Hengli Spring Box

An ideal constant-force spring is one that applies a constant force throughout its range of motion, meaning it does not follow Hooke's Law. In reality, constant-force springs do not provide true constant force; they are made from materials that do follow Hooke's Law. Typically, constant-force springs are constructed from coiled strips of spring steel, so that the spring is in a coiled form when relaxed. The approximation of constant force comes from the long stroke and the static preload position, so the initial force does not start from zero but from a finite value. For relatively small changes around this initial position, the force is approximately constant.