Relief device, its loosening operation tool, and relief device for bolt-nut fastening portion

摘要

An anti-loosening member which can not be easily removed if it is fastened, but can be removed using a dedicated loosening operation tool if necessary, and the means of which can not be easily understood by a third party, Provide a tightening and loosening operation tool. An anti-loosening member (1) includes a coil spring (2) fitted in a bolt member (8), which can not be withdrawn within a through hole (31) formed in an envelope (3). The inner circumferential surface of is formed into a smooth cylindrical surface so that the coil spring 2 can always idle. In the peripheral wall portion 33 of the through hole 31, two operation holes 34 are formed which penetrate the peripheral wall portion 33 in the radial direction of the through hole 31 and open at close positions of both retaining ring portions 32 respectively. The tightening and loosening operation tool 4 has a holding surface 5 that can be attached to the outer peripheral surface of the outer covering 3 of the pressure reducing member 1, and is inserted into the operation hole 34 of the pressure reducing member 1 on the inner side surface As a result, a single operation pin 6 is provided inside the through hole 31 to project the tip. [Selected figure] Figure 9