NCCCO Mobile Crane Operator 4 — Questions and Answers
Question 1: When operating a mobile crane on a slope, the load chart ratings are based on which condition?
- Level ground within 1% grade (Correct answer)
- Slopes up to 5% grade
- Any slope up to 10%
- The rated capacity applies on all terrain
Correct answer: Level ground within 1% grade
NCCCO load charts are based on the crane being level within 1% grade; operating on slopes beyond that requires deration.
Question 2: Which document must the operator review before each shift to understand site-specific hazards?
- The crane manufacturer's specification sheet
- The lift director's pre-lift meeting notes or site safety plan (Correct answer)
- OSHA 1926.1400 in full
- The daily weather forecast only
Correct answer: The lift director's pre-lift meeting notes or site safety plan
A pre-lift meeting and site safety plan identify hazards, utilities, ground conditions, and emergency procedures specific to that lift.
Question 3: What is the purpose of a load moment indicator (LMI) on a mobile crane?
- To calculate the exact weight of the load
- To provide the operator a continuous warning when approaching or exceeding rated capacity (Correct answer)
- To replace the load chart entirely
- To measure wind speed at the boom tip
Correct answer: To provide the operator a continuous warning when approaching or exceeding rated capacity
An LMI monitors the combination of load and radius and alerts the operator when rated capacity is being approached or exceeded.
Question 4: A mobile crane's maximum rated capacity at a given radius is reduced when the load is handled:
- Over the rear of the crane only
- Over the side vs. over the front or rear, depending on crane design (Correct answer)
- Only when the wind exceeds 25 mph
- With a headache ball instead of a hook block
Correct answer: Over the side vs. over the front or rear, depending on crane design
Many mobile cranes have lower rated capacities when lifting over the side compared to front or rear due to structural and stability differences.
Question 5: Before making a pick, the operator must verify ground bearing pressure does NOT exceed:
- The crane's maximum load chart rating
- The ground's or mat's bearing capacity at the outrigger pad locations (Correct answer)
- The tipping load divided by four outrigger pads
- The manufacturer's boom weight specification
Correct answer: The ground's or mat's bearing capacity at the outrigger pad locations
Ground bearing capacity at each outrigger pad must be confirmed adequate to prevent settlement or crane tip-over.
Question 6: Which condition requires an operator to immediately cease operations and notify the competent person?
- Ambient temperature drops below 40°F
- A load line becomes kinked or birdcaged (Correct answer)
- The load swings more than 5 degrees during travel
- The jib angle exceeds the recommended setting by 2 degrees
Correct answer: A load line becomes kinked or birdcaged
A kinked or birdcaged wire rope is damaged and must be removed from service immediately to prevent failure.
Question 7: What does 'two-blocking' mean in crane operations?
- Using two separate hoist lines simultaneously
- The load block contacts the boom tip sheave, causing rope or component failure (Correct answer)
- A rigging method using two snatch blocks for mechanical advantage
- Operating the crane with two outriggers fully extended
Correct answer: The load block contacts the boom tip sheave, causing rope or component failure
Two-blocking occurs when the hook block is hoisted until it contacts the boom tip sheave, potentially causing catastrophic rope failure.
NCCCO Mobile Crane Operator 4
When operating a mobile crane on a slope, the load chart ratings are based on which condition?