Page 43 - The Unofficial Guide to Lego Mindstorms Robots

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3. You can use gears to transfer motion from one axis to another. The gears in Hank's body transfer motion from the motors to
the drive axles of the treads, as shown in Figure 2-13.

Figure 2-13.
Using gears to transfer motion

The Palette of LEGO Gears

L EGO offers an impressive array of gears. The LEGO community has adopted names for these gears, which I will use
o
th ughout this book. Refer back to Figure 2-3; it shows the gears that come with RIS and their names. For the most part, gears
r
ar e named based on the number of teeth they have. The 40t gear, for example, has 40 teeth. The number of teeth is directly
proportional to the gear's radius, so the 24t gear has a radius exactly three times as large as the 8t gear.

S pecialty Gears

You're probably comfortable with the 8t, 16t, 24t, and 40t gears. They can be put together to transfer rotational motion from
o ne axis to another. In particular, these gears are used to transfer motion between parallel axes.

The gears in the bottom row of Figure 2-3 can be used to transfer motion between perpendicula r axes. Two of these are bevel
and crown gears.

The worm gear is a real character, for two reasons:

1. W hile the other gears attach firmly to the shaft, the worm gear can slide freely along the shaft. If you want it to stay in one
p lace, you'll need to anchor it down somehow.

2. The worm gear really works only one way: you drive the worm gear, and it drives another gear. There's no way to turn the
o ther gear and have it translate to motion in the worm gear.