What are some hand signals for mobile cranes?

The four most common signals for mobile crane operators are hoist, lower, boom-up and boom-down, according to the Associated General Contractors of California. The official hand signals for the Signalperson Certification Exam, administered by the National Commission for Certification of Crane Operators, are available online at AGC-CA.org.

AGC California provides a PDF version of the NCCCO Signalperson Reference Manual. Candidates for the exam should be familiar with all crane operator and signaling sections of ASME B30.5-2007 and OSHA 29 CFR Part 1926.

The "hoist" signal uses the right arm extended to the side at a right angle at the elbow, and the right index finger pointing upward and making small circles, explains AGC California. "Lower" is signaled the same way, but with the right index finger pointing downward. The "boom-up" signal has the right arm extended to the side and the fist forming a thumbs up. "Boom-down" is the same, except the fist is forming a thumbs down.