| 摘要 |
A drive element (10) is provided for coupling together rotatable shafts (12 and 14). The shafts (12 and 14) are able to rotate about their respective longitudinal axes (12A and 14A). Additionally, the shafts (12 and 14) can pivot relative to each other about a pivot point P which is coincident with the geometric centre of the drive element (10). Drive element (10) includes a groove (20) for receiving a tongue (16) of shaft (12); and, a tongue (22) which is seated in a groove (18) formed in shaft (14). Surface (26) of the groove (20) and surfaces (34) on opposite sides of the tongue (22) are shaped so that as the axes of rotation (12A and 14A) of the shafts (12 and 14) are pivoted relative to each other through a predetermined range of angles the respective loci of closest contact between the shafts (12 and 14) and the pivot point P remains constant. Accordingly the total length of a universal coupling drive (24) composed of the shaft (12) element (10) and shaft (14) remains constant for that predetermined range of pivoting of the shafts (12 and 14).
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