PULLEYS

 

A pulley is a simple machine made with a rope, belt or chain wrapped around a grooved wheel. A pulley works two ways. It can change the direction of a force or it can change the amount of force. A fixed pulley changes the direction of the applied force.  A movable pulley is attached to the object you are moving.

IMA:  Ideal mechanical advantage (Friction losses are ignored.)

AMA:  Actual mechanical advantage (Friction losses are not ignored.)

Single fixed pulley:

It has a fixed axle. Its axle is fixed or anchored in place. A fixed pulley is used to redirect the force in a rope.

Load = 60 N
Effort Force = 60 N
IMA = 1

Single movable pulley

It has a free axle. Its axle is free to move in space. A movable pulley is used to transform forces.  If one end of the rope is anchored, pulling on the other end of the rope will apply a doubled force to the object attached to the pulley.

Load = 60 N
Effort Force = 30 N
IMA = 2
Compound pulleys:

Compound pulley is a combination fixed and movable pulley system.  It has a block and tackle in a compound pulley where several pulleys are mounted on each axle.  This will increase the mechanical advantage.  Compound pulleys are given below:
 

Compound pulley

Load = 60 N
Effort Force = 30 N
IMA = 2

Compound pulley

Load = 60 N
Effort Force = 30 N
IMA = 2

Load = 60 N
Effort Force = 15 N
IMA = 4

 

Load = 60 N
Effort Force = 10 N
IMA = 6
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