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Discussion Starter · #1 ·
Ok, So I have two forklift motors. I have not laid hands on them yet because they are many hours north of me and I have to make a trip. But, I want to know as much as possible before I head up there.

I have the pump motor pump motor 2.jpg

which, I believe is non reversible. How do I quickly ascertain which is the positive terminal and which is the negative. I don't want to let the smoke out of this thing trying to figure out which way it turns.

Then I have the drive motor. Drive motor 2.jpg

I know that you jump two leads front to back and (I believe) diagonal but, much like the pump motor, I don't know which are the hot leads and which are the negative. Do I reverse the rotation by changing the orientation of the jumper?


I had expected to figure all of this out while disassembling the fork lift but I ended up getting these already removed.

Is there a good book - resource I could use for reducing the number of stupid questions I need to ask. I started on the "Choosing" sticky but that's a lot of pages to muddle through.

Thanks in advance.
 

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So far, that stickie has been my best source for information. Read through it by searching the thread for what you want using the search bar. As for your question, considering if it is series wound, you will have 2 terminals at the armature (A1/A2) and 2 terminals going to the field (S1/S2 or F1/F2). Wire A2 to S1 and then A1(+) and S2(-). A2 to S2 with A1(+) and S1(-) will give the reverse.
 

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On unidirectional series motors the field is internally connected in series with the armature (thru the brushes). So you essentially have one each, A and S terminal. It is irrelevant which polarity of source is connected to which terminal. Rotation will remain the same.
To reverse rotation direction on a series motor one must reverse polarity of either the field or armature, but not both. That's why both field terminals (S1 & S2) and both armature terminals (A1 & A2) are made available. Overall source polarity is irrelevant, just the polarity of the armature relative to the field.
This is basic DC motor theory stuff. Try to find a tutorial site or textbook on the subject.
Regards,
major
 

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Discussion Starter · #4 · (Edited)
Thanks .. . . It has been a long time since I've dealt with anything that isn't plug and play.

I think I'll holler at the fellow that runs the dc motor repair place north of me (I live in the boonies, the closest semi civilization is 80 miles north) and ask him if he can recommend a title.

"DC motors for Dummies"
or maybe
"How to F&$% with a fork lift motor and not burn your shop down"

I found a small article that says I can reverse the pump motor - I just have to open it up and reverse the field internally. Hopefully it will turn the way I need and I won't have to get into it.
 
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