NCCO MOBILE CRANE EXAM ACTUAL EXAM
300 QUESTIONS AND ACCURATE DETAILED
ANSWERS
1. When a mobile crane is set up on outriggers, the lifting capacity compared to
working on rubber (tires) is:
A) Lower
B) Higher
C) The same
D) Dependent on boom length only
Correct answer: B) Higher ✅
Rationale: Outriggers increase the crane's stability footprint, allowing higher load
capacities than on rubber where suspension and smaller base reduce stability.
2. A load chart shows 30,000 lbs at a 20 ft radius. The actual operating radius is 22 ft.
The operator should:
A) Use the 20 ft capacity
B) Add counterweight to compensate
C) Use the capacity for 22 ft (which will be lower)
D) Increase engine RPM
Correct answer: C) Use the capacity for 22 ft (which will be lower) ✅
Rationale: Load charts are radius-specific. As radius increases, capacity decreases. Using
the capacity for a shorter radius would overload the crane.
3. The primary purpose of a Load Moment Indicator (LMI) is to:
A) Measure wind speed during lifts
B) Warn when the load approaches rated capacity
C) Calculate sling angles automatically
D) Monitor hydraulic oil temperature
Correct answer: B) Warn when the load approaches rated capacity ✅
Rationale: LMI senses load weight and radius, providing alarms before reaching structural
or stability limits to prevent overloads.
4. Net capacity of a crane is defined as:
A) Chart capacity plus hook block weight
B) Chart capacity minus weight of hook block and rigging
C) Gross capacity divided by radius
D) Chart capacity multiplied by wind factor
Correct answer: B) Chart capacity minus weight of hook block and rigging ✅
,Rationale: Net capacity = rated capacity minus all lifting attachments (hook block, slings,
etc.). The actual load must not exceed net capacity.
5. When outriggers are fully extended, the tipping axis runs through the:
A) Center of rotation of the turntable
B) Outrigger float centers (pads)
C) Tires on the opposite side
D) Boom heel pins
Correct answer: B) Outrigger float centers (pads) ✅
Rationale: The crane tips over an axis formed by the outrigger pads at ground contact;
tires are off the ground and do not affect the tipping axis.
6. A load chart states “capacity based on 75% of tipping.” The crane will tip at
approximately what percentage of the charted load?
A) 75%
B) 100%
C) 133%
D) 150%
Correct answer: C) 133% ✅
Rationale: *Chart capacity is 75% of tipping load, so tipping load = chart capacity / 0.75
= 1.33 × chart capacity (133%).*
7. Adding an auxiliary boom head (jib) to the main boom will typically:
A) Increase main boom capacity at the same radius
B) Decrease main boom capacity at the same radius
C) Have no effect on main boom capacity
D) Only affect capacity if the jib is offset
Correct answer: B) Decrease main boom capacity at the same radius ✅
Rationale: The jib adds weight and increases the bending moment on the main boom,
reducing its structural capacity at any given radius.
8. A telescopic boom crane at 40 ft radius has a capacity of 22,000 lbs with a 70 ft boom.
If the boom length is extended to 90 ft at the same radius, capacity will:
A) Increase
B) Decrease
C) Remain unchanged
D) Double
Correct answer: B) Decrease ✅
Rationale: Longer booms have greater deflection and higher bending moments, reducing
load capacity even at identical radius.
,9. The range diagram on a load chart provides information about:
A) Lifting capacity at each radius
B) Boom angle, radius, and height combinations
C) Wind limits for each boom length
D) Hydraulic flow rates
Correct answer: B) Boom angle, radius, and height combinations ✅
Rationale: A range diagram shows the operating envelope: given boom length and angle,
what radius and hook height are achieved.
10. Ground conditions for crane setup must be:
A) Level within 5 degrees
B) Firm, drained, and able to support outrigger pressures
C) Asphalt only
D) Within 10% of crane weight
Correct answer: B) Firm, drained, and able to support outrigger pressures ✅
Rationale: The ground must support outrigger loads without settling. Soft, uneven, or wet
ground can cause instability or tipping.
11. The term “duty cycle” on a load chart applies to:
A) Occasional lifts
B) Continuous repetitive lifting (e.g., clamshell, magnet)
C) Pick-and-carry only
D) Maintenance lifts
Correct answer: B) Continuous repetitive lifting (e.g., clamshell, magnet) ✅
Rationale: Duty cycle charts account for higher frequency and fatigue loads; they are
required for operations like digging or magnet work.
12. A crane is level when the bubble in the circular level is:
A) Touching one line
B) Centered within the circle
C) At the highest point
D) At the lowest point
Correct answer: B) Centered within the circle ✅
Rationale: The circular level (bull’s-eye) must be centered to ensure the crane is level,
critical for accurate load chart use.
13. If the operator sees a hand signal “stop” but the signal person gives a different
motion command, the operator should:
A) Follow the motion signal
B) Stop all crane functions
C) Sound the horn and continue
, D) Ask the rigger
Correct answer: B) Stop all crane functions ✅
Rationale: Any stop signal overrides all other commands. Safety requires immediate
cessation of movement until the situation is clarified.
14. The minimum distance for a crane’s rotating superstructure from a power line up to
50 kV is:
A) 5 ft
B) 10 ft
C) 15 ft
D) 20 ft
Correct answer: B) 10 ft ✅
Rationale: OSHA 1926.1408 requires 10 ft clearance for lines up to 50 kV. For higher
voltages, distance increases.
15. When using a sling at a 60° horizontal angle (included angle between legs = 60°),
the tension in each leg compared to a vertical lift is:
A) Less
B) Greater
C) Equal
D) Zero
Correct answer: B) Greater ✅
Rationale: *Sling tension = (load / number of legs) / sin(angle). At 60°, sin60=0.866, so
tension is about 15% higher than vertical.*
16. A 2-leg bridle sling has a 60° included angle between legs. The load is 10,000 lbs.
The tension per leg is approximately:
A) 5,000 lbs
B) 5,774 lbs
C) 6,667 lbs
D) 10,000 lbs
Correct answer: B) 5,774 lbs ✅
Rationale: *Tension per leg = (10,) / sin(60°) = 5,.866 = 5,774 lbs.*
17. The crane operator must conduct a pre-operation inspection:
A) Weekly
B) At the start of each shift
C) Only after repairs
D) Monthly
Correct answer: B) At the start of each shift ✅
300 QUESTIONS AND ACCURATE DETAILED
ANSWERS
1. When a mobile crane is set up on outriggers, the lifting capacity compared to
working on rubber (tires) is:
A) Lower
B) Higher
C) The same
D) Dependent on boom length only
Correct answer: B) Higher ✅
Rationale: Outriggers increase the crane's stability footprint, allowing higher load
capacities than on rubber where suspension and smaller base reduce stability.
2. A load chart shows 30,000 lbs at a 20 ft radius. The actual operating radius is 22 ft.
The operator should:
A) Use the 20 ft capacity
B) Add counterweight to compensate
C) Use the capacity for 22 ft (which will be lower)
D) Increase engine RPM
Correct answer: C) Use the capacity for 22 ft (which will be lower) ✅
Rationale: Load charts are radius-specific. As radius increases, capacity decreases. Using
the capacity for a shorter radius would overload the crane.
3. The primary purpose of a Load Moment Indicator (LMI) is to:
A) Measure wind speed during lifts
B) Warn when the load approaches rated capacity
C) Calculate sling angles automatically
D) Monitor hydraulic oil temperature
Correct answer: B) Warn when the load approaches rated capacity ✅
Rationale: LMI senses load weight and radius, providing alarms before reaching structural
or stability limits to prevent overloads.
4. Net capacity of a crane is defined as:
A) Chart capacity plus hook block weight
B) Chart capacity minus weight of hook block and rigging
C) Gross capacity divided by radius
D) Chart capacity multiplied by wind factor
Correct answer: B) Chart capacity minus weight of hook block and rigging ✅
,Rationale: Net capacity = rated capacity minus all lifting attachments (hook block, slings,
etc.). The actual load must not exceed net capacity.
5. When outriggers are fully extended, the tipping axis runs through the:
A) Center of rotation of the turntable
B) Outrigger float centers (pads)
C) Tires on the opposite side
D) Boom heel pins
Correct answer: B) Outrigger float centers (pads) ✅
Rationale: The crane tips over an axis formed by the outrigger pads at ground contact;
tires are off the ground and do not affect the tipping axis.
6. A load chart states “capacity based on 75% of tipping.” The crane will tip at
approximately what percentage of the charted load?
A) 75%
B) 100%
C) 133%
D) 150%
Correct answer: C) 133% ✅
Rationale: *Chart capacity is 75% of tipping load, so tipping load = chart capacity / 0.75
= 1.33 × chart capacity (133%).*
7. Adding an auxiliary boom head (jib) to the main boom will typically:
A) Increase main boom capacity at the same radius
B) Decrease main boom capacity at the same radius
C) Have no effect on main boom capacity
D) Only affect capacity if the jib is offset
Correct answer: B) Decrease main boom capacity at the same radius ✅
Rationale: The jib adds weight and increases the bending moment on the main boom,
reducing its structural capacity at any given radius.
8. A telescopic boom crane at 40 ft radius has a capacity of 22,000 lbs with a 70 ft boom.
If the boom length is extended to 90 ft at the same radius, capacity will:
A) Increase
B) Decrease
C) Remain unchanged
D) Double
Correct answer: B) Decrease ✅
Rationale: Longer booms have greater deflection and higher bending moments, reducing
load capacity even at identical radius.
,9. The range diagram on a load chart provides information about:
A) Lifting capacity at each radius
B) Boom angle, radius, and height combinations
C) Wind limits for each boom length
D) Hydraulic flow rates
Correct answer: B) Boom angle, radius, and height combinations ✅
Rationale: A range diagram shows the operating envelope: given boom length and angle,
what radius and hook height are achieved.
10. Ground conditions for crane setup must be:
A) Level within 5 degrees
B) Firm, drained, and able to support outrigger pressures
C) Asphalt only
D) Within 10% of crane weight
Correct answer: B) Firm, drained, and able to support outrigger pressures ✅
Rationale: The ground must support outrigger loads without settling. Soft, uneven, or wet
ground can cause instability or tipping.
11. The term “duty cycle” on a load chart applies to:
A) Occasional lifts
B) Continuous repetitive lifting (e.g., clamshell, magnet)
C) Pick-and-carry only
D) Maintenance lifts
Correct answer: B) Continuous repetitive lifting (e.g., clamshell, magnet) ✅
Rationale: Duty cycle charts account for higher frequency and fatigue loads; they are
required for operations like digging or magnet work.
12. A crane is level when the bubble in the circular level is:
A) Touching one line
B) Centered within the circle
C) At the highest point
D) At the lowest point
Correct answer: B) Centered within the circle ✅
Rationale: The circular level (bull’s-eye) must be centered to ensure the crane is level,
critical for accurate load chart use.
13. If the operator sees a hand signal “stop” but the signal person gives a different
motion command, the operator should:
A) Follow the motion signal
B) Stop all crane functions
C) Sound the horn and continue
, D) Ask the rigger
Correct answer: B) Stop all crane functions ✅
Rationale: Any stop signal overrides all other commands. Safety requires immediate
cessation of movement until the situation is clarified.
14. The minimum distance for a crane’s rotating superstructure from a power line up to
50 kV is:
A) 5 ft
B) 10 ft
C) 15 ft
D) 20 ft
Correct answer: B) 10 ft ✅
Rationale: OSHA 1926.1408 requires 10 ft clearance for lines up to 50 kV. For higher
voltages, distance increases.
15. When using a sling at a 60° horizontal angle (included angle between legs = 60°),
the tension in each leg compared to a vertical lift is:
A) Less
B) Greater
C) Equal
D) Zero
Correct answer: B) Greater ✅
Rationale: *Sling tension = (load / number of legs) / sin(angle). At 60°, sin60=0.866, so
tension is about 15% higher than vertical.*
16. A 2-leg bridle sling has a 60° included angle between legs. The load is 10,000 lbs.
The tension per leg is approximately:
A) 5,000 lbs
B) 5,774 lbs
C) 6,667 lbs
D) 10,000 lbs
Correct answer: B) 5,774 lbs ✅
Rationale: *Tension per leg = (10,) / sin(60°) = 5,.866 = 5,774 lbs.*
17. The crane operator must conduct a pre-operation inspection:
A) Weekly
B) At the start of each shift
C) Only after repairs
D) Monthly
Correct answer: B) At the start of each shift ✅
