Load Moment Indicators and Safety Devices Flashcards

A crane equipped with an LMI is being used on a job site where the LMI is inoperable. Under OSHA 29 CFR 1926.1416, the operator may:

Answer: Not operate the crane until the LMI is repaired or replaced

OSHA 1926.1416 classifies a malfunctioning LMI as a safety device defect that must be corrected before the crane is returned to service.

What is the primary purpose of a hoist drum rotation indicator on a lattice boom crane?

Answer: To indicate the approach of a minimum drum wrap (two-block precursor)

A hoist drum rotation indicator alerts the operator when the rope is nearly fully unspooled, helping prevent losing the minimum required wraps and a potential two-block condition from below.

Which statement about LMI accuracy tolerances is correct per industry standards?

Answer: LMIs are generally required to be accurate within ±5% of actual load

Industry standards and most manufacturer specifications require LMI systems to be accurate within ±5% of actual load under normal operating conditions.

When an LMI is set up for a crane operating in 'free on wheels' mode versus 'on outriggers fully extended', which configuration will show HIGHER rated capacities?

Answer: On outriggers fully extended, because of the increased stability base

Operating on fully extended outriggers provides the widest and most stable support base, resulting in significantly higher rated capacities than free-on-wheels operation.

A swing brake safety device on a crane is primarily designed to:

Answer: Hold the upper structure in position against unintended rotation

The swing brake locks or holds the rotating upper structure (superstructure) to prevent unintended or uncontrolled slewing, especially on slopes or in windy conditions.

If an operator bypasses or overrides an LMI system to complete a lift, who bears responsibility for that decision according to NCCCO and OSHA standards?

Answer: The operator, employer, and any qualified person who authorized the bypass

OSHA and NCCCO standards place shared responsibility on the operator for operating the equipment safely, and on the employer and qualified person for authorizing or allowing an unsafe bypass of safety devices.

What effect does operating a crane with the boom below its minimum rated angle have on the LMI's ability to protect the crane?

Answer: The crane may operate outside the load chart range, making LMI readings unreliable or invalid

Load charts and LMI programming have a minimum boom angle below which no rated capacity exists; operating there places the crane outside the designed envelope where the LMI data is valid.