Patent GB-191105868-A (GB)
Title: Improvements in and relating to Tripping Devices for Printing Presses.
Inventor: UPHAM BURT FROST
IPC: B41F33/08
Filed: 1911-03-08
Granted: 1911-09-14
Abstract: 5868. Upham, B. F. March 8. T r i p p i n g - arrangements.-In a machine in which the impression cylinder is fed with sheets from a number of feed - tables, means are provided for throwing off the impression if a sheet is not fed from any table and for throwing on the impression before the next sheet comes into printing position, so that it is not necessary to stop printing if the feed from one table goes wrong. The actual tripping-means comprise a lever fitted with a pivoted dog, which is actuated by feeler mechanism arranged at each feed table to throw the dog into connexion with a notched lever, which is oscillated as many times per revolution of the impression cylinder as there are feed-tables, and the connexion between the two levers is broken after the impression has been thrown off and thrown on again, the notched lever then oscillating idly. As applied to a rotary machine of the kind described in Specification 2530/10, an impression cylinder 4 is supplied with sheets from two tables 9, 28, and coacts with a printing-cylinder 3 fitted with two formes P, P<1>. The sheets are fed by hand or automatically over the tables 9, 28, and if either sheet is incorrectly fed, a sheet-feeler mechanism of known kind, such as shown in Fig. 7, operates the tripping-devices. This feeler mechanism comprises a detecting-finger 5<m>, which, when a sheet is missing, causes a pawl on a rocking arm 5<r> to engage a notched segment 5<c> on an arm attached to a shaft 5<b>, arranged near the feed end of the table. Two similar shafts 5<b> are connected by lever and link mechanism to a lever 4<j>, the links 4<l>, 4<m>, being slotted to permit of independent operation. The lever 4<j> transmits motion to a spring-controlled dog 1<b> on one arm of a lever 1, and causes the dog 1<b>, which is normally out of contact with a notched lever 2, to engage with a notch in the lever as shown in Fig. 4. The connexions between the lever 4<j> and dog 1<b> comprise rods 4<a>, 4<b> which are yieldingly connected by a spring 4<c> which permits relative movements of the rods should the dog 1<b> engage the lever 2 before its notch is in the correct position to receive the dog. The lever 2 is oscillated by a cam 2<o> driven at twice the angular speed of the cylinder 4. When the dog 1<b> engages the lever 2, the lever 1 is raised to the position shown in Fig. 4, and the cylinder 4 is moved bodily out of printing position by the actuation of eccentric mechanism 8<c>, 8b which controls the position of sliding blocks 8<a> in which the cylinder is journaled. The cylinder 4 is returned to the printing position in time to print the next sheet by the return of the lever 2. When the reversal of motion of this lever takes place, a spring 1<j> forces the other end of the dog lb into engagement with the other end of the notch in lever 2, as shown in Fig. 5, and the lever 1 and the eccentric mechanism it operates are returned to normal position. Excessive throw of the lever 1 is prevented by a pin 1<2> engaging a slot in the lever.