What is the pulley?
by Hi-Tech on Jul.10, 2010, under Mechanics
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. Maybe most of you are not familiar with it, but it is a very important mechanical part. There is usually a rope, cable, belt, or chain runs over the wheel and inside the groove if present.
What are the pulleys used for? Generally, they are used to change the direction of an applied force, transmit rotational motion, or realize a mechanical advantage in either a linear or rotational system of motion. They can be used in ships, cars, and many other places.
Now, I’d like to introduce a basic usage of pulleys. Most of you know something about cars, but are you knowledgeable about car components? I think few of you can nod your head. Among various components, pulleys can be applied to improve the efficiency of performance. But how do pulleys work? Most of you know the importance of the engine. In a car, the engine may provide more power than just the wheels. Therefore, it is very necessary to improve the working efficiency of the engine. Doing this requires the usage of pulleys. For example, the engine works with the help of a belt and pulley system. Besides, when you wish to do up your car, you should learn something about engine pulleys. This kind of pulleys may sound unfamiliar to most of people. The engine has several belts that drive various parts of the engine, while belts need pulleys so that they can be held in place and drive the parts of the engine properly.
Two or more pulleys together are called a block and tackle. It is also call the rope and pulley systems. The simplest theory of operation for a pulley system assumes that the pulleys and lines are weightless, and that there is no energy loss due to friction. It is also assumed that the lines do not stretch.
Although the above analysis is not complete enough for you to know well about pulleys, you can still learn the basic information about it. I think it will be of some help for you to bear this information in mind.
Article Source: http://EzineArticles.com/?expert=Ling_Lois
