Old Century Repulsion start motor

Mark · Dec 10, 2008

I bought an old Wards 8" Hammer mill last spring and it came with this equally old Century 3 hp, single phase, electric motor. According to an old MW ad I read, these motors were offered with the mill. It is a big bassard!

I plugged the motor in, for the first time, today. It is wired for 110 at the present and it took right off, smooth as butter. After about 5 minutes, it made a semi "clunk" noise, slowed down quite a bit and I quickly unplugged it. No smoke, not hot...no obvious signs of self destruction. I plugged it back up and it just hums and won"t start.

I am an electric motor moron and freely admit it. Even at that.....I think these repulsion start motors have some kind of start winding/clutch gizmo that starts the motor, kicks out and then serves some other function while it runs.

Whatever....it won"t start or run now. So, would some electric motor specialist please stand up and offer a suggestion as what to look for and how to fix this beast. I don"t think it is anything major...but it could be. My intention is to change it over to 230 volts for lower amp draw, if and when I put it in service. Thanks.

buickanddeere · Dec 10, 2008

Put the main windings in series instead of in parallel for 240.
The motor starts in repulsion with induced rotor current flowing through the brushes and commutator.
At transition speed. Centrifical force lifts the brushes off the commutator and drops the shorting ring onto the commutator. The motor now runs as an "ordinary" induction motor.
The motor start direction is changed by sliding the brush holders.
Starting torque is extreme and inrush current modest. Sometimes to prevent twisting parts off or slipping belts. The brush holders are backed off from the max torque position(s) a wee bit.
An excellent motor other than the extra moving parts and less energy efficient than the newest motors.

TractormanNC · Dec 10, 2008

Biggest problem with these old motors is the moving parts as B&D said. With all the dust around a hammer mill, it will probably be gummed up. If you are comfortable doing it, take it apart carefully and clean it and oil the bearings. If not, find some OLDTIMER to help you. Don't take it to a modern electric motor shop as they will laugh at you.

2t2@IA · Dec 10, 2008

Can't really give advice except to say that those old R/I motors are some of the best ever built in my opinion (which may not be worth much). Lots of starting torque. We are still using an old 3hp to power an "inside elevator" in our old corn crib. I think others have given good advice.

Mark · Dec 10, 2008

A grateful thank you to each of you.

I hoisted the monster up on the bench and found an "old-timer"(73) who gushed when he saw it. "An old Century!"

"Yank them covers off, boy." I did. He looked and poked around a minute and said, "I think where it sat so long, when you turned it on, it dragged dirt under the brushes. Clean it and blow it out..that thing"ll run." I got a can of CRC electric motor cleaner and squirted down the brush holders and all the other stuff in that area, rotated the shaft and squirted some more. I let it sit and drain a while and plugged it in. Ahhh! What joy!

Plate says 33.6 amps on 115 volts/17.0 on 230. This sucker draws some juice!

There"s no telling how much corn "meal" it has ingested over the years, but it"s still quiet and smooth. The old feller that looked at it said the brushes still has lots of life in them. Good!

Again, thank you, one and all.

Janicholson · Dec 10, 2008

They are as simple as most generators or brushed motors. They do have a governor, not tough. JimN

Tim in OR · Dec 11, 2008

I've got an old Century 1/2 hp motor. My grandad had it first, running many things including a cement mixer. My dad had it on a grinder mounted on a 3' chunk of 18" X 24" fir timber. I rember My dad grinding on something steel, and getting the wood so hot it started on fire. As a kid it was impresive.
Now I keep it for a keepsake. The old cloth covered wire is rotted, thus making it un usable till I put a new cord on it.
Tim in OR

Old Century Repulsion start motor

Mark

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buickanddeere

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TractormanNC

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2t2@IA

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Mark

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Janicholson

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Tim in OR

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