Self-tapping screw type fastener and push rod for brake booster using the same

摘要

A self-tapping screw type fastener of the present invention is characterized in that an external thread 7 of an adjusting rod (self-tapping screw) 5 is screwed into and fastened to an output rod 1 with tapping an internal thread 3 in an inner peripheral surface of a smooth prepared hole 2 of the output rod 1. The adjusting rod 5 has a threaded shaft 13 with the external thread 7 formed thereon and a smooth guide shaft 14 projecting from an end of the threaded shaft 13. The outer diameter R1 of the smooth guide shaft 14 is set to be smaller than the major diameter R4 of the external thread 7 and to be slightly larger than the minor diameter R2 of the external thread 7 or the minor diameter R3 of the internal thread 3. Because of the diameter difference "t" between the diameter R1 and the diameter R2 or R3, a step 20 is formed so that the step comes in contact with the nearest ridge of the internal thread 3, thereby preventing the adjusting rod 5 from getting loose.