US2365294A - Sheet feeder - Google Patents

Description

D. P. SANFORD SHEET FEEDER Dec. 19, 1944.

Filed ma 11, 1942 7 Sheets-Sheet 1 Dec. 19, 1944. P. SANFORD SHEET FEEDER Filed May 11, 1942 7 Sheets-Sheet 2 333M; 241;, a4 M Ymw D. P. SANFORD SHEET FEEDER Dec. 19, 1944.

D. F SANFORD Dec. 19,. 1944.

SHEET FEEDER Filed May 11, 1942 7 Sheets-Sheet 4 D, P. SANFORD SHEET FEEDER Filed May 11, 1942 7 Sheets-Sheet 5 944- D. P. SANFORD 2,365,294

SHEET FEEDER Filed May 11, 1942 7 Sheets-Sheet 6 Dec. 19, 1944. D. P. SANFORD 2,365,294 v I SHEET FEEDER Filed May 11, 1942 7 Sheets-Sheet 7 .z -55. 2 /6 2; Wm v Patented Dec. 19, 1944 E IE.

super manna David P. Sanford, Elizabeth, N. J., assignor to American Type Founders Incorporated, 'Elizas beth, N. J., a corporation of New Jersey Application May 11, 1942, Serial No. 442,490

32 Claims.

This invention relates to sheet feeding devices and more particularly to mechanism for controlling the feeding of successive sheets of paper or anism of the type described and one which will be efiicient and positive in its action, of simple and *compact. construction, and susceptible of applicationto various types of sheet feeding devices.

Although the invention may be made a part of sheet feeders of widely varying modes of construction and operation, and which can be utilized fol-forwarding sheets to different machines for treating or handling sheets, such as punching, folding, slitting. gluing, and wrapping machines or the like, it is illustrated and described herein for purposes of exemplary disclosure as forming a partof asucti'on sheet feeder of the type which forms the subject matter of United States Patent No 2,263,891 in the name of thepresent applicant, such feeder being'used in connection with a printing press having a rotary impression cylinder as the sheet carrying member of the printing couple. Also, as set forth in the specification of that patent, the sheets may be forwarded totheir destination either in spaced sequence, or in overlapping relationship so as to eilect what is I known as stream feeding.

In feeding sheets to'the impression cylinder of a printing press, whether of the single revolution or the two revolution type, it is necessary to provide means for momentarily halting the successive' sheets at the front end of the feed board preparatory to their seizure by the cylinder grip pers at the proper points during the printing cycle. This means not onlydetains' the sheets until the properinstant of. seizure by the grippers but also serves to correct the alignment of the sheets and register them before they leave the feed board. conventionally. front stop gauges or the adjustment of the press for single revolution or two revolution operation. I

Sheet detectors and interrupters have also been provided for stopping the sheet feeder and the press. and also for tripping the impression, when a sheet is not presented to the front or drop guides at the proper time. Reference is made to the United States Patent No.-1,469,515 to William M. Kelly for an exemplary disclosure of such a detector-interrupter arrangement.

The present invention, in its preferred embodiment, contemplates the provision of a combined drop guide an'dasheet detector mechanism, which is preferably-carried by the feeder at the front end of the feed board and disposed in operative relationship to the impression cylinder of the press to be fed. Preferably the vertically swingingdrop guide element and the associated pivoted detector member are disposed for rotation about the same horizontal transverse axis and are conveniently mounted upon-the same cross shaft. The detector member carrying a freely pivoted latch eleof the sheets, by a cam or other instrumentality moving in synchronism with the operation of the feeder. The actuating mechanism has three different positions during its cycle, such as would be determined by three concentric levelsof a driving-cam. At one extreme position, the detector member is at its lowest point and the desheet stopping and registering position at this drop-guidesare provided for this p r se. These guides are supported as a part of the ordinary cylinder or bed-and-cylinder press, and are actuated in synchronism with the opening and closing I 'thecylinder grippers and-in accordance with time. In the normal intermediate position of the actuating mechanism, the interrupter member is raised from the planeof the sheets, but there is a lost motion connection which permits the drop guide to remain down in sheet holding position. In the opposite extreme position, the detector member is raised still further, and the drop guide is also then held up in its sheet releasing position for the passage of a sheet to the cylinder rippe -j H The actuating mechanism embodies a trip device whichis adapted to be moved by 9. 681110! projection carried by the impression cylinder at a point adjacent its periphery and a predetermined distance from the cylinder grippers. When the trip device is disposed in the path of the proie'ction and is struck by the cylinder cam, the

actuating member moves the drop guide upward and allows the cylinder gripper to seize the sheet and remove it from the feed board.

The trip device is, however, disposed in the In a single revolution press, the driving cam for the actuating mechanism lowers the detector member and the drop guide into the path of the sheets and normally operates to release a sheet to the grippers by presenting the tripirdevice to the cylinder projections once during each revolution of the impression cylinder. However, in the case of a press arranged for two revolution operation, the timing is such that the trip device is held in operative position only during alternate passages of the cylinder carrying the tripping projection or cam.

The presence or absence of a properly aligned sheet at the drop guides during the time the actuating mechanism is in its lowermost position,

determines whether or not the press and feeder are interrupted. If, for some reason, no sheet is presented to the drop guides-or rather to the closely adjacent detector latchthe latch attaches the whole movable assembly to a fixed part of the feeder and not only prevents the actuating mechanism from returning to its intermediate position where the cylinder would trip the drop guide, but also causes other tripping devices to interrupt the operation 'of the feeder and of the press, and to trip the impression of the latter machine.

Two or more transversely spaced detector and drop guide devices are provided and this makes it necessary that each sheet be delivered square ly with its forward edge parallel with a line joining the drop guides, to prevent the tripping of the interrupter. Obviously, if only one of these gauges or guides were provided the sheet could be served to the press in a, canted position, whereby it would notv be seized by all of the cylinder grippers, and the free end of the sheet would then becrumpled or folded back and the increased thickness of this portion of the sheet would be apt to damage the form. Therefore, it is a further object of the invention to provide means for keeping the cylinder grippers open when the interrupter is tripped by the misalignment of a sheet, so that the forwardly extending corner of a crooked Sheet will not be seized. Even though the press has been tripped by the other mechanism of the interrupter provided forthat purpose, it frequently happens that the momentum of the press causes the cylinder gripper to seize the extended'corner, pull the sheet through the drop guides, and carry it down to the form.- All of these protective measures are comprised within the objects and purposes of the present invention.

It is a further objectof the invention to provide a combined drop guide and sheet detector which includes a latching or stopping mechanism and which may be adjusted as a unit transversely of the feed board to accommodate sheets of various widths. In the preferred embodiment, this I combined unit is mounted upon a single shaft and the various parts are so interlocked thatthey may be shifted along the shaft and secured in new positions without disturbing the relationship of the various parts, and with an absolute minimum of adjustment operations.

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying draw ings in which on embodiment of the invention is illustrated by way of example.

In the drawings:

Figure 1 is a view in vertical longitudinal section of the upper portion of a printing press sheet feeder embodying the principles of the invention;

Figure 2 is a fragmentary vertical longitudinal sectional view of a portion of the superstructure of the feeder proper;

Figure 3 is a detail view. in front elevation of a portion of the feeder and control mechanism;

Figure 4 is a view similar to Figure 3 with certain of th control parts omitted for the sake of clearness;

Figure 5 is a further simplified view with parts shown in both Figures 3 and i omitted;

Figure 6 is a view in vertical longitudinal section of the left hand portion of Figure 1 on an enlarged scale, and showing most of the feed board supported elements in side elevation;

Figure 7 is a vertical longitudinal sectional view through the sheet guiding and detector mechanism at the left hand side of Figure 5, and taken substantially on line l-l of Figure 10;

Figures 8 and 9 are fragmentary views in transverse section taken on lines 8-4 and 8-9 respectively of Figure 6;

Figure 10 is a top plan view of the delivery end of the feed board showing the front stop and detector mechanisms;

Figure 11 is a view in front elevation of one of the drop guide and detector devices as viewed from the left hand side of Figure 10;

Figure 12 is a view in side elevation of the unit shown in Figure 11 with the transverse shaft and bar shown in cross section;

Figure 13 is a detail view in side elevation of a lost motion connection between the detector and drop guide rock arm and the longitudinal actuating shaft;

Figure 13A is a similar view showing the same parts in another position;

Figures 14 and 15 are views in side elevation and vertical longitudinal section respectively, of the stop and detector devices, corresponding to Figures 6 and 7 but showing the parts in a different position of operation;

Figures 16 and 17 are similar views showing the same parts in still another position;

Figure 18 is a vertical sectional view taken substantially on line l8-l8 of Figure 10;

Figure 19 is a fragmentary view similar to Figure 18 but showing the cylinder grippers in a tripped position, as in normal operation;

Figure 20 is a fragmentary plan view similar to the upper end of Figure 10 but on an enlarged scale and showing in more detail the connection between the detector mechanism and the cylinder grippercontrols;

Figures 21 and 22 are fragmentary detail views taken on line 2I--2f of Figure 20 and showing two positions of the locking arm for the cylinder gripper controls;

Figure 23 is a detail view in vertical section taken on line 23-43 of Figure 20, the gripper actuating controls being in locked retracted position;

Figure 24 is a plan view of the controls similar to Figure 20 but with the element for actuating the grippers to seize a sheet projected into operative position; and Figure 25 is a view similar to Figure 23 and taken on line 25-25 of Figure 24, and showing the parts in thesame position as in the latter figure.

In Figures 1-5 inclusive of the drawings, there is illustrated a sheet feeder such as that shown in Patent No. 2,263,891, but in which certain details of the control and operating. means are shown in addition to the pile supporting elevator, forwarding tape conveyor and other of the mech-. anisms described in the prior patent. The upper portion of the sideframes of the feeder are indicated at Ill and i2 respectively. In Figures 3, 4, and 5, the suction valve and other controlmechanism are shown supported by the near frame member l2 instead of the further frame member III as in the larger views. The pile elevator is shown at l4 in an upper position, to which it has been brought by the step by step action of the cam operated pawl I5 upon the ratchet wheel 16. The ratchet wheel is mounted upon the shaft I! which also carries the pinion l8 meshing with the gear l9 secured to the elevator shaft upon which a cog-wheel 2i carrying the chain 22 is mounted. This step by step upward feed of the elevator is controlled by the mechanism indicated generally by the numeral 25 and which is described in detail in the applicant above mentioned patent. The feed board installation is .indicated at 21 and carries the usual hold down dethe rod. A coil spring 58 of a definite normal length is placed between the washer 56 and the end nuts 51. The arrangement of the coil spring, washer 56, and shoulder 53' is such that there is provided a lost'motion connection, the-idle movement between the rod 50 and the crank 55 being of a lengthindicated at a: and :c' in Figures 13 and 13A. The reasons for thi lost motion connection willbe apparent as the description proceeds. The crank lever 55 serves as an operating member for both the drop guide and the detector mechanism and is fixed to the transverse actuating shaft 66 which extends across the front terrupter devices are alternately raised and lowvices and the tape conveyor, the tapes 28 of ered to permit'the passage of successive sheets during the normal operation of the machines and in synchronism with the printing cycles of the press. All of these devices which form essential parts of the present invention will be described in detail. However, it will be well to first set forth the feeder and press controlling means which are to be interrupted by the devacuum and both the electrical and mechanical tripping mechanisms are intermittently actuated during the feeding cycles and between the successive transfers of the sheets from point to point so that the detector and interrupter devices may interpose themselves, in the event that no sheet is fed at a certain point. to prevent the next normal operation of these controls, and to positively, actuate certain stopping and interrupting mechactuate the sheet detector and drop guide mechanism and to prepare the way for inhibiting the.

actuation of the other devices in the event the detector mechanism indicates the absence of a sheet. This cam is adapted to rock lever by contacting the cam follower roller 46 carried by the upper end of that lever. The lever is pivoted to a fixed portion of the frame as at 41 and is connected at its lower end as at 48 with the book'- like connection head 49 of the substantially horizontal forwardly extending connecting or actuating rod 56. One end of this rod 50 is adjustably threaded into the connecting head 49 and locked in fixed position by means of a nutv 5|. The forward end of the operating rod 50 is diminished in diameter as at 52, and passes through a pin 53,

pivotally carried by the lower end of a bellcrank lever 55. The formation of the narrowed portion 52 of the rod 50 produces a shoulder-as at 55' (Figures 13 and 13A) and upon the other side of the .pin 63 a washer 56 is loosely disposed upon tector mechanism. The cam 42 is provided with three principal levels which yield three different well-defined positions for the lever 45 and the mechanism actuated thereby. The high level of the cam 42 is designated by the reference character 42A and the intermediate level by the reference character 42B, and the low level by' the character 42C. The relative positions ofthe cam follower roller 46 when guidedby these cam portions is shown diagrammatically in the upper right hand comer of Figure 6 of the draw-- ings. 1 It will be noted thatjin this figure and roller 46 and the lever 45 are in the positions 'which they occupy when in contact with the level 42A, regardless of the position of the cam and other portions of the feeder mechanism in those figures. The positions of the detector and drop guide devices under the influence of the intermediate portion of the cam are shown in Figures 14 and 15 of the drawings; and the positions of these parts, under normal conditions of operation, under the influence of the lowest portion42C of the cam,- are shown in Figures 16 and 17 of the drawings. The operation of these parts will be apparent as the present description proceeds.

Adjacent one side wall l2 of the feeder frame, and located at an intermediate point in the suction line extending from the sheet separatin and feeding devices (described in Patent No. 2,263,891) and the suction pump, is the suction chamber 65. A conduit leading to the sheet feeder headfrom this chamber is shown at 66 in Figures 3 and 4 and a similar conduit 61 connects the suction chamber with a suitable vacuum' pump, not shown. The suction chamber. 65 is provided with an opening 66 which. is closed by means of the. valve 10 when a sheet is being lifted from the pile and fed to the forwarding conveyors. At intervals between successive feeding operations, the valve 10 is removed from the opening 66 and the suction chamber 65 vented to the atmosphere. The

valve III is carried by a rocking lever arm 12 which is pivoted as at 13 to the boss 14 which may be formed on the casing of the valve chamber '65, as clearly shown in Figures 2 and 4 a:

the drawings. Beyond the pivot I3, the lower 'portion of the lever I2 is provided with a cam followerroller I which follows the cam I8, this cam having only two levels which serve to move the valve I8 alternately to open and closed" position. The cam movement is opposed by a spring device which includes the rod II which is pivoted to the lever I2 as at I8 and is sur-- rounded by the coil spring 18 which exerts expansive pressures between the shouldered portion of the rod 11 and a part 88 of the feeder control mechanism which is designated generally by the numeral 25 (see Figure 1). Thus it will be seen that the spring arrangement urges the valve toward closed position and is opposed by the cam 16.

The lowermost end of the lever I2 is provided with a projecting pin 82 which has a flat side formed thereon against which the squared end 83 of a rocking latch lever 84 is adapted to abut, under certain abnormal circumstances, in order to hold the valve in its open position to interrupt the vacuum line controlling the feeding of the sheets. clearly in Figures 2 and 4 of the drawings. This latch lever is pinned to a transverse stub shaft 85 which passes through the frame I2 of the feeder device. To the outer end of the shaft 85 there is secured a manually operable arm 88 by which the latch lever 84 may be positively moved for certain purposes to be later described. The

I other arm 88 of the lever 84 extends diagonally upward as shown in Figure 2 of the drawings and terminates in the vicinity of the pin or projection 88 carried by the short arm 88 which moves with the lever 45 and may well beformed upon the same boss 9| which provides the pivotal point 41 for the main lever. This is most clearly shown in Figure 3 of the drawings. It may be mentioned briefly at this point that whenever the main control lever 45 occupies the position shown in Figures 1, 2, and 6 of the drawings, that is as would be effected by the high level 42A of the control cam, whether during the intermittent movement to this position between feedin impulses or when it is latched by the detector-interrupter, the valve I8 is retained in open position by the lever 84 which is urged to this latching position by the pressure of a spring (not shown) and is permitted to move to this blocking position by the movement of pin 89 toward the left in-Figure 2. Then, if the control lever 45 is free to move back, following the levels 4213 and 42C of the cam, the pin 88 moves against the end 88 of the lever 84 and displaces the opposite end 83 from the pin 82 and permits the spring deviceTI-BO to close the valve I8.

For controlling the impression throw-off of the printing press by means of the detectorinterrupter and for opening the switch controlling the power supply to the feeder or the printing press or both of them, the following means are provided. Another cam 85 is carried by the cam shaft 48, this cam being for the purpose of rocking a bell crank lever 88 which is pivoted to the frame I2 as at 88. The upper arm of the bell crank 85 carries the roller 88 which follows the cam 85 whereby the crank 88 is given an oscillating movement in a vertical direction. The lower longer arm of the crank 86 carries a pawl or latch member I88 which is pivotally mounted as at I8I.

When the main control lever 45 is in the position shown in Figure 2, the latch or pawl I88 has This position of abutment is shown its lower end I82 resting upon the shoulder I83 near the upper end of the vertically extending bar I85. As shown in Figure 1 of the drawings the bar I85 is pivoted to a multiple rock arm I88 to which a pawl IN is connected. This pawl is arranged in conventional manner to trip the switch I88 to stop the sheet feeder (and the press also, if desired) and is ,also arranged to actuate mechanism of conventional type, part of which is indicated generally at H8, for tripping the impression of the press. 7

During normal operation, the cam 85 swings the lever 85 which carries the pawl I88 intermittently up and down and the downward movement of the lever occurs shortly after the main control lever 45 leaves the upper level of the control cam 42. Under these conditions the pin II 2 carried by the arm II3 which stems from the same boss or hub 8| as the lever 45 and the arm 88, moves against the right hand side of the upper end of the latch I88, as viewed in Figure 2, and prevents the toe I82 of the pawl I88 from contacting with the shoulder I83 of the bar l85, and the impression and switches are not tripped, If, however, the control lever 45 is latched in the position shown in Figure 2, by means of the detector-interrupter mechanism to be described, the toe I82 of the pawl is permitted, to descend upon the shoulder I83 of the bar I85 upon the next downward movement of the bell crank 96, which will immediately trip the switch I88 and actuate the impression throw-oil I I8.

It will be readily seen from the foregoing description that upon the normal swinging operation of the control lever 45 by means of the cam 42, the valve I8 will be intermittently opened and closed permitting the vacuum or suction devices of the feeder to operate in normal sequence, and the lever or crank arm 88 will move idly up and down without tripping the throw-oil mechanism. Whether or not the valve is latched in open position as shown in Figure 2 and the pawl I88 tripped to actuate the throw-oil bar I85, is dependent upon the latched position of control lever 45. It will be seen from Figure 2 that the main control cam 42 has left the lever 45 which must obviously have been latched by the detector-interrupter devices and the parts are therefore shown in this figure in their tripped or interrupted position. The valve 68 is open to the atmosphere and thecrank 88 has descended or isdescending to move the bar I85 to trip the driving mechanisms.

The novel drop guide and detector-interrupter deviceswhich control the passage of successive sheets from the feed board to the press, and which determine whether ornot the control lever 45 is allowed to oscillate normally, will now be described. In this connection particular reference will be made to Figures 6, 7, and 14-17 inclusive for an explanation of the operation of these devices. Referring now more particularly to Figures 6 and 10 0f the drawings, it will be seen that at the forward end of the feed board 21 there is disposed a transverse bracket or table II5 from which a feed board extension plate H6 (Figure 15) projects tangent to or very slightly above the cylinder bearers of impression cylinder 35 when ofi impression. Also carried by the forward end of the feed board assembly are the tongues or strips II'I upon which the sheets are guided to the point where they are to be seized by the cylinder grippers. At one end of the front plate or table I I 5 of the feed board there is secured a fixed bracket I28 and at the other end another bracket I 2i in which the transverse rock shaft 60 is in its lowermost position as limited by'the contact of the parts I36 and I31. However, when the detector arm I45 is moved to its extreme uppermost position shown in Figure 17, the surface I52 contacts with the lower end of the screw I50 and moves the drop guide arm I26 upwardly out of I the way of the sheets passing-to the cylinder.

and detector units which are designated generally by the reference numeral I25. The drop guide portion of this assembly will be described first. This device comprises a rocking member I26 which may be formed of a single casting and is provided with perforated, spaced, downwardly extending ears I21 which are freely rotatably and slidably mounted on the rock shaft 60. The drop guide element I26 extends forwardly'and is provided witna cylindrical bore which is adapted to receive the shaft I28 upon the feed end of which is bolted the downwardly projecting drop guide plate I30. Spaced arms I3I. extenddownwardly and forwardly from the member I26 and serve to prevent rotation of the plate I30. The

rod I28 is adjustable forwardly and rearwardly against the pressure of the-spring I32 by means of the knob I33 and may be secured in fixed adjusted position by means of the set screw "I34.

The lower end of the drop guide plate I 30 is normally disposed below the level of the sheet guiding tongues H1 and thus serves to stop the forward edges of the sheets and hold them until it is actuated to release the sheets to the cylinder rippers.

Slightly forwardly of the front edge of the table or plate H5 is disposed the transverse fixed bar I35 and this bar is provided with inserted abutment pins I36 against which the lower end of an adjustable bolt I31 may strike to determine the lowermost position of the drop guide. This arrangement is most clearly shown in Figure 7 of the drawings. At spaced intervals along the bar I35, and adjacent the units I are formed forwardly projecting wedge-shaped latch blocks I40, which are elongated in a direction transverse to the path of the sheets.

The detector portions of the assemblies I25 comprise the detector arms I45 which are keyed to the rock shaft 60 between the ears I21 of the drop guides as at I46 (see Figures '1, 15, and 17) and secured by means of the set screws I46 at adjusted positions along the shaft in accordance with the width of the sheets being fed. The forward end of the detector arm I45 is split to receive the pivoted latch I46 which in its lowermost position is disposed in the pathway of the sheets across the tongues H1 and immediately in advance of the drop guide plate I as shown in Figure '1. The latch element is'provided with a hooked portion or shoulder I46 which when it -is in its lowermost position rests beneath the forwardly projecting nose of the latch block I40 as clearly shown in Figure 7. Since the detector arm I46 is disposed between the ears I21 of the drop guide and-directly beneath the drop guide rocking movement of the drop guide. Ari adjustermost position as shown inFigure 7 of the drawlugs and when it is inits position indicated in Figure 15 0f the drawings, the drop arm I26 is An upper hold-down tongue H1 is pivoted as at I55 to the ('etector arm I45 and adjusted by means of the s: t screw I56 to a position in which it is allowed to bear lightly upon the sheets as they are fed tothe front stop guide, but it is adapted to be moved upwardly a slight distance when the parts are in their uppermost position as shown in Figure 1'1.

Referring now-more particularly to Figures 11 and 12 of the drawings, it will be seen that means are provided for urging the drop guide member I26 downwardly toward the lowermost position where the drop guide plate I30 prevents the passage of a sheet. This means includes a flat plate I60 which is provided with a circular opening through which the shaft 60 passes. This plate has a foot I6I which extends under the bar I35.

A pin I62 on this piateis connectedby means of the spring I63 to a pin I64 secured on the drop guide arm I26. This spring thus insures that the drop guide arms return to the position shown in Figures 7 and 15. The plate I60 is attached to the drop guide arm extension I21 by means of the headed studs I65, these studs being threaded into the arm I21 but having a certain clearance with the margins of the openings I66 in the plate I60 through which they pass. arm I26 to rotate about the shaft 60 relatively to the plate I60, and of course the plate I60 is moved along with the unit I25 whenever the unit is adjusted along the shaft 60 to accommo date sheets of differing widths.

One of the more essential novel features of the present invention willv now be described. This involves the means for enabling the impression cylinder itself to trip the drop guides to permit the passage of a sheet, only when a sheet is presented to the guides at the proper time and its with a cam roller I16 carried upon a pin I11 (see Figures 6, 8, and 9). At another portion of the arm I15 a pin I18 is secured, which pin has an extension I16 rotatably received within an opening in one end of a short connecting link I80. The other end of this link is pivotally mounted 1 on the end I8I of a pin I62 which is rigidly supported by the fixed bracket I20 disposed at one side of the forward end of the feed board.

Rigidly carried,by the impression cylinder 35 at one side thereof is the drop guide tripping cam plate I86, having a gradually inclined approach surface I86 which adapted to strike the cam roll I16 when that roll is lowered into the path of the slope I86 and raise the roll together with the cranks by which it is supported, to rock the shaft 60 and thus the drop guides I26 and permit the passage of a sheet just in time to be seized by the cylinder grippers. When the parts are in the position shown in Figures 6 and 7, either one of two conditions prevail, that is, when applied to a two'revolution press. In one of these conditions the detectorinterrupter has latched the parts in an oil position so that the cam plate I85 will not contact the roller I16, and this is due to the functioning of the detector in the absence of a sheet. Under the other condition, the same position of parts will prevail, but this is during the idle or return revolution of the impression cylinder and the parts are held in this position, not by the latch I48, I40 but by the high level 42A of the operating cam. This also, of course, prevents the tripping of the drop guide by the cam plate I05.

Now, during the normal operation of the device, assuming that the sheet has been properly fed against the drop guide plate I30 and has moved the latch I48 forwardly from beneath the latch block I40, the roller 46 of the control lever 45 moves down on the intermediate level 42B of the control cam. Then the spring I90 which is compressed between the collar I9 I, pinned to the rod 50, and the abutment I92 forming a part of the guide bracket I93 for the rod, urges the roller 40 to follow the cam .and moves the rod 50 to the left as viewed in Figure 6. The slack or lost motion indicated by 'x in Figure 13 is then taken up and the shoulder 53' abuts the pin 53, and the parts are in the position shown in I3A where the slack or lost motion spacing is at x on the opposite side of the pin. This movement rocks the crank 55 in a clockwise direction and 'moves the lever arm I15 downwardly so that the roller I16 is disposed in the path of the cam plate I85. The rocking of the shaft 60 also raises the detector arm I45, together with again shifted to the positions they occupy in Figures 6 and 7, by the high level 42A of the cam again acting on the control lever 45. It will be apparent from the foregoing detailed descriptions that the detector devices, of which there are two or more spaced apart transversely of the forward edge of the feed board, will interrupt the feeding and the operation of the press whenever any one of the detector latch fingers is allowed to be detained by the latch block I40. Therefore, the protective device is not only operative whenever no sheet is fed at the proper time of rotation of thecylinder, but also in cases where a sheet is improperly fed through misalignment-transversely of the feed board. Y

As a corollary to the last-named function and operation of the device comprising the present invention, further mechanisms are provided for preventing the cylinder grippers closing upon the projecting corners or advanced edge portion of a crooked sheet, and thus carrying a crumpled or folded sheet through the printing couple, with resultant damage to the form. Normally, alternately projected elements are operative adjacent one margin of the impression cylinder to actuate the cylinder gripper tumbler to snap the latch I40 which has been freed from the overhanging latch block I40 by the contact with the sheet and this movement continues until the approximate point where the top surface I52 of the arm I45 abuts the screw I50. This is the position the parts occupy when the cam I05 is approaching the roller I15 prior to the point when the sheet is to be seized by the,-

cylinder grippers and near the beginning of the printing revolution. When the cam plate I85 strikes the roller I16, the roller, together with its arm or bracket I15, is swung toward the left as seen in Figure 16 and the bell crank 55 is rotated further in a clockwise direction and through its rigid connection with the shaft 50 and the detector arm I45 moves these parts in the same direction. Since contact has already been made between the surface I52 and the screw I50 this further movement of the parts carries with them the drop guide body I25 and raises the plate I30 high enough to permit the passage of a sheet as clearly shown in Figure 17 of the drawings. This additional movement effected by the rotation of the impression cylinder is accomplished rather suddenly and while the rod 50 is still in its intermediate position. This causes the slack or.lost motion space :c' to be taken up and thespace transferred to x on the opposite side of the pin 53. However, almost immediately following the tripping of the drop guides by the cam plate I05-onthe cylinder, the roller 46of the control lever 45 has moved to .the right (Figure 6) while traversing the lowest level 420 of the control cam and the rod 50 is shifted further to the left-under the influence of the springs I90 and the parts are maintained in their uppermost position which.they occupy in Figures.

16 and 17, until the entire sheet has been transferred from the feed board by the cylinder grippers. Then .prior to the movement of the next succeeding sheet to the delivery point of the feeder at the front guides, the parts are the grippers-into contact with the forward edges of the sheets simultaneously with the raising of the front or drop guides, and to actuate the gripper tumbler in the opposite direction to release'the grippers upon delivery of a sheet during alternate revolutions of the cylinder. The mechanism about to be described is associated with the rock shaft 60 of the detector-drop guide assembly and serves to block the tumbler actuatingpin upon failure of proper feeding. The grippers are thereby prevented from closing at all whether no sheet is presented or a canted or misaligned sheet is presented to the guides.

Referring more particularly to Figures 10 and 18-25 inclusive of the drawings, it will be seen that the impression cylinder 35 is provided with the conventional set of cylinder gripper fingers 200 which are mounted on the gripper shaft 20I, these devices occupying a cut-away segment of the cylinder. The shaft 20I rocking movement within bearings carried by the cylinder and carries upon its outwardly projecting'end a tumbler member 202 by which the grippers are alternately thrown into operative and inoperative position. The tumbler member 202, together with its associated devices, is very similar to the vcorresponding parts of the patent to Stobb No. 2,184,725 of December 26, 1939, the tumbler being provided with slots 203 and 204. which open in opposite directions, the slot 203 being adapted to receive the actuating pin forthrowing the tumbler into gripper closing position, and the slot 204 arranged to receive another pin or proiectable element for throwing the tumbler into gripper releasing position. A rod201 is pivoted to the tumbler member as at 200 and is arranged to slide through an opening in a pin 209 carried by the cylinder 35. A. coilspring 210 surrounds the rod 201 and is com-' pressed between the shoulders or seating poris mounted for and another crank arm 220 at the other. The crank arm 2I9 is pivotally connected as by means of the pin and slot connection 222 with one end of a pin 225 which is slidably mounted within an opening in the cylinder bearing housing2I 5.

A second pin 230 is slidably mounted within an extension 232 of the housing 2I5. 'This pin is provided with a semi-cylindrical projecting end 235 which is adapted to engage and actuate the cylinder'gripper tumbler and is for the greater part of its length provided with a cylindrical bore in which a pin 236 may reciprocate while under Under normal operation of the press agdjeeder.,.thaend 23 5- is -in-its'outwardlyproj ected position, as shown in Figures 24 and 25 of the draw-- ings, when the mouth of th slot 203 approaches the pin whereupon the end or the pin enters the slot and causes the tumbler to move from the position shown in Figure 18 to the position shown in Figure 19 whereupon the sheet is gripped and carried through the press. At a certain point during subsequent rotation of the cylinder a cam device (not shown) of conventional structure and arrangement strikes the end 235 of the pin 230 causing it to move through the housing 232 so that the spring-pressed smaller pin 236 rocks the crank 220 outwardly, rotating the shaft 2! and causing the crank 2!!! to project the other pin 225 through its opening in the housing 2I5 and positioning its outer end so as to enter the slot 204 of the tumbler and release the grip- Pers at the proper point for delivery of the printed sheet. Then, preparatory to again receiving a sheet, a cam device strikes the project ing end of the pin 225, reverses the movement of the cranks 2I9 and 220 and pressure of the pin 242 upon the spring-pressed pin 236 causes the tumbler actuated pin 230 to again project to an operative position to cause the grippers to close. This alternating cycle of movement continues so long as normal feed of the sheets is maintained.

The upper surface of the tumbler actuating pin 230 is kerfed or slotted as at 245 and the housing 232 is also kerfed as at 246, these kerfs being in registry when the pin 230 is in retracted position as shown in Figures 20 and 23.

Asclearly shown in Figures 20, 21, 22 and 23 of the drawings a sleeve 250 carrying a locking arm 25I, is rotatably mounted upon the end of the rock shaft 60 opposite to that at which the operating bell crank 55 is secured. The sleeve 250 is semi-circularly cut away adjacent its outer end as indicated at 252 to provide a shoulder 254 upon the lower side thereof, against which a pin 255 secured to the shaft 60 may abut. The outer end of the lock arm 25l is provided with a squared foot portion 258 which is adapted to enter the kerf 246 of the housing 232 and in certain position of operation of the pin 230 it may also enter the kerf 245 of this pin and lock it against projection and thus prevent the actuation of the tumbler.

During normal operation of the press, the rock shaft 60 will oscillate together with the crank 55 the cam 42 onthe lever 45. The arrangement of the lock a'rm is such that as the shaft- '60 rocks, the pin 255 presses aaginst the shoulder 254 and moves'the latch arm 25I alternately into and out of the kerfs.245 and 245. The removal of the latch arm from the kerfs is synchronized with the projection of the pin 230- to control the grippers. However, when one ormore of the detectors remain latched, the shaft 6|) does not rotate and the lock arm 25l remains within the kerf 245 of the pin 230. Then, upon the next operative movement of the crank 220 when the pin 225 is cammed, the pin 236 will be forced inward against .the pressure of the spring 238, but the main tumbler actuating pin 230 will not be projected. Thus, the next actuation of the grippers 200 will not take place and thegrippers will be'pree vented from closing upon the unoccupied blanket of the cylinder or upon any portion of a canted or misaligned sheet. It will thus be seen that not 'only does my improved detector and front guide mechanism serve to interrupt miemand throw-OtFthe-impresSioIiTBiFaIsO prevents the cylinder grippers from closing and thus prevents damage to the operating portions of the press.-

Although the operation of certain parts of the device has been indicated as the construction of these elements has been described, it will be well to review the entire operation of the drop guide and detector-interrupter mechanism as 'a whole.

As already described, the variouscams carried latch device I45, I48 to alternately dispose it in the path of the sheets and remove it therefrom, but also intermittently removes the camroller I18 from the path of the cylinder cam plate J85.

Thus the three devices describednamely, the valve I0,'the rock arm 96, and the trip means I15, I'IG-are alternately placed in a temporary throw oil?" position where they can be retained in case the detector-latch is not displaced by the presence of a sheet. If a sheet is properly prej'e I sented, the latch I48 is freed from the blockv I40 and the device I45 is raised by the rocking. er the crank 55 and the trip arm I15'androller I16 lowered to the positions shown in Figures 14and ,15. Then as has been described. the cam plate I85 contacting the roller I16 on the arm I15 raises both of the devices I45 and I26 to the position shown in Figures 16 and 1'1 whereupon the sheet is seized by the grippers. Duringthe movement of the parts from the position shown in Figures 6 and 7 tome successive positions shown in 'Figures'14 and 15 and'Figuresv l'6 ..and 17, the other cams on the shaft 40 act topermit the restoring of the valve 10 to closed position and permit the rocking of the crank 96 to its normal 7 upward position.

and rod 50 under the influence of the action or 15 Also the return movement of lever 45 follow- Y ing the lower portions of the cam 42' under'the influence of the spring I90,'.mov es the lever 84 in a clockwise direction as viewedfin Figure 2 so that the end 83 thereofis removed from the pin 82 so that the valve arm I2. may'follow the valve cam I6 and the valve may be closed under the influence of the spring". At the same time the pin-'III carried by the arm H3 rigid with the lever 45 strikes the upper end of the pawl I and removes the toe I02 from the'shoulder I03 of the bar I05; thus preventing the tripping of the-switches and the impression when the crank 98 is moved downwardly under the influence of the cam 95. Also during the normal operation of the device, the rock shaft 60 causes the control lever 45, this lever and all of its associated parts including the rod 50 and the bell crank 55 remain locked in the position shown in Figure 6." Under these conditions, the cylinder cam plate I85 will not strike the cam roll I16 and the front guide will not be tripped; the lever 04 will not be displaced by the pin 85 and the valve lever 12 will remain in open position, de-

stroying the effectiveness of the vacuum in the sheet feeder; and the pawl I00 wi11 not be displaced from the position shown in Figure 2, whereupon the downward movement of the bell crank 06 caused by the cam 95 will depress the bar I05 and trip the switch I08 and the impression' throw-off devices IIO. Also the shaft 60 fails to rock, the lever I remains in the slot or kerf 245, the gripper actuating pin is retained in retracted position, and the cylinder grippers do not function Thereupon, the reason for the non-feeding of the sheet may be ascertained and the devices placed in proper running order. Before restarting the feeder and press, it may be necessary to manually rock the lever 84 by means of the handle 86 (Figures 2 and 4) so as to permit the valve 10 to be closed to feed several sheets from the pile down to the-drop guide,

scribed without departing from the scope of the invention as defined in the accompanying claims. Having thus described theinvention, what is claimed as new and desired to be secured by element, a common pivotal axis for said elements about which .said elements separately-move, and means operated by the source of power for driving the feeder for normally intermittently swinging the drop guide into and out of the path of the sheets moving along the feed board, means associated with said guide and detector element for preventing the normal operation of 7 said drop guide when no sheet is presented to the detector element of the combined device 2. In a power driven sheet feeder for printing presses or similar machines, a feed board extending toward the machine to which the sheets are to be fed, a combined drop guide and sheet detector device carried by the front end of said feed board, said device comprising a pivoted detector element and a pivoted drop guide element, a common pivotal axle for said elements, the detector element being fixed to said axle and the drop guide mounted loosely thereon in position to be contacted and moved by said detector element, means operated by the source of power for driving the feeder for normally intermittently swinging the drop guide into and out of the path of the sheets moving along the feed board, and

means associated with said guide and detector element for preventing the normal operation of said drop guide when no sheet is presented to the detector element of the combined device.

3. In a power driven sheet feeder for printing presses or similar machines, a feed board extending toward the machine to which the sheets are to be fed, a combined drop guide and sheet detector device carried by the front end of said feed board, said device comprising a pivoted drop guide element and a separately pivoted detector element, means operated by the source of power for driving the feeder for normally intermittently swinging the drop guide into and out of the path of the sheets moving along the feed board, means for regularly and intermittently setting-the sheet feeding mechanism in condition for being rendered inoperative during a subsequent phase of its normal cycle and alternately unsetting said condition, means associated with said guide and detector elements for directly preventing the normal operation of said drop guide and preventing the unsetting of the feeder mechanism when no sheet is presented to the detector element 'of the combined device.

4. In a power driven sheet feeder for printing presses or similar machines, a feed board extending toward the machine to which the sheets are to be fed, a combined drop guide and sheet detector device carried by the front end of said feet board, said device comprising a pivoted detector element and a pivoted drop guide element. means operated by the source of power for driving the feeder for normally intermittently swinging the drop guide into and out of the path of the sheets moving along the feed board, means carried by the machine to which sheets are to be fed for tripping the drop guide to release sheets from the feed board immediately before the operation of swinging the drop guide out of said path effected by said first named means, and means associated with said guide and detector element for preventing the normal operation of said drop guide when no sheet is presented to the detector element of the combined device.

5. In a. power driven sheet feeder for printing presses or similar machines, a feed board extending toward the machine to which the sheets are to be fed, a'combined drop guide and sheet detector device carried by the front end of said fed for positively tripping the drop guide to redevice.

. aseaaoc lease sheets from the feed board immediately before the operation of Swinging the drop guide out of said path effected by said first named means, said first named means serving to prolong the duration of the displacement of the drop guide after it is tripped, to permit the passage of the full length of a sheet, and means associated with said guide and detector element for preventing the normal operation of said drop guide by the first named means and the tripping of the guide by the machine carried means when no sheet is presented to the detector element of the combined device. v

6. In combination with a printing press or the like having an impression cylinder "and sheet feeding means therefor, a feed board, a front drop guide device positioned adjacent the forward end of said feed board, and a sheet detector adjacent thereto, a trip element on said impression cylinder adapted 'to intermittently contact a portion of said drop guide device to remove the drop guide from the path of the sheets, and means operated by said detector in the absence of a sheet at the proper time, to prevent contact between said trip element and said drop guide 7. In a sheet feeding device for printing presses having an impression cylinder as one member of the printing couple, and intermittently operated sheet grippers on said cylinder, in combination, a feed board along which successive sheets are fed disposed with its front edge in close juxtaposition 'der grippers, a member operatively connected to to the'impression cylinder of the press, a drop guide carried by the feed board adjacent said front edge, a cam block on the periphery of said impression cylinder for tripping the drop guide to release a sheet just prior to its seizure by the cylinder grippers, a member operatively connected to said drop guide and adapted to be projected into the path of said block to be actuated thereby to trip the drop guide, and means for projecting said member into the path of the cam block only when a sheet is properly positioned at saidv drop guide.

8. In a sheet feeding device for printing presses having an impression cylinder as one member of the printing couple, and intermittently operated sheet grippers on said cylinder, in combination, a feed board along which successive sheets are fed disposed with its front edge in close juxtaposition to the. impression cylinder of the press, a drop guide carried by the feed board adjacent said front edge, of said impression cylinder for tripping the drop guide to release a sheet just prior to its seizure by the cylinder grippers, a member operatively connected to saiddrop guide and adapted to be' projected into the path of said block to be actuated thereby to trip the drop guide, means for projecting said member intermittently into the path of said block and withdrawing it therefrom during the normal operation of said device, and

means for rendering said last named means inef-- fective when no sheet is fed to the drop' guide.

9. In a sheet feeding device for printing presses having an impression cylinder as one member of g the printing couple, and intermittently operated sheet grippers on said cylinder, in combination, a feed board along which successive sheets are feed disposed with its front edge in close juxtaposition to the impression cylinder'of the press, a combined sheet detector and drop guide device carried by the feed board adjacent said front edge. a cam block on the periphery'of said impression cylinder for tripping said device to resaid'drop guide and detector device and adapted to be projected into the path of said block to be actuated thereby to trip the drop guide, means means ineffective when no sheet is fed to the dropguide. I

10. In a self contained power driven sheet feeding device adapted tobe disposed closely adjacent and in feeding relationship to printing presses having an impression cylinder as one member of the printing couple, and intermittently operated sheet grippers on said cylinder, in combination, a feed board along which succes sive sheets are fed disposed with its front edge in close juxta-position to the impression cylinder of the press, a drop guide carried by the feed board adjacent said front edge, a projection on the periphery of said impression cylinder for tripping the drop guide to release a sheet just prior to its seizure by the cylinder grippers and follow up means for retaining said drop guide in tripped position during the passage of the entire sheet.

11. In a sheet feeding device for printing presses, having an impression cylinder as one member of the printing couple, and intermittent- 1y operated sheet grippers on said cylinder, in combination, a feed board along which successive sheets are fed disposed with its front edge in close juxtaposition to the impression cylinder of a a cam block on the periphery sion cylinder at a point on its periphery, a combination device'carried by the feed board adjacent its front end andcomprising three pivotally mounted members, namely a drop guide, a sheet detector, and a member adapted to. be projected into the path of said tripping block, drive means associated with the sheet forwarding mechanism of the sheet feeder, operative connections between the respective three members of said combination device and between said drive means and said device, whereby the latter is actuated through three stages, one in which thedropguide is in operative sheet registering position, the detector is inthe path of the sheets, and the projectable member is retracted; a second stage in which the drop guide is still in operative position, thedetector is partially retracted and clear of the path 01' the sheets, and the projectable member is in projected position in readiness to betripped by said block; and a third stage in which the drop guide is'heldin operative sheet delivery position, the detector is retracted further, and the projectable member is in anotherretracted position.

12. In a sheet feeding device for printing presses having an impression cylinder as one member of the printing couple. and intermittently operated sheet grippers on said cylinder, in

combination, a feed board along which successive sheets are fed disposed with its front edge in of said impressioncylinder for tripping said dovice to release a sheet just prior to its seizureby the cylinder grippers, said combined device comprising a freely pivoted drop guide element and a positively actuated detector member having means moving therewith to be projected into the path of said block, said drop guide being disposed in the path of movement of said detector member toward displaced position, whereby said block moves said last named means, said detector member, and finally said drop guide.

13. In a sheet feeding device for printing presses having an impression cylinder as one member of the printing couple, and intermittently operated sheet grippers on said cylinder, in combination, a feed board along which successive sheets are fed disposed with its front edge in close juxtaposition to the impression cylinder of the press, a drop guide carried by the feed board adjacent said front edge, a tripping block carried by said impression cylinder at a, point on its periphery, a projectable element operatively connected with said drop guide and movable to and.

from the path of said block, drive means actuated in synchronism with the operating mechanism of the sheet feeder and operatively connected with said element and said drop guide for alternately moving said guide into and out of operative position in the path of the sheets and said element out of, into, and beyond the path of said block, a lost motion connection between said drive means and said element, whereby said element and said drop guide may be moved by contact with said block and independently of said drive means, and a lost motion connection between said element and said drop guide whereby said element may be moved into the path of the block without moving the drop guide, but both will be moved together during movement of said element beyond said intermediate position in the path of said block.

14. The device as set forth in claim 13 in which the operative connection between said element and said drop guide includes a sheet detector provided with latch means which during normal operation when sheets are properly presented to the drop guide, is inoperative, but which in the absence of a sheet locks the projecting element in retracted position and the drop guide in sheet stopping position.

15. The device as set forth in claim 11 in which the means for operating the combined device during normal operation is a cam driven in synchronism with the sheet forwarding mechanism of the feeder and a cam following lever operatively connected with the device, and means are provided in connection with the sheet detector for holding the lever away from said cam when no sheet is presented to the drop guide.

16. The device as set forth in claim 11 in which the means for operating the combined device during normal operation is a cam driven in synchronism with the sheet forwarding mechanism of the feeder and a cam following lever operatively connected with the device, and in which there are provided means in connection with the sheet detector for holding the lever away from said cam when no sheet is presented to the drop guide, and means carried by said cam-following lever for interrupting the operation of the feeder when said lever is prevented from following said cam. 1

1'7. A combined drop guide and sheet detector device for use in a sheet feeder for a printing press having an impression cylinder, said device comprising a freely vertically pivoted drop guide arm, a sheet detector arm vertically pivotally mounted concentrically with said drop guide arm and disposed at a predetermined distance beneath the latter, whereby when said detector is swung upwardly beyond a predetermined point the drop guide isalso raised.

18. A combined drop guide and sheet detector device for use in a sheet feeder for a printing press having an impression cylinder, said device comprising a freely pivoted drop guide arm, a sheet detector arm pivotally mounted concentrically with said drop guide arm and disposed beneath the latter, whereby when said detector is swung upwardly beyond a predetermined point the drop guide is also raised, and adjustable contact means between said arms for regulating the timing of the raising of the drop guide arm by the detector arm.

19. A device as set forth in claim 1'7, which includes spring means for urging the drop guide arm downwardly in opposition to the upward movement of the detector arm, whereby the drop guide arm will maintain contact with the detector arm during their upward movement together regardless of the abruptness of the movement.

20. The device as set forth in claim 1'7 which includes two means for moving the detector arm and thus the drop guide arm, one of said means being operated by the sheet feeder drive and in synchronism therewith and the other by a tripping member carried-by the impression cylinder.

21. The device as set forth in claim 17 which includes two means for moving the-detector arm and thus the drop guide arm, one of said means being operated by the sheet feeder drive and in synchronism therewith and the other by a tripping member carried by the impression cylinder,

- the first of said two means including a, lost motion connection for enabling the second means to operate in advance of the other.

22. In a printing press and sheet feeder assembly, an impression cylinder, a feed board extending toward said cylinder, 9. combined drop guide and sheet detector device carried by the front end of said feed board, said device comprising a pivoted detector element and a pivoted drop guide element, a common pivotal axle for said elements about which said elements are separately pivoted, cylinder grippers carried by said cylinder for seizing a sheet from said feed board upon release by said drop guide, means for actuating said cylinder grippers in synchronism with the operation of said drop guide, means controlled by said axle for alternately obstructing and freeing said cylinder gripper actuating means, means operated by the source of power for driving the feeder for normally intermittently rocking said axle, swinging the drop guide into and out of the path of the sheets moving along the, feed board, and operating said controlled andsheet detector device carried by the front end of said feed board, said device comprising a pivoted detector element and a'pivoted drop guide element, a common pivotal axle for said elements, the detector element being fixed to said axle and the drop guide mounted loosely thereon in position to be contacted and moved by said detector element, cylinder grippers carried by feed board, cylinder sheet feeder adapted to said impression cylinder,

said cylinder for seizing a sheet from said feed board upon release by said drop guide, means for actuating said cylindergrippers in synchronism with the operation of said drop guide, means for alternately blocking and unblocking the movement of said cylinder gripper actuating means, said blocking means being operatively connected with said axle to be contacted and moved thereby under normal operating conditions, means operated by the source of power for driving the feeder for normally intermittently rocking said axle, swinging the drop guide into and out of the path of the sheets moving along the feed board, and operating said controlled means, and means associated with said guide and detector element for preventing the normal operation of said axle, and consequently of said drop guide and said cylinder gripper actuating means, when a sheet is not properly presented at said .drop guide.

24. In a printing press and sheet feeder assembly, an impression cylinder, a feed board extending toward said cylinder, a front. guide and a sheet detector carried by the forward end of said grippers carried by said cylinder for seizing a sheet from said feed board upon release by said front guide, a tumbler member for alternately opening and closing said grip pers in timed sequence with the cycle of operation of the press, alternately actuated pins adapted to be projected into and out of the path of said tumbler for respectively opening and closing said grippers, one sible and contractible, means operatively connected with said detector device for blocking a portion of said pin and preventing its projection, whereby the grippers are rendered inoperative when no portion of the sheet is presented to the detector device at the proper time.

25. A substantially self-contained power driven be disposed adjacent a of said pins being extentumbler for respectively opening and closing said said axis.

and operatively connected with said detector device for blocking the pin which closes thelgrippers and preventing its projection, whereby L-the grippers are rendered inoperative when no sheet is presented to the detector device at the proper time.v

27. In a power driven sheet feeder for printing presses or similar machines, a feed board ex tending toward the machine to which sheets are to be fed, a .transverse rock shaft carried by the feed board, a sheet detector carried by said shaft for pivotal movement about the axis of said shaft, and a frdnt drop guide carried by said shaft and separately mounted for pivotal movement about 28. In a power driven sheet feeder for printing presses or similar machines a feed board extending toward the machine to which sheets are to be fed, a transverse rock shaft carried by the feed board, a sheet detector carried by said shaft for pivotal movement about the axis of said shaft,

and a front drop guide carried by said shaft and separately mounted for pivotal movement about said axis, and means for interrupting the operaprinting press or the like to which sheets are to 1 be fed, said printing press having a rotatable impression cylinder, cylinder grippers carried by and means for intermittently actuating said grippers'to seize a sheet is presented, thereby lockingsaid shaft from rocking and retaining said arm in position obstructlng the actuation of the cylinder grippers.

26. In a printing press and sheet feeder assembly, an impression cylinder, a feed board, extending toward said sheet detector carried by the forward end of said feed board, cylinder grippers carried by said cylinder for seizing a sheet from said feed board cylinder, :1 front guide anda tion of the feeder also carried by the same shaft and responsive to the sheet detector.

29. In a power driven sheet feeder for printing presses or similar machines, a feed board extending toward the machine to which sheets are to be fed, a transverse, rock shaftcanried by the feed board, and a combination sheet detector and drop guide device carried by said shaft and comprising a detector element and a drop guide element each separately pivoted about the axis of said shaft, the combination device being adjustable longitudinally of said shaft to selected positions suitable to the size of sheet being fed.

30. The mechanism set forth in claim 29 in which there is provided feeder interrupting means controlled by said detector element through said rock shaft itself, whereby the selective adjustment of the combination device only along the shaft is sufficient to accommodate the mechanism to sheets of'various widths.

31. In a selfcontained power driven sheet feeder adapted to be disposedadjacent a printing press or similar machine for feeding sheets thereto, the combination of a feed board extending toward the machine to which the sheets are to be fed, a driving member'carried by said feeder,

' guide and sheet detector by said feed board and associated with said guide 32. In a self-contained power driven sheet to be disposed adjacent the imfeeder adapted pression cylinder of a printing press or similar machine for feedingsheets thereto, the combiof said machine, a combination drop guide and sheet detector device carried entirely by the front,

end of said feed board, means on said feeder device, an element carried by said feed board and operatively connecting said device with said drivconnected to said drop guide portion and proing member for normally and intermittently jected toward said impression cylinder only when swinging the drop guide portion of the device a sheet is properly fed to said drop guide, and a into and out of the path of the sheets moving 5 tripping projection fixed on the periphery of said along the feed board, means also carried by said impression cylinder and adapted to p the p feed board and associated with said guide and guide to permit a Sheet 190 be released y e detector element for preventing the normal opersaid'element is projected into the path of said ation of said drop guide when no sheet is prep n. sented to the detector element of the combined 10 DAVID P. SANFORD.

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