Abstract: A pneumatic rockdrill having a housing; a cylinder connected to a compressed air supply inlet by a set of air passages; an impact piston, at least part of which is reciprocable within the cylinder; and a controller for the supply of compressed air from the air supply inlet to the cylinder. At least one pair of contact surfaces are located at the interface between the piston and the cylinder, where those relatively moving parts contact one another. At least one water supply inlet and water paths connected to the water supply inlet(s) are configured so as in operation to convey water to a drilling tool to flush a hole being drilled, and to supply water to wet the contact surfaces.

Abstract: The hydraulic reciprocating mechanism has a housing and a piston located reciprocably in the housing. The piston and housing define a supply chamber and a return chamber. The return chamber has valve seats at either end. There is an inlet to the supply chamber for pressurized hydraulic fluid and an exhaust outlet from the return chamber. An interconnecting passage extends between the supply chamber and the return chamber. A single popper valve is located reciprocably in the return chamber and is moved by hydraulic forces between positions in which it seats on the respective valve seats. In one position of the popper valve it closes the exhaust outlet and opens the interconnecting passage to admit hydraulic fluid from the supply chamber to the return chamber. This has the result hydraulic fluid in the return chamber drives the piston in one direction.

Abstract: This invention relates to a cyclic hydraulic actuator, and more particularly to an actuator for a rock drill and includes: a housing; at least two chambers in the housing; a fluid passage between a first of the chambers and the outside of the housing for feeding a liquid at supply pressure to the chamber during operation of the actuator; a fluid passage between a second of the chambers and the outside of the housing for exhausting liquid from the second chamber during operation of the actuator; a piston reciprocable on an axis in at least the first and second chambers with the piston including an exposed piston area in each of the two chambers for causing, with the liquid at supply pressure, reciprocation of the piston; an inlet valve for opening and closing the second chamber to liquid at supply pressure in the first chamber; an exhaust valve for opening and closing the exhaust passage; the inlet and exhaust valves, chambers and exposed piston areas being so arranged that during cyclic operation of the actua