If you decrease the size of the driven pulley the fan will turn faster.
You can achieve the same effect by increasing the size of the drive pulley.
calculate speed drive pulley.
Use an easy-out of harder metal after drilling a small hole with harder metal.
Fixed Pulley and Compound Pulley.
there are many advantages of pulley and they are it change the direction of force
yes
your questoin is not specific, there are many pulley's
depending on the pulley, you must remove the belt and the bolts holding the pulley in place. some cars have pulleys that are harder to remove and have what is called a torx nut. this requires a special socket. it is easy to remove a pulley if you start with the belt on so it doesnt move
it is time to change bearing on that pulley
Snub pulleys are used to increase the angle of wrap of the driver pulley or and to change the direction of belt(deflector pulley)
Are you talking about the "idler pulley"? They are quite simple to change. Loosen the serpentine belt by using a socket on the center of the tensioner pulley, slide the belt off the idler pulley, use a socket to pull the center bolt of the idler pulley and replace the pulley with a new one.
can change a direction of a force
a pulley