Which locking device is the simplest for preventing loosening due to vibrations?

The simplest locking device for preventing loosening due to vibrations is jam type nuts. This method utilizes two nuts tightened against each other on a threaded bolt. When properly applied, the friction created between the two nuts helps to keep them secure, effectively preventing the nut from loosening under vibration. The direct interface and mechanical locking between the two nuts provide a reliable resistance to loosening, making it a straightforward and effective solution.

Other locking devices, while they can be effective in certain scenarios, may not be as simple or efficient as jam type nuts. For example, lock washers require specific placement and can sometimes bend or deform if over-tightened, which compromises their effectiveness. Thread sealing compound is primarily designed to seal threads against leakage rather than to prevent loosening. Split pins require the additional step of inserting and bending the pin through a hole in the bolt, making them more complex to implement compared to the straightforward design of jam type nuts.