A printing unit in a sheet-fed printing machine includes a printing cylinder, an upstream transfer cylinder and a downstream transfer cylinder. The transfer cylinders each include a device for decelerating/accelerating a sheet. The device, in particular, includes at least one gripper bar being movable in a substantially radial direction to change the tangential speed of the gripper bar and thus of the sheet. A printing unit of this construction allows the sheets to be transported at a lower speed and at a shorter distance from one another during the printing process, resulting in a better print quality and a higher throughput of the machine. A sheet-fed printing machine including such a printing unit is also provided.