Abstract: The invention relates to a balanced supporting arm, comprising a substantially elongate structural member which is mounted on a supporting assembly for tilting movement and which is provided with at least one bellows mounted under at least one end of the supporting arm. According to the invention, the bellows has an inoperative condition wherein it is at least substantially empty and an operative condition wherein it is filled with a gas under a predetermined working pressure. The balanced supporting arm comprises means for detecting the tilting speed of the supporting arm and, further, means, connected with the means for detecting the tilting speed, for bringing the bellows from the inoperative condition into the operative condition when the means for detecting the tilting speed detect that the tilting speed exceeds a predetermined value.