Do you believe split-lock washers actually lock threaded fasteners?

Yes. The split-lock washers are made from hardened spring steel that strongly resists compression. When the threaded fasteners are tightened, the protruding corner edges of the split-lock washers bite into both compressing surfaces in a manner that resists counter-clockwise rotation due due vibration in a manner similar to a ratchet &pawl. The geometry of forcing the sharp protruding corner into the contact fastener flat surface ensures that there will be some bite. If the split lock washer isn't made from spring steel or isn't harder that the fastener surfaces, it will not be as effective. I've left the split washers out of many toys I've assembled over the years and always regretted it afterwards.

Purpose Of Lock Washer

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RE:

Do you believe split-lock washers actually lock threaded fasteners?

If your answer is "yes", explain how it works?

If your answer is "no", explain why not?

Brian Z has it. But it's still important to use the proper torque since the tension between the OD threads and ID threads is the primary fastening "mechanism".

Yes, they actually do.

Because it will provide more grip and friction between screw and nut.

So, these are preferable.