| 摘要 |
<p>A hammer drill with an air cushion impact mechanism has a latch device, comprising a resilient annular body (50; 50a), for the ram (27), and an annular resilient damping element (50; 50b) for damping the recoils of the beat piece (29). The annular body (50; 50a) and the damping element (50; 50b) are located within the rotationally driven spindle (39) of the tool bit holder (3) in a plane normal to the spindle axis, and are held against axial displacement between an annular plate 51 and a washer 52 (51,52) common to them both. The latch device and the damping element are preferably O-rings, one inside the other, and may be integral (50) or separate (50a and 50b). The damping element (50b) is preferably thicker axially than the latch device (50a). Recoil blows from the beat piece are transmitted to the plate 51 and from there to the member 50 which is compressed to damper the blow. At idle the ram 27 moves forward sufficiently for the inner ring of the member 50 to engage a groove 35 of the ram 27 to latch the ram. <IMAGE></p> |
