Timepiece barrel assembly with reduced core diameter

A Timepiece barrel assembly including a barrel arbour pivoting about a pivot axis and extending between, on the one hand, at a first end, a first shoulder for guiding the pivoting of the barrel arbour in a bridge, and on the other hand, at a second end, a second shoulder for guiding the pivoting of the barrel arbour in a plate, said barrel arbour including, between said first shoulder and said second shoulder, a median shoulder onto which there is driven a core, said barrel assembly including at least one barrel mainspring mounted between, at a first outer end, a barrel drum pivoting about said pivot axis, and at a second inner end, a receiving surface of said core, wherein said barrel arbour includes, between said first shoulder and said core, a ratchet-holder integral with said barrel arbour and including a shoulder for driving on or fixing a ratchet, wherein said core includes, on the side of said ratchet-holder and at a distance therefrom, a first, top, outer, shafted part on which the pivoting of said drum is guided by a bore of said drum, and further wherein said ratchet is fixed in immediate proximity to said first outer shafted part on the same side as said shafted part relative to said first shoulder but not in contact with said first outer shafted part, and wherein said ratchet-holder directly or indirectly limits the shake of said drum relative to a bearing surface comprised in said core at the edge of said receiving surface for said spring.