a tool for improving drill bit penetration in the drilling of oil , gas and water wells and the like is provided . the tool includes a housing and a mandrel connected for co - rotation and limited axial movement under the influence of a spring fluid . the mandrel and drill bit in conjunction with the spring fluid form a spring - mass system having a damped fundamental frequency of oscillation approximately equal to a characteristic frequency of forces which act on the drill bit during drilling . resonance causes the forces acting on the bit to be amplified and magnified , thereby increasing the drilling rate .