| 摘要 |
<p>The device consists of a casing (1), a striker (2) mounted inside it and provided with openings (5), an air-distributing sleeve (6), an elastic element (7) and a threaded bushing (8). The external surface of the threaded bushing (8) is provided with grooves (9) oriented at an angle to the axis of the device. The earth enters the grooves (9) of the threaded bushing (8) during the movement of the device and creates a circumferential force fixing the threaded bushing (8) in relation to the casing (1).</p> |
