NCCCO Load Moment Indicators and Safety Devices 2

Question 1

What is a Load Moment Indicator (LMI) and what information does it provide to the crane operator?

Accepted Answer

An LMI is an electronic safety system that measures the actual load on the crane's hoist line and the current boom and radius configuration, calculates the percentage of rated capacity being used, and provides a warning when the crane approaches or exceeds its rated capacity

Answer

An LMI measures the speed of the hoist drum in real time

Answer

An LMI only measures the weight of the load — it does not calculate capacity percentage

Answer

An LMI is a manual chart taped inside the crane cab — not an electronic device

Question 2

If a crane's LMI system shows the crane at 95% of rated capacity but the operator believes the load weighs less than what the LMI indicates, what should the operator do?

Accepted Answer

Stop the lift and have the LMI system inspected and recalibrated by a qualified technician before continuing. Do not bypass or override safety devices

Answer

Override the LMI alarm and continue the lift since they know the actual load is lighter

Answer

Reduce the load by 5% as estimated and resume the lift

Answer

Call the crane manufacturer to ask if the reading is acceptable

Question 3

What is the purpose of the RCL (Rated Capacity Limiter) function in a crane's safety system, as distinguished from the RCI (Rated Capacity Indicator)?

Accepted Answer

The RCI (indicator) provides information and warnings to the operator, while the RCL (limiter) actively intervenes by automatically stopping certain crane functions when the rated capacity is reached

Answer

RCL and RCI are identical — the terms are completely interchangeable

Answer

RCL limits crane speed; RCI measures load weight only

Answer

RCL applies only to tower cranes; RCI applies to mobile cranes

Question 4

How must a crane's LMI system be verified before being relied upon for production lifting?

Accepted Answer

The LMI must be calibrated and verified with a known test load at the beginning of each day's operations, and the system's accuracy must be within the manufacturer's specified tolerance before it is used as the capacity reference

Answer

LMI systems are factory-calibrated and never need field verification

Answer

LMI verification is only required after the crane has been repaired or transported

Answer

LMI verification can be performed by the operator using the crane's internal self-test function only

Question 5

What is an anemometer and why might it be required as part of a crane's safety instrumentation?

Accepted Answer

An anemometer is a wind speed measuring instrument. It may be required on large cranes, tower cranes, and crawler cranes because wind creates significant additional forces on large loads and boom sections that can cause overload or instability

Answer

An anemometer measures hoist drum rotation speed

Answer

An anemometer measures the angle between the load line and vertical to detect load swing

Answer

An anemometer is a ground pressure monitoring device for outrigger pads

Question 6

What does ASME B30.5 require regarding the inspection of load moment indicators and other safety devices?

Accepted Answer

Safety devices including LMI, ATB, and boom angle indicators must be checked for proper function before each shift, with any deficiency corrected before the crane is placed in service

Answer

Safety devices require inspection only during the annual comprehensive crane inspection

Answer

Safety device inspection is optional if the operator has more than 5 years experience

Answer

Safety devices only need inspection when they trigger alarms or malfunctions