Thames & Kosmos Geared-Up Gadgets handleiding

Niet gecategoriseerd

Thames & Kosmos

28 pagina's

PDF beschikbaar

Handleiding

Geared-Up Gadgets

› › › CHECK IT OUT

››› Hold two of the gear wheels together, so that the

cogs on the edges (the “teeth”) interlock. Turn one

of the wheels. The other wheel will turn as well,

automatically moving along with the first gear. This

demonstrates that interlocking gear wheels can

transmit a rotational movement.

Pay close attention to the direction of rotation: The

second wheel turns differently than the first one.

When the gear wheels

have different diameters

and, as a result, a

different number of

teeth, their rotational

speeds will also be different. The larger wheel turns

slower than the smaller one.

This shows that gear wheels can be used to convert

a slow rotational movement into a faster rotational

movement and vice versa. For example, if the larger

gear wheel has 40 teeth and the smaller wheel has

10, the smaller wheel will complete 4 rotations in the

time it takes the larger wheel to do one rotation. This

relationship between the input speed and the output

speed is known as the gear ratio. In this case, the ratio

is 1:4.

››› Use your other hand to slow down the second gear

wheel while you turn the first wheel. You will notice

that you need to apply a lot of force. This shows that

interlocking gear wheels also transmit force.

Two gear wheels on parallel shafts are known as spur

gears. If you want to transmit a rotational movement to

an axle standing perpendicular to the gear wheel, you

can use a bevel gear (you’ll use two of those for your

helicopter model). It’s also possible to arrange multiple

gear wheels one after the other to convert a slow

rotational movement into one or multiple very quick

rotational movements — as you’ll see when making the

hand mixer model.

Gear trains can be found inside many machines and

devices. For example, in mechanical clocks, the kind

you might see in a museum, gear wheels enable the

movement of a gear wheel propelled by a spring or

weights to be transmitted to the hands of the clock

Thanks to the different gear ratios, the hands can move

quickly (the second hand), slowly (the minute hand), or

even slower (the hour hand).

This means that you can usually choose between

multiple “gears,” that is, you can switch between

various different gear ratios.

This has a significant advantage, as gear trains don’t

just transmit rotational speeds, they also transmit

force. Cycling is easiest when you can keep pedaling at

the same speed. If you want to cycle over flat terrain

or downhill, you can switch into a high gear in the rear.

This connects the crankset with a much smaller gear on

the rear wheel. The force from the pedals is converted

into a much greater driving force making the bike move

faster.

If you’re cycling uphill, you can switch to a large gear

in the rear and a small gear in front. This allows you

to apply a smaller force on the pedals and turn them

at a faster rate but the rear wheel will rotate a larger

amount.

Before building any of the models,

you should carry out the following

little experiment.

››› In the field of engineering, two or more

interconnected gear wheels are called a

gear train, or transmission. They come in

many different shapes and sizes.

››› Bicycles generally have a chain drive,

in which gear wheels of various sizes are

connected by a chain.

Bekijk gratis de handleiding van Thames & Kosmos Geared-Up Gadgets, stel vragen en lees de antwoorden op veelvoorkomende problemen, of gebruik onze assistent om sneller informatie in de handleiding te vinden of uitleg te krijgen over specifieke functies.