low rpm gear drives

i am interested to find low rpm gear drives something in the range of 12 to 28 rpm . 12 24 or 115 volts but perfer 12 dc

Got to provide a little more information, Scale? Make? Engine? and also what you are trying to acheive.

If you’re looking for a low RPM output gearhead motor, check

http://www.allelectronics.com

between north west short line and allelectronics i still cannot find what i’m looking for.
the gear drive is not for any scale or engine-- i’m using them to drive conveyors and snake lines on my logging modules., and other slow moving items

Take a look at these:
http://www.allelectronics.com/cgi-bin/category.cgi?category=400400&item=DCM-245&type=store

Run this one at 6 volts, and it will give you around 20 rpm.
http://www.allelectronics.com/cgi-bin/category.cgi?category=400400&item=DCM-171&type=store

http://www.allelectronics.com/cgi-bin/category.cgi?category=400500&item=ACM-105&type=store

Run this one at 4 volts, and it will give you around 20 rpm.
http://www.allelectronics.com/cgi-bin/category.cgi?category=400200&item=DCM-220&type=store

Try Jameco Electronics at www.jameco.com. They list gearhead motors in 12 and 24 VDC.