| 摘要 |
The invention provides a valve arrangement for use in a hydraulic percussive rock drill (10) wherein a piston (18), located in a cylinder (12, 14), is caused to reciprocate by hydraulic fluid flow, the valve arrangement including a valve (24) controlling the said hydraulic fluid flow, the valve being positioned between opposing first and second surfaces (26A, 32A) of two walls (26, 32) in which are formed at least first and second ports (28, 34) respectively, the valve having at least a third port (38) which is movable into register, and out of register, with the first and second ports, and having first and second hydraulic fluid sealing surfaces (24A, 24B) which respectively engage with the said first and second surfaces (26A, 32A) at least when the third port (38) is out of register with the first and second ports (28, 34); and a hydraulic rock drill (10) having an above-mentioned valve arrangement. |
