The main purpose of using pulleys for lifting pulleys is to thread steel wire ropes, change the direction of movement of steel wire ropes, and achieve the goal of saving effort.

According to their different functions, pulleys can be divided into fixed pulleys, movable pulleys, pulley groups, guide pulleys, etc. In lifting operations, if only fixed pulleys are used, the direction of force can only be changed and cannot achieve labor-saving effects. Although only movable pulleys can achieve labor-saving effects, they cannot change the direction of force and also require labor-saving. Therefore, fixed pulleys and movable pulleys must be connected together to form a pulley group to meet the requirements of lifting and transportation operations.

According to their materials, pulleys are divided into cast iron pulleys, cast steel pulleys, nylon pulleys, and aluminum alloy pulleys. Cast iron pulleys are further divided into gray cast iron pulleys and ductile iron pulleys. Gray cast iron pulleys have good processability and minimal wear on steel wire ropes, but are prone to breakage of wheel rims and have a very short lifespan. They are mostly used in lower working levels; Ductile iron pulleys have higher strength and impact toughness than gray cast iron pulleys, so they can be used in cranes with higher working levels. Cast steel pulleys have higher strength and impact toughness, but slightly poorer processability. Due to their harder surface, they wear steel wire ropes severely and are mostly used in working conditions with higher working levels. Large sized pulleys often use welded pulleys, which are roughly the same as cast steel pulleys but lighter in weight, some can be reduced to about a quarter.