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Discussion Starter #1
I recently bought an air compressor from an auction and noticed that it's turning the pump the wrong way. The pump has an arrow on the pulley that points counter clock wise, and the motor is turning it clockwise. It still pumps air, but I imagine it would be much more efficient if it was pumping the right way.

So my question is can you reverse a motor? I know some can. It's a century 1.5 hp.

Thanks - Doug
 

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Discussion Starter #4 (Edited)
Sorry AC single phase 220

Edit, more Info:

I replaced the wire that went from air manifold to the motor. That was just two wires for each leg of the 220 and I thought I screwed it up, so I swapped sides and that didn't help. I didn't think it would, but I tried anyways. There are a couple of wires on the motor that look like they can be arranged differently. I looked for a website for century motors but couldn't find one.
 

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It probably has the capacitor startor on it right? If so take the cover off and on the inside there maybe something that says switch wire such and such with such and such for reversing. I have seen ac single phase motors with this info on them you just have to look very closely to it and you will find it.
 

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if you don't find it under the cap cover or on the wiring end cover take the numbers off of it and talk to the local rewinding shop or motor sales. They should have a catalog that will give them info on the motor if it can be reversed or not.
 

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as jeep 2.5 said, it's all about the starter. The true AC just jeeps it turning, you have to have a capacitive starter or DC starter to get it going. The directiong that starts it in determines which way it continues to spin in. You should be able to reverse the starter by changing the starting direction. (ie switch a wire as per instructions)
 

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Discussion Starter #8
thanks for the help, I'll get the model # this weekend and see if I can't find a diagram. If not i'll ask a shop which wire to switch or what needs to be done.

Thanks - Doug
 

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I think you dug too deep. Normally the wiring diagram is on the backside of the small-flat-coverplate of the endcap. Might also be useful to see the last picture except outside looking in. Some motors are "non-reversing", just meaning that they don't provide an easy way to change the direction ... but all motors can be changed if you get a bit creative.

Here's a website that might be useful, you have a "capacitor-start/capacitor-run" type motor:
http://www.lmphotonics.com/single_phase_m.htm

So to reverse the motor direction you'll need to find which wires go to one of the windings, then just swap that pair of wires. If you accidentally swap one wire from each winding then it will just run in the same direction again.

(edit) Forgot to add, if it's a single stage pump the direction won't matter except for the oil slinger (if it's an oil bath type). For a two-stage it will make a difference.

CP
 

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Discussion Starter #11
It is a single stage pump, but for the couple of minutes it has been on it has gotten pretty hot.

So basically all I need to do is find one of windings wires and swap them like below? Thanks for the help - Doug

 

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Or here, Or even there.



Once you get two wires pulled you can use an ohm meter to check if they both go to the same winding. Both should have infinite (or really high) resistance to all other connections in the motor. If you have one wire from each winding, then they will both have low resistance (near zero ohms) to all other connections in the motor.

CP
 

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Discussion Starter #13
So I went up to the ranch this weekend where the shop is and started looking the motor over. I figured out which two wires to switch and then was putting the wiring plate back on and decided to look at it again. It has to large diagrams that take up the whole thing about how to wire it for different voltages. I'm about to put it on and notice in very small letters at the bottom it says to switch the red and black wires to reverse the motor!!

I was like son of a bitch, I should have read the small print!! So I reversed what I had done internally and did it the way it said too.

Thanks for all the help!!
 
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