Pulleys and compound pulley systems

In a system of pulleys the equilibrium between the forces depends on the path that the rope follows.

PULLEYS:
FIXED PULLEY:Has an axle mounted in bearings attached to a supporting structure. A fixed pulley changes the direction of the force on a rope or belt that moves along its circumference. F = R

MOVEABLE PULLEY: Has an axle in a movable block. A single movable pulley is supported by two parts of the same rope and has a mechanical advantage of two. F= R/2