Constant torque spring is made of stainless steel. The external
force rewinds the spring from the natural state to the output wheel
for energy storage. When the external force is removed, the spring
will return to its natural state, and at the same time, the output
wheel produces a fixed torque to store the elasticity, so it is
called a fixed torque spring. It belongs to the constant force
spring in a way of use.
