GB589522A - Improvements in flat-bed printing machines - Google Patents

Abstract

589,522. Printing - machines. RANGER, A. W. March 24, 1945, Nos. 7475 and 26955. [Class 100 (ii)] . In a flat-bed continuous single revolution printing-machine the impression cylinder 1, which is mounted in fixed bearings, is driven for part of a revolution by a bed rack 7 engaging a segmental gear 6 on its shaft 2, and during the return stroke of the bed the revolution of the cylinder is completed by gearing comprising an eccentric segmental gear 40, Figs. 1 and 2, which engages a cam-shaped gear 41 fixed to the shaft 2, the gear 40 taking up the drive just before the bed completes its printing movement and driving the cylinder during the quick return motion of the bed. The speeds synchronize at the moment of change of drive. The bed is reciprocated by a quick return railroad gear operated from a slotted lever 11 and a crank-pin 15 on a shaft 17 driven from a main shaft 18, the shaft 17 being geared to the gear 40. The bed is cushioned at each end of its stroke by a dash-pot device comprising a piston connected by a rod 30 to the lever 11, and fitting in a cylinder 26 fitted with central apertures 27 and apertures 28 at each end. The bed is mounted so that it can be lowered from the cylinder during make-ready, and to effect this the tracks 10 upon which the bed runs is supported so that each track can pivot about its left hand end which rests on the frame 5. The tracks 10 are normally kept raised by sliding or rotating wedge members 44 resting on frame or cross frame members 5, 45, and operable by a crankshaft 50 to move the bed into and out of active position. The tracks 10 are supported by a trapezoidal metal spring plate 55 secured to the frame by bolts 56, and to the track by bolts 58 and dowels 61. To ensure correct registration of the cylinder and bed after the bed has been lowered the bed rack 7 is formed of two parts, 70, 70<1> which can slide vertically relatively to one another, and the part 70' engages a shelf 74 on the frame when the bed is lowered together with the part 70. On re-engagement the part 70 engages the same tooth of the gear 6 from which it was disengaged.