TYPES OF 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.  Effort force here is the tension in the rope when the speed of the pulley is zero or constant.  Tension in the rope is the same at every point in the rope in case the friction is ignored.

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

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

Types of pulleys are given below:

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