| 摘要 |
<p>A screw is provided with a socket (26) whereby it can be driven either by a Phillips driver or by a square (Robertson) driver. The wings (34) of the socket have end walls (40) that curve convexly to such an extent that both the Robertson and the Phillips drivers are of the conventional size for that size of screw, yet each end wall is clear of the corner of the square recess (28), right down to the bottom of the end wall. The vertical side faces (30) for a Robertson driver have portions inclined at different angles. The upper and lower portions are inclined respectively at a greater angle to the vertical and a smaller angle to the vertical as compared to the side faces of a conventional Robertson driver. Consequently, a Robertson driver will contact the side faces part way along the faces.</p> |
