To provide a device for adjusting in steps and maintaining preload torque to print product chucks on a folding drum.

Each print product chuck includes a cam and a shaft on which a plurality of print product chucks are mounted. A cam-driven element 19 is mounted on the shaft, and a torsion bar 20 is connected to the cam driven element 19. A torque applying element that applies preload torque to the torsion bar 20 is provided, the preload torque working to bring the cam driven element 19 into contact with the cam. Further, a mechanism is provided for adjusting the preload torque to the torsion bar 20 in steps. The mechanism has a first face gear on the inside end face of the torque applying element and has a second face gear on the outside end face of the opposite member, both of the gears meshing with each other. The preload torque to the torsion bar 20 is adjusted in steps by the relative movements of the face gears.