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Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 3/5/2000 8:16 AM MST


In Reply to: Works for us... posted by Nate Smith on 3/4/2000 8:25 PM MST:



Whether or not dynamic braking works or not is all determined by efficiency and ratio.

Unless the cable takes some goofy routings, I suppose we can say your cable is about 90% efficient.

The weight of your machine is 130 lbs. Using a 1/8 inch radius, this translates to 16 inch lbs of torque, but because of the 90% efficiency and the two motors, each motor see less than 7 inch lbs.

I can't recall the exact numbers but I have a vague recallection that it takes about 1 Newton-meter to backdrive those motors (without dynamic braking). 9 inch-lbs is about 1 Newton-meter.

SO... As you can see, your machine was right on the ragged edge of backdriving without dynamic braking. Dynamic braking provide extra bit you needed to keep from falling off the hill.

If on the other hand, your machine put 14 inch pounds of torque on those Delphi Power Sliding Door Mechanism, all the dynamic braking in the world was not going to keep you from falling.

Joe J.

P.S. I almost hate to share this with folks at this moment, but I was withing a eyelash of getting two electro-mechanical brakes donated to the kit in 2000 (at the time I had no indication that hanging would be part of the game, I just thought it would be a cool addition to the kit). Only a freakishly unluck chain of events managed to prevent it from happening. Ah well, better luck next year. I am also hoping to get some electro-mechanical clutches donated as well -- give me time....