NCCCO Tower Crane Erection, Climbing, and Dismantling 2 — Questions and Answers
Question 1: Who must supervise tower crane erection and dismantling?
- Any construction worker
- A competent person with specific knowledge of the tower crane model and the manufacturer's erection/dismantling procedures (Correct answer)
- The building architect
- Only the crane rental company
Correct answer: A competent person with specific knowledge of the tower crane model and the manufacturer's erection/dismantling procedures
OSHA requires a competent person specifically knowledgeable about the tower crane model being erected/dismantled. This person must understand the manufacturer's procedures and potential hazards.
Question 2: What is 'climbing' a tower crane?
- An operator climbing a ladder to reach the cab
- The process of increasing the tower height by inserting new tower sections, allowing the crane to grow taller as the building rises (Correct answer)
- Moving the crane to a higher floor
- Raising the boom angle to its maximum
Correct answer: The process of increasing the tower height by inserting new tower sections, allowing the crane to grow taller as the building rises
Climbing involves hydraulically jacking up the top section of the crane and inserting a new tower section underneath. This allows the crane to increase in height as construction progresses.
Question 3: What is the greatest hazard during tower crane climbing operations?
- Height
- Structural instability during the transition when the crane is temporarily supported by the climbing frame rather than bolted tower connections (Correct answer)
- Wind at elevation
- Noise from hydraulic jacks
Correct answer: Structural instability during the transition when the crane is temporarily supported by the climbing frame rather than bolted tower connections
During climbing, the crane's upper structure is temporarily supported by hydraulic jacks rather than permanent bolted connections. This creates a period of reduced stability where precise procedures are critical.
Question 4: What weather condition most affects tower crane erection and dismantling?
- Rain
- Wind — tall, lightweight tower sections and boom components have large sail areas and are extremely sensitive to wind at elevation (Correct answer)
- Temperature
- Humidity
Correct answer: Wind — tall, lightweight tower sections and boom components have large sail areas and are extremely sensitive to wind at elevation
Tower crane components are long and relatively lightweight, creating large sail areas. Wind at elevation is typically stronger than at ground level, making component handling dangerous in even moderate winds.
Question 5: What must be verified before each climbing operation?
- That lunch has been delivered to the cab
- Hydraulic system integrity, climbing frame bolt torque, tower section alignment, weather conditions, and clear communication between all crew members (Correct answer)
- That the building has reached the next floor
- Only that the hydraulic jacks are working
Correct answer: Hydraulic system integrity, climbing frame bolt torque, tower section alignment, weather conditions, and clear communication between all crew members
Pre-climbing checks include hydraulic system inspection, climbing frame integrity, bolt torque verification, weather assessment, communication check, and confirmation that the area below is clear.
Question 6: How are tower sections typically lifted into position during erection?
- By helicopter
- By the tower crane itself (self-erecting) or by an assist mobile crane (Correct answer)
- Carried up by workers
- Pushed up from the ground with hydraulic rams
Correct answer: By the tower crane itself (self-erecting) or by an assist mobile crane
Tower sections are lifted into position either by the tower crane using its own hoist (for climbing operations) or by a mobile assist crane during initial erection and final dismantling.
NCCCO Tower Crane Erection, Climbing, and Dismantling 2
Who must supervise tower crane erection and dismantling?