What is a sheave?
Crane hot rolled sheave is the core component of the crane lifting mechanism. Its function can be simply understood as "a deflector and labor-saving helper for the wire rope".
Appearance: A round wheel with grooves (like the pulleys on fitness equipment) with a steel wire rope in the middle.
Material: Usually cast steel or alloy steel, wear-resistant and pressure-resistant.
What is sheave used for?
(1) Change the direction of the wire rope Just like the guide ring of a fishing rod guides the fishing line, the pulley changes the direction of the wire rope from "pulling upward" to "pulling horizontally" or diagonally.
Example: The hook of a tower crane can move left and right, which is to change the direction of the rope by the top pulley.
(2) Save effort and amplify the pulling force The pulley group (a combination of multiple pulleys) can reduce the required pulling force by multiples.
Physics principle: For each additional movable pulley, the pulling force is halved (the "movable pulley saving effort" principle of junior high school physics).
Example: With a pulling force of 1 ton, 4 tons of cargo can be lifted through 4 pulley groups.
Common Problems And Solutions
Problem 1: Wire rope jumps Phenomenon: The rope is out of the pulley groove or drum groove.
Cause: The pulley is skewed and the rope arrangement on the drum is uneven.
Solution: Adjust the pulley position and install a rope arrangement device.
Problem 2: The pulley bearing is stuck Phenomenon: The pulley does not rotate, and the wire rope is hard and smokes.
Cause: Long-term lack of lubrication or rust caused by water ingress.
Solution: Add high-temperature grease (such as lithium-based grease) every month.
Problem 3: Drum presses the rope Phenomenon: The new rope presses the old rope, resulting in local extrusion and deformation.
Cause: The drum has too many layers of winding (generally no more than 3 layers).
Solution: Use a longer drum or thicker wire rope.
Why does the pulley break?
Common faults:
The groove is worn out deep (wire rope wear is accelerated).
The bearing is stuck (the pulley does not turn, the rope is hard).
Prevention method:
Add lubricating oil once a month.
Replace the rope groove if it is found to be worn more than 3mm.
