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View Full Version : [OCCRA]: New DeWalt Problems


iwanttodunk
10-09-2008, 02:54 PM
I'm experiencing a problem with the new DeWalt cutting out when I drive them. During our weekly adult hour thing we asked one of our engineers David Bowden about this problem and he told us motors prefer to drive in one direction. Originally we had one new DeWalt motor on our robots left side and one older DeWalt on the right side. I noticed when I drove the robot backwards the new motor cutting out and when I drove forward the motor was fine, there were no problems with our old DeWalt motor, this would mean the new DeWalt motor turned fine clockwise but cut in and out moving counter-clockwise. I also noticed that the new DeWalts have no back drive where as the old DeWalts could be turned when there was no power connected to them. As it stands now we are switching our motors back to the ones we used last year. Are we the only team having problems with them or is this a common problem and if so how do we fix it? Also we are running them on 30 amp fuses, are these the correct size for the new DeWalt motors?

Mike Martus
10-09-2008, 06:47 PM
The problem you describe has several issues to consider.

While there is some fact that motors running in reverse are not as efficient the difference is usually not measurable.

The cutting out of the motors is usually the auto reset breaker tripping. What you need to investigate is WHY is the breaker tripping.

Breakers trip when the circuit draws a load greater than its rating. In your case it is 30 amps.

I would suggest that you look close at the following:

Drag / friction on your drive system
Alignment of sprockets
Load on motor - Are you trying to drive four wheels one on each corner and "Scrub" turn causing the breaker to trip?

If the breaker is tripping at start - Full joystick throttle - you need to look to the gear ratio. Example: What happens if you try to take off from a light in your manual transmission car and you forget you are in 3rd gear? There is a balance between speed and power .... you cannot have both with a single gear transmission ratio (DeWalt). If the breaker trips when you are trying to turn..... it is usually the gear ratio and the amount of "Drive Friction"... in other words you are asking the motors to do to much work.

The back drive issue is due to the transmissions still having the "Pins" in place. You will want them, removed for Dewalts used on a drive system.
If you do not understand how to do this download the White paper " Nothing But Dewalts" found on this site.