| 摘要 |
A power transmission device allowing axial displacement for use in drilling machines and the like comprises an element which is rotatable by means of a motor (2) by the intermediary of means engaging each other and having complementary internal and external grooves and ridges, and which is axially displaceable relative to a frame (1). The novel features of the invention reside in that a first element (13) is hollow and provided with longitudinal internal grooves and ridges (15), that a second element (17) is provided only at a free end extending into the hollow element, with short external grooves and ridges (19), the first element (13) being radially non-displaceably mounted at both ends while the second element (17) is mounted by means of a single bearing at the frame (1). |
