NCCCO Load Moment Indicators and Safety Devices 5 — Questions and Answers
Question 1: 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:
- Continue operations using the load chart and strict manual monitoring
- Continue only if a qualified rigger is present
- Not operate the crane until the LMI is repaired or replaced (Correct answer)
- Operate at 50% of rated capacity without restriction
Correct 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.
Question 2: What is the primary purpose of a hoist drum rotation indicator on a lattice boom crane?
- To measure wind speed near the drum
- To warn the operator of excessive line speed
- To indicate the approach of a minimum drum wrap (two-block precursor) (Correct answer)
- To count total number of lifts for maintenance scheduling
Correct 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.
Question 3: Which statement about LMI accuracy tolerances is correct per industry standards?
- LMIs must be accurate to within ±1% of actual load at all times
- LMIs are generally required to be accurate within ±5% of actual load (Correct answer)
- Accuracy requirements vary by lift classification only
- No accuracy tolerance standards exist for LMI systems
Correct 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.
Question 4: 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?
- Free on wheels, because the crane can travel
- On outriggers fully extended, because of the increased stability base (Correct answer)
- Both configurations show identical capacities
- Free on wheels, because outriggers add weight reducing capacity
Correct 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.
Question 5: A swing brake safety device on a crane is primarily designed to:
- Prevent the boom from luffing beyond maximum angle
- Hold the upper structure in position against unintended rotation (Correct answer)
- Stop the hoist drum in case of LMI overload
- Limit maximum line speed during picking
Correct 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.
Question 6: 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?
- Only the crane manufacturer for allowing a bypass feature
- The operator, employer, and any qualified person who authorized the bypass (Correct answer)
- Only the lift director who planned the lift
- The rigger who rigged the load
Correct 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.
Question 7: What effect does operating a crane with the boom below its minimum rated angle have on the LMI's ability to protect the crane?
- The LMI provides greater protection at low boom angles
- The crane may operate outside the load chart range, making LMI readings unreliable or invalid (Correct answer)
- No effect; the LMI adjusts automatically for any boom angle
- The LMI automatically locks boom movement below minimum angle
Correct 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.
NCCCO Load Moment Indicators and Safety Devices 5
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: