Page 306 - The Lost Ways

In a sawmill case, there is no need for the force that the water wheel produces to change
direction, but there is a need for a large change in speed. This is why two stages of gear

reductions might be used.

In order to do this, two more gears are needed. These go on an intermediate axle,
between the drive gear and the driven gear. Doing this ensures that the two gears on that
axle are rotating at the same speed. If the driven gear on that axle is small and the drive
gear is large, as in the previous image, we end up with two stages of speed increase. If we
assume that the gears in the diagram have the same number of teeth as the diagram
above, then we are going to have a doubling of the doubling of the original speed, or

we’re going to have the final speed as four times the original.
Belts

There’s another mechanical device that was used in these old mills, especially in sawmills,
and that was the drive belt. Your car has a drive belt in it, which we refer to as a serpentine
belt. It takes the power that the engine produces and uses part of that to drive the

alternator, water pump, air conditioning compressor, and power steering pump.

The reason belts are used is that they allow for the transmission of mechanical energy
from one point to another without altering that energy in any way. Assuming that the
pulleys are the same size at both ends, the speed, force, and direction of movement stays
the same, even when transmitted over long distances.

Today’s belts are made of rubber and reinforced with nylon strands. This provides a very

strong, flexible belt that won’t break easily. However, before the Industrial Revolution,

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