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a device that prevents a nut or bolt from working loose in a threaded joint under variable, impact, or vibratory loads. The most reliable and versatile types of lock nut incorporate a locking element between the nut and the bolt. Such lock nuts are used to attach roller bearings to the front axles of motor vehicles, where the loosening of a nut could cause an accident. Lock nuts placed between the nut and the part to be held in place are reliable if the threaded bolt (anchor bolt or stud) cannot turn. Threaded connections can also be secured by check nuts and by spring washers.