Japan Tokyo-Metal’s “YOSHER” Washer under Development

Tokyo-Metal Co., Ltd. is developing an upgraded spring washer named “YOSHER”. It operates as follows. When the washer is fastened under a crooked state, the rebound force on the washer will help hamper loosening. This simple mechanism never exists in previous washers, and it can prevent accidents caused by loosening and dropping.The fundamental concept of “YOSHER” washer is “a auxiliary hardware of reliability and safety”, aiming at preventing bolts and nuts from loosening. The inner bore of the washer crooks along the thread root. When fastening with a parent metal and a nut, “YOSHER” can bite into the thread root and a part of its bore will crook and protrude over one crest, turning into a ring shape. Thus, a rebound force is formed between the parent metal and the nut, further preventing loosening.