The Unofficial LEGO MINDSTORMS NXT Inventor's Guide

BUILDING WITH GEARS 63

The worm gear has only one tooth.

If you twist or rotate the worm gear’s axle, how fast

does the 24t gear revolve? Very slowly. In fact, you’ll

find that for every complete rotation of the axle, the

worm gear turns only one tooth on the 24t gear. The

gear ratio is 24:1, so for every twenty-four rotations

of the worm gear, the 24t gear rotates only once. This

increases torque dramatically, but it also reduces speed

dramatically. As a general rule, gear trains that use

worm gears are slow but powerful.

The worm gear must always be the driver gear.

Try to turn the 24t gear, using it as the driver gear.

You’ll quickly see t