NCCCO Mobile Crane Operator Fundamentals 4 — Questions and Answers
Question 1: When a mobile crane is traveling on a public road, the boom must typically be:
- Raised to maximum height
- Lowered and secured in the travel position (Correct answer)
- Extended to full length
- Rotated 90 degrees from center
Correct answer: Lowered and secured in the travel position
During road travel, the boom must be lowered and secured to keep the crane within legal height limits and maintain stability.
Question 2: Which factor is NOT typically considered when selecting outrigger pad size?
- Crane rated capacity at the given radius
- Ground bearing capacity
- Outrigger float area
- Color of the pad material (Correct answer)
Correct answer: Color of the pad material
Pad color is irrelevant; pad size is determined by crane load, outrigger float area, and ground bearing capacity.
Question 3: The term 'two-blocking' refers to:
- Using two load blocks simultaneously
- The upper and lower block making contact (Correct answer)
- Rigging with two sling legs
- Setting two outriggers on a single pad
Correct answer: The upper and lower block making contact
Two-blocking occurs when the lower load block contacts the upper sheave block, which can cause the hoist rope to part.
Question 4: A load chart for a lattice boom crane shows a note 'on outriggers fully extended.' This means:
- You may use the chart with outriggers partially extended
- The rated capacities only apply when outriggers are fully extended (Correct answer)
- Outrigger extension is optional for light loads
- The values apply on rubber only
Correct answer: The rated capacities only apply when outriggers are fully extended
Load chart configurations must be matched exactly; using partially extended outriggers voids the rated capacities shown.
Question 5: What is the primary purpose of a crane's anti-two-block (ATB) device?
- Prevent the hook block from swinging
- Automatically stop hoist motion before two-blocking occurs (Correct answer)
- Limit maximum boom angle
- Prevent boom from extending too far
Correct answer: Automatically stop hoist motion before two-blocking occurs
The ATB device detects when the load block approaches the boom tip sheaves and automatically cuts power to the hoist before contact occurs.
Question 6: When operating a mobile crane near energized power lines, OSHA requires a minimum clearance of ___ for lines up to 50 kV:
- 3 feet
- 10 feet (Correct answer)
- 20 feet
- 50 feet
Correct answer: 10 feet
OSHA 1926.1408 requires a minimum 10-foot clearance from energized lines up to 50 kV unless the utility owner de-energizes the line.
Question 7: Before beginning a lift, the operator should verify the load weight against the load chart using:
- Only the rigging weight
- The net load plus all rigging, attachments, and below-hook devices (Correct answer)
- The load weight minus the hook block
- An estimated visual approximation
Correct answer: The net load plus all rigging, attachments, and below-hook devices
The total load on the crane hook includes the load itself, all rigging hardware, spreader bars, and the hook block weight.
NCCCO Mobile Crane Operator Fundamentals 4
When a mobile crane is traveling on a public road, the boom must typically be: