Page 27 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

8 Making Things Move

FIGURE 1-6 A bottle opener as a second class lever

Third Class Levers FIGURE 1-7 Using a ladder as a third class lever
In a third class lever, the input is
applied between the fulcrum and the
output, as shown in Figure 1-7. This is
known as a force reducer.

Why would you want a machine that
reduces force? Most of the time, it’s
used when this arrangement is the
only option available to lift or move
something, due to space or other
constraints. Although a higher force is
needed at the input, the advantage of
a third class lever is that the output
end moves faster and farther than the
input.

Your arm is a good example of a third class lever. As you can see in Figure 1-8, your
bicep muscle is attached between your upper arm near your shoulder and forearm