Patent ID: 8887835

Claim:
A drilling apparatus comprising: a hydraulically powered hammer comprising: a piston to impact a drill bit; a shuttle valve to control reciprocation of the piston; an accumulator for hydraulic fluid; at least one drill rod comprising: a first connection valve for connection of the drill rod to a connection valve of the hammer; and a second connection valve for connection of the drill rod to the first connection valve of a like drill rod or to a rotation device, wherein the piston and shuttle valve are positioned substantially in-line to the axis of movement of the hammer; the accumulator is positioned proximate to the shuttle valve; and the first connection valve and second connection valve comprise at least one poppet valve positioned proximate to a corresponding valve seat in a hydraulic fluid return line, wherein the at least one poppet valve is biased onto said corresponding valve seat to prevent reverse flow of return hydraulic fluid through the first and second connection valves while allowing for forward flow of return hydraulic fluid through the first and second connection valves.