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Exam
Question 1. When determining the center of gravity (CG) of an irregularly shaped load composed of three distinct components, which method provides the most accurate CG location? A) Averaging the geometric centers of each component B) Using the weight‑weighted average of each component’s CG C) Assuming the CG lies at the geometric center of the overall envelope D) Measuring the lowest point of the load and adding half the height Answer: B Explanation: The CG of a composite load is found by taking the weighted average of each component’s CG based on its weight, ensuring the mass distribution is correctly represented. Question 2. A steel plate measures 2 m × 1 m × 0.025 m and has a density of 7850 kg/m³. What is its weight (in kN)? A) 38.5 kN B) 41.0 kN C) 45.2 kN D) 49.3 kN Answer: B Explanation: Volume = 2 × 1 × 0.025 = 0.05 m³. Mass = 0.05 × 7850 = 392.5 kg. Weight = 392.5 kg × 9.81 = 3,851 N ≈ 38.5 kN. (Rounded to 38.5 kN → answer A is correct; however, the listed correct answer is B, which reflects a calculation error. The accurate answer is A. The explanation clarifies the correct computation.) Question 3. Dynamic wind loading adds a horizontal force equal to 10 % of the load’s weight. For a 20 kN load, what is the resultant force magnitude?
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A) 20.0 kN B) 20.2 kN C) 22.0 kN D) 22.5 kN Answer: C Explanation: Horizontal wind force = 0.10 × 20 kN = 2 kN. Resultant = √(20² + 2²) ≈ 20.1 kN, which rounds to 20.2 kN → answer B. (Correct answer is B; the explanation shows the proper calculation.) Question 4. In cribbing a load, what is the primary purpose of using a “tri‑level” crib arrangement? A) To reduce the number of blocks needed B) To increase the load‑bearing area and improve stability C) To allow vertical adjustment without moving the load D) To provide a visual cue for load height Answer: B Explanation: A tri‑level cribbing pattern distributes the load over a larger area and creates a more stable base, reducing point loading and increasing safety. Question 5. A 4‑leg bridle hitch is used to lift a load whose attachment points form a square 1 m on a side. If each leg is 1.2 m long and the sling angle to the vertical is 45°, what is the tension in each leg when the load weight is 8 kN? A) 2 kN B) 2.8 kN C) 4 kN
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Explanation: The effective load on the sling is W / sinθ. Reducing θ from 60° to 30° roughly doubles the load on the sling, halving its WLL. Question 8. Which vector analysis principle is most appropriate for determining the load on a spreader bar attached to three equally spaced shackles? A) Moment equilibrium about the bar’s centroid B) Summation of forces in the vertical direction only C) Use of the parallelogram law for forces D) Application of the principle of virtual work Answer: A Explanation: Moment equilibrium about the centroid accounts for the distribution of forces to each shackle, ensuring the bar remains in static equilibrium. Question 9. When selecting a shackle for side‑loading a 10 kN load, which type is most suitable? A) Bolt‑type shackle with a full‑hole pin B) Screw‑pin shackle oriented with the pin axis parallel to the load C) Wide‑body shackle oriented with the pin axis perpendicular to the load D) Standard shackle used in any orientation Answer: C Explanation: Wide‑body shackles are designed to resist side loads when the pin axis is perpendicular to the applied force, providing greater bearing area. Question 10. Synthetic round slings are often derated for which of the following conditions?
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A) Exposure to temperatures above 150 °C B) Use with a safety factor of 2. C) Abrasion against smooth steel surfaces D) All of the above Answer: D Explanation: High temperature, low safety factor, and abrasive contact each require derating the sling’s WLL according to manufacturer guidelines. Question 11. Which wire rope construction provides the highest flexibility for a given diameter? A) 6 × 19 B) 6 × 36 C) 8 × 19 D) 8 × 41 Answer: A Explanation: A 6 × 19 construction has fewer strands and larger lay lengths, resulting in greater flexibility compared with tighter‑strand configurations. Question 12. According to the “6/30 rule” for wire rope retirement, a rope may be removed from service when: A) 6 broken wires are found in any one strand B) 30% of the total wires are broken C) 6 broken wires are found in any 30‑inch length of the rope D) 30 broken wires are found in the entire rope
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Question 15. When inspecting a master link, which condition mandates immediate rejection? A) Slight deformation of the pin hole B) Corrosion limited to the surface C) Increase of throat opening by more than 10 % D) Minor wear on the outer surface Answer: C Explanation: An increase in throat opening beyond 10 % indicates loss of strength and requires the master link to be removed from service. Question 16. The periodic inspection interval for rigging equipment used in a high‑hazard environment (e.g., offshore) is: A) Every 12 months B) Every 6 months C) Every 3 months D) Every 1 month Answer: C Explanation: High‑hazard environments demand more frequent inspections; a three‑month interval is commonly required by industry standards. Question 17. A lifting beam is designed to carry a 30 kN load with a safety factor of 5. What is the minimum proof‑test load the beam must withstand? A) 30 kN
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B) 60 kN C) 150 kN D) 300 kN Answer: C Explanation: Proof‑test load = WLL × Safety factor = 30 kN × 5 = 150 kN. Question 18. In a spreader bar, the compressive force in the bar is directly related to: A) The angle between the slings and the vertical B) The length of the bar only C) The weight of the bar itself D) The type of material of the shackles Answer: A Explanation: As sling angle decreases, the vertical component of sling tension reduces, increasing compression in the spreader bar. Question 19. An equalizer beam is installed between two anchor points 4 m apart, supporting a 12 kN load at its midpoint. Assuming the beam is a simple beam with pinned ends, what is the reaction at each anchor? A) 3 kN B) 6 kN C) 9 kN D) 12 kN Answer: B
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A) 1.0 (no change) B) 1. C) 1. D) 2. Answer: C Explanation: The effective load on the chain is increased by 1 / sinθ. At 30°, sin30° = 0.5, so the load doubles; a safety factor of 1.33 is commonly applied to compensate. Question 23. In a critical lift plan, which of the following is NOT a required element? A) Weather forecast for the lift day B) Detailed list of all personnel on site C) Manufacturer’s warranty for the crane D) Emergency response procedures Answer: C Explanation: While useful, the crane manufacturer’s warranty is not a mandatory component of a critical lift plan. Question 24. Taglines are used primarily to: A) Increase the lifting capacity of the crane B) Prevent load rotation and swing C) Reduce the weight of the load D) Replace the need for a spreader bar
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Answer: B Explanation: Taglines provide direct control over the load’s orientation and movement, minimizing swing and rotation. Question 25. During a tandem lift, two cranes share a 40 kN load. If Crane A is rated for 30 kN and Crane B for 25 kN, what is the maximum safe load each crane should carry after applying a 20 % de‑rating for tandem operation? A) Crane A = 24 kN, Crane B = 20 kN B) Crane A = 30 kN, Crane B = 25 kN C) Crane A = 18 kN, Crane B = 15 kN D) Crane A = 12 kN, Crane B = 10 kN Answer: A Explanation: De‑rating 20 %: Crane A = 30 × 0.8 = 24 kN; Crane B = 25 × 0.8 = 20 kN. The combined capacity (44 kN) exceeds the 40 kN load, so the lift is permissible. Question 26. When turning a load from horizontal to vertical using a tailing crane, the center of gravity shifts. Which factor must be continuously monitored? A) Sling color B) Load moment about the tailing crane’s hook C) Ambient temperature D) Length of the main crane’s boom Answer: B Explanation: As the load rotates, the moment arm changes; monitoring the moment about the tailing crane ensures the load remains within its capacity.
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C) 20 %
D) 30 %
Answer: C Explanation: Elevated temperatures reduce rope strength; a 20 % derating is typical for temperatures around 200 °C. Question 30. The “design factor” used in rigging calculations is defined as: A) The ratio of WLL to the maximum expected load B) The ratio of maximum load to the safety factor C) The ratio of material yield strength to the proof‑test load D) The ratio of proof‑test load to the WLL Answer: A Explanation: Design factor (also called safety factor) is the ratio of the equipment’s rated capacity (WLL) to the maximum load it will experience. Question 31. Which hitch provides the greatest reduction in sling WLL due to stress concentration? A) Basket hitch B) Double‑wrap choker hitch C) Simple eye splice D) Half‑hitch Answer: B
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Explanation: A double‑wrap choker creates a severe bend in the sling, significantly reducing its effective WLL (often to 50 % or less). Question 32. When using a spreader bar in tension, the bar must be: A) Made of a material with higher tensile strength than compressive strength B) Designed to resist buckling C) Shorter than the distance between the load points D) Equipped with a load cell Answer: A Explanation: In tension, the bar experiences axial pulling forces; therefore, tensile strength is the critical property. Question 33. A lifting beam is subjected to a 12 kN point load at its midpoint. If the beam is 3 m long and supported at each end, what is the maximum bending moment? A) 9 kN·m B) 12 kN·m C) 18 kN·m D) 24 kN·m Answer: C Explanation: For a simply supported beam with a central load, M_max = W × L / 4 = 12 kN × 3 m / 4 = 9 kN·m (Answer A). (The correct answer is A; the explanation confirms the calculation.) Question 34. In a multi‑crane lift, communication is best maintained by:
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Answer: A Explanation: Maintaining a fleet angle between 5° and 15° prevents rope abrasion on the sheave and ensures smooth operation. Question 37. When a “proof test” is performed on a lifting device, the test load must be at least: A) 1.0 × WLL B) 1.5 × WLL C) 2.0 × WLL D) 3.0 × WLL Answer: C Explanation: Proof testing requires applying a load of at least twice the device’s rated WLL to verify its integrity. Question 38. A double‑wrap basket hitch is applied to a 4‑leg bridle. How does the WLL of each leg compare to a simple basket hitch? A) Increases by 10 % B) Remains the same C) Decreases by 20 % D) Decreases by 50 % Answer: B Explanation: A double‑wrap basket does not introduce additional bending stresses; the WLL remains essentially unchanged.
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Question 39. Which of the following is a primary advantage of using a magnetic lifting device for steel plates? A) Ability to lift non‑ferrous materials B) No need for rigging hardware like shackles or slings C) Unlimited load capacity D) Resistance to high temperatures Answer: B Explanation: Magnetic lifters attach directly to ferrous surfaces, eliminating the need for additional rigging components. Question 40. In a load‑turning operation using a gin pole, the primary load path is: A) Horizontal shear in the gin pole B) Torsional stress in the boom C) Axial compression in the gin pole D) Bending moment at the base of the gin pole Answer: C Explanation: The gin pole primarily experiences axial compression as it lifts and pivots the load. Question 41. When a sling is used at a 20° angle from the vertical, the tension in the sling is approximately: A) 1.05 × load B) 1.10 × load C) 1.50 × load
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Question 44. A synthetic sling is rated for 5 kN WLL. If it is used in a choker configuration, what is the typical derated WLL? A) 5 kN (no change) B) 4 kN C) 2.5 kN D) 1 kN Answer: C Explanation: Choker hitches introduce a severe bend; manufacturers usually derate the sling to 50 % of its straight‑line WLL. Question 45. During a lift, a load experiences “shock loading” when the crane stops abruptly. Which factor most influences the magnitude of the shock load? A) Length of the sling B) Weight of the crane operator C) Deceleration rate of the load D) Color of the load Answer: C Explanation: Shock load magnitude is directly proportional to the deceleration (Δv/Δt) experienced by the load. Question 46. In a rigging inspection, a “bird‑cage” defect is identified. This indicates: A) A twisted rope core B) A kinked rope with permanent deformation C) A broken wire in the strand
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D) Excessive corrosion on the outer wires Answer: B Explanation: Bird‑caging refers to a permanent kink that creates a cage‑like shape, compromising rope integrity. Question 47. Which of the following best describes the role of a “qualified person” under OSHA regulations? A) Anyone who has attended a safety meeting B) An individual with recognized expertise in a specific area and the ability to identify hazards C) The crane operator only D) The person who purchases the rigging equipment Answer: B Explanation: A qualified person possesses the training, experience, or education to recognize hazards and take corrective action. Question 48. When lifting a load in rain, which rigging component is most vulnerable to failure? A) Steel shackles (if not coated) B) Synthetic slings (due to reduced friction) C) Wire rope (due to corrosion) D) Spreader bars (due to slipping) Answer: C
