Screw capper

A screw capper including conveying means for conveying a vessel, and a capping head for screwing and tightening a cap onto the mouth of a vessel being conveyed by the conveying means, the capping head comprising holder means for holding a cap, means for rotating the holder means, elevating means for elevating the holder means, and load imparting means for imparting a load which is directed toward the vessel located below the holder means;

• the screw capper further comprising means for detecting an angle of rotation of the holder means, and a controller for controlling a load imparted by said load imparting means, the controller being operative from the beginning of a screwing and tightening operation until the angle of rotation of a holder means exceeds a specific angle where a load is changed to control the load imparted by the load imparting means to a low value and operative upon detection of an angle of rotation of the holder means which exceeds the specific angle to control the load imparted by the load imparting means to a high value.