As we all know,there are some noisy in construction site.If we can correctly use hand signals,it will make a good effect for our work.Now,let ZZHZ tells you the detailed information:
1.Lift the arm of crane    
  Streth out one of your hands,thumb up, the other fingers hold together,and move your arm up.                 
2.Put down the arm of crane
  Streth out one of your hands,thumb down,the other fingers hold together,and move your arm dowm.

3.Rotate the arm of crane
  Make the arm at the level pointing to the direction of rotary,streth out thumb,seperate with the other fingers,rotary with the aix of wrist.
4.Lift the arm of crane slightly
  Put one arm at the front of chest,five fingers unbend,the palm upwards,stay unmovable;the other hand oppose to the plam of the front hand,move up slightly.
5.Put down the arm of crane slightly
  Put one arm at the front of chest,five fingers unbend,the palm downwards,stay unmovable;the other hand oppose to the plam of the front arm,move down slightly.