constant-force spring

An example of a constant force generator is the constant-force spring.

Constant-force spring - a tightly rolled ribbon that exerts a nearly constant force as it is unrolled.

A constant-force spring is a spring for which the force it exerts over its range of motion is a constant.

Generally constant-force springs are constructed as a rolled ribbon of spring steel such that the spring is relaxed when it is fully rolled up.