National Commission for the Certification of Crane Operators (NCCCO) Mobile Crane Practice Exam

Which of the following is considered duty-cycle work?

1. Rigging

2. Clam-shell digging

3. Steel erection

4. Equipment inspection

The correct answer is: Clam-shell digging

Duty-cycle work refers to operations where a crane engages in repetitive lifting and placing activities over an extended period. Clam-shell digging specifically involves the crane's hook and bucket or clamshell device being used to dig, lift, and reposition materials like soil or gravel multiple times in a cycle. This continuous operation qualifies as duty-cycle work due to its repetitive nature and the engagement in a consistent rhythm during the digging process. Other operations listed, such as rigging, steel erection, and equipment inspection, do not involve this continuous cycle of movement and repositioning for material handling. Rigging refers to the setup of load-bearing equipment, which is a preparatory step rather than a repetitive operation. Steel erection involves the placement of steel beams or structures, which may have a different operational rhythm and isn't as defined by the repetitive nature of duty-cycle activities. Equipment inspection focuses on assessing crane functionality, ensuring safety and compliance, rather than engaging in any active repetitive lifting tasks.