UNIVERSE | SCIENCE | TECHNOLOGY on Instagram: "HANDCUFFS MECHANISM 🔒 | How Do Handcuffs Work? Handcuffs may look simple, but inside they use a clever mechanical locking system designed for quick restraint and high security. Each cuff has a ratcheting arm with teeth, similar to a zip tie. When the arm is pushed in, it rotates around a pivot and clicks tighter with every movement. Inside the cuff, a pawl (locking tooth) engages these teeth, allowing the cuff to tighten but not loosen on its own.