NCCCO Load Moment Indicators and Safety Devices 4

Question 1

During a lift, the LMI alarm sounds and crane motion stops. The operator believes the load is within the chart. What is the MOST likely cause?

Accepted Answer

The boom configuration entered does not match actual rigging

Answer

A mismatch between the boom length or jib configuration entered into the LMI and the actual crane setup is the most common cause of unexpected capacity limit alarms.

Question 2

Which ASME B30 standard directly governs the use of rated capacity limiters on mobile cranes?

Accepted Answer

ASME B30.5

Answer

ASME B30.5 covers mobile and locomotive cranes and includes requirements for rated capacity limiters and load moment indicators.

Question 3

A load line pull indicator shows 18,000 lb with two parts of line reeved. What is the approximate gross load on the hook?

Accepted Answer

36,000 lb

Answer

With two parts of line, the gross load equals the line pull multiplied by the number of parts, so 18,000 lb × 2 = 36,000 lb.

Question 4

Why must the operator deduct the weight of the hook block and rigging when using an LMI to assess available net load capacity?

Accepted Answer

Hook block and rigging are part of the gross load but not the net payload

Answer

The LMI measures gross load including the hook block and all rigging; the net payload capacity is reduced by those weights, so they must be subtracted to know how much actual cargo can be lifted.

Question 5

When operating a crane with a luffing jib, which additional LMI input is critical compared to a fixed-angle jib?

Accepted Answer

Luffing jib angle

Answer

A luffing jib changes the working radius as its angle changes, so the LMI must receive the current jib angle to calculate the correct load moment and rated capacity.

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO Load Moment Indicators and Safety Devices 4