Pulleys

images3.wikia. nocookie.net/ __cb20120908072020/ runescape/ images/e/e3/ Lumbridge_ Flag_Raise.gif

A pulley is a wheel (usually with a grooved rim) which is used to transfer force or speed or to turn another wheel. Pulleys connected in pairs by a looped belt can be used in a similar fashion to gears.

A rope connected to a load can be pass through one or more pulleys to to move the load from the other end. Using a single pulley changes the direction of the force. Using multiple pulleys makes it easier to move the load (in addition to possibly changing the direction). This happens because more rope must be pulled in order to move the load the same distance. The more pulleys used, the easier it is to move, but the more rope that must be pulled to move the load the same distance.

coolclips.com/ AGifm/ tf05192/ CoolClips_ wb022647.gif

This video is about using pulleys to make it easier to move the load.

Click on the player to watch.

http://www.youtube.com/c92DaO9e_l4




Facts about belted pulleys:

www.bbc.co.uk/ schools/ gcsebitesize/ design/ graphics/ mechanismfinish printrev6.shtml

Two pulleys connected by an uncrossed belt turn in the same direction.

www.bbc.co.uk/ schools/ gcsebitesize/ design/ graphics/ mechanismfinish printrev6.shtml

Two pulleys connected by a crossed belt turn in opposite directions.






www.osha.gov/ SLTC/ etools/ machineguarding/ images/ pulley.gif

When two pulleys of the same size are connected by a belt, they turn at the same speed.

www.kanabco.com/ vms/Media/ mill_machine/ pulley1.gif

When two pulleys of different size are connected by a belt, the smaller one turns faster and the larger one turns slower.



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