a machine has a movable boom for lifting a load , and an overload sensing device mounted on the boom to sense boom deflection . the overload sensing device includes a rigid beam having one end secured to a vertical side plate of the boom only by anchors spaced widely apart , welded preferably on opposite sides of the centroid or neutral axis of the boom side plate . the beam has a free end , on which an adjustable contact plate is carried , to engage a switch adjustably carried on a mounting plate secured to the beam side plate .