Pulley group is an important part of the lifting machinery. It can save labor and change the direction of force action.
The pulleys are divided into cast iron pulley, cast steel pulley, nylon pulley and aluminum alloy pulley according to their materials.

The cast iron pulley is further divided into gray cast iron pulley and ductile iron pulley. The gray cast iron pulley has good process performance, small wear on the steel wire rope. But easy to break the drum, and the life is extremely short, which is mostly used in the lower working grade. The ductile iron pulley has higher strength and impact toughness than the gray cast iron pulley. So it can be used for high working grade cranes.

Cast steel pulleys have higher strength and impact toughness, but the process is slightly worse. Due to the hard surface, the wire rope is seriously worn. Large-size pulleys are mostly welded pulleys. These pulleys are roughly the same as cast steel pulleys, but they are light in weight and can be reduced to about a quarter. At present, nylon pulley and aluminum alloy pulleys have been widely used on cranes. The nylon pulleys are light and wear-resistant, but the rigidity is low; the aluminum alloy pulleys have low hardness and wear on the steel wire ropes.

The diameter of the pulley group has a direct effect on the service life of the wire rope. When the wire rope passes through the pulley one time, it must be bent one time, so that repeated bending repeatedly is one of the important reasons for the damage of the wire rope.

1. The pulley in normal operation can be rotated flexibly by hand, and the lateral swing shall not exceed D0/1000 (D0 is the nominal diameter of the pulley).
2. The chip, dust and other stolen goods of grease groove and oil hole on the shaft must be cleared up, oil hole and bearing spacing sleeve on the oil groove shall be aligned.
3. When there is a crack on the pulley, it should be scrapped and welding repair is not allowed.
4. The radial wear of the pulley groove shall not exceed 30% of the rope diameter. Pulleygroove wall wear should not exceed the original wall thickness of 30%.Shaft hole inside defect area should not be more than 0.25 c㎡, depth of no more than 4 mm.

1. Clean and check the condition of wear and tear of pulley, Pulley should be changed in time if it exceed discard standard.
2. Cast steel pulley can be welded and remade. If the cast iron pulley is cracked or broken, welding is not allowed; it should be scrapped and replaced.
3. The oil hole and lubricating oil groove of the pulley shaft shall be cleaned, and the bearing, spacer sleeve and expanding ring shall be cleaned and installed

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