A hydraulic impact machine is a special machinery,its main output working parameters are impact energy and impact frequency.

Authors analysed the working parameter adjustment methods of home and abroad hydraulic impact machine,and showed their defects.

Analysis and countereasure on hydraulic impact phenomena in hydraulic systems;

Characteristics analysis of coupling vibration of hydraulic impact

By analyzing the impact phenomenon of hydraulic support's hydraulic system,this research finds out the cause of hydraulic impact lies in the discontinuity of hydraulic flow velocity.

On the hydraulic shock in steering system of submarine;

On the basis of system design, the author analyzes the origin of hydraulic shock and cavitation erosion etc phenomena.

Through analysis of the hydraulic shock produced in the course of reversing of the reversing valve used in the cylinder pump circuit pump, the paper shows that this hydraulic shock in the return oil pipe in the hydraulic cylinder is the result from the mutual effect due to the oil inertial force and the loading inertia force.

Some unresolved problems are put forward according to the using conditions of the domestic reverse-circulation percussion rigs, and the rig's percussion mechanism, "invalid percussion", the utility of hydraulic system and safety in production are discussed in this paper.

Some key technical problems in research and manufacture of CFZ-1500 percussion reverse circulation drill are discussed in this paper, including crank connecting rod clevel automatical percussion mechanism, forced balance of synchronous hoist system, reverse circulation system as well as percussion bit.