we destroyed our cutter motor

October 4, 2009 - 5:43 pm 3 Comments

As the competition gets closer, the probability of a major vehicle failure increases exponentially. Right on schedule, we managed to destroy a pricey cutter motor 2 weeks before the competition. Unfortunately, the motor has an 8 week lead time. The motor highlighted in this story is used to drive the chain that moves buckets down into the regolith and back up into the vehicles collection bin.

As you can see below, the drive shaft is slightly bent. It doesn’t look like much, however, it causes about a 3 amp variation in power consumption when running with no load.


How did this happen you ask? Well, since we do not have a fullscale regolith box to test in, we tried to test our excavator in some very hard packed dirt. The only problem was that, we didnt know there were rocks embedded in the dirt. The BFD dug into one and stalled the motor. As you can see below, the motor jumped up to almost 12 amps! We drew less that 4 amps cutting in that hard dirt before we hit the rock, which is pretty good.

cutter_stalled

3 Responses to “we destroyed our cutter motor”

  1. Paul Ventimiglia Says:

    We feel your pain. 3 days ago, we were driving in our testbox, and we only have about 4-5in of sand depth. As a result, because our robot sinks into the sand a lot more than regolith, we tried digging the concrete floor. This caused all of our scoops to bend.

    They are now bent back, but weakened of course. Testing is killer! We also had to sift out 1000lbs of small rocks from our “sand” (with just manpower) because it would jam up our chains and cause things to almost break. Wouldn’t happen with nice fine sand or regolith, but this is what we get…

    Hope you can bend the shaft back or modify it!

  2. Paul Ventimiglia Says:

    Wow, seeing the cutter and hopper taken off of your robot is scary! Just saw the webcam. Get it back on there soon.

  3. Gene Montleone Says:

    We burnt a motor yesterday. We had a loose screw on the brake and part of the brake got caught in the chain, spiked the current but took out the motor.

    It was an older model motor with high torque that they don’t make any more.
    Fortunately we had a used spare.