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Old 22-03-2013
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Default Car going in reverse, grr help!

Ok, so I've put the electrics in my car but no matter what I do it only drives in reverse. It's a hobbywing v2.1 esc, futaba t3vcs tx, micro spectrum rx and a speed passion v3.

I have reversed the channel on the transmitter but that soaps the brake over so that when I push forward it applies the brake and push the stick back makes it go in reverse.

I've just taken all the gear out of another car and it was fine. I'm sure I've missed something really silly so please tell me what setting to change.
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Old 22-03-2013
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Is it a durango?
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Old 22-03-2013
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No, it's a kyosho.
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Old 22-03-2013
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Obviously, you've tried re-calibrating the esc to the transmitter?

With the durango, mine went backwards at first - I'd put the diffs in upside down...
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Old 22-03-2013
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agree with Col you've got the front & rear diff fitted wrong way round.
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Old 22-03-2013
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Yes i recalibrated it and even did it back to front but it still goes in reverse. I think it could be that the diff is back to front. It's a lazer zx-5 gearbox
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Old 22-03-2013
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Reverse the motor direction? Change x2 of the cable pairings from the esc to motor, usually it would be A-A, B-B, C-C, (first letter esc, second motor) crossover A&B so it goes A-B, B-A, C-C and it will run the otherway. Apologies if im teacing my grandmother to suck eggs
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Old 22-03-2013
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Thanks for the replies. Turns out it was the diff. Turned it round and all is well with the world

Tramp, I do understand what you mean ( electrical engineer)
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Old 22-03-2013
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if running sensored then not able to switch motor poles.
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Old 26-03-2013
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*embarrassed* yeah I thought I may be telling you something you already knew, but I thought id put it out there just incase you didn't! What sort of electrical engineer? graduate or from tools? Im an electrical fitter so 3 phase (squirrel cage) induction motors are a staple (and dc motors too but they dont really relate to rc ones!)

How are the motors sensored? A single proxy on the rotor? An encoder or resolver? (too big for the motor cans?) I doubt it would be a tacho or hall effect sensor as that would just indicate rpm and not actual rotor position.
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Old 26-03-2013
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they are hall sensors and reversing the A and B wires is not good advise as the chap has already checked his electrics it was clearly a mechanical error.
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Old 27-03-2013
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I disagree,

He said it was running forward in another car and now in a new car it is running in reverse.
To me this screams that the new cars gearbox has a different number of counter rotating gears and thus requires an opposite rotation on the input shaft, as far as I am aware i gave the correct advice for reversing the direction of rotation of the motor. I freely admit it wasnt model specific advice & I wouldn't have known that the diff could have been fitted upside-down on this particular car. But now I know I can bear that in mind for next time someone's car runs in reverse.

A question regarding sensored motor reverse running, can you think of any particular setups which will only run forward and not in reverse? I cant see how a sensored motor would stop you switching x2 phases and running a motor in reverse. Id like to google an example and see. Afterall if a motor was only designed to run one way it would be stamped on it right? As someone could use it with a non competition esc with reverse function
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Old 27-03-2013
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Duncan you twonk!!!!!!
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Old 27-03-2013
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Gents,

the motor and electrics were working correctly. What it turned out to be was that the previous owner to me had done a little maintenance before selling it to me and had put the diff in the wrong way round. All sorted now.

If it were a normal 3 ph motor you could have changed 2 phases over which obviously would have reversed it. The sensor system on these needs to see it fire in sequence, a-b-c a-b-c, a bit like a motor on a car, if you swap the leads over its not going to like it.
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Old 30-03-2013
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pleased its all sorted

i did hear of another unfortunate fellow who had inadverantly loaded a reverse rotation profile onto his SP/Hobbywing ESc

i know this may be brand specific and wasnt your problem but its another thing to bear in mind for future

also on the point of swopping motor cables aero modellers do this on non sensored motors too as they are rarely labeled from new again sensored motors are a different kettle of fish

fid
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