BALANCE COCK

The balance cock is the part (a Bridge), fixed to the Main plate, which supports from above the upper pivot of the Balance staff ; the lower pivot, meanwhile, rests in the main plate. Derived from the bridge, the balance cock is held by only one screw (and positioned by feet), which distinguishes it from bridges fixed by several points. It carries the upper shock absorber of the Balance and, in traditional constructions, the stud holder and sometimes the Regulator assembly used to correct the Daily rate. Historically, on antique watches and clocks, the balance cock was a richly decorated piece, pierced and engraved, a true signature of the Horologist (watchmaker). In modern horology, it retains a major mechanical role: its rigidity and the precision of its positioning determine the verticality of the balance staff, and thus the quality of the Oscillation and of the rate. Some calibers replace the balance cock with a balance bridge fixed at both ends, reputed to be more stable. The balance cock is often the subject of careful finishing (Beveling / Angling, Circular graining, Engraving).