1. Scope of application
In the hoisting mechanism of the crane, the pulley plays a role of saving effort and supporting the steel wire rope and guiding it.
The pulleys of light and medium type bridge cranes can be made of grey cast iron ht15-33 and nodular cast iron qt-10.
For the pulley of the bridge crane with heavy duty type above, it can be made of cast steel ZG25 or ZG35.
For large diameter pulleys (D>800mm), carbon steel q235-a can be welded.
The diameter of pulley has a direct influence on the service life of wire rope.
Every time the wire rope passes through a pulley, it must be bent once. Such repeated bending is one of the important reasons for damage of the wire rope.
2. Safety inspection of pulley
The normal working pulley can rotate flexibly by hand, and the lateral swing shall not exceed d0/1000 (D0 is the nominal diameter of the pulley).
It is necessary to clean up the scraps, dust and other booty from the lubrication oil groove and oil hole on the shaft, and check whether the oil hole is aligned with the oil groove on the bearing spacer sleeve.
When there is a crack on the pulley, it should be scrapped and not allowed to be used by welding.
Radial wear of pulley groove shall not exceed 30% of the rope diameter.
Pulley groove wall wear should not be more than 30% of the original wall thickness.
Shaft hole inside defect area should not be more than 0.25 C ㎡, depth of no more than 4 mm.
3. Maintenance of pulley
Clean the pulley, check the abrasion of the pulley, and replace it in time if it exceeds the scrap standard.
The cast steel pulley can be welded and made again.
Cast iron pulleys should crack or break, no welding repair, should be scrapped for replacement.
The oil hole and lubricating oil groove of the roller shaft shall be cleaned and the bearing, spacer sleeve and expansion ring shall be cleaned before loading