1. In carding, a large cast iron shell, with an outer diameter of 40 to 45 inches, completely covered with card clothing on the surface. The shell is mounted rigidly on a shaft which projects at each end to rest in bearings. The cylinder must be accurately balanced since it rotates at speeds of 160 revolutions per minute and higher. 2. The main roll, or pressure bowl, on roller printing machines. The engraved rolls that apply color are arranged around the cylinder. (Also see PRINTING, Roller Printing.) 3. A slotted cylindrical housing for the needles in a circular-knitting machine. The number of slots per inch in the cylinder determines the cut of the machine.