Repeater mechanism with tensioned chain

A repeater mechanism for a timepiece with a striking mechanism, which comprises:

• an hour snail;
• an hour part bearing an hour feeler-spindle and mounted in rotation about an hour axis between:
• a resting position in which the hour feeler-spindle is offset angularly from the hour snail;
• a reading position in which the hour feeler-spindle comes in contact with the hour snail;
• an hour spring which returns the hour part towards its reading position;
• a striking mechanism barrel, which comprises:
• a barrel shaft;
• a barrel drum,
• a barrel spring, an internal end of which is integral with the barrel shaft and an external end of which is integral with the barrel drum;
• a pulley;
• a chain which is able to be wound up partially on the pulley, the chain being hooked, by a proximal end, on the pulley and, by a distal end, on the hour part;
• wherein the pulley is mobile in rotation relative to the barrel shaft, and the striking mechanism barrel comprises:
• a ratchet, integral in rotation with the barrel shaft and:
• coupled in rotation with the pulley as long as the hour part exerts a traction force on the chain;
• uncoupled in rotation from the pulley as soon as the traction force exerted on the chain by the hour part in the reading position is cancelled out;
• a pulley spring interposed between the ratchet and the pulley, and which exerts on the latter a resistant torque which keeps the chain under tension when the ratchet is uncoupled in rotation from the pulley.