Alternative to break motor

[moosetracks555]

I am using a standard motor and helical bevel gearbox in a lifting application. In order to prevent the load from back driving the gearbox when it stops I am using a break motor. It all works great. I am concerned about the life of the break motor. We are using a frequency drive to bring the load to a stop before engaging the break to eliminate break pad wear. We are using a 3HP break motor from leeson, and just looking at the mechanics of their break it does not look like it was designed to engage and disengage 500 times / day. I was at six flags riding the tony hawk ride and notices they were using sew eurodirves to stop the cars, but it just looked like a standard motor and parallel shaft gearbox. Would something like a vector motor / vector drive have the ability to hold the load? Or do you have any other suggestions?

 

[BobM3]

I don't know of any motor (without a mechanical brake) that could hold the load when the motor/drive loses electrical power. Have you though about a worm gear reducer?

 

[moosetracks555]

I am not worried about falling when loosing electrical power. I am looking for something to hold it at the top. A servo motor could do this, but that would be too costly for this application.

 

[itsmoked]

Certainly a vector VFD would be able to do that. That would actually be a great choice. You may need some aux cooling if you do a lot of holding.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Just to be clear though, you must use a Closed Loop Vector motor / drive system, where you have an encoder feedback to the VFD from the motor. Sensorless Vector drives, no matter what the manufacturers claim, are NOT capable of supplying full torque at zero speed to hold a load.

Read;
faq237-1062
faq237-1063

 

[moosetracks555]

Jraef,

That is what type of vector motor/drive I was referring to. Is there a spec that shows how much torque I could expect at zero hz? They say full torque at zero hz. Is that really what they are capable of?

Thanks for the info.

 

[jraef]

Yes, they are really capable of it. But read all the info in the faqs and the above posts, as well as doing a Keyword search in here on "Hoist VFDs". There are caveats a-plenty.

Typically I don't recommend doing it for the novice VFD user, I would suggest getting someone involved who has specific experience in applying vector VFDs to hoists. A relatively minor error can result in a runaway load, something you likely want to avoid.