Selection and Maintenance of Crane Pulley
Nowadays, the economic development is faster and faster, which directly promotes the development of construction industry. As one of the main equipment of construction, the working strength of crane is larger and larger, under the condition of long-term and high-strength cyclic operation, it will cause damage to the crane itself and the components. Thus it requires to consider how to reduce the working strength of crane, as one of the important components of crane, the pulley must be considered when it comes to crane parts.
The main purpose of using pulley on crane is to wear around the rope, change the movement direction of rope, and achieve the purpose of saving effort. According to the differences of function, crane pulley can be divided into crown blocks, travelling block, block and tackle, guide pulley, etc. In the lifting operation, if only use crown blocks, you can only change the direction of force, can not play a role in labor saving; although the use of travelling block can play the role of labor saving, but can not change the direction of force. In order to meet the requirements of crane operation, it is necessary to connect the crown blocks and travelling block.
According to the differences of materials, crane pulley can be divided into hot rolling pulley, cast iron pulley, cast steel pulley, nylon pulley and aluminum alloy pulley. Cast iron pulley, nylon pulley and aluminum alloy pulley are suitable for the condition of small lifting capacity and low working level, while hot rolling pulley and cast steel pulley are suitable for large lifting capacity and high working level, what’s more, nylon pulley and aluminum alloy pulley are also suitable for explosion-proof crane. The choice of pulley material can be taken into account according to the lifting weight, work level, explosion-proof requirements, and so on.
In order to reduce the force on the wire rope, new rope on the pulley groove diameter should be slightly larger than the new wire rope diameter, no matter made of what kind of materials, pulley on the crane is being worn. The wear form of crane pulley is related to the behavior in service, the more frequent use, the more serious the wear. As the condition of crane pulley has a great influence on the service life of wire rope, it is necessary to carry out regular inspection of pulley, and focus of the inspection is the pulley groove wear.
The wear of crane pulley is caused by the wire rope entering the pulley, when the pulley is too narrow, it will reduce service life of wire rope, and reduce the performance of the newly installed wire rope, new steel wire rope will bear great pressure from the radial. For high performance resistance rotating wire rope, damaged pulleys are especially destructive, the pressure can cause a rope break or a change in the strand structure in a very short time, such as jump wire, rope run out, and wave deformation. The damage of high performance resistance rotating wire rope can be judged by the length difference between the core and the outer rope, according to the requirements of ISO4309, this type of damage is up to the scrap standard. The owner of crane can prevent the damage by replacing new pulley or processing the rope race. All pulleys used on crane shall be tested before install the new wire rope. As long as the surface of rope groove is smooth, and the width of rope groove is larger than the actual diameter of wire rope, no adjustment is required.