Horological mechanism for displaying at least the single time indication and timepiece comprising such a mechanism

A horological mechanism comprising a barrel drum mounted pivotally free around a barrel shaft, a barrel spring being housed inside the barrel drum, said barrel spring comprising a first external coil wherein the barrel spring is attached to the barrel drum, and a last internal coil wherein the barrel spring is attached to the barrel shaft, the winding of the barrel spring being done by a winding rod which meshes with the barrel drum via a winding geartrain, a barrel ratchet being fixedly mounted on the barrel shaft, the horological mechanism also comprising a finishing geartrain which includes a first finishing wheel with which the barrel ratchet meshes, and which transmits a driving force from the barrel drum to an escapement mobile the purpose of which is to maintain the oscillations of a regulating member which, by its oscillations, regulates the rate of the horological mechanism, the horological mechanism also comprising an hour wheel frictionally mounted on the barrel shaft and to which an hour hand is attached for displaying a time, said hour wheel being frictionally coupled with the barrel shaft, a kinematic chain extending from the barrel ratchet to the escapement mobile being calculated so that the barrel ratchet, and therefore the hour wheel, rotate at the rate of one complete revolution in 12 or 24 hours.