Abstract: A windable clockwork for metronomes comprises a clockwork frame, a stem rotatably mounted in this frame, a spiral spring connected to this stem, a housing enclosing the spring, and a blocking mechanism which prevents the stem and the spring from reverse motion during the winding. The blocking mechanism comprises two coaxially arranged parts made from a plastic material, namely a locking disc and a spring disc. One of these parts is stationarily arranged on the frame and the other is connected to the stem. The locking disc comprises at its periphery at least one integrally formed stop and the spring disc carries at least one likewise intergrally formed, resilient tongue which in one rotational direction of the stem glides elastically past the stop, but in the opposite rotational direction abuts the stop and blocks the reverse motion of the stem and the spring.