How to reverse a motor?

[Jason Rodgers]

I have an old Emerson Electric motor that I need to reverse (spin the opposite direction). The plate says:

HP: 1/4, RPM: 1725, Volts: 110, Cyc: 60, Amps: 4.8
FR: S60PR, Style: 1233 25419

From what I can tell with a bit of googling, it probably started out life as a fan motor. I found it on the sidewalk in my neighborhood, put out with a few other things with a "free" sign after an estate sale cleared out. It had a simple 2-prong power cord wired to it, and there are only two leads (black and white). Switching leads doesn't affect the direction of spin. Runs great, just the wrong direction for my needs. Can it be flipped?

[Jim McConkey]

This motor cannot be reversed. Use two gears, one on the motor, and one on the thing you want to drive. Or a twisted belt does the same thing.

[Randy Cordle]

Many fractional horsepower single phase motors can be reversed, but they are built to have the ability to easily change the rotation. Those motors which have the ability to be reversed will have a small diagram inside of the connection housing where the A.C. power lead is connected.

Fractional horsepower (and larger) 3 phase motors are reversed by swapping any two of the three power connections, but that obviously doesn't apply here. I only mention it to point out that 3 phase motors are the ONLY motors easily reversed by the input power connections.

[Jason Rodgers]

So, a "no" and a "maybe."

Jim, if I were to twist the belt, what sort of alignment and spacing do I need on the pulleys? For example, they're obviously coplanar and the belt is taught in its current setup. There is a 2" diameter pulley on the motor and a 4" on the tool.

Randy, the name and rating plate holds the only written information I can see on this motor. If I pull off an end cap, is there something I could look for in the guts?

Thanks, guys!

[Chuck Tweedy]

I repeat - mount it on the other side.

[Randy Cordle]

So, a "no" and a "maybe."

Randy, the name and rating plate holds the only written information I can see on this motor. If I pull off an end cap, is there something I could look for in the guts?

Thanks, guys!

Don't pull the entire end cap. If the motor doesn't have a removable plate where the line power connects to it then it won't have the extra termination point necessary for reversal.

[Jason Rodgers]

The only thing under the terminal plate is two posts with nuts sticking out of brown fiber material. No marks or indication even of hot and neutral. This may be the most obvious sign that it doesn't matter which way you wire it, the thing is only spinning one way.

By the way, this whole setup is for the vintage scroll saw I've cleaned up and posted in the Jam under "What's happening... July 4th." I'm not able to turn the whole motor around and keep it manageable for storage. Of course, I could find another motor, but I'm set on using what I have. I will, however, experiment with twisting the belt and orienting the motor vertically.

Thanks for the help!

[Chris Thomasi]

I assume this is an induction motor i.e. brushless? If it has two removable endcaps and they are the same dimensions, you can simply flip the rotor to reverse it. NOTE WELL : any pulleys etc that are mounted on a screw thread are right or left hand threaded so they are self tightening in normal direction of rotation, reversing may cause them to come loose!!!!
To reverse brushed motors just swap brush connections. Same warming apples re:pulleys etc.

[Jason Rodgers]

You know, I had read something about flipping the core, but didn't know if my motor was a candidate. Yes, the housing is basically three pieces: a center barrel, and two end caps that are nearly identical (except one has the terminal access), all held together with four long bolts. The shaft is not threaded, so that's not an issue. I will look into this!

[Jason Rodgers]

Well, I popped open that motor today and decided that I didn't want to muck with it. It works now, and there'd be a good chance that it wouldn't once I started digging around in there. So, I decided to try twisting the belt. Had to mount the motor at a 45 degree angle, but it works!

Thanks for the input and ideas!

[Jason Rodgers]

Update: went to an uh-MAZ-ing estate sale today and picked up another motor - GE, same specs, correct rotation - for $5. All good.

[Chuck Tweedy]

and what else did you get at the uh-MAZ-ing estate sale??