Spreader Bars and Lifting Beams Flashcards

What is the primary purpose of a spreader bar in a rigging operation?

Answer: To hold sling legs apart and prevent inward compressive forces on the load

A spreader bar holds sling legs apart, preventing the inward compressive forces that would otherwise act on the load if slings converged directly toward the crane hook.

What does the marking 'SWL' on a spreader bar indicate?

Answer: Safe Working Load — the maximum load the bar can safely carry

SWL stands for Safe Working Load and indicates the maximum load the spreader bar is rated to safely carry under normal working conditions.

Which type of force does a spreader bar primarily experience during a lift?

Answer: Compression — because the sling legs push inward on both ends

Sling legs converge toward the crane hook, pushing inward on both ends of the spreader bar and placing it under compressive force.

What document must accompany an engineered spreader bar when used on an Australian worksite?

Answer: An engineer's design certificate or test certificate confirming the rated SWL

An engineered spreader bar must be accompanied by a design or test certificate from a competent engineer confirming its rated SWL and fitness for purpose.

Before each use, what is the minimum inspection requirement for a spreader bar?

Answer: Visual inspection for cracks, deformation, corrosion, and legible SWL markings

A pre-use visual inspection checking for cracks, deformation, corrosion, and legible SWL markings is the minimum required before each use.

What effect does increasing the length of a spreader bar have on the sling loads during a lift?

Answer: Sling loads decrease because the slings become more vertical

A longer spreader bar creates more vertical sling angles, which reduces the vector load on each sling and improves lifting efficiency.

What is the minimum information that must be legibly marked on a spreader bar before it can be used?

Answer: SWL and a unique identification number

As a minimum, a spreader bar must be legibly marked with its Safe Working Load and a unique identification number for traceability and inspection purposes.