The invention provides a closure chuck usable with a capping machine for mounting an insertion closure on a possibly misaligned flange around an opening in a container. This bar comprises a base associated with a adjusting screw one end of which rests on the bottom plate. A brace pushes and maintains the sleeves at the bottom of the notches causing an elastic deformation of the sleeves which grip the upper edges of the intermediary discs and an end disc producing pleats between consecutive intermediary discs. Where the shared power bus is active, the generator is synchronized with the shared power bus before the generator is brought online.