356,713. Printing-machines. SMITH, W. H., 352, Inglewood Drive, Toronto, Canada. June 6, 1930, No. 7529. [Class 100 (ii).] Tripping - arrangements ; rotary offset machines.-A rotary printing- machine which may be of the offset type is constructed with means for positively stopping the impression cylinder at a predetermined position, means for lowering the cylinder definitely at the stopping position thereof, and means for simultaneously starting the drive of the impression cylinder and restoring it to printing position. As applied to a two-colour offset printing-machine in which there is a small gap X, X<1>, Fig. 1, between the two ends of each printing surface on the printing cylinders 7, 12, the impression cylinders 9, 14, Figs. 1 and 2, are adapted to be stopped in a position just after the end of the impression has been printed, and when the impression is restored the printing can again take place from the end X. The offset cylinders 8, 13 and impression cylinders 9, 14 are mounted in eccentric bearings formed respectively with arms 10<x>, 15<x>; 11<x>, 16<x> connected by adjustable links 17, 18, to permit of simultaneous tripping of the offset and impression cylinders. The links 18 of the impression cylinders are pivoted to a lever on a spring-impelled shaft 20 which is normally held from rotation by a pawl 45. This pawl 45 is operated to release the shaft 20 when a clutch member comprising geared bolts 58, 59, Fig. 8, is operated to throw out the drive of the impression cylinder 9. The bolts 58, 59 are mounted in spaced discs 50, 51, keyed to the shaft 9x of the impression cylinder 9, and when a trip finger 70, Figs. 4 and 8, keyed to the bolt 56 is maintained by a spring 73 in contact with a pin 71, reduced parts of the bolts are received partly in circular recesses in a driving gear 30 which gears with a gear on the main driving shaft 26, Figs. 1 and 2, and partly in recesses in a sleeve keyed to the shaft 9<x>. When, however, the trip finger 70 is engaged by a stop finger 78 the bolts are rotated to free the shaft 9x from their driving action. The stop finger 78 is controlled by a lever 135, Fig. 10, which, when operated in a clockwise direction, moves a detent 127 so that a recess 130 in the detent can engage a pin 119 to rotate a shaft 110 anticlockwise, and raise the finger 78 through connections 114, 115, Figs. 1 and 2. The detent 127 is reciprocated from a cam 144, Fig. 1, driven by gearing from the gear of the offset cylinder 8, and so the trip mechanism operates in timed relation to the printing members. A cam 149, Fig. 1, on the shaft of the lever 135 operates the button 151 of a switch 150 to slow down the press while the tripping occurs. The engagement of the stop finger 78 with the trip finger 70 checks the rotation of the disc 51 in a clockwise direction, and a spring carried by the finger 78 raises a pivoted dog which engages a stop on the disc 51 to check rotation in an anticlockwise direction. The disc 50 is acted on by an adjustable braking shoe when the impression cylinder is depressed to its tripped position. The movement of the trip finger 70 from its fullline position shown in Fig. 4, in which the clutch is engaged, to the dotted line position, in which the clutch is disengaged, causes it to act on the end 45<x>, Fig. 2, of the pawl 45, and release the shaft 20 which operates the links 18 to trip the impression cylinders. The offset cylinders 8, 13, Figs. 1 and 2, are tripped simultaneously by an arm 94 fitted with a projection 95 which releases a latch pawl 47 from a notch 41<x> of a collar 41 secured to a spring- impelled shaft 19 connected by a lever arm 38 to the links 17. To restart the mechanism the offset cylinders are returned to printing position by operation of a hand-lever 41‹, and the clutch is re-engaged by a reverse operation of the lever 135. The impression cylinders are returned to printing position by returning the shaft 20 to normal position by means of a slotted link 97 which is moved to the right by a lever arm on a shaft 85 which is operated by a spring 89 when permitted by a cam 104 on the shaft 26, and when a pawl 84 is released from a notch 91. The pawl 84 is operated to effect this return by the trip finger ,70 when moving in a direction to throw in the clutch. The cam 104 resets the parts ready for further action. The offset cylinders are geared together by a shaft 32 and bevel gears, and the impression cylinder shaft 9x drives by bevel gearing a shaft 162 which drives the other impression cylinder 141, numbering mechanism, perforating and punching mechanism, and zig-zag folding mechanism 173, 174. The numbering mechanism may be tripped when desired by means of a trip cam 196 which is set by mechanism similar to that which operates the trip finger 70 operating in synchronism therewith.