OVERVIEW
Nowadays, social and economic develops faster and faster, Directly accelerate the development of the industry. Lifting Crane as one of the major engineering equipment , The working duty of the crane is also growing, In long-term working high strength working terms, It will cause damage to crane and components. This trend push us to consider how to reduce the working strength of the crane.
The main purpose using pulley on crane is worn around the wire rope, changing the movement director which in the end achieve the tension relieving.
FEATURES
Based on the different functions,pulley can be devided into crown block,full block,pulley block and boom sheave.In lifting operations,if only use crown block,it will only change the moving direction of wire rope but will not save the effort.If only use full block,it will save effort but will not change the moving direction of wire rope.If we combine the crown block and full block together,it will achieve both functions for the crane.
According to different materials,pulley can be devided into cast iron pulley,cast steel pulley,nylon pulley and aluminum pulleys.More ever the cast iron pulley can also be devided into gray cast iron pulley and nodular cast iron pulley,gray cast iron pulley has a good performance,little wear of the wire rope,but its outer rim easily being damaged,so it is widely used in the light working duty cranes.Nodular cast iron pulley can bear more collide than gray cast iron pulley so it is widely used in the heavy duty cranes.
Cast steel pulley has a higher strength and toughness,but less manufacturability,cause of the hardness surface,it will cause a big wear damage to wire rope,mostly used in the heavy duty conditions.Large diameter pulley will use welding material,it is similar to cast steel pulley,but a lighter weight,some can even reduce the weight to one quarter of the cast steel type.Nylon pulley and aluminum pulleys have already been widely used on the cranes.Nylon pulley light and wearable,but low stiffness.aluminum pulleys low hardness and low wear damage to wire rope.