| 摘要 |
A percussion device having, inside a machine housing (7), a movable percussive piston (2), the movement of which being controllable through a movable valve body (5), which is arranged to, in dependence of a signal indicating the axial position of the percussive piston, alternately to a pressure source and to a low pressure connect a chamber, in which a driving surface on the piston (2) is located, whereby control channel means (10, 12; 10', 12') for transmitting said signal have opening means opening into a cylinder space for receiving the piston (2) for co-operation with a control edge (11,13) on the piston. Adjustment means are arranged for making possible an adjustment of which axial position of the piston said signal is transmitted. The adjustment means includes at least one axially displaceable control means (9, 9', 9''), which contacts the piston, and which includes a portion (10, 12; 10', 12') of the control channel means including the opening means. The invention also concerns a rock drilling machine and a method. |
