Will someone explain gearing and motors for me?

[Carefree_Dude]

I'd like to build a small steam engine using power functions and the M or E motors. The XL is far too big. I'm concerned about having improper gearing and burning out the motor though. How do you know if you geared things properly?

[andythenorth]

How do you know if you geared things properly?

Your engine will go too fast or too slow :)

Primarily, in this context gearing affects speed. It also affects torque, but that's usually limited by traction / adhesion. You get more adhesion if your motor drives a lot of wheels and/or you have a high adhesive weight over the driven wheels.

The most likely cause for burning a motor out is running it near-stall speed for long periods. The only way to have that happen in a train is to have an awful lot of adhesion, I reckon you'll see slip before then. But PF motors have stall protection anyway (far as I know)

I have one XL motor driving this truck. http://www.brickshelf.com/cgi-bin/gallery.cgi?i=3053953

The wheels have a lot of grip and the motor will stall before the wheels slip (if driven against a fixed obstacle for example). The stall protection eventually kicks in on the motor (probably not something to test too often

I could probably be more accurate on the physics, but the above is a good basic rule of thumb for MOCS.

Edited August 24, 2010 by andythenorth

[Jurgen Krooshoop]

Sariel has made an excellent tutorial on LEGO gears. A definite "must-read" for everyone starting to use Lego-gears.

You can find this tutorial here or download it as PDF here.

Edited August 24, 2010 by Jurgen Krooshoop

[La Petite Brique]

Thanks for the links ! Very useful.

[Carefree_Dude]

Sariel has made an excellent tutorial on LEGO gears. A definite "must-read" for everyone starting to use Lego-gears.

You can find this tutorial here or download it as PDF here.

Very helpful information, thanks