Spring component maintaining tension against the mainspring's ratchet wheel, preventing unwinding and producing the characteristic clicking sound when winding.
A click spring is a small, curved spring that works with the click (pawl) and ratchet wheel in the winding mechanism. When you wind a watch, the click spring pushes the click into the ratchet wheel's teeth, preventing the mainspring from unwinding. It produces the characteristic clicking sound of winding and maintains power in the movement between winds.
The clicking sound during winding comes from the click (pawl) being pushed into each tooth of the ratchet wheel as the crown is turned. The click spring provides tension, snapping the click against each tooth. In automatic watches, a similar mechanism using a rotor produces clicks during wrist movement, though some movements use silent automatic systems.
A broken click spring can cause the mainspring to unwind rapidly — potentially damaging the movement — because there's nothing preventing reverse rotation of the ratchet wheel. Symptoms include the crown suddenly spinning freely or reduced power reserve. This requires immediate professional repair, as continued winding with a broken click spring risks damaging other movement components.