor is not actually moving.
Gary, I had not considered the self heating at 15kHz of the PTC as an issue. However, I think you may be right. If any teams can give us some more data on this, it would be appreciated.
I am going to guess that this operation takes about fifteen minutes per motor. Would that sound accurate?

[ratdude747]

Originally Posted by Al Skierkiewicz

Larry,
I could see that using a right and left motor with the pins in place could lead to some locking of one or the other of the motors when used with either controller. However, I have also seen a number of teams use this configuration for arms without any reported difficulty. In those cases the teams intended that the anti-back drive keep their arm in place. They seemed happy with the performance.

I see. 1747 did have overheat issues as the result of mixing left and right motors on thier 2011 arm joint. They had locking pins in 1 of the two motors (it also happened wit 2 pinned motors). They ultimately resorted to attaching 2 victor fans to each motor to make the arm usable.

Originally Posted by Al Skierkiewicz

I am going to guess that this operation takes about fifteen minutes per motor. Would that sound accurate?

Sounds like a reasonable estimate...

[ratdude747]

I have uploaded an updated version.

Changes:

-Added a time estimate (15 minutes/ motor) and note about saving the old pins as suggested
-converted the JPEG compression to lossless
-Added my new personal Logo to the end.