| 摘要 |
A pressure-medium driven percussion device including a body, a drill shank gliding axially in the body for transmitting percussions to a drill rod and a percussion piston moving in the body for directing percussions axially to the drill shank. The drill shank includes a lifting piston which moves in a lifting cylinder within the body. The body further includes a channel passing to the lifting cylinder for supplying and removing pressure medium into and out of the lifting cylinder and seals located between the body and the drill shank at both sides of the lifting cylinder. An equalizing channel is located between each seal and a corresponding choking slot. A valve connects the equalizing channels to the source of pressure medium when a channel passing to lifting cylinder is connected to a pressure medium container, and, correspondingly, to the pressure medium container when the channel passing to the lifting cylinder is connected to the source of pressure. |
