Previous in Forum: What is an XOX Type Bolt?   Next in Forum: Gulf Oil Leak?
Close
Close
Close
2 comments
Rate Comments: Nested
Anonymous Poster

Torque and Small Motors

06/17/2010 10:17 AM

By training, I'm an EE. It's been years since I had the one Dynamics course in school. But somehow I got suckered into measuring the torque of the small shaded pole motors that we use in our appliances. I also managed to inherit some equipment from the previous holder of my position.

So, what I have is a hysteresis brake. It can load a motor with up to 40 oz-in. of torque load. Apparently, my predecessor used to load motors with this brake, measure the input power (electrical, for efficiency calculation)and the speed (for power out, mechanical) at a given torque load. When the motor was loaded so much that it stalled, he called that the stall torque. He left no notes as to why he was measuring this way or any other information, just lots of measurement logs.

My question is: what is the correct method to measure torque on a small motor? In searching the web, I've seen torque transducers that bolt on between the brake and the motor. What's the correct way to use such a transducer? Any and all info on the subject would be greatly appreciated.

Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: Torque and Small Motors

06/17/2010 9:42 PM

My question is, are your motor performance specs based on his testing? It may not matter what the correct way to measure torque is if these figures are published.

I'm surprised that there no test procedures.

Your turn.

Reply
Anonymous Poster
#2
In reply to #1

Re: Torque and Small Motors

06/18/2010 7:42 AM

Small but growing company. Hence, no written procedures.

We sell kitchen appliances. The need to accurately measure the torque has only come up recently. As prices for goods from China have crept upward and product margins have constricted, we've started cutting costs by tightening specs such as motor torque. In years past, we had simply over-spec'd the torque so that there was little concern. Our latest product has some issues because the motor stalls if you sneeze at it.

My fundamental issue is trying to confirm measurements made at the factory in China. The motor manufacturer has a full blown test rig. I've seen pictures and charts from this rig, but I've never seen it in person, and it's not likely that I will either. To buy such a rig here in the States would cost $20-30K and the owners are unwilling to put that out at this time. So now I'm looking a putting something together. I think having the hysteresis brake is a start, but from what I've been able to gather around the web, some sort of torque transducer is in order.

Reply
Reply to Forum Thread 2 comments

Previous in Forum: What is an XOX Type Bolt?   Next in Forum: Gulf Oil Leak?

Advertisement