melex 36 volt fast in reverse

[bananaman]

I have a Melex 36 volt with electronic speed control and it will literally spin backwards when mashing the accelerator ,but in forward it goes alot slower.Anyone know what I can check.Thanks in advance.
CE

[bananaman]

TTT! NO one has any ideas?

[philtay]

What Melex is it? I've got a 212 and having tested 2 motors now, both are definitely a lot quieter and smoother running in reverse.

When I took apart both motors, I could see why. The motor brushes are angled badly against the commutator, which is crazy and obviously a design fault. If these are worn for any reason, this might be why you are having the problem. Although you'll notice more noise going forward as a result.

Failing that, the obvious one is to clean the contacts on your forward and reverse switch as one dirty one on the F side will produce the problem you describe. Also, it's worth undoing, cleaning, and remaking all the wire contacts from the F-R switch to the motor in case one of those is dirty too.
One diagnostic test you could do is to swap round the A1 and A2 wires going to the motor. The F-R switch will then be reversed in it's action. Then, if the cart goes fast forward and slow in reverse, it's an issue with your F-R switchj contacts or wiring. If the forward-slow reverse-fast thing is still true then the issue is the motor brushes, which can be replaced easily enough.

[adamj12b]

Based on philtay's post I think I have an idea.

Most electric motors are designed to run in one direction only. They will run in the oposite direction, but with less efficiently. When the brush's are at an angle, the motor is really ment to only spin in the direction the brush's are pointing.

If the brush's were perpendicular to the comm of the motor, you would not notice as big a difference.

You might be able to play with the brush timing of the motor a bit to help, but I dont think its going to do much. Seems mostly a design flaw...

-Adam