A construction site is a noisy place to work, which makes nonverbal communication absolutely crucial for the job. The accepted method for the industry is hand signals. The Occupational Safety and Health Administration, or OSHA, actually requires a signal person be on every single site. All of our operators, oilers, drivers and mechanics are familiar with these signals, and we want to make sure you are too.
Source: http://www.craneblogger.com/crane-resource-library/crane-hand-signals/
Hoist
With forearm vertical, forefinger pointing up, move hand in small horizontal circles.
Lower
With arm extended downward, forefinger pointing down, move hand in small horizontal circles.
Use Main Hoist
Tap fist on head; then use regular signals.
Use Whipline
Tap elbow with one hand; then use regular signals.
Raise Boom
Arm extended, finger closed, thumb pointing upward.
Lower Boom
Arm extended, finger closed, thumb pointing downward.
Move Slowly
Use one hand to give any motion signal and place other hand motionless in front of hand giving the motion signal. (Hoist slowly shown as example.)
Raise the Boom & Lower the Load
Arm extended, fingers closed, thumb pointing upward, other arm bent slightly with forefinger pointing down and rotate hand in horizontal circles.
Lower the Boom & Raise the Load
Arm extended, fingers closed, thumb pointing downward, other arm with forearm vertical, forefinger pointing upward and rotate hand in horizontal circles.