As the title says, I need to find an external rotor motor, preferably working at 480 VAC. Desired rpm would about 450, or 900 tops. Power of between 5 and 7 HP. The thing is that it has to be heavy duty, and able to sustain some impact (it's not for a vehicle application), or at least able to be mounted on heavy duty ball bearings that will withstand the harsh treatment. Max outside diameter would be about 16 inches, and the minimum desirable inside diameter about 8 inches.

I've already found a couple of suppliers, but they're focused on the automotive industry, and I'm not sure if such motors would be able to comply with the harsh requirements.

Here's looking at you, @MaxHeadRoom

 

If you mean an Out-runner style, the only one I am currently aware of is the Fischer-Paykel used in modern washing machines.
Max.

 

If you mean an Out-runner style, the only one I am currently aware of is the Fischer-Paykel used in modern washing machines.
Max.

I'm afraid that won't do ... I need a high-torque, heavy duty, low rpm motor ... and I don't feel like designing my own, that would take years!

Here's what I found so far:

https://fischer-elektromotoren.eu/torque-motors-outer-rotor/

These guys seem to have something similar to what I want. But I'm not sure about the heavy-duty requirement ... guess I'm gonna have to ask and find out.

 

I've just found the motors you mentioned. They seem interesting, but way too small. The most powerful motor they list has about 0.85 HP. I wonder if they could be stacked and synced to increase the total output power?

https://www.fisherpaykeltechnologies.com/products/direct-drive-motors/

 

As a last resort, you might consider a planetary gear reduction for a higher RPM motor.

I can't think of where you might find one that size. Maybe in an industrial drive or drilling application.

 

As a last resort, you might consider a planetary gear reduction for a higher RPM motor.

I can't think of where you might find one that size. Maybe in an industrial drive or drilling application.

View attachment 177442

Yeah, of course I considered a planetary gear. But this is for a continuous heavy duty application and I've seen how gears age quickly and wear out. Besides, weight and noise are also a problem.

 

Is it possible to manufacture with a normal 3ph motor and attach a outer flywheel to the normal shaft.
Start it up in Star-Delta.
Max.

 

Is it possible to manufacture with a normal 3ph motor and attach a outer flywheel to the normal shaft.
Start it up in Star-Delta.
Max.

The thing is that the motor has to be hollow. I plan to run a stationary shaft through it, and the motor would be traveling back and forth as it does its job.

 

I see what you mean about gear wear and noise but this has been rolling around in my head since my last post.

An 8" diameter ID and a 16" OD leaves room for a lot of 4" diameter motors driving an internal or external ring gear. Bearings for the ring gear could be mounted on the motor shafts at their pillow blocks.

 

To get rid of the gears, you could replace them with rubber wheels but then you are relying on friction.

 

To get rid of the gears, you could replace them with rubber wheels but then you are relying on friction.

Yes, but like I said, this is for a heavy duty application. I'm talking about a power of approximately 5 HP ... Right now I'm considering sync belts and pulleys.

 

All of your requirements kind of suggest a hydraulic motor.They are low speed and powerful. Getting an electric motor to run that slow means the use of gear reduction. There are hydraulic motors in some big earth moving equipment, industrial 4X4's and some fork lifts use them too.

 

All of your requirements kind of suggest a hydraulic motor.They are low speed and powerful. Getting an electric motor to run that slow means the use of gear reduction. There are hydraulic motors in some big earth moving equipment, industrial 4X4's and some fork lifts use them too.

Yes, hydraulic motors have been on the table from the very beginning. It's just that I'm trying to consider all the options before I make a decision.

 

outer rotor motors are still produced even in the larger sizes, but they are not used in very many places, and so they are seldom advertised, and never to the general public. I suggest starting by asking the Baldor applications people about what they can provide, since I don't recall the name of a company who had the add that I saw. Also try Marathon motors. and you are searching in the category of Integral Horsepower Motors, IHP for short.