Gears are wheels with teeth on them. The teeth, or cogs, of one gear mesh with
the teeth of another gear to transmit force between them. A combination of two
or more gears is called a transmission, or gear train. You can see transmissions with
meshing gears inside old toys or old clocks. Gearboxes can be found inside the trans-
mission system of cars, which combine meshing gears of different sizes. This allows
the car’s driver to easily change between different speeds.
Do you know how gears work? You can learn how gears work and why they are useful
by reading this manual and building the models in this kit that use gears. The building
blocks in this kit were designed based on the number ten and its multiples, including
the size of the components, the distance between the holes, or the unique gears.
This makes it easy to both assemble the gears and also conveniently calculate the
gear ratio or change the rotary speed. Different from other gear designs that use the
number seven or eight as their fundamental number, these gears were created to
be perfect for teaching science to kids because they are easy to assemble and they
make it easy to calculate gear ratios (explained below).
We recommend a gradual learning process using these gears, which begins with very
basic assemblies to understand how each of the components fit together. After you
build all of the models in this instruction book and understand how to use gear trains,
you can put your unlimited creativity to work and design vehicles and machines on
your own. Let your imagination guide you!
Now let’s look closely at gears and how we use them. Find the gears in this kit. The
wheels which have many tooth-shaped objects sticking out of their edges are gears.
Two gears can mesh with each other using the teeth on the edges. When one gear
rotates, the other one will be driven to rotate as well. The intermeshing teeth of the
two gears transmit torque (turning force) and rotation.
The big gear has more teeth than the small gear. Despite the number of teeth or the
size of the gears, all of the teeth on all of the gears in the same gear system must all
be the same size. In simple gear trains, the driver and driven gears will rotate in oppo-
site directions. When a third gear is inserted between the driver gear and driven gear,
and makes them rotate in the same direction, it is called an idler gear.
The gears in this gear system come in five different types: 20T, 40T, 60T, 80T, and
160T, the extra large gears.
The gear set contains both spur and bevel gears. This kit contains “spur gears,”
which mesh in the same plane and regulate the speed or the turning direction of the
shafts, and “bevel gears” (the beveled edges of the gears) which mesh together at
right angles to the initial turning plane of the gears and shafts to change the plane
of rotation.
6
REMOTE-CONTROL MACHINES
|
About the Gears
Fig. 7 The intermeshing of gears can
effectively transmit force to cause
rotation. The red circle represents the
actual diameter of the transmission,
which is called the pitch diameter. The
special shape of the teeth allows for
smooth intermeshing and transmits
power along the pitch.
Fig. 8 Gear ratio calculation
Fig. 9 Gears
160T Gear is not
included in this kit.
GEAR
40 teeth
driven gear
20 teeth
driver gear
40
20
2
1 ( 2:1 )
Velocity
ratio
Tooth number of the driven gear
Tooth number of the driver gear
=
=
=
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