NCCCO - National Commission for the Certification of Crane Operators Mobile Crane Operator Test 1 — Questions and Answers
Question 1: When setting up a mobile crane on outriggers, what must the operator verify before beginning any lift?
- The outrigger pads are centered under the crane body, not the outrigger floats
- The outrigger floats are fully extended and bearing on ground of adequate capacity, with the crane level within manufacturer tolerances (Correct answer)
- The outrigger cylinders are extended to their maximum stroke regardless of ground conditions
- All outriggers are set to equal height using a tape measure
Correct answer: The outrigger floats are fully extended and bearing on ground of adequate capacity, with the crane level within manufacturer tolerances
Outrigger floats must be fully extended (unless the load chart specifies a partial-extension configuration) and the ground must be capable of bearing the imposed load. The crane must also be level within the manufacturer's specified tolerance — typically ±1% — because load charts are based on level operation.
Question 2: A mobile crane's load chart lists capacities based on different boom lengths and radii. What is the 'radius' as used in crane load charts?
- The horizontal distance from the center of rotation to the center of the load (Correct answer)
- The length of the boom from the boom foot pin to the boom tip sheave
- The vertical height from the ground to the hook at maximum lift
- The distance from the front of the carrier to the load
Correct answer: The horizontal distance from the center of rotation to the center of the load
Radius is the horizontal distance from the crane's center of rotation (centerline of the turntable) to the center of the suspended load. As radius increases, rated capacity decreases due to the increased overturning moment.
Question 3: What action should a mobile crane operator take if a load starts to swing uncontrollably during a pick?
- Increase hoist speed to get the load above the swing arc
- Lower the load as smoothly and quickly as possible to a safe location (Correct answer)
- Rotate the upper works in the opposite direction to cancel the swing
- Extend the boom to increase the radius and slow the load
Correct answer: Lower the load as smoothly and quickly as possible to a safe location
When a load swings uncontrollably, the safest immediate response is to lower it to a stable surface. Attempting to counter-rotate or extending the boom can worsen the dynamic loading and risk tipping the crane.
Question 4: Under OSHA 1926 Subpart CC, who is responsible for ensuring that the weight of the load to be lifted is known before the lift begins?
- The signal person, who must weigh the load before any communication begins
- The employer, though the operator may also refuse the lift if the weight is unknown (Correct answer)
- The rigger, who must stamp the load weight on the rigging hardware
- The crane manufacturer's representative on site
Correct answer: The employer, though the operator may also refuse the lift if the weight is unknown
OSHA 1926.1412 and 1926.1416 place the duty on the employer to provide the operator with the load weight. The operator has the authority and responsibility to refuse a lift if the weight is unknown or if conditions are unsafe.
Question 5: What does 'structural competency' of a mobile crane refer to?
- The operator's formal education credentials as verified by NCCCO
- The crane's ability to handle a load without any component failing due to stress (Correct answer)
- The rated capacity after deducting the weight of all rigging hardware
- The travel speed rating of the carrier on public roads
Correct answer: The crane's ability to handle a load without any component failing due to stress
Structural competency means the crane's structural members — boom, jib, and frame — can withstand the stresses imposed by the load without failing. Load charts account for both tipping (stability) limits and structural limits; the governing limit is the lower of the two.
Question 6: When is a crane operator required to halt operations and consult with a competent person before continuing?
- Any time the wind speed exceeds 5 mph at the job site
- When the operator encounters site conditions not addressed by the manufacturer's specifications or the pre-lift plan (Correct answer)
- Only when the load exceeds 75% of the rated capacity at the given radius
- Whenever a new signal person takes over mid-shift
Correct answer: When the operator encounters site conditions not addressed by the manufacturer's specifications or the pre-lift plan
OSHA 1926.1417 requires the operator to stop and seek guidance when site or lift conditions fall outside the planned scope or the manufacturer's specifications — for example, unexpected soft ground, obstructions, or a load heavier than anticipated. Operating outside known parameters without reassessment is prohibited.
NCCCO - National Commission for the Certification of Crane Operators Mobile Crane Operator Test 1
When setting up a mobile crane on outriggers, what must the operator verify before beginning any lift?