# Choosing an electric motor

1. Jul 28, 2012

### ENgez

Hello,
I am designing a helicopter winch (basically, a drum to spool and retrieve a cable), and need to select a DC electric motor from some catalog.

This motor needs to fit inside an cylinder of radius 165 mm and height of 200 cm or less. it has to be a Permanent Magnet (PM) engine. and needs to be able to spin CW and CCW.

As the winch drum spins at 60 RPM, preferably i would like a motor which could get me close (although those i found give about 2000 RPM at minimum), making the transmission simpler to design.

I come from a mechanical engineering background, so my knowledge about where to look up these engines is limited and so are my results in finding good catalogs. any help would be greatly appreciated.

thank you.

2. Jul 29, 2012

### jim hardy

that's big, ~13 inch diameter by 6$1/2$ feet long?

you haven't said what kind of power or torque you need. What does it lift?

And why permanent magnet?

http://lancet.mit.edu/motors/index.html

google search on this phrase
"dc motor catalog"
showed a long list of manufactureres
but you're right it's hard to find an online catalog with details.

changing search to this phrase narrowed it down a bit
"dc planetary gearmotor catalog"

these guys looked interesting
http://www.dumoremotors.com/planetary-gear-motors.html

Last edited: Jul 29, 2012
3. Jul 29, 2012

### ENgez

it needs to lift 1300 kilograms. and the diameter of the drum is 330 milimeters. and from what i gathered permanemt magnet is the engine of choice for winches, due to good dynamic properties.

4. Jul 29, 2012

### jim hardy

check if my arithmetic's right here?
that's going to be about 1550 ft-lbs of torque after your reduction gears?
i think you said drum runs at 60 rpm, which at that torque is = ~18 hp?

so you need a 20-25 hp motor about 6 inch diameter..... sounds like a job for planetary gears.

really you're in mechanical design territory where i am not qualified to offer advice.
But maybe above will help you describe your need to a manufacturer's sales engineer??