Download Digger Derrick Operator Recertification Program Certification Review Guide [DDORP] and more Exams Technology in PDF only on Docsity!
Certification Review Guide [DDORP]
Question 1. What is the primary purpose of using outrigger pads when setting up a digger derrick? A) To increase the boom length B) To distribute surcharge pressure over a larger area C) To lower the machine’s center of gravity D) To provide a platform for the operator Answer: B Explanation: Outrigger pads spread the weight of the machine over a bigger surface, reducing ground pressure and preventing settlement on soft soils. Question 2. Which soil type typically has the lowest bearing capacity for a digger derrick? A) Compacted clay B) Loose fill (sand and gravel) C) Bedrock D) Well‑graded sand Answer: B Explanation: Loose fill lacks cohesion and can compress under load, offering the lowest bearing capacity compared to more stable soils or rock. Question 3. When identifying underground hazards, which of the following is NOT a common utility to locate before operation? A) Gas lines B) Water mains C) Fiber‑optic cables
Certification Review Guide [DDORP]
D) Asphalt pavement Answer: D Explanation: Asphalt pavement is a surface material, not an underground utility; gas, water, and fiber‑optic lines must be identified to avoid accidental strikes. Question 4. According to OSHA, the “Limits of Approach” for a 15 kV overhead line is: A) 10 ft (3 m) B) 15 ft (4.5 m) C) 20 ft (6 m) D) 30 ft (9 m) Answer: C Explanation: OSHA’s Table 1‑1 sets a 20 ft (6 m) minimum approach for lines up to 15 kV to protect workers from electrical hazards. Question 5. Which device is specifically used to prevent the head‑ache ball from striking the boom tip during a lift? A) Load Moment Indicator (LMI) B) Anti‑Two Block (A2B) C) Hydraulic Overload Protection (HOP) D) Swing‑limit sensor Answer: B Explanation: The A2B system detects impending two‑block conditions and locks the hoist to protect the boom tip from impact.
Certification Review Guide [DDORP]
D) Using a larger diameter auger than recommended Answer: C Explanation: Uneven soil resistance can cause the auger to rotate while translating, creating a corkscrew motion especially under high torque. Question 9. Which component of the pole handling system is used to plumb a pole vertically? A) Pole claw (grabber) B) Winch drum C) Hydraulic cylinder D) Swing lock Answer: A Explanation: The pole claw grips the pole and, together with the winch, allows the operator to raise and align it vertically (plumb). Question 10. The digital readout of a Load Moment Indicator (LMI) primarily displays: A) Hydraulic pressure in the boom cylinder B) The current swing angle in degrees C) The calculated moment (load × radius) in kip‑ft or kN‑m D) The engine RPM Answer: C Explanation: An LMI calculates and shows the moment created by the load at a given radius, warning the operator when limits are approached.
Certification Review Guide [DDORP]
Question 11. What wind speed (in mph) generally requires the operator to cease pole‑raising operations on a typical digger derrick? A) 15 mph B) 20 mph C) 25 mph D) 30 mph Answer: C Explanation: Most manufacturers set a 25 mph (≈ 40 km/h) wind limit for pole work due to increased “sail area” and risk of pole swing. Question 12. How does cold weather affect hydraulic fluid in a digger derrick? A) Increases viscosity, reducing flow rate B) Decreases viscosity, increasing flow rate C) No effect on viscosity D) Causes the fluid to expand, raising pressure Answer: A Explanation: Low temperatures thicken hydraulic fluid, raising viscosity and potentially slowing cylinder response. Question 13. The “boom angle” is measured between the boom and which reference line? A) Ground surface B) Horizontal plane of the turntable C) Vertical mast
Certification Review Guide [DDORP]
Question 16. The “Design Factor” (Safety Factor) for a synthetic rope is typically: A) 3. B) 4. C) 5. D) 6. Answer: D Explanation: Synthetic ropes are often assigned a higher design factor (≈ 6.0) due to their lower fatigue resistance compared with steel wire rope. Question 17. Which part of the live mast houses the hydraulic cylinders that raise and lower the boom? A) Winch drum housing B) Rotation gear box C) Boom pivot housing D) Mast cylinder cradle Answer: D Explanation: The mast cylinder cradle contains the hydraulic cylinders responsible for boom lift and lower functions. Question 18. During a daily inspection, the operator should check the condition of: A) Only the boom tip for cracks B) All hydraulic hoses, pins, and safety devices C) The engine oil level only D) The radio antenna for signal strength
Certification Review Guide [DDORP]
Answer: B Explanation: Daily inspections cover hydraulic hoses for leaks, pins for wear, and safety devices (LMI, A2B) to ensure safe operation. Question 19. Dielectric testing of insulated boom sections is required when the boom may contact which of the following? A) Concrete structures B) Non‑metallic poles C) Live electrical conductors above 50 kV D) Ground water Answer: C Explanation: Dielectric testing verifies insulation integrity for booms that could approach high‑voltage lines (≥ 50 kV). Question 20. Which statement best describes the limitation of “insulating” equipment compared to “non‑insulating” equipment? A) Insulating equipment can lift heavier loads B) Insulating equipment is only rated for voltages up to 15 kV C) Insulating equipment eliminates the need for a spotter D) Insulating equipment cannot be used in wet conditions Answer: B Explanation: Insulating equipment is typically rated for lower voltages (often ≤ 15 kV); beyond that, non‑insulating equipment with proper clearances is required.
Certification Review Guide [DDORP]
D) Weight of the operator’s safety harness Answer: B Explanation: The headache ball and its rigging are always considered a deduction because they are part of the lifting system. Question 24. The “Bold Line” on a load chart indicates: A) Maximum hydraulic pressure limit B) Structural limit (boom strength) versus stability limit (tipping) C) Recommended wind speed limit D) Minimum required clearance from power lines Answer: B Explanation: The bold line distinguishes whether the capacity limit is due to structural strength or stability (tipping) of the machine. Question 25. When transitioning from a fully retracted boom to a fully extended boom, the operator must: A) Increase the hydraulic pressure by 20 % B) Re‑calculate the load radius for the same load weight C) Reduce the swing speed to half D) Disable the LMI Answer: B Explanation: Extending the boom changes the radius, affecting moment; the operator must verify that the load remains within capacity at the new radius.
Certification Review Guide [DDORP]
Question 26. How is the center of gravity (CG) of an irregularly shaped load most accurately determined? A) By using the load’s weight only B) By measuring the distance from the load’s geometric center to the hook C) By performing a moment balance calculation using weight distribution data D) By assuming the CG is at the midpoint of the load’s length Answer: C Explanation: A moment balance (Σ M = 0) using known weight distribution points provides the precise CG location for irregular loads. Question 27. OSHA Subpart CC primarily governs which aspect of digger derrick operation? A) Electrical safety around power lines B) Crane and derrick safety in construction C) Hazard communication and labeling D) Personal protective equipment (PPE) standards Answer: B Explanation: OSHA 1926 Subpart CC covers safety requirements for cranes and derricks used in construction. Question 28. Which OSHA standard addresses safety for workers exposed to electric power generation, transmission, and distribution? A) 1926. B) 1910.
Certification Review Guide [DDORP]
Question 31. An operator has the right to refuse a lift if: A) The load is heavier than the net capacity by 5 % B) The wind speed exceeds the manufacturer’s limit C) The swing radius is larger than the boom length D) The boom angle is less than 30° Answer: B Explanation: Exceeding wind speed limits creates an unsafe condition; the operator may refuse the lift for safety. Question 32. The “Total Lift Plan” must be developed by: A) The site foreman only B) The crane manufacturer’s representative C) The qualified lift supervisor, often the operator, in coordination with the crew D) The equipment rental company Answer: C Explanation: A qualified lift supervisor (often the operator) prepares the lift plan, considering all variables and coordinating with the crew. Question 33. Which of the following is a correct method for establishing a safe “Limits of Approach” when working near a 30 kV line? A) Maintain a minimum distance of 10 ft (3 m) B) Use insulated links and stay within 15 ft (4.5 m) C) Keep a minimum distance of 30 ft (9 m)
Certification Review Guide [DDORP]
D) No specific distance is required if a spotter is present Answer: C Explanation: For 30 kV lines, OSHA recommends a minimum approach distance of 30 ft (9 m) unless protective measures are used. Question 34. During a pole‑raising operation, the “sail area” of the pole is most affected by: A) The pole’s length and diameter B) The weight of the headache ball C) The boom’s hydraulic pressure D) The ground’s bearing capacity Answer: A Explanation: The sail area is the surface area exposed to wind; it increases with pole length and diameter, influencing wind limits. Question 35. Which maintenance action should be performed monthly on the digger derrick’s rotation gear? A) Replace all hydraulic fluid B) Lubricate gear bearings and inspect for wear C) Paint the gear housing D) Adjust the boom angle sensor Answer: B Explanation: Monthly lubrication and wear inspection of the rotation gear ensures smooth operation and prevents gear failure.
Certification Review Guide [DDORP]
Answer: A Explanation: The headache ball acts as a counterweight, helping to balance the load and improve stability. Question 39. Which of the following is a required element of a site’s “Public Access Restriction” plan when operating a digger derrick? A) Posting warning signs and establishing a barrier zone B) Providing free helmets to all by‑standers C) Installing extra lighting on the boom D) Offering a guided tour of the operation Answer: A Explanation: Restricting public access involves signage and physical barriers to keep unauthorized personnel away from hazardous zones. Question 40. If the boom angle is set to 45°, and the boom length is 30 ft, what is the tip height above the ground? A) 15 ft B) 21.2 ft C) 30 ft D) 42.4 ft Answer: B Explanation: Tip height = Boom length × sin(45°) = 30 × 0.707 ≈ 21.2 ft.
Certification Review Guide [DDORP]
Question 41. Which of the following statements about “hydraulic overload protection (HOP)” is correct? A) It permanently disables the hoist when activated B) It provides an audible alarm and trips the pump to prevent damage C) It increases hydraulic pressure to maintain lift speed D) It only monitors the swing motor Answer: B Explanation: HOP detects excessive hydraulic pressure, sounds an alarm, and may shut down the pump to protect the system. Question 42. During a cold‑weather operation, the operator notices the boom lifts slower than usual. The most likely cause is: A) Low hydraulic fluid viscosity due to cold B) Increased hydraulic fluid viscosity reducing flow rate C) Over‑pressurization of the boom cylinder D) Expansion of the boom steel causing binding Answer: B Explanation: Cold temperatures increase hydraulic fluid viscosity, which slows cylinder movement. Question 43. Which OSHA regulation defines the minimum safe distance for a worker to operate a crane near a live 115 kV line? A) 10 ft (3 m) B) 20 ft (6 m) C) 30 ft (9 m)
Certification Review Guide [DDORP]
Question 46. Which factor does NOT directly affect the stability of a digger derrick during a lift? A) Ground bearing capacity B) Boom angle C) Hydraulic fluid color D) Load radius Answer: C Explanation: Hydraulic fluid color is unrelated to stability; ground capacity, boom angle, and load radius are critical factors. Question 47. In a load chart, the “transition radius” refers to: A) The radius at which the load capacity changes from structural to stability limit B) The maximum radius allowed for pole work C) The radius where the boom tip reaches its highest point D) The distance between the boom base and the operator’s seat Answer: A Explanation: The transition radius marks where the limiting factor switches between structural strength and tipping stability. Question 48. Which of the following is a correct method for inspecting the winch drum for wear? A) Listening for abnormal noise while operating the winch B) Visually checking for gouges, cracks, and uneven wear on the drum surface
Certification Review Guide [DDORP]
C) Measuring the drum temperature with an infrared thermometer D) Counting the number of rotations per minute Answer: B Explanation: Visual inspection for physical damage (gouges, cracks, uneven wear) is the standard method for assessing drum condition. Question 49. When a digger derrick is positioned with the turntable aligned to the rear, the primary stability benefit is: A) Reduced swing arc B) Improved operator visibility C) Greater weight distribution over the outrigger pads D) Decreased hydraulic pressure Answer: C Explanation: Aligning the turntable rearward places the boom’s load over the outrigger pads, enhancing weight distribution and stability. Question 50. Which OSHA hand signal indicates “stop all motion”? A) Both arms raised, palms facing each other B) One arm extended forward, palm down C) Both arms crossed over the chest D) One arm waving side to side Answer: C Explanation: Crossing both arms over the chest signals “stop all motion” to the crane operator.
