The flat spiral spring, also known as a clock spring, is a type of spring that is fixed at one end while the other end acts with torque; under the action of torque, the spring material undergoes bending elastic deformation, causing the spring to twist in the plane, and the magnitude of its angle of deformation is proportional to the torque.

The flat spiral spring is classified according to whether it contacts adjacent working parts:

1. non-contact type flat spiral spring,
2. contact type flat spiral spring.

The fixed end of the flat spiral spring has the following fixing methods:

1. hinge fixing,
2. pin fixing,
3. V-shaped fixing,
4. washer fixing.