Hydroacoustic apparatus and valving mechanisms for use therein

An impact tool for producing percussive forces for application to a load which comprises

• a housing having a generally cylindrical opening therein,
• a hammer mounted in said opening for oscillatory movement in opposite directions axially of said opening toward and away from an impact position, said hammer and said housing including a side wall defining in said opening an annular cavity,
• a valve mechanism modulating the flow of hydraulic fluid into and out of said cavity for producing pressure variations therein for sustaining the oscillations of said hammer,
• said valve mechanism including a valve element mounted in said cavity for movement in opposite directions axially of said cavity,
• pressurized hydraulic fluid supply and return means in said housing including supply and return ports into said cavity spaced from each other in a direction axially of said cavity and disposed in porting relationship with said valve element to alternately open and close said ports as said valve moves in said opposite directions,
• said hammer having a radially extending portion which engages said valve element when said hammer moves in one of said opposite directions and moves said valve element therewith in said one of said opposite directions,
• said valve element and the side wall of said housing which defines said cavity forming a chamber therebetween extending axially of said housing, said valve element having a portion extending radially into said chamber and presenting an area in a plane perpendicular to the axis of said housing,
• means communicating with at least one of said pressurized hydraulic fluid supply and return means for providing communication between said chamber and said supply and return means for applying hydraulic forces acting continuously in the other of said opposite directions upon said valve element to move said valve element continuously in the other of said opposite directions.