US2384046A

US2384046A - Sheet feeding mechanism

Info

Publication number: US2384046A
Application number: US516959A
Authority: US
Inventors: Frederick W Seybold
Original assignee: American Type Founders Co Inc
Current assignee: American Type Founders Co Inc
Priority date: 1944-01-04
Filing date: 1944-01-04
Publication date: 1945-09-04
Anticipated expiration: 1962-09-04

Description

Sept. 4, 1945.

F. W. SEYBOLD SHEET FEEDING MECHANISM "i Shgets-Sheet 1 Filed Jan. 4, 1944 F. W. SEYBOLD SHEET FEEDING MECHANISM Sept. 411945.

'7 Sheets-Sheet 2 Filed Jan. 4, 1944 g MMQZQ W 9 F Sept. 4, 1945. F.. w. SEYBOLD SHEET FEEDING MECHANISM Filed Jan. 4, 1944 7 Sheets-Sheet 3 m W D. w\ j Q J m m m H w .PHN MVI {H n n" n I M Ii IL w y u V W M HA A x\\\ W NW. mm NM. HA

F. W. SEYBOLD SHEET FEEDING MECHANISM Sept, 4, "i945.

Filed Jan. 4, 1944 7 Sheets-Sheet 4 Sept; 4,-1945. F. w. vabw 2,384,045

SHEET FEEDING MECHANI SM Filed Jan. 4, 1944 7 Sheets-Sheet 5 Q a Maw #7 w agwatzm Sept- F. w. SEYBOLD 2,384,046

SHEET FEEDING MECHANISM Filed Jan. 4, 1944 7 Sheets-Sheet 6 F. W. SEYBOLD SHEET FEEDING MECHANISM 7 Sheets-Sheet '7 Filed Jan. 4, 1 944 Patented Sept. 4, 1945 SHEET FEEDmG MECHANISM Frederick W. Seybold, Westfield, N. J assignor to American Type Founders Incorporated, Elizabeth, N. J a corporation of New Jersey Application January 4, 1944, Serial No. 518,959

18 Claims.

This invention relates to sheet feeding devices and more particularly to devices of this general character which are adapted for use in the successive feeding of individual sheets from a pile to a printing press or similar machine.

The general object of the invention is to provide an improved machine of the class described which embodies novel features which make for increased efficiency, accuracy, and speed of operation.

It is conventional in the art of sheet feeding to provide in advance of the printing press cylinders, or of the operative mechanism of a folding, slitting, or similar machine, a feeding device or installation which consists generally of a pile elevator, a sheet separator, and a forwarding conveyor for delivering the successive sheets to the machine being fed. Means are usually provided for the synchronization of the action of the separator and that of the forwarding conveyor so that the separated and lifted sheets are properly transferred from the separating grippers to the conveyor grippers so as to effect either sequential or stream feeding. Means are also provided for gauging the height of the pile of sheets with respect to the zone of operation of the sheet separating instrumentalities, whereby the gradual exhaustion of the pile is countered by a corresponding elevation of the pile board so as to maintain the successive top sheets of the pile at an approximately constant level.

For accomplishing this latter purpose, feelers or hold-down elements of various types have been employed which take the form of fingers, rollers, or other pressure devices which bear upon the top of the pile, usually near the forward or rear edges. These elements are operatively connected with the pile elevator mechanism so that when they are lowered by depletion of the pile beyond a predetermined level, the elevator mechanism is set in operation; and when the gauge element is raised to normal position again, the operation of the elevator is stopped,

For greater economy and ease in construction, operation, and maintenance, the top of the pile of sheets in the feeder should bees free from operating mechanism as possible, consonant with eflicient and continuous feeding. Furthermore, it is obvious that such mechanism as is necessary should be as' simple and direct in its movements and action as it is possible to attain.

With these points in mind, the objects and purposes of the present invention will be readily understood. The invention contemplates the tain partial areas of the sheets. These relative provision of means for combining the functions of the sheet-separating and feeding grippers and the pile height gauge. The usual gauge finger is eliminated and certain novel and improved operativ connections are made between the elevator and the grippers, whereby whenever the downward travel of the latter toward the .pile to pick up a sheet exceeds a predetermined distance due to depletion of the pile, the pile elevator is brought into action to restore the level. According to optiontal embodiments of the invention described herein, the operative connections are either electrical or involve fluid pressure.

Bymeans of the present invention, the pile level is automatically kept at the correct height for feeding, since the gauging is done at the point of seizure of the top sheets and not at the rear edge of the pile or at some other remote point. The positioning of the pile height control at a point spaced from the grippers has resulted in missed sheets and a consequent tripping of the interrupter, or has required frequent re-adiustments of the pile height governor during the operation of the feeder.

It will be readily appreciated that in cases in which sheets are required to be fed two or more times through a printing press for successive printing operations, the pile height may be higher or lower at the gauging point than at the gripping points due to the layer of ink at cerpositions of gripper level and pile heightgovernor level, chang as the sheets are fed and can only be corrected by adjustment of the pile' height governor.

Another object attained by the present invention, which results from the elimination of a front edge gauge or hold-down, is the simplification of the cycle of movement of the separating and feeding grippers, making any rearward disengaging movement of the top sheets unnecessary.

Thus, the present invention provides marked improvements in the sheet separating and feeding mechanism itself and also in the operative connections between said mechanism and the pile elevator. I

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which certain embodiments of the which have been omitted for the sake of clearness of illustration;

Figure 3 is a fragmentary view in transverse the pile board 20 which is secured upon either side to the brackets 2|. These brackets are guided for generally vertical movement upon the guide bars 22 supported by the feeder frame. The forward edge of the pile board 20 and the forward side of the pile of sheets is guided by section of the feeder as taken on the line 33 or\. means of the framing 23 and the pile board is Figure 1;

Figures 4 and 5 are fragmentary views in verti- ,cal longitudinal section showing the sheet gripper actuating mechanism in two different operative positions;

Figure 6 is a detail view in vertical section showing the elevator actuating pawl and ratchet and means for rendering it operative and inoperative;

Figures 7 and 8 are vertical sectional views of a vacuum relieving valve in the elevator control system, in closed and open positions respectively;

Figure 9 is a view in vertical longitudinal section of one of the suction grippers, two shifted positions of the gripper member being indicated in broken lines;

Figure 10 is a horizontal sectional view of the gripper as taken on the line Ill-I0 of Figure 9;

Figure 11 is a fragmentary view similar to Figure 9 but showing the gripper member in depressed position for seizing a sheet from the pile;

Figure 12 is a detail view in vertical section of the suctiorrcontrolling means for the grippers;

Figure 13 isa somewhat diagrammatic view, for the most part inside elevation, of an installation for electrical control of the pile elevator movement; and

Figure 14 is a view partly in side elevation and partly in longitudinal vertical section of a suction gripper modified for electric control.

For purpose of exemplary illustration, the novel sheet feeder has been shown in the drawings as applied to a printing press having a. rotary impression cylinder, but it is understood that so far as the generic aspects of the inventionare concerned, the feeder may be applied to any type of machine or instrumentality for treating or handling sheet material; and although specific language is employed in the specification in describing the various parts of the device, it is not to be read in any limiting sense and the scope of the invention is to be determined by the appended claims.

Referring more particularly to Figure 1, 2, and 3 of the drawings, it will be seen that the sheet feeder mechanism is disposed between two side frames 10 and H, which side frames may be either separately formed or made a part of the printing press frame indicated at I2. The impression cylinder of the press is diagrammatically shown at I 3 and is provided with the conventional cylinder grippers (not shown) which are adapted to seize the sheets to be printed from the inclined feed board l5 as they are successively brought to the front stops of the feed board as by means of the sheet conveyor indicated generally by the reference character C. This conveyor will be described in somewhat more detail, although its construction, arrangement, and operation form'the subject matter of a copending application.

The successive sheets are fed-to the upper receiving end of the conveyor C by means of the separating and feeding devices designated in their entirety by the reference character F, the sheets being removed successively from the top of the pile P (see more particularly Figures 1, 4, and 5). The pile of sheets is supported upon a apted to be raised and lowered by means of the cables which are trained around the winding pulleys 26 which are fixed on the transverse rotary shaft 21.

Fixed to the elevator shaft 21 is a gear 30 which meshes with a pinion 3| which is secured to the stub shaft 32 which also carries a ratchet wheel 35 which is adapted to rotate as a unit with the pinion 3|. A hand crank 36 may be secured upon the end of the shaft 32 outside of the side frame II for manual operation of the elevator. A holding dog 31 is carried by the stud 38 projecting from the frame I and it will be readily perceived that this holding dog /prevents the counterclockwise movement of 'the ratchet wheel (as viewed in Figure l) and thus prevents the lowering of the feed board 20. The board may, of course, be manually lowered by means of the crank 36 when the dog 3'! is held out of engagement with the ratchet.

For gradually raising the feed board and the pile of sheets, step by step, during the feeding operation, there is provided an arm or lever 40 which is freely pivoted upon the stub shaft 32 and is provided with a pivoted driving pawl 4|, the nose of which is adapted to engage the teeth of the ratchet 35. Upon one end of the arm 40 there is rotatably mounted a follower roller 42 which may be brought into operative contact with the cam 45. The cam 45 is mounted upon the transverse cam shaft 48 supported in the side frame II and in a bracket 49 which is in turn supported at its ends by means of the cross bars 50, 5| which extends from one side of the feeder frame to the other. The cam shaft 48 carries a sprocket wheel 53 about which the drive chain 54 is trained, this chain being driven from the sprocket 55 mounted upon a main driving shaft 56. One part of the chain 54 also engages the idler sprocket 51 which is adjustably mounted by means not shown, sothat the cha n may be kept at the proper tension.

A spring extending between the arm 40 and any suitable fixed point on the feeder frame, serves to urge the follower roller toward the cam 45, and this roller will follow the cam surface until prevented by the elevator control mechanism to be presently described.

By reference more particularly to Figures 4, 5, 9, 10, and 11 of the drawings, the construction and operation of the suction grippers which serve to separate the top sheets from the pile and feed them to the chain conveyor C will be better understood. There are provided upon either side of the pile of sheets tw o approximately vertically extending

rocker arms

64 and 65. the lower ends of these arms being pivotally mounted upon the studs 66, These rocker arms serve to pivotally support, at their upper ends, the transverse hollow shaft or tube 10. At an intermediate point, the hollow shaft 10 carries one or more suction gripper members G. By reference to Figures 9 and 11, it will be seen that these gripper members comprise the cylinders15 and a hollow tubular shank 16, the end of which surrounds he tubular shaft 10 and is provided'with gripping flanges ll through which the bolt 18 passes and which serves to secure the gripper member G rigidly upon the tubular shaft I0. The opening I! in the shaft II communicates with the passageway in the shank I8 of the gripper member. The tubular shaft I0 is provided with a nipple 02 to which a flexible hose 0! is connected, the hose 02 leading to the box 84 from which another hose 8! leads to a suction pump or other suitable source of sub-atmospheric pressure. The box 04 has an opening 06 therein, as clearly shown in Figures 1 and 12 and this opening provides a vent to the atmosphere which is adapted to be alternately opened and closed by means of the valve 01 carried upon the rocker arm 80, pivoted at I! and adapted to be actuated by means of the cam 00 against which the follower roller 0| is adapted to bear. The cam 00 is mounted upon the cam shaft 40 already described. By this means, vacuum controlling the suction gripper members G is alternately applied and relieved in synchronism with the timing of the pick-up, transport. and delivery of the sheets from the pile and into the zone of operation of the conveyor C. I

The gripper members G are maintained in their proper angular position with respect to the top of the pile and the delivery point adiacent the conveyor C by means of the following connections;

Pivotally mounted at its lower end upon the stud supported by one of the side frames, is the generally vertical extending arm 00, this arm being considerably shorter than the rocking arms 00 and 65. The upper end of this arm 96 is pivotally connected by means of the pintle 01 with the forwardly projecting end of the link 90. The rearward end of the link 90 is fixed to the hollow shaft III for rocking movement therewith. One of the vertical shafts 64 is provided with a forwardly projecting arm 99 which carries the follower roller I00 which bears against the cam IOI which is also carried by the cam shaft 40. In order to urge the arms 64 and" toward the cam and to cause the roller I00 to follow the irregularities of the cam, at least one of the arms 04, 00 is provided with the projection I03 to the end of which a rod I04 is pivoted, the lower end of therod Ill passing freely through an eye I05 fixed to the frame. The rod I04 is surrounded by a coiled compression spring I08 which serves to urge the gripper supporting linkage system in a counterclockwise direction around the pivots 00 as shown in Figure 1 of the drawings.

The

arms

84, 65, the short arm 00, and the arm or link 98 serve to form a quadric linkage system which causes the hollow shaft and its attached suction grippers to revolve around the points 00 and also to oscillate about the axis of the shaft I0 to cause the grippers to function properly, as will now be descr bed in more detail.

Referring more particularly to Figure 9 of the drawings, it will be seen that there is mounted for vertical reciprocation within the cylinder" I! of each of the gripper members G, a piston IIO carried upon a hollow piston rod or stem H2. The lower end of the stem I I2 passes through an opening in the bottom of the cylinder I! and has the suction cup I I4 secured to the end thereof as by means of the threaded ring III. A coil spring IIB disposed between the bottom wall of the cylinder I5 andthe upper inner wall of the piston IIII, urges the piston and its attached suction cup toward the upper end of the cylinder 15. The upper end of this cylinder is closed by means of a cover plate Ill. A slight projection, which may comprise an annular extension of the stem or piston rod II2, projects upwardly somewhat beyond the end wall II! of the piston, as

creases.

shown at I20. the hollow piston rod I I2 shown at I20 are slotted as at HI and the end wall II! of the piston III is provided with one or more small by-pass openings I22. The downward movement of the piston III and thus of the suction cup II, is limited by the abutment of the lower end of the skirt of the piston 0- with a ledge I23 adjacent'the bottom wall of the cylinder II.

It will thus be seen that upon reduction of pressure in the vacuum system which includes the tubular shaft III, the passageway 00, and the cylinder II, the atmospheric pressure upon the top of the piston will cause the piston and its suction gripper to descend toward the pile of sheets and to come in contact with the uppermost sheet of the pile as indicated in broken lines at Illa. When at this point, the cup I I4 and the hollow piston rod II2 will be cut off from the atmosphere whereupon the sub-atmospheric pressure on the opposite sides of the piston will equalize, through the openings I2! and I22, and the top sheet will be gripped by the suction cup. Immediately, due to this equalization of pressures, the spring II! will be able to exert its expansive force and will raise the piston and the cup I I4 to which the sheet is attached. During this telescoping action of the suction gripper, the cam "I will permit the spring I 08 to swing the suction grippervsystem forwardly so that the suction cup with its. attached sheet Swill move from the position indicated at Illa to the raised forward position I Ilb where the forward edge of the sheet 8 is presented to the chain conveyor grippers 0. At this point, when the conveyor gripper 0 have seized the sheet, the valve 01 vents the box 04 and relieves the vacuum in the grippers, thus releasing the sheet to the control of the conveyor C which drags it forwardly down the feed board I5 toward the impression cylinder I2 of the printing press.

During the seizing, lifting, and transferring of the sheet by the gripper members G, the opera tion is preferably assisted by means of air blasts directed against the rear edge of the pile, by suitable means well-known in the art or described in my earlier patents.

As the sheets in the pile If are successively removed during the progress 01' the feeding, the pile level lowers and the travel of the suction cup II 4 and the piston N0 of the gripper device inthe elevator mechanism is idle, the pawl arm 40 being held away from the actuating cam II by I20 which is centrally pivoted at a fixed point I21. The other end of this crank is connected by means of the long link I28 to a piston rod I29 which carries the piston I 30 which is adapted to reciprocatewithin the cylinder III secured to the side frame II. The piston I30 is adapted to reciprocate between the position shown in solid lines and that shown in dotted lines in Figure 6, the movement of the piston toward the right being stopped by the sleeve or boss I02. An opening is formed in the cylinder I3I upon the right-hand side of the piston and a nipple III secured therein, this nipple, being connected to a T I" to which a pipe line I" leads from a suction pump or other source of reduced pressure,

which may be the same source to which the hose The upwardly extending walls of 1 During this portion of the operation,'

85 connects the gripper actuating system. So long as the source of reduced pressure is allowed to freely communicate with the cylinder I3I, the

piston I30 will be held in its right-hand position, and through the linkage system I25I28, the arm 40 will be held away from the cam 45, against the tension of the spring 68.

When the height of the pile of sheets is diminished beyond a predetermined travel of the suction cup II4, means, are provided for breaking the vacuum applied to the cylinder I3I and thus permit the piston I30 to move to the left and bring the pawl arm 40 into engagement with the cam 45 and so actuate the ratchet 35 to raise the pile board 20 and restore the proper operating level of the top of the pile.

Referring again to Figures 9 and 10 of the drawings, it will be seen that there is provided an opening I40 in the side wall of the cylinder of the gripper device G. This opening is so positioned with relation to the vertical dimension of the cylinder and the travel of the piston IIO that it is uncovered by the skirt of the piston I only when its downward movement approaches the bottom stop ledge I28, as indicated in Figure 11. From the opening I40 a tubular conduit I4I leads to one end of the cylinder I42 which is secured to the side frame II and inv which a piston I45 reciprocates. The space above the piston is vented to the atmosphere as at I46 and the piston I45 is normally urged upwardly by means'of the coil spring I41 which surrounds the piston rod I48 and is compressed between the top of the cylinder and 'a shoulder formed by the enlargement I48 on the piston rod. The upper end of the piston rod carries the conical valve head I50 which is adapted to seat within lower end portion N5; of the hollow piston stem 4 the countersunk entrance I5I of the bore I52 in the valve block I53. A tubular conduit I55 connects the valved opening with the T I34 and thus with the vacuum system in advance of the actuating cylinder I3I.

The enlargement I48 upon the piston rod I48 is provided with a conical upper surface I58 which forms an inclined shoulder upon which a keeper or latch member I58 may rest, as indicated in Figure 8, in order to retain the valve member I50 in lower open position. Normally, however, the parts are in the positions shown in Figure 7 in which the valve I50, I5I is closed and the vacuum in the system I3I, I34, I35, I55 is maintained. The latch or retaining element I58 is pivotally mounted upon the bracket I54 as at I60 and a crank arm I6I rigid with the latch member I58 extends toward the cam shaft 48. This arm is provided with a follower roller I62 which bears against the cam 45, the same cam which actuates the pawl arm 40.

Now when the suction cup II4 descends to an extreme lower point of action as indicated in Figure 11, the vacuum within the cylinder 15 connects through the opening I40 and the pipe I4I with the cylinder I42 upon the underside of the piston I45, whereupon the piston I45 descends against the compression of the spring I41 and the valve I50, I5I is vented to the atmosphere. This breaks the vacuum behind the piston I30 within the cylinder I3I and the spring 60 brings the pawl arm 40 into operative engagement with the cam 45, and upon the high part of the cam contacting the roller 42, the pawl arm rocks outwardly and the pawl 4I ratchets the wheel 35 forwardly for apredeter-' mined distance, thus rotating the gear 30 and the pulley 26, and through the cable 25 raising the pile board 20. Since the action of the gripper the valve I50, I5I be kept open long enough for the remainder of the elevator control system to come into action. In order to accomplish this, the latch I58, due to the force of gravity on the actuating arm I6I-, moves to the left in Figures '7 and 8 and remains in contact with the inclined surface I56 of the enlargement I49 of the valve stem I48. This keeps the valve I50 in retracted open position until the high part of the cam 45 swings the arm I6I in a counterclockwise direction, thus releasing the latch I58 and permitting the valve element I50 to close uponthe opening I5I under the influence of the spring I41. By this time the mechanism, will have raised the pile of sheets into the sphere of action of the gripper G. However, if by that time, the pile has not been raised sufficiently, the vent I40 in the gripper cylinder 15 will again be uncovered during the excessive descending movement of the piston -I I0, whereupon the valve I50 will again be opened, the vacuum broken, and the pawl arm 40 rocked through another ratcheting cycle. An adjustable needle valve I63 is placed in the vacuum line I35 in order to make the action of the piston I30 more responsive when the valve I50, I5I is opened to the atmosphere.

In Figures 13 and 14 of the drawings, there is illustrated,.somewhat diagrammatically, an alternative system of pile elevator control which is operated electrically instead of by means of fluid pressure. In this embodiment, the principal operative parts, of the gripper G are the same as in the earlier described embodiment, but the I I2 is provided with a laterally extending bracket or plate I65, this plate being provided with a threaded opening I66 which is adapted to adjustably receive the lower threaded end of the rod I61. A lock-nut I68 is threaded upon the rod and serves to hold the rod in selective adjusted positions with respect to the bracket or plate I65, and thus with respect to the suction cup II4. A switch box I10 is secured adjacent the upper end of the cylinder 15 of the gripper G and is preferablyconstructed of electrical insulating material. Two electrical contact elements "I and I12 are secured within the box and are provided upon their outer ends with terminal connections I13, I14. A pair of cooperating contact elements I15 and I16 are carried by a conducting plate I11 and this contact carrying plate is mounted for limited vertical reciprocation upon a bushing member I18 which passes through an opening in the bottom of the box I18. The rod I61 passes through the bushing I18 and also through a spring stop bracket I19 secured to the lower end of the cylinder 1'5. Flanges are formed on the bushing I18 and a coil compression spring is seated between these flanges and the upper surface of the bracket I 19. end of the rod I61 projects through an opening I8I in the top of the box I10 and the rod is provided with a knurled knob I82 at its extreme upper end.

It will be readily seen that during the normal vertical reciprocation of the suction cup II4, the

rod I61 will also reciprocate through the bush- Q gradually depleted and the level of feeding falls, the travel of the cup I I4 increases and when this travel reaches a predetermined limit indicated by The upper the distance I, the shoulder stop knob I82 on the end of the rod I61 will strike the plate I11 and displace it downwardly against thepressure of the spring I80. This will break the connections between the pairs of contacts I", I15 and I12, I18, and will set the elevator actuating mechanism into operation by means presently to be described. The critical distance 1 is adjusted by threading the rod I61 a longer or shorter distance into the bracket I65 and then setting the adjustment by means of the lock-nut I68. It is obvious that the travel of the knob I62 to abut the plate I11 will be the same as the critical feeding travel of the cup I I4. 3

The pawl-carrying rocking arm in this embodiment is modified slightly and is designated by the reference numeral 40'. The follower roller 42 is normally held out of contact with the cam 45 by means of the energization of the solenoid I85, the armature of which consists of the plate I86 and the core I81. The armature is connected by meansof the linkage I88 with the right-hand end of the pawl arm 40. The spring 60' serves to urge the arm 40' in a counterclockwise direction toward contact with the cam 45. A limit switch of any suitable or conventional type is indicated at I90, this switch being normally closed to complete the circuit L through the switch I10 and the solenoid I85. The switch I80 may be opened or closed by movement of the arm I8I which carries a. roller I92 adapted to be contacted by the camining surface I83 on the right-hand end of the pawl arm 40'. The actuating arm IQI is shown in switch-closed position in Figure 13 of the drawings. The arm I8I is biased toward the switch-opening position in a clockwise direction by spring means (not shown) In operation the electrical control elevator ac tuating system functions as follows. Durin nor mal feeding the circuit L is energized and the parts are all in the position shown in Figure 13. As soon as the travel of the suction gripper II4 exceeds the distance I, the switch I10 is opened; the solenoid I85 is de-energized; the spring 60' returns the follower roller 42 to contact with the cam 45; and the cam surface I83 permits the arm I8I to move the limit switch to open position. The limit switch, 01 course, is provided in order to prolong the period of operation of the elevator beyond that which would be effected bythe breaking of the contacts of the switch I10, the.

action of this switch and of the gripper mechanism being too rapid to be relied upon to effect the elevator operation. When the circuit is broken, the cam 45 actuates the arm 40 through one ratcheting movement of the pawl 4|. Durscribed herein without departing from the scope f of the invention as defined by the subioined claims. Also, although the invention has been described by reference to an approximately vertical pile which is raised as the sheets are fed from the top thereof, it is obvious thatthe broad principles of the invention may be applied to sheet feeders in which a bank of sheets is advanced substantially horizontally during removal of the sheets from the forward end thereof. Therefore, the words of direction or orientation "vertical, upward," top and the like, as employed in the specification and certain of the claims are used in an. exemplary or illustrative sense and not in limitation of the scope of the invention. I

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a-sheet feeder, in combination, a pile board, means for advancing the pile board, mechanism for separating and removing the successive top sheets from a pile of sheets on said pile board, said mechanism including a sheet seizing member adapted to move intermittently through successive cycles of movement to and from contact with the top of the pile as the feeding progresses, the travel of the member toward the pile lengthening gradually as the pilev is depleted, a normally inoperative connection between the advancing means and the pile board, means operatively connected with said member for momentarily rendering said connection operative whenever during a cycle of movement of saidmember the travel of said member toward the pile exceeds a predetermined distance, holding means for keeping said connection operativ during a longer portion of said cycle until said advancing means shall have been effective to advance the pile appreciably and means for automatically releasing said holding means.

2. In a sheet feeder, in combination, a pile board, means for advancing the pile board, mechanism for separating and removing the successive top sheets from a pile of sheets on said pile board, said mechanism including a sheet seizing member adapted to move intermittently through successive cycles of movement to and from contact with the top of the pile as the feeding progresses, the travel of the member toward the pile lengthening gradually as the pile is depleted, a normally inoperative connection between the advancing ing this ratcheting movement, thecurved end I83 of the pawl arm contacts the roller I92 and moves the limit switch arm I8I downwardly closing the switch and completing the circuit at this point. In the meantime, thepile has probably been raised suiliciently by this ratcheting movement to restore the height so that the switch1|10 remains closed during the next succeeding movements of the rod I61 along with the gripper cup. If a single ratcheting movement of the arm 40' has not been sufficient to raise the pile to within the limits of the feeding distance I, then the switch I10 will again be opened and another ratcheting movement of the arm 46' will take place. By this means, the pile level will be maintained so that the feeding operation is continuous.

Various changes and modifications may be made in the embodiments illustrated and demeans and the pile board, means operatively connected with said member for momentarily renderingsaid connection operative whenever the travel of said member toward the pile exceeds a predetermined distance, holding means for keeping said connection operative during a longer portion of said cycle, and connections'between said holding means and said pile advancing means for restoring said holding means to ineffective condition upon the completion of a predetermined pile advancing movement.

3. In a sheet feeder, in combination, a pile board, advancing means for said pile board, means for separating and removing the successive top sheets from a pile of sheets on said pile board including a member adapted to move intermittently to and from contact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted, power actuated means for rendering said pile advancing means normally inoperative, means operatively connected with said member for interrupting the transmission of power to said pile advancing means upon a movement of said member in the direction toward said pile beyond a predetermined amount, means simultaneously acting to hold said power off during further movement of said member, and means operatively connected with said pile advancing means for restoring said holding means to inoperative position upon the occurrence of a pre-.

' determined pile advancing movement.

4. In a sheet feeder, in combination, a'pile board, advancing means for said pile board, means for separating and removing the successive top sheets from a pile of sheets on said pile board including a member adapted to move intermittently to and from contact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted, vacuum actuated means for rendering said pile advancing means normally inoperative, means operatively connected with said member for breaking the vacuum connection to said pile advancing means upon a movement of said member in the direction toward said pile beyond a predetermined amount, holding means simultaneously acting to keep said vacuum broken and means operatively connected with said pile advancing means for restoring said holding means to inoperative position upon the occurrence of a predetermined pile advancing movement.

, 5. In a sheet feeder, in combination, a pile board, advancing means for said pile board, means for separating and removing the successive top sheets from a pile of sheets on said pile board including a member adapted to move intermittently to and from contact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted, electrically actuatedmeans for rendering said pile advancing means normally inoperative, means operatively connected with said member for cutting off the supply of current to said electrically actuated means upon a movement of said member in the direction toward said pile beyond a predetermined amount, holding means simultaneously acting to keep said current off during further movement of said member, and means operatively connected with said pile advancing means for restoring said holding means to inoperative position upon the occurrence of a predetermined pile advancing movement.

6. In a sheet feeder, in combination, driving means for said feeder, a pile board, pawl and ratchet devices operatively connected with said pile board for advancing the same step by step, cam means operated by said driving means and adapted to contact said pawl device to actuate the same, resilient means urging said pawl device into operative contact with said cam means, power actuated means for normally holding said pawl device away from said cam means against the exertion of said resilient means, means for separating and removing the successive top s eets from a pile of sheets on said pile board including a member adapted to move intermittently to and from contact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted; means operatively connected to said member for interrupting the transmission of the power to said power actuated means upon a movement of said member in the direction toward said pile beyond a predetermined amount, means simultaneously acting to hold'said power off during some further movement of said member, and means operatively connected with said advancing means for restoring said holding means to inoperative position upon the occurrence of a predetermined pile advancing movement.

7. In asheet feeder, in combination, a pile board, means for advancing said pile board,

means for separating and removing the successive top sheets from the pile of sheets on said pile board, said means including a suction gripper adapted to move intermittently to and from contact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted, a vacuum controlled retaining member for preventing actuation of said pile advancing means, a

conduit connecting said retaining means with a source of reduced pressure, a valve connected with said conduit, vacuumoperated means for opening said valve to theatmosphere, a conduit connecting said vacuum operated means 'with said suction gripper, whereby a movement of said gripper toward the pile beyond a predetermined tact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted, a vacuum controlled retaining member for preventing actuation of said pile advancing means, a conduit connecting said retaining means with a source of reduced pressure, a valve in said conduit, vacuum operated means for opening said valve to the atmosphere, a conduit connecting said vacuum operated means with said suction gripper, whereby a movement of said gripper toward the pile beyond a predetermined distance connects its source of vacuum with the vacuum operated valve actuating means, and thus breaks the vacuum system controlling said retaining member and permits the pile advancing means to operate, a latch for retaining said vacuum breaking valve in open position although the gripper continues to move to and from the pile, and means operatively connecting said latch with said pile advancing means for releasing the latch and restoring the vacuum system upon the completion of a predetermined actuation ofsaid pile advancing means.

9. In a sheet feeder, in combination, a pile beard, means for advancing said pile board, means for separating and removing the successive topsheets from the pile of sheets on said pile board, said means including a member adapted to move intermittently to and from contact with the top of the pile as the feeding progresses, the travel of said member toward the pile lengthening gradually as the pile is depleted, an electromagnet for normally retaining said pile advancing means in inoperative position, an electric circuit connecting said electromagnet with a source of current, a switch in said circuit normally closed and adapted to be opened by a movement of said member beyond a predetermined point toward the pile, whereby the circuit to said electromagnet is opened momentarily releasing said pile advancing means for operation.

a second switch in said circuit 'lialso normally means at a point in its cycle of pile advancing movement to close said second named switch thus restoring the retaining circuit, energizing said electromagnet, and rendering said advancing means again inoperative.

10. In a sheet feeder of the class described, Em

combination, means for supporting a pile of sheets to be fed, a suction gripper supported for operation adjacent the top of said pile to remove the successive top sheets therefrom, said gripper comprising a cylinder having side and end walls, a piston mounted for reciprocation in said cyline der, a hollow piston rod projecting from said piston through an opening in one end wall of said cylinder, a suction cup on the projecting end of said rod, means maintaining the interior of said cylinder upon the side of said piston from which I said rod projects in continuous communication with a source of subatmospheric pressure, a spring urging said piston and piston rod toward retracted position, a small by-pass opening through said piston for permitting the gradual equalization of pressure upon both sides of ,the piston when said suction cup is covered by a sheet.

11. A sheet feeder mechanism as set forth in claim in which there is provided a small projection upon the opposite side of. the piston to provide a limiting abutment against the closed end of the cylinder.

12. In a sheet feeder of the class described, in combination, means for supporting a pile of sheets to be fed, pile support advancing means, vacuum actuated means for controlling the operation of said pile support advancing means, a suction gripper supported for operation adjacent the top of said pile to remove the successive top sheets therefrom, said gripper comprising a cylinder having side and end walls, a piston mounted for reciprocation in said cylinder, a hollow piston rod projecting from said piston through an opening in one end wall of said cylinder, a suction cup on the projecting end of said rod, means maintaining the interior of said cylinder upon the side of said piston from whichsaid rod projects in continuous communication with a source of subatmospheric pressure, a spring urging said piston and piston rod toward retracted position, a small by-pass opening through said piston for permitting the gradual equalization of pressure upon both sides of the piston when said suction cup is covered by a sheet, an opening in the side wall of said cylinder at a point normally continually covered by said piston in its reciprocation in the cylinder but adapted to be uncovered and thus placed in communication with the reduced pressure in said cylinder whenever the travel of said gripper exceeds a predetermined distance, and a conduit connecting said opening with said vacuum actuated means, whereby said advancing means may be actuated to restore the normal level of feeding.

13. In a sheet feeder of the class described, in combination, means for supporting a pile of sheets to be fed, pile support advancing means, electrically actuated means for rendering said pile advancing means inoperative, an extensible gripper device supported for operation adjacent the top of said pile to remove the successive top sheets therefrom, an electric switching device in the circuit with said electrically actuated means and carried by one of the relatively moving parts of said extensible gripper device, an element carried vby the other of said parts and havin means thereon for actuating said switching device upon extension of said gripping device beyond a predetermined point in a direction toward said pile,

thereby interrupting the current to the electrically actuated means to permit the pile support advancing means to operate, means for adjusting the effective length of said element to vary said predetermined point of actuation of said switch.

14. In a sheet feeder of the class described, in

combination, means for supporting a pile of sheets to be fed, pile support advancing means, electrically actuated means for rendering said pile advancing means normally inoperative an extensible gripper device supported for operation adjacent the top of said pile to remove the successive top sheets therefrom, an electric switching device in circuit with said electrically actuated means and carried by one of the relatively moving parts of said extensible gripper device, said switching device comprising a pair of contacts normally incircuit closing position, an element carried by the other of said parts and having means thereon for actuating said contacts to open said circuit upon extension of said gripping device beyond a predetermined point, thereby interrupting the current to the electrically actuated means to permit the pile support advancing means to operate.

15. Ina sheet feeder of the class described, in combination, a frame, means for supporting a pile of sheets, a delivery device to which the sheets are fed, a gripper member for supporting and feeding the sheets to said delivery device, an elongated arm pivoted at its lower end to said frame and extending upwardly from the pivot point, means pivotally connecting said gripper member with the upper end of said arm, means for swinging said arm about said pivot point to move said gripper member from a seizing point upon-the top of the pile to a delivery point above and laterally removed from said seizing point, a shorter arm pivoted at its lower end to the frame at a point well above the pivot point of said firstnamed arm, a link pivotally connecting the two arms adjacent their upper ends, said link being rigid with said gripper member, whereby the proper angularity of said gripper member with respect to the pile at said seizing point and to the delivery device at said delivery point, is maintained.

16. In a sheet feeder of the class described, in combination, a frame, a support for a pile of sheets, a delivery device adjacent said pile to which the sheets are fed, a suction gripper member adapted to seize a sheet from the top of the pile and transport it to said delivery device, a pair of. elongated arms each pivoted at its lower end upon one side of the pile, said arms projecting upwardly from their pivot points and extending beyond the level of the top of the pile, a hollow shaft extending between the upper ends of saidarms and mounted for limited rock said shorter arm beingconnected by a link with said hollow shaft, said link being pivotall'y connected at one end with said shorter arm arid having its opposite end rigidly secured to said hollow shaft.

17. In a sheet feeder oi the class described, in combination, means for supporting a pile of sheets to be fed, pile support advancing means,

, .electricaily actuated means for controlling said advancing means, a sheet operating gripper mounted for movement to and from the top of the pile to remove the successive'top sheets therefrom, an electric circuit including said electrically actuated means, switch means in said circuit, means for momentarily actuating said 18; In a sheet feeder of the class described, in combination, means for supporting a pile of sheets to be fed, pile support advancing means, electrically actuated means for rendering said advancing means inoperative, a sheet operating gripper mounted for movement to and from the top oi the pile to remove the successive top sheets therefrom, an electric circuit including said electricaily actuated means, a switch in said circuit having contacts normally closed but adapted to be opened momentarily upon movement of the gripper toward said pile beyond a predetermined point during depletion'ot the pile to de-energize said means for holding theadvancing means inoperative, a second switch in said circuit normally closed, and means associated with said advancing means for opening said second switch while said first switch contacts are momentarily open, and closing said second switch only after the occurrence of a predetermined operation of said advancing means.

FREDERICK W. SEY'BOLD.