GB265667A - Improvements in or relating to printing presses - Google Patents

Abstract

265,667. Goss Printing Press Co. of England, Ltd., and Smith, E. J. Nov. 4, 1925. Feeding webs. - A web-renewing mechanism for a printing-press comprises means for starting the reserve roll when the joining of the old and reserve web is effected, and means for subsequently controlling the speed of the reserve roll. The rolls may be associated with feed-belts driven by differential gears having speed regulating-means comprising brakes which are operated by mechanical or electromagnetic means and are controlled manually or automatically. In the mechanism shown in Fig. 1, webs pass from supply and reserve rolls A, B and are led between rollers C, D forming part of the web-renewing mechanism described in Specification 260,049, the rollers being mounted on rocking arms C', D<1> secured to shafts C<2>, D<2> having meshing gears C<3>, D<3>, and the shaft D<2> having a hand-lever E which is depressed to bring the rollers into engagement. The web rolls engage belts F passing round pulleys F<1>, F<2>, the pulleys F<1> being secured to shafts G each provided with the differential driving-mechanism shown in Fig. 4. The driving mechanism consists of bevel wheels L mounted in a loose drum N and gearing with fast and loose bevel wheels P, K on the shaft G; the wheel K is secured to a pinion H which engages a pinion I on a driving-shaft J. The drum N co-operates with a sliding brakeshoe R, Fig. 1, operated in opposition to springs by an electromagnet S. When the brake is applied, the shatt G is driven by the differential gear, the speed being reduced by reducing the pressure ot the brake shoe. The hand-lever E on depression bridges contacts 2, 10, Fig. 6, in circuit with the electromagnets S, and relay switches W which are in circuit with manually or automatically controlled rheostats T. When the hand-lever is depressed, the brakes are applied by the electromagnets S, and on raising the hand-lever the relay switches maintain circuits through the electromagnets and rheostats. Either brake can be applied, without depressing the hand-lever, by means of normally open pushbuttons V in circuit with the associated electromagnets. Normally closed push-buttons U are provided for breaking the circuits of the associated electromagnets S and thereby arresting the belts F. The web may control automatically rheostats for the electromagnets S, the web being looped round a pilot roller carried by a spring-controlled lever having a rod provided with contacts co-operating with the rheostats. In some cases the rheostats may be associated with a press controller, such an arrangement being shown in Fig. 8, and comprising an arm 16 passing over contacts 15. A rod 18 geared to the arm carries a piston 19 working in a dashpot 20 provided with a rod 21 carrying contacts co-operating with rheostats 26 in series with rheostats T. Normally the rheostats are cut out, a spring 25 maintaining the dashpot in depressed position. When the arm 16 moves to full-speed position the piston is depressed idly, oil passing through a port 19<a> provided with a ball-valve. When the arm is moved in the opposite direction, oil passes through a small passage 19<b> regulated by a screw 19<c>, a slow movement of the arm being ineffective, whilst a quick movement raises the dashpot, and the rheostats insert resistance in the circuits of the electromagnets S. When the arm is stationary the dashpot drops to the lowest position. The brake shoes R may, as shown in Fig. 9, be mechanically controlled by a pilot roller 29<c> engaging a loop in the web. The arms C<1>, D<1>, Fig. 1, carrying the rollers C, D are secured to shafts 27, 28 provided with loose levers 29, 32 having meshing gears 30, 31, the lever 29 being connected to a lever 29b carrying the pilot roller. The brake shoes R are connected to levers 37, 38 which are connected by links 35, 36 to levers 33, 34 loosely mounted on the shafts 27, 28 and having projections 33a, 34<a> engaging projections on collars 39, 40 secured to the shafts. The levers 29, 32 have latches 41, 42 engaging projections 33<b> 34<b> on the levers 33, 34. On depression of a hand-lever on the shaft 27 the rollers C', D<1> are moved into engagement and the brake shoes R are applied to the drums N, the belts F being thereby caused to run at full speed. The latches 41, 42 maintain the brake shoes in engagement with the drums when the hand-lever is, raised. When the pilot roller falls, the brake shoes are relieved and the speed of the belts is reduced, and when the pilot roller rises the speed of the belts is increased. Either brake shoe can be released, to arrest the associated belt, by releasing the latch 41, or 42. The levers 29, 32 may be operated manually. A device may be provided for controlling the brake shoes on breakage of the web.