Spreader Bars and Lifting Beams Flashcards

How does a lifting beam differ structurally from a spreader bar?

Answer: A lifting beam resists bending moments; a spreader bar resists compression

A lifting beam is designed to resist bending (flexural) forces from loads suspended below it, while a spreader bar is designed to resist compressive forces from inward-pulling slings.

As the sling angle measured from vertical increases beyond 45 degrees when used with a spreader bar, what happens to the compressive force in the bar?

Answer: The compressive force increases significantly

As sling angles increase beyond 45° from vertical, the horizontal component of sling forces grows rapidly, driving up the compressive load on the spreader bar.

Under which circumstance must a spreader bar be immediately removed from service?

Answer: When visible cracks, deformation, or missing/illegible SWL markings are found

Visible cracks, deformation, or missing/illegible SWL markings indicate compromised structural integrity, requiring immediate removal from service.

Which Australian standard specifically covers the design and use of lifting devices such as spreader bars and lifting beams?

Answer: AS 4991 (Lifting devices)

AS 4991 (Lifting devices) is the Australian standard specifically covering the design, manufacture, testing, and safe use of lifting devices including spreader bars and lifting beams.

If a spreader bar's test certificate cannot be located on site, what must the rigger do?

Answer: Not use the spreader bar until a valid certificate is produced

Without a valid test certificate, the spreader bar's design and rated SWL cannot be verified, so it must not be used until proper documentation is produced.

Where should the crane hook attach when a spreader bar is rigged for a standard lift?

Answer: To the central lifting lug or pick point on top of the spreader bar

The crane hook must attach to the central lifting lug on top of the spreader bar to ensure the load is balanced and the bar is loaded correctly.

What is the function of end retention pins or end stops on a spreader bar?

Answer: To prevent slings from sliding off the end fittings during the lift

End retention pins and stops are safety devices that prevent slings from accidentally sliding off the end fittings of the spreader bar during a lifting operation.