Mechanical vibrator having eccentric masses

A mechanical vibrator for vibrating screens or other equipment, comprising:

• a bearing housing affixed to a side wall of the equipment and carrying, internally and symmetrically to a center line:
• a pair of bearings;
• a shaft supported by the pair of bearings and having an inner end portion and an outer end portion projecting outwardly from the bearing housing, wherein the inner end portion and the outer end portion of the shaft respectively affix a first counterweight and a second counterweight having respective first and second eccentric masses of different values and presenting respective first and second radial extensions and first and second distances to the center line of the bearing housing, which are dimensioned so that said first and second counterweights generate equal loads on the bearings and balance of bending moments on the side wall of the equipment, said second counterweight selectively and removably attached a third counterweight presenting a third eccentric mass, which is maintained aligned with the center line of the bearing housing to provide a respective variation of the total eccentric mass of the vibrator, without changing the balance of the distribution of loads on the bearings.