| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small pressure angle by orienting a side wall of an arm in such a way that a vertical line drawn from a longitudinal axis is not shorter than the radius of a circle inscribed in a central member of a male coupling member. SOLUTION: First side walls 25, 25' are respectively formed at arms 12, 12', and both arms come in contact along these side wails. A clearance is formed between second side wails 26, 26', and a clearance is also formed between the trailing end parts 13, 13' of the arms 12, 12'. The second side walls 26, 26' are so oriented that vertical lines N, N' drawn from an axis A are not shorter than the corresponding radii R, R' of circles inscribed in the corresponding central portions 11, 11'. A second wall is therefore reinforced considerably. The second side walls are preferably directed substantially in a tangential direction with respect to the inscribed corresponding circles and C' so as to avoid stress concentration in the contact areas. |
