Abstract: A plate clamping device for clamping flexible printing plates in rotary printing machines includes an upper guiding rail and a lower guiding rail to receive and clamp a printing plate therebetween. The device is provided with two spaced from one another bolts and a clamping arrangement centrally positioned between said bolts. The clamping arrangement includes an eccentric stud extending normally to the elongation of the lower rail and a wedged key mounted between the upper rail and the stud. The stud has a surface having a flat portion, a transition curved portion and a cylindrical portion. The wedged key is arranged in engagement with this surface and upon rotation of the stud the key may rest on the flat portion of the stud when the device is in a plate-releasing position or the key may engage with the cylindrical portion of the stud whereby the key is self-arrested and the rails clamp a printing plate.

Abstract: An arrangement for facilitating the mounting of printing plates on a plate cylinder of an offset printing machine. Two arms are mounted atop the machine at the opposite lateral sides thereof and have free ends provided with hooks. A rail is suspended from these hooks and carries quick-coupling devices which engage the trailing edge of a printing plate to be mounted. The hooks are suspended on ropes which are wound upon rollers mounted on the free ends of the arms; turning of the rollers in a sense causing unwinding of the ropes is resisted by torque springs or similar devices; this resistance can be varied to compensate for printing plates of different weights. Thus, the weight of the printing plate cannot cause the ropes to unwind; however, when the leading edge of the printing plate is connected to the plate cylinder and the cylinder is slowly rotated to take the plate up on it, the pull exerted by the cylinder causes unwinding of the ropes.