| 摘要 |
PURPOSE: To secure the heat-resisting quality of the coupling portion of an outer shaft and an inner shaft and realize the reduction of collapse load and in addition shorten a time needed for large collapse load. CONSTITUTION: The female serration groove 13 of an outer shaft 11 inner periphery surface and the male serration groove 14 of an inner shaft 12 outer periphery surface are engaged with each other. A recessed portion 16 is provided on the outer periphery surface of the inner shaft 12 in adjustment with the valley portion 15 of the male serration groove 14, and a steel ball 17 is inserted into this recessed portion 16, and part of this steel ball 17 is made to bite into the top portion 18 of the mountain portion of the female serration groove 13. A flat portion 19 is provided by removing part of the male serration groove 14, and the frictional engagement between the male serration groove 14 and the top portion 18 crushed by means of the steel ball 17 is prevented. |
