NCCCO Digger Derrick Stability &
Capacity Practice Exam Fall 2026| 250
Most Tested Questions Collection &
Verified Detailed Answers With
Rationales| Tutor Verified Success
Exam) Graded A+
1.
What is the primary purpose of a digger derrick's load chart?
A. To determine engine horsepower
B. To identify the maximum permissible load under specified
operating conditions
C. To determine fuel consumption
D. To establish tire pressure
Answer: B. To identify the maximum permissible load under
specified operating conditions
Rationale: The load chart establishes rated capacities for particular
configurations, radii, boom positions, and other operating conditions.
2.
Which factor most directly affects a digger derrick's lifting capacity as
the load is moved farther from the machine?
A. Paint thickness
B. Load radius
C. Cab temperature
D. Engine oil viscosity
Answer: B. Load radius
,Rationale: Increasing load radius increases the overturning moment
and generally reduces the machine's rated capacity.
3.
What is load moment?
A. Load weight divided by boom length
B. Load weight multiplied by the horizontal distance from the tipping
axis
C. Boom length multiplied by engine speed
D. Load weight minus machine weight
Answer: B. Load weight multiplied by the horizontal distance from
the tipping axis
Rationale: Load moment represents the rotational effect of the
suspended load about the applicable tipping or stability axis.
4.
A 2,000-lb load is positioned 10 ft from the applicable tipping axis.
What is the load moment?
A. 200 lb-ft
B. 2,000 lb-ft
C. 12,000 lb-ft
D. 20,000 lb-ft
Answer: D. 20,000 lb-ft
Rationale: Load moment = 2,000 lb × 10 ft = 20,000 lb-ft.
5.
If the load radius increases while load weight remains constant, what
generally happens to overturning moment?
A. It decreases
B. It remains unchanged
,C. It increases
D. It becomes zero
Answer: C. It increases
Rationale: With constant load weight, increasing the moment arm
directly increases the overturning moment.
6.
What is the most important source for determining the allowable
capacity of a specific digger derrick configuration?
A. Operator preference
B. Manufacturer's load chart
C. Paint identification code
D. Fuel gauge
Answer: B. Manufacturer's load chart
Rationale: The manufacturer's load chart provides the rated
capacities applicable to the machine and configuration.
7.
Which condition can significantly reduce stability?
A. A level, firm setup
B. Fully deployed stabilizers on suitable ground
C. A sloped or weak supporting surface
D. A properly centered load
Answer: C. A sloped or weak supporting surface
Rationale: Poor ground conditions can allow stabilizers to settle or
shift, reducing effective support and stability.
8.
What is the purpose of stabilizers on a digger derrick?
, A. Increase engine speed
B. Provide additional support and improve machine stability
C. Reduce hydraulic pressure
D. Increase fuel capacity
Answer: B. Provide additional support and improve machine
stability
Rationale: Stabilizers increase the support footprint and help
maintain stability during lifting operations.
9.
Why must stabilizers generally be deployed according to the
manufacturer's requirements?
A. To change the machine's color
B. Because capacity and stability calculations depend on the machine
configuration
C. To increase tire wear
D. To reduce boom length
Answer: B. Because capacity and stability calculations depend on
the machine configuration
Rationale: Stabilizer position and configuration can materially affect
the machine's rated capacity and stability.
10.
What does "working radius" generally describe?
A. The horizontal distance from the applicable reference point to the
center of the load
B. The tire circumference
C. The boom's paint color
D. The distance between two outriggers only
Answer: A. The horizontal distance from the applicable reference
point to the center of the load
Capacity Practice Exam Fall 2026| 250
Most Tested Questions Collection &
Verified Detailed Answers With
Rationales| Tutor Verified Success
Exam) Graded A+
1.
What is the primary purpose of a digger derrick's load chart?
A. To determine engine horsepower
B. To identify the maximum permissible load under specified
operating conditions
C. To determine fuel consumption
D. To establish tire pressure
Answer: B. To identify the maximum permissible load under
specified operating conditions
Rationale: The load chart establishes rated capacities for particular
configurations, radii, boom positions, and other operating conditions.
2.
Which factor most directly affects a digger derrick's lifting capacity as
the load is moved farther from the machine?
A. Paint thickness
B. Load radius
C. Cab temperature
D. Engine oil viscosity
Answer: B. Load radius
,Rationale: Increasing load radius increases the overturning moment
and generally reduces the machine's rated capacity.
3.
What is load moment?
A. Load weight divided by boom length
B. Load weight multiplied by the horizontal distance from the tipping
axis
C. Boom length multiplied by engine speed
D. Load weight minus machine weight
Answer: B. Load weight multiplied by the horizontal distance from
the tipping axis
Rationale: Load moment represents the rotational effect of the
suspended load about the applicable tipping or stability axis.
4.
A 2,000-lb load is positioned 10 ft from the applicable tipping axis.
What is the load moment?
A. 200 lb-ft
B. 2,000 lb-ft
C. 12,000 lb-ft
D. 20,000 lb-ft
Answer: D. 20,000 lb-ft
Rationale: Load moment = 2,000 lb × 10 ft = 20,000 lb-ft.
5.
If the load radius increases while load weight remains constant, what
generally happens to overturning moment?
A. It decreases
B. It remains unchanged
,C. It increases
D. It becomes zero
Answer: C. It increases
Rationale: With constant load weight, increasing the moment arm
directly increases the overturning moment.
6.
What is the most important source for determining the allowable
capacity of a specific digger derrick configuration?
A. Operator preference
B. Manufacturer's load chart
C. Paint identification code
D. Fuel gauge
Answer: B. Manufacturer's load chart
Rationale: The manufacturer's load chart provides the rated
capacities applicable to the machine and configuration.
7.
Which condition can significantly reduce stability?
A. A level, firm setup
B. Fully deployed stabilizers on suitable ground
C. A sloped or weak supporting surface
D. A properly centered load
Answer: C. A sloped or weak supporting surface
Rationale: Poor ground conditions can allow stabilizers to settle or
shift, reducing effective support and stability.
8.
What is the purpose of stabilizers on a digger derrick?
, A. Increase engine speed
B. Provide additional support and improve machine stability
C. Reduce hydraulic pressure
D. Increase fuel capacity
Answer: B. Provide additional support and improve machine
stability
Rationale: Stabilizers increase the support footprint and help
maintain stability during lifting operations.
9.
Why must stabilizers generally be deployed according to the
manufacturer's requirements?
A. To change the machine's color
B. Because capacity and stability calculations depend on the machine
configuration
C. To increase tire wear
D. To reduce boom length
Answer: B. Because capacity and stability calculations depend on
the machine configuration
Rationale: Stabilizer position and configuration can materially affect
the machine's rated capacity and stability.
10.
What does "working radius" generally describe?
A. The horizontal distance from the applicable reference point to the
center of the load
B. The tire circumference
C. The boom's paint color
D. The distance between two outriggers only
Answer: A. The horizontal distance from the applicable reference
point to the center of the load
