PRESSURE REVERSING VALVE ASSEMBLY FOR A DOWN-THE-HOLE PERCUSSIVE DRILLING APPARATUS

摘要

A pressure reversing valve for a down-the-hole percussive drilling ("DHD") apparatus has a first valve pressure surface, a second valve pressure surface and a third valve pressure surface. The first valve pressure surface engages an internal surface of a housing of the DHD hammer. The second valve pressure surface is in communication with a high pressure port of the DHD hammer. The third valve pressure surface is in communication with a passageway that extends through a distributor within the DHD hammer. The valve also includes a valve passageway that extends through the valve and which is in communication with a first volume of the DHD hammer. The first volume is formed by surfaces of the distributor and the third valve pressure surface.