When an operator can't see the load or its path, a signal person directs the lift. Every signal has one agreed meaning, so everyone on the crew has to know them. Post the signal chart where the crew can see it on the job site.
The standard crane hand signals. The written descriptions are below.
Audible signals (horn)
- One sound: Stop
- Two sounds: Go forward
- Three sounds: Back up
Stop signals
- Stop: Arm extended, palm down, move the arm back and forth horizontally.
- Emergency stop: Both arms extended, palms down, move both arms back and forth horizontally.
- Dog everything: Clasp hands in front of the body. Hold everything where it is.
Hoist signals
- Hoist: With the forearm vertical and the forefinger pointing up, move the hand in a small horizontal circle.
- Lower: With the arm extended downward and the forefinger pointing down, move the hand in a small horizontal circle.
- Use main hoist: Tap a fist on the head, then use regular signals.
- Use whipline (auxiliary hoist): Tap the elbow with one hand, then use regular signals.
- Move slowly: Use one hand to give any motion signal and hold the other hand motionless in front of the hand giving the signal (for example, hoist slowly).
Boom signals
- Raise boom: Arm extended, fingers closed, thumb pointing upward.
- Lower boom: Arm extended, fingers closed, thumb pointing downward.
- Raise the boom and lower the load: Arm extended, thumb pointing up, flex the fingers in and out as long as load movement is desired.
- Lower the boom and raise the load: Arm extended, thumb pointing down, flex the fingers in and out as long as load movement is desired.
- Swing: Arm extended, point with a finger in the direction of the boom's swing.
- Extend boom (telescoping booms): Both fists in front of the body with the thumbs pointing outward.
- Retract boom (telescoping booms): Both fists in front of the body with the thumbs pointing toward each other.
- Extend boom, one-hand signal: One fist in front of the chest with the thumb tapping the chest.
- Retract boom, one-hand signal: One fist in front of the chest with the thumb pointing outward and the heel of the fist tapping the chest.
Travel signals
- Travel: Arm extended forward, hand open and slightly raised, make a pushing motion in the direction of travel.
- Travel, both tracks: Use both fists in front of the body, making a circular motion about each other to show the direction of travel, forward or backward (land cranes only).
- Travel, one track: Lock the track on the side shown by the raised fist. Travel the opposite track in the direction shown by the circular motion of the other fist, rotated vertically in front of the body (land cranes only).