[FTC]: AndyMark Neverest motor wear and tear?

[madz]

Hi everyone,

We have a robot that is about 30-35 pounds. It has good traction on the ramp, but we are sometimes having a problem driving up to our usual location. We practiced all day today, always keeping a fresh battery on the robot. We know the batteries are good because they are checked with a battery beak (usually over 13V).

The first part our practice, we can drive up to our usual spot every single time with no problem. As we got later in the day, we couldn't even get over the first churro, even with a fully charged battery. We notice that some of our wheels don't spin at all when trying to go up the ramp in that case. We already checked for extra friction points in the drivetrain (we had that problem before). It drives fine on the ground.

Driving up the mountain, a couple of motors (diagonally opposite from each other, so one driving one wheel, the other driving two) get pretty warm.

It sounds like we need more torque, but only after using the robot for a long period of time.

Robot has 4 AndyMark Neverest 40 motors driving 6 6" wheels (2 upper wheels are driven by 1 motor; 1 lower wheel on ramp driven by 1 motor). It has a 4:3 gear ratio on the sprockets.

Now that we are thinking about it, our original drive train (which didn't have as much traction) had them same problem after running a long practice session.

Edited: We also noticed that the voltage can drop to 9 or 10 volts from 13+ when we are driving up the mountain. It does the same thing when we stall against the wall.

So a few questions:

1) We think there are motors we purchased in Sep/Oct 2014. Do they usually wear out after a lot of use? We'd guess yes.
2) Do motors usually lose torque after they've been running a while?
3) Is there a good way to measure the torque output of the motors?

We're looking into new motors or upping the torque by changing the the gear ratio.

Anyone have any thoughts / ideas?

Thank you, The Rockettes