What is a pulley and gear ?

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lilyqianweiku
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Joined: Mon Aug 15, 2011 3:55 pm

What is a pulley and gear ?

Post by lilyqianweiku »

They are quite useful in our daily life as well as in many different industries. They both have a wide range of applications. Therefore, it is quite necessary to have a basic idea about them.

First of all, we should know the definition of these important things. What is a pulley? A pulley, also called a sheave or a drum, is a mechanism composed of a wheel on an axle or shaft that may have a groove between two flanges around its circumference. There is usually a rope, cable, belt, or chain runs over the wheel and inside the groove if present.

It has many advantages. It can be the force needed to move an object. A pulley is made from a wheel and a rope. It is used to make lifting easier. A single pulley changes the direction of the lifting force. For example, if you are lifting a heavy object with a single pulley anchored to the ceiling, you can pull down on the rope to lift the object instead of pushing up. The same amount of effort is needed as without a pulley, but it feels easier because you are pulling down. But things will be very different if you fix one end of rope and use two pulleys. If you add a second pulley, the amount of effort to lift the heavy object is much less-with half the load on the rope ignoring the friction. Except for this, pulleys have many other important applications. They can be used in cranes, sailing ships, and an elevator's cable, etc.

Then let us see something about the gear. The same question comes again. What is a gear? A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. It also has many advantages. It can be used to slow things down, change direction, speed things up and so on. In order to have gears meshed, they must have teeth of the same size and design. Meshed gears have at least one pair of teeth engaged at all times. They will rotate in opposite directions. Gears have a wide range of applications. They are applied in bicycles, cars, non-digital clocks and watches, etc. There are also many types of gears which have different functions.

All in all, the above mentioned mechanical components, i.e. pulleys and gears, are both necessary in this society. Therefore, learning something about them is becoming very necessary, too.
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