PULLEY

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1. PULLEY

A pulley is a rope, belt, or chain wrapped around a wheel. Pulleys can be fixed or moveable.

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•THE DIAGRAMS BELOW SHOW HOW A PULLEY CAN BE COMPARED TO A LEVER.

PULLEYS ARE A TYPE OF LEVER.

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1.1 Mechanical advantage

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Is defined as the ratio of load to effort. The higher the mechanical advantage, the easier is it to lift a weight.In the example, the LOAD and the EFFORT is equal and there is no mechanical advantage

2. PULLEY SYSTEM

YOU HAVE TO CALCULATE OUTPUT RPM DRIVEN PULLEY :

DIAMETER DRIVER PULLEY X RPM DRIVER PULLEY = DIAMETER DRIVEN PULLEY X RPM DRIVEN PULLEY.

200 mm x 90 rpm = 600 mm x RPM DRIVEN PULLEY

RPM DRIVEN PULLEY = (200 x 90) / 600 = 30 rpm

Look how the driven pulley turns three times slower than the driver pulley. You can get this result:•600 mm(driven)/ 200 mm(driver)=3 Or •90rpm(driver)/ 30 rpm(driven)

2.1 Pulleys turn in the same way

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Sometimes it is necessary to reverse the rotation of the driven pulley wheel in relation to the driver pulley. This is achieved by twisting the belt as shown in the diagram above.

2.2. Reversing rotation.

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http://www.edheads.org/activities/simple-machines/frame_loader.htm

http://www.technologystudent.com.