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GEARS AND GEAR RATIOS
Gears are actually just wheels with teeth on them. The
teeth allow the wheels to mesh together and turn each
other. In other words, they allow forces to be
transmitted from one wheel to another.
The mechanical advantage of a gear is evident when a large
gear meshes with a small gear. One full turn of the large gear
will produce, say, three full turns of the small gear. Because of
this, the smaller gear always turns faster than the larger. On the
other hand, the larger gear turns with greater force than the
smaller one. So, in this way, gears can be used to make slow
turning motion into rapid turning motion, or to covert small
forces into large forces. Multiple gears meshing with each other
are called gear trains, or transmissions.
The levers connected to the tops of the
hydraulic cylinders help you transfer the force
from your hand to move the pistons inside the
cylinders. Levers are rigid bars that pivot on a
point called the fulcrum. A weight (or load) at
one point on the bar can be moved by applying a
force (the effort) to another point on the bar. If
the distance from the fulcrum to the effort (the
effort arm) is greater than the distance from
the fulcrum to the load (the load arm), then a
smaller force can move a larger load. This is
how the lever makes work easier.
40 teeth
Driver gear
Velocity
Your claw machine has a gear train
controlling the left-right motion of the
arm. The gear connected to the crank (or
any input force) is called the driver gear.
The gear that is turned by the driver gear
is called the driven gear. Gears of
different sizes are used to increase or
decrease the speed or the force of rotary
motion, called torque. The relationship
between the number of teeth on meshing
gears is called the gear ratio. The gear
ratio indicates the change in speed or
torque from one gear to the other.
20 teeth
Driven gear
Number teeth driven gear
=
ratio
Number teeth driver gear
20
1
=
=
(1:2)
40
2
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