455,739. Printing surfaces. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.- (Wood Newspaper Machinery Corporation; 501, 5th Avenue, New York, U.S.A.) Oct. 30, 1935, No. 29932. [Class 100 (ii)] In a plate-clamping device for a printing-cylinder, the movable end clamp is directly coupled by linkage to a lever which is pivotally mounted on the cylinder and is adapted to be engaged by means on the frame of the machine as the cylinder rotates and to be actuated thereby to release the plates. The plates P, P<1>, Fig. 9, are clamped by an end clamp 15 and a central clamp 16, the former being fixed to and the latter loose on a rod 14. For releasing the plates, links 23 adjustably connected to the clamp 15 are moved outwards, further compressing a spring 20, which is normally held between nuts 19 on the rod 14 and a fixed abutment and guide 13, and serves to press the clamp 15 against the plate P. The outward movement of the links 23 moves the clamp 15 and the rod 14 outwards until the nut 18 on the rod 14 engages the clamp 16 when this also moves outwards away from the inner plate P<1>. To impart the necessary outward movement to the links 23, a lever 24, Fig. 5, pivoted at 26 is connected at one end to the links and carries a cam roller 25 at the other end. A cam 30 fixed to a shaft 29 can be moved to a position to be engaged by the roller 25 by means of a hand lever 39 which is normally locked with the cam in the inoperative position by a spring-pressed pin 34. The lever 39 may be moved to rotate the shaft 29 in an anti-clockwise direction against the pressure of a spring so that the cam 30 is in the path of the roller 25. Rotation of the printing cylinder then causes the roller 25 to engage the cam and continued movement of the cylinder moves the links 23 outwards and releases the plate clamps. Further movement of the cylinder carries the roller 25 off the cam 30 and the clamps move back under the action of the spring 20 to the locking position ; upon releasing the handle 39, the cam 30 is moved automatically to its inoperative position. To prevent the roller 25 from engaging the forward end of the cam 30 and causing damage, a pivoted arm is connected at one end to the shaft 29, its other end carrying a cam projection which, when the cam 30 is in such a position as to be liable to damage, is in line with one or other of two cam projections carried by the impression cylinder. As the impression cylinder rotates, one or other of the projections engages the projection on the pivoted arm and forces it and with it the shaft 29 and cam 30 into either its operative or inoperative position. In an alternative construction of safety device, a V-shaped member is carried by the upper end of the lever 24 above the roller 25, this V-shaped member being adapted to engage a V-shaped projection on the front end of the cam and deflect this either to a fully-in (and operative) or fully-out (and inoperative) position. Alternatively, the cam may carry a flexible strip which engages the roller 25 when this is about to come into contact with the cam. In a modification shown in Fig. 15, a cam 52 is pivoted at 53 and is connected by a link 59 with a handle 55 which is fixed to a shaft 64. Movement of the handle 55 from the full-line to the dotted line position raises the cam so that it is no longer in a position to engage the cam roller 25 for moving the links 23. A spring-pressed rod 65 pivotally attached to an arm 63 fixed to the shaft 64 constitutes an over-centre device which holds the cam 52 in both the operative and inoperative position. The handle 55 is locked in the inoperative position by a spring-pressed projection 56. A pivoted shield 88 for the printing cylinder carries a projection 89 which forms a stop for an extension on the arm 63 when this arm is in the position it occupies when the handle 55 is in the inoperative position. This constitutes a lock which prevents operation of the handle 55 and the plate releasing mechanism when the shield 88 is down and the press is operating. When unclamping the plates, the shield is raised and the handle 55 is moved to the vertical position, in which the cam is lowered. The cam is locked in this position by the over-centre device 63, 65 and by a stud 70 on the cam housing engaging in an aperture in a spring plate 81 carried by an extension of the arm 63. Upon rotating the printing cylinder the cam roller 25 engages the cam 52 and unlocks the plates. Upon further rotation of the cylinder, the plates are automatically clamped and a projection 85 on the cylinder first forces the plate 81 out of engagement with the stud 70 and then engages a surface 86 on the extension of the arm 63 and moves this and the shaft 64 in a clockwise direction, thus forcing the arm 55 and the cam 52 to the inoperative position.