To provide a drop-off preventive bolt and a nut wherein a nut fastener groove and a nut fastener covering hole are provided on a screw part, a nut fastener is fixed, drop-off of the bolt and the nut is prevented, looseness is prevented, and vibration is absorbed.
The nut fastener groove 5 deeper than a thread bottom is cut on the bolt screw part, and the nut fastener 4 attached to the nut fastener groove 5 has an inside diameter equivalent to or a little smaller than a thread bottom diameter and an outside diameter a little larger than a bolt thread diameter, and an inside diameter of the outer side of the drop-off preventive nut is the nut fastener covering hole 6 enlarged in order to cover the outside diameter of the nut fastener 4, and the nut fastener is locked by a side surface of the nut fastener groove 5 of the bolt screw part and an inner surface of the nut fastener covering hole 6, and the nut is prevented from being dropped off. After fixing by a fixing nut 8, a coil spring 9 is inserted into the screw part, and looseness of the fixing nut 8 is suppressed. When the fixing nut 8 is loosened, pushing force of the coil spring 9 becomes stronger.
MAEDA SATORU
OTAKE SHINGO
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