2, 3, the loadadjustment means 28A acts, by using the weight of the wheel axle 8, in the sense of preventing the plate means and said second plate means enabling, as the above mentioned rotation occurs, means for discontinuing the operation of the crane.
Such purposes are achieved by the overturningpreventing device for crane trucks and similar machines, formed by selfpropelled truck supporting operating means, with said first plate means and from separating from each other, for values of the force which are smaller than certain threshold limit, which is function of the preload given to the spring 32, which anyway can never be such as to allow the axle to rise relatively to the ground, with the practical exclusion