Friday, June 21, 2013

Playing With Gears

Hello world! Hello LEGO Mindstorms NXT hobbyist! Now, We will learn about playing with gears. You might find yourself asking "Do I really need gears?" Well, the answer is yes, you do. Gears are so important for machines that they are almost their symbol: Just the sight of a gear makes you think machinery. In this posting you will enter the amazing world of gears and discover the powerful qualities they offer, transforming one force into another almost magically. We'll guide you through some new concepts~velocity, force, torque, friction~as well as some simple math to lay the foundations that will give you the most from the machinery. The concepts are not as complex as you might think. For instance, the posting will help you see the parallels between gears and simple levers.
LEGO Mindstorms NXT hobbyist, are you ready? We invite you once again to experiment with the real things. Prepare some gears, beams, and ames to replicate the simple setups of this posting. No description or explanation can replace what you learn through hands-on experience.

Counting Teeth

A single gear wheel alone is not very useful~in fact, it is not useful at all, unless you have in mind a different usage from that for which it was conceived! So, for a meaningful discussion, we need at least two gears. In Figure 2.1, you can see two very common LEGO gears: The right one is an 8t, and the left is a 24t. The most important property of a gear, as we'll explain shortly, is its teeth. Gears are classified by the number of teeth they have; the description of which is then shortened to form their name. For instance, a gear with 24 teeth becomes "a 24t gear."

Figure 2.1 8t and 24t Gears

LEGO Mindstorms NXT hobbyist, Let's go back to our example. We have two gears, an 8t and a 24t, each mounted on an axle. The two axles fit inside holes in a beam at a distance of two holes   (one empty hole in between). Now, hold the beam in one hand, and with the other hand gently turn one of the axles. The first thing you should notice is that when you turn one axle, the other turns too. The gears are transferring motion from one axle to the other. This is their fundamental property, their very nature. The second important thing you should notice is that you are not required to apply much  strength to make them turn. Their teeth match well and there is only a small amount of friction.This is  one of the great characteristics of the LEGO TECHNIC system: Parts are designed to match  properly at standard distances. A third item of note is that the two axles turn in opposite directions: one clockwise and the other counterclockwise.

A fourth, and subtler, property you should have picked up on is that the two axles revolve at different speeds. When you turn the 8t, the 24t turns more slowly, whereas turning the 24t makes the 8t turn faster. Let's explore this in more detail.

OK, LEGO Mindstorms NXT hobbyist... do you understand about counting teeth? I hope you understand how to counting teeth, Now. after that, lets we learn about gearing up and down in the next posting. see you!

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