Which type of washer is specifically designed to prevent nuts from loosening?

Shake-proof washers are designed specifically to prevent nuts from loosening due to vibrations or movement. They typically feature a unique shape or serrated edges that create friction and hold the nut securely in place. When a nut is tightened onto a shake-proof washer, the design helps to resist rotational movement and the loosening that can occur from vibration or dynamic loads. This type of washer is particularly valuable in applications where mechanical components are subjected to constant movement or vibration, ensuring a more reliable and secure joint.

Standard washers, while they serve to distribute load and protect surfaces, do not inherently provide any anti-loosening properties. Split-lock washers, on the other hand, do offer some resistance to loosening but are not as effective as shake-proof washers in high-vibration situations. Fender washers are primarily used to increase the bearing surface of a fastener and do not serve the purpose of preventing loosening.