Reversing the rotation on a generator-How do you do it?

Anonymous-0

Well-known Member
I'm working on an Allis M crawler that I am putting an 6 v electrical system on. The problem is that the mounting of the generator causes the generator to turn in the direction opposite of what is typical.

I have an Autolite three brush generator that I think is not a good place to start.

I heading to LeSeuer show next weekend...what generator should I try to buy? Once I get it, how do I make the change?

Thanks in advance for the help!
Terry
 
It's been my understanding that in general it doesn't matter which direction the generator spins. Someone that knows that specific equipment may know if there are any quirks to that equipment that would prevent it.
 
To reverse the direction you have to reverse the relationship of the power applied to the armature (spinning part) vs the stator (fixed part). Since the fixed part is usually an electrical magnetic (soft iron core with the "field" wire wrapped around it), you need to reverse the N S pole relationship:

Did you ever read up on installing a generator on an engine? They tell you how to, but in short the task is to flash the stator with the right magnetic polarity to put out the right polarity voltage for your system.

What I would do is to make your mechanical installation, but before you make the electrical hookup, google "flashing a generator" and in reading what they say, just reverse the leads. Or post the question on here and what ever they say, just reverse the wires you connect to where to do the flashing.

If they say connect the pos to terminal x (whatever it is), connect the neg there and reverse the other terminal likewise. Remember this is a "flashing" which means just run the wires across the terminals which will spark and shoot current through the stator windings but that will polarize the iron core which lies inside the outer case.

Then hook it up normally except for the output wire which you want to check the voltage polarity before you hook it to your regulator. Crank her up, take your reading, if good, shut her down, connect your output lead and you're good to go.

That's what I'd do.

Mark
 
ELECTRICAL ANSWER

As long as youre rotating an armature (basically a coil of wire) inside a magnetic field a DC Generator still produces voltage REGARDLESS which direction the armature is rotating. Youre still rotating a coil of wire inside a magnetic field thats North on one end and South on the other...BE SURE TO RE POLARIZE THE GENNY PRIOR TO START UP HOWEVER because until the field curent flows (creating the stronger electromagnetic field) the residual magnetic portion of the fields determines charging current.

MECHANICAL CONSIDERATIONS

(A) If the brushes that ride on the commutator wear in to one angle and you change rotation of the armature there could be some problems until things get worn in and accustomed to one particular direction. If all is new and the brushes are still flat and theres not too much play then it wouldnt matter so much which initial direction the armature rotated.

(B) If theres a fan on the pulley end it either pushes air from front of engine out towards the rear or vice versa, while it makes some difference since air is different temp up by radiator towards engine rear, I dont think there would be too much, if any, heating problems BUT NO WARRANTY ON THAT Im an electrical NOT mechanical kinda guy..

NOW IF YOURE TALKING ABOUT REVERSING DIRECTION OF A DC MOTOR I.E. IF YOURE APLYING DC VOLTAGE INTO IT AND WANTING IT TO TURN A DIFFERENT DIRECTION things are a bit different BUT YOUR POST SAID GENERATOR NOT MOTOR

If it were a Permanent Magnet Motor and you reverse input polarity it spins the opposite direction,,,,,,,,If its an electromagnetic field motor (like a tractor starter motor) reversed input polarity DOES NOT change direction

REGARDLESS be sure to Polarize the Genny BEFORE starting the tractor

John T
 
(quoted from post at 06:48:16 04/19/13) I'm working on an Allis M crawler that I am putting an 6 v electrical system on. The problem is that the mounting of the generator causes the generator to turn in the direction opposite of what is typical.

I have an Autolite three brush generator that I think is not a good place to start.

I heading to LeSeuer show next weekend...what generator should I try to buy? Once I get it, how do I make the change?

Thanks in advance for the help!
Terry
here is MORE to it than these other posters seem to know. The brushes are angled relative to centerline of commutator. That angle is opposite for CW vs CCW rotation. Also, the relationship of the field produced by field coils relative to armature reaction field will be all wrong when rotated opposite of direction that it was designed to rotate. Minor detail, but fan different too. In other words, they are differently designed generators. Compare a 1962 standard generator to the 1962 Corvair generator.
 
Exactly, once the brushes get worn down at an angle due to the relatively loose fit in the brush holders if you reverse direction there can be problems. Brushes Ive replaced are worn at one angle based on direction of rotation. When all is new the brushes havent yet worn down to one angle however. Likweise the fan is moving air in one particular direcion but I doubt overheating problems, just cant say on that one.

Fun sparky chat


John T
 
According to Mac's Auto-Truck Electric, Oberlin, Ohio, the field windings must be changed. If you're going to a show, I would look for something period correct made by Delco, because this would be the easiest thing to find obsolete parts for.
 
There is much more to it than 'how brushes wear'. As I said earlier the armature reaction field will be in wrong position, resulting in insufficient output, excessive brush arcing, etc. A different design for CW VS CCW rotation. The illustration shows the brush lead.
 
GOTTA LOVE THIS FUN SPARKY CHAT EVEN IF OTHERS ARE BORED TO TERARS LOL

At the very least it could help and maybe work if the brushes were removed and reversed 180 so the angle would be more in line. An old genny I have down in the shop has the brushes like 90 degrees up to the commutator (unlike your first drawing more like second) and its brush wear has only a slight angle due more to the fact that the brushes arent fit prefectly tight into the holders. Of course I have no idea of that gennys model nor the one the poster has nor the one in your picture etc etc so I just cant say sittin here how well his will work, but at the least I can continue to say there could be a problem due to brush angle, regardless if his brushes are perpendicular or angled and at the least Id consider reversing the brushes 180 in their holders or install a new set that hasnt worn into any sharp angle and that could indeed work. Or if his brushes havent yet worn too much of an angle and are closer to perpendicular HECK IT MAY BE OKAY AS IS LOL

HOPE HE LETS US KNOW

Best wishes, God Bless n thanks for the fun chat

John T
 
Install a wide pulley on the generator the style normally used as an idler and use the generator as a belt tensioner, with the pulley riding against the outside of the belt = rotation reversed.
For the small amount of HP required to drive a small generator like that belt slippage should not be an issue.
Dave
 
It may be hard to match up and get such an idler to fit buttttttttt that would reverse the direction. Usually I see that arrangement turning an easier to turn load like a fan or something, a genny doesnt turn quite as easy. In addition theres the brush angle orientation were discussing below to throw in the mix grrrrrrrr theres never any easy solution it seems lol

John T
 
Just get an early Corvair generator. They were designed to rotate CCW as viewed from front (opposite of nearly everything else). You could change to 12v or have a generator shop install 6v fields. Another option is the alternator, available in 6v or 12v and unlike generators, alternators don't care which way you spin them (no commutators).
 
I have to agree, probably the BEST ADVICE, have a real Generator Shop (if any exist near him, we still have one around here) handle it or go the Alternator route and be done with it....

There used to be one "real" genny repair person here in Bloomington, IN and 2 in nearby Bedford, now Jenkins in Bedford (been there forever) is the ONLY remaining place with all the big neat old analog Sun equipment and other "stuff" looks like a Frankenstein Movie set lol

Ol John T and all
 
It is driven off of the same shaft as the magneto via a pulley. The butt end of the generator is nearest the radiator fan
 
I have an engine I bought as a replacement for my DC4, I believe it came out of a Case combine from the DC4 era.
It drives the generator off the back of the governor then the magneto is driven off the back of the generator, so the generator has a shaft coming out both ends.
One set up like this could easily be driven from either end for CCW engine rotation.
Dave
 
so is the engin you're putting in this still rotate the same way the old engine did? and you're just putting the genny on the other side of the block?still on the front of the engine? if yes to all three , then it will still be turning the same direction...
 
(quoted from post at 22:06:59 04/20/13) so is the engin you're putting in this still rotate the same way the old engine did? and you're just putting the genny on the other side of the block?still on the front of the engine? if yes to all three , then it will still be turning the same direction...

toadady the engine swap on my DC4 is not relevant to Terry Nowak's question I was just pointing out that it came with a double shafted generator that would work for the application he is trying to find a generator for.
Dave
 
Hi guys...thought I would update you on my progress.

I have determined that Cub Cadet lawn tractors used a ccw 12v generator/starter (Delco part numbers: 1101691, 1101996, 1101997, 1101692
1101951, 1101967, 1101986 and 1101998).

So my next step is to find one of these and then:
1) Remove the 12v field coils and put in 6v field coils

2) Wire it up to act only as a generator.

So my next question is...will this work? Can I just use any 6v voltage regulator?

Thanks for the help,
Terry
 
(quoted from post at 06:18:28 04/29/13) Hi guys...thought I would update you on my progress.

I have determined that Cub Cadet lawn tractors used a ccw 12v generator/starter (Delco part numbers: 1101691, 1101996, 1101997, 1101692
1101951, 1101967, 1101986 and 1101998).

So my next step is to find one of these and then:
1) Remove the 12v field coils and put in 6v field coils

2) Wire it up to act only as a generator.

So my next question is...will this work? Can I just use any 6v voltage regulator?

Thanks for the help,
Terry
t least two factors are important in matching a VR to a generator:1) type-A (internally sources field) VS type-B (externally sourced field)........VR must be a match in field sourcing to generator. 2) the VR current regulating limit should match generator current output.
 

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