Lego Fairground Gears Page 2
Workshop Programme Teachers' Notes
Fairground Gears
...Gears cont.
Gear wheels are wheels with teeth around
the edge. When two or more gear wheels
mesh they have the effect of transmitting
circular movement and power. They can
change the direction of movement and make
things move at a slower or faster pace.
Two gear wheels work together when the
teeth of the first gear wheel mesh with,
and turn the teeth of the second. When
this happens the gear wheels rotate in
opposite directions.
When three gear wheels mesh, the first
and third gear wheels will turn in the
same direction, but the one in the middle
will turn in the opposite direction.
In most cases, the larger the gear wheel
is, the more teeth it has. Gear wheels of
the same size and with the same number
of teeth will turn at the same speed.
A large gear wheel driving a small gear wheel
(the follower) will make the smaller one turn
faster. This is called gearing up and is
common in bicycles and drills.
When a small gear wheel drives a large
follower, the larger one will turn slower.
This is called gearing down. This principle is
best known in windmills and watermills as
well as in winches.
