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752,764. Duplicating-machines; feeding sheets. RITZERFELD, W., and RITZERFELD, G. Sept. 9, 1954 [Sept. 25, 1953], No. 26154/54. Classes 100 (1) and 100 (2). An automatic sheet-feeding mechanism for a duplicating machine comprises a fixed feed table 7, Fig. 6, on which a pile of sheets is located by side ledges 6, each ledge having an abutment 13 engaging the leading edges of the sheets, a feed member 8 reciprocable towards and away from the printing cylinder in time with the rotation of the printing cylinder 1, the feed member carrying a friction member 25 rotatable in one direction only and a transfer member 14, having an inclined surface, between the abutment and the printing drum. In operation, the friction member 25 during its working stroke towards the printing cylinder bears without rotating against, and carries with it, the uppermost sheet 12 in such a manner that the sheet is first loosened from the pile while its leading edge is still held by the abutments, and caused to buckle at 12a as shown in Fig. 2. Subsequently the leading edge snaps over the abutments and is guided by the transfer member into the bite between the printing drum 1 and the impression cylinder 2. On the return stroke the friction member rotates and rolls over the succeeding sheet of the pile. The feed member 8 is reciprocated by an arm 9, Fig. 6, connected to it by a link 11. Another link 5 connects the arm 9 to a follower lever 4 cooperating with cam 2 on the shaft of the printing cylinder which moves the arm in one direction, the return movement being effected by a spring 3. Wheels 8a at each side of the feed member run on the tops of the ledges 6 as it is reciprocated, and the friction member 25, mounted at the other end, rests by gravity on the top of the pile. The friction member comprises a plurality of knurled or serrated rollers which are rotatable in one direction only. The downward pressure exerted by the rollers is adjustable according to the stiffness of the paper being used by a weight 18, Fig. 2, displaceable along the length of the feed member. The cam 2 is formed so as to cause the feed member to make one reciprocation for each revolution of the printing cylinder or more than one if it is desired to feed more than one sheet. The feed member may be retained against reciprocation by a manually operable lever (not shown) which, in the operative position, serves to retain the feed member at one end of its stroke. The locating ledge 6 on one side is adjustable along transverse slots in the table 7 to accommodate sheets of different sizes. The abutments 13 slope backwardly at an angle a, Fig. 2, and are formed on their opposed faces with inclined surfaces 13a for engagement by the corners of the sheet. Damping sheets.-The sheets may be damped as they pass over the horizontal extension 16 of the guide 14 by contact with a moistening device. Alternatively a further pair of rollers 22, 23, Fig. 6, may be provided adapted to forward the sheet to the printing cylinder. The upper roller 23 is kept damped by contact with an absorbent roller 24 against which liquid is sprayed. The roller 24 is made of a plurality of rings of foamed rubber and is geared to roller 23 so as to be driven at a different, e.g. a slower, speed from roller 23. A variable-speed gearing may be used so that the amount of liquid transferred to roller 23 can be finely adjusted. Stopping machine when pile is exhausted.- Means may be provided for stopping the machine when there are no further sheets on the table 7. A detector lever 27, Fig. 9, pivoted at 28 and accommodated in a slot 7a in the table is normally held by the weight of sheets on the table in a position (shown in full lines) where its upper edge is aligned with the upper surface of the table. When the last sheet is gone the lever swings to the dotted line position by the action of an adjustable weight 28. On the next return stroke of the feed member 8 a projection 29 engages the lifted end of lever 27 and rotates the lever further in a clockwise direction. This causes a pin 31 on a threearmed lever 32 to be engaged by the end of an arcuate slot in lever 27 whereby the lever 32 is displaced against a spring into the position where its left-hand arm abuts the underside of the table 7. During this movement a pin on lever 32 causes counterclockwise rotation of lever 34 and thereby clockwise rotation of a retaining lever 37. The printing cylinder is driven by a continuously rotated ratchet wheel 43 engaged by a pawl 42 on the cylinder. A stop lever 41 is spring-loaded towards a position where its end would engage and disconnect the pawl from the ratchet wheel thereby stopping the cylinder. The lever 41 is held inoperative by a pin 40 on a disc 39 which is itself held by the retaining lever 37 engaging in a notch 38. When the pile is exhausted displacement of lever 37 releases disc 39 which rotates and allows stop lever to disconnect the driving pawl 42. Engagement between the projection 29 and the end of lever 27 also serves to lift the feed member so that a pin 19 thereon is raised above a spring-loaded catch finger 19a. This allows the catch finger to snap inwardly under the pin 19 and retain the feed member in the raised position. When a fresh pile of sheets is placed on the table the mechanism is re-set by pulling the catch finger 19a outwardly and allowing feed member 8 to rest on the top of the pile. The catch finger is then held inoperative by abutment with the end of pin 19 as shown in Fig. 9. Also disc 39 is rotated back to the latched position thereby enabling the pawl 42 to re-engage the ratchet wheel 43 so that printing may recommence.
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