To ensure the consistency of roller pressure,comparison is done to the five main top cradles such as the cylindrical spiral spring top cradle,plate spring top cradle,integrated air-bag top cradle,isolated air-bag top cradle and cylindrical top cradle SCP2 series regarding their drafting structure and performance.Highlight is given to the classification,structure,and the features of the cylindrical top cradle.The innovated points are listed with the cylinder,locking assembly,fastening assembly,pressure adjus...