Patent GB-159938-A (GB)
Title: Improvements in printing presses
IPC: B41F3/58
Filed: 1919-11-11
Abstract: 159,938. Droitcour, M. A. Nov. 11, 1919. Bed-reciprocating apparatus.-A bed-reciprocating apparatus which is especially applicable to the beds of cylinder printing-machines is so constructed that the reversing movements at the ends of the strokes are effected by an oscillating lever with segmental gears which engage a rack which is reciprocated in a direction opposite to the bed so as to effect a good balancing. In the machine shown the main reciprocation of the bed is effected by a pair of gears which engage racks which are at an equal distance from the centre of the bed, these gears being driven from an oscillating gapped gear which is idle during the reversing movements. The reversing segmental gear acts on racks at the ends of the bed which are arranged centrally thereof, so that in each case the drive is central, and lateral twisting movement or strain is prevented. As shown, the bed 2 is driven normally by gears 14, Fig. 3, on a shaft 13 which is driven from a main driving- shaft 4. The bed is supported at each side on frames 16 with rpllers 17 moving on bearing tracks 18, the frames 16 being formed with racks 20 which engage gears 12 on the shaft 13. The bed is also formed at each end with racks 34 adapted to be engaged by a segmental gear 33 on a lever 31 freelv mounted on the shaft 13. The shaft 13 is fitted with a gapped gear 22 which at the commencement of the printing operation is brought into gear with the shaft 4 by means of a sliding freely mounted gear 11 on a stub shaft, which is movable together with a pair of connected gears 8, 10, by a shipper 12 operated when it is desired to change the direction of drive by a rack bar 44, gear 43, rack bar 41 and a cam 39 on a shaft 38 driven from the shaft 13. A gear 7 on shaft 4 engages a gear 21 to drive a gear 62 fixed to the cylinder 3 in a continuous manner, and when the gear 11 engages both gears 21, 22, the latter is geared to the former and rotates uniformly with it. The gear 22 then advances the bed until it leaves the gear 11 at its gapped end, the drive by the gears 14 then ceasing, and the drive is taken up by the reversing lever 31 which is oscillated by a crank driven by gearing 23, 24 from the shaft 4. This crank reciprocates a crosshead 28, Fig. 7, on guide bars 29, the crosshead being fitted with a vertical shaft 35 with gears 36 engaging fixed racks 37 to prevent twisting of the crosshead. The crosshead carries a rack 30 engaging a toothed segment 32 at the lower end of the lever 31. This segment is of greater radius than the upper one 33 which gears with the racks 34, and a crank pin 26 of a greater throw than the radius of segment 33 may be employed. After the bed has been reversed, the pinions 8, 10, 11, are moved on the shaft 9 to move the pinion 11 out of the path of the gear wheel 22, and to bring the wheel 10 into its path, and when this wheel 10 engages the end of the gapped teeth the drive of this wheel 22 is in the reverse direction. its connection to the shaft 4 being now via gears 6, 8, 10. The gear 22 is rotated when not connected to the shaft 4 by means of the racks 15 and gears 14. The cylinder 3 is mounted so as to be automatically raised during the return motion of the bed, and pedal-operated means for maintaining the cylinder in its raised position is also described.