A ratchet for winding a barrel, including an axial passage for fitting the ratchet onto an arbor carrying pivotal drive mechanism. The ratchet includes, in the axial passage, a strip spring permitting fitting of the ratchet onto the arbor, and exerting a bearing force on the pivotal drive mechanism, wherein the at least one strip spring forms a complementary drive for pivotally driving the arbor. A timepiece barrel for pivotal assembly between a bottom plate and a bridge includes a spring housed between a pivoting drum and a ratchet and hooked between, at an outer end thereof, the drum, and at an inner end thereof, an arbor, the arbor pivoting integrally with the ratchet about a pivot axis.