Economical timepiece barrel

The method of assembling a timepiece barrel in a receiving structure, wherein the following are used:

• one said barrel including:
• a drum coaxial to a barrel arbour in a pivoting direction, said drum being arranged to confine at least one barrel spring, a first end of which is fixed or hooked to said drum and a second end of which is fixed or hooked to a core, which is coaxial to said barrel arbour and guided on said barrel arbour,
• said barrel arbour being removable and including a shoulder arranged to cooperate with a bore of said core and further including a first arbour stopping surface and a second arbour stopping surface, which face each other and are arranged to limit together the axial travel of said barrel arbour, in said pivoting direction, relative to said structure,
• said core being pivotally guided in a bore comprised in said drum, and including a first core limiting surface, which is arranged to limit the axial travel of said core in said pivoting direction, relative to an inner face of said drum, and a second core stopping surface, which is opposite said first core limiting surface and arranged to limit the axial travel of said core, in said pivoting direction, relative to an outer face of said drum, and said core including a means of axially supporting and centring a ratchet, and a means of pivotally driving said ratchet,
• one said structure including at least one first wall and one second wall together delimiting a chamber for receiving said barrel, and said first wall and said second wall each including a bore, coaxial to the other, for receiving and pivotally guiding said barrel arbour, said first wall including a first complementary arbour stopping surface to form an axial travel limit for said first arbour stopping surface, and said second wall including a second complementary arbour stopping surface to form an axial travel limit for said second arbour stopping surface, to limit together the axial travel of said barrel arbour in said pivoting direction, relative to said structure,
• further wherein the following steps are performed in succession:
• said core is inserted into said drum so that said drum is arranged, on the one hand, imprisoned between said first core limiting surface and said second core stopping surface, and on the other hand to pivot freely about said core, by immobilising said first core limiting surface and said second core stopping surface relative to said core and, in order to do so, one end of said core is deformed in the shape of a rivet seam;
• said at least one barrel spring is inserted into said drum, and said first end is fixed or hooked to said drum, and said second end is fixed or hooked to said core;
• a ratchet is immobilised on said axial supporting and centring means and said means of pivotally driving said ratchet comprised in said core;
• said sub-assembly formed by said barrel drum, said barrel spring, said core and said ratchet is inserted between said first wall and said second wall of said structure, and said bore of said core is positioned in alignment with said coaxial bores of said structure;
• said barrel arbour is passed from one of the sides of said structure through one of said walls of said structure, though said core, then through the other of said walls of said structure, said barrel arbour is then immobilised by fixing said first arbour stopping surface and said second arbour stopping surface thereto.