US3076648A

US3076648A - Sheet separating and lifting sucker

Info

Publication number: US3076648A
Application number: US645392A
Authority: US
Inventors: Norman W Taylor
Original assignee: Harris Intertype Corp
Current assignee: Harris Graphics Corp
Priority date: 1957-03-11
Filing date: 1957-03-11
Publication date: 1963-02-05
Anticipated expiration: 1980-02-05

Description

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Feb. 5, 1963 N. W.'TAYLOR SHEET SEPARATING AND LIFTING SUCKER Original Filed June 9, 1953 Feb. 5, 1963 N. w. TAYLOR SHEET SEPARATING AND LIFTING SUCKER 3 Sheets-Sheet 3 Original Filed June 9, 1953 INVENTOR. NMMAN l4. 72x4 0!? By 2 7 Arrow/V576 United States Patent Ofiice 3,076,648 w r we are;

gzrrislntertype Corporation, a corporation of Dela- Continuation of application Ser. No.. 369,498, June 9, 1953. This application Mar. 11, 1957, Ser. No. 645,392 39 Claims. (Cl. 271-31) This invention relates to improvements in sheet sepa rating and lifting suckers. More specifically it has to do with automatic means for maintaining the sucker at its most efficient elevation above the pile throughout slight changes in the height of the pile. In conventionalpile feeders means is pro-vided'under the control of a feeler or pile height gauge for raising the pile a small increment at a time to maintain the top of the pile at the proper level. A number of sheets are removed between successwe pile raising operations, the number varying with the thickness of the stock. In the case of large sheets at least it is common to lift each sheet with two suckers spaced apart transversely. The different parts of the pile under these two suckers may vary considerably in height due to all or moisture in the pile, but more especially due to nk on the sheets from a previous printing. These variations'are beyond the control of' the height gauge.

The present invention is designed to regulate automatically the minimum height'of each sucker as it descends to take the uppermost sheet of the combed group of sheets and lift it from the pile, the control for one sucker being independent of the control for the other.

One of the objects of the invention therefore is the provis on of means for automatically stopping the dc scent of the sucker at the moment it reaches a predetermined height above a feeler near the sucker.

Another object is the provision of means actuated by a feeler contacting the top of the pile for determining the position of stop means which limits the extent to which the sucker may be lowered.

Another object is'the utilization of one ofthe conventional elements of a sheet separating mechanism, which in the illustrated case is a comber, as the feeler which actuates the stop means.

A further object is the provision of a stop cam which is turned through 'a variable angle by the descent of the feeler for cooperation with a stop element carried by the sucker support.

A further object is the provision of a stop cam having a variable position which depends upon the variable position of 'the'feeler, the height of which is affected by the variable height of the pile as the uppermost sheets are fed off and by the intermittent lifting of the pile to-compe'nsate for the sheets fed off.

b Still another objeet is the provisionjof a frictional interlock between the stop cam and the stop element'o-n the sucker lever for preventing further movement of the stop cam as well as of the sucker lever until the interlock is released by the rising movement of the lever which causes thesucker tolift' the sheet Other objects and features of novelty will appear as ward from the rear of a pile of sheets showing a sheet. comber, utilized also as a feelenanda separating and lift ing sucker with portions of; their operating mechanism; FIGrZ is a side elevation, partly in section upon the line 2-2 of FIG. 1; 7

FIG. 3 is a; side e1eva tional view partly in section upon the line 3-3 of FIG. 1;

FIG. 4 is a detail sectional view of cooperating stop means,'the view being taken substantially on the line 4-4 ofPIG; 3;

FIG. 51s a similar view showing a modified'co'nst'ruc tion; FIG. 6 is a view similar to thatof FIG. 2 but showing the cornber raised out of operative position;

FIG. 7 is a view similar to FIG. 3 but with the sucker lever raised somewhat'and the sucker in telesco'ped posi tion, and

FIG. 8 is a timing diagram. 1 I

The present application is a continuation .of 'rn'yco pending application, Serial No. 360,498, filed'lune'9, 1953, nowabandoned.

Referring to FIGS. 1, 3 and 7, 16 is a'ho'llow brace joining the side members, not shown, of afeeder frame; Conveniently this brace may be an air or vacuur'n'co'n ductor. Beneath thebrace 10 there is a shaft 11 which is rotated byany suitable. means one revolution for each feeding cycle. Spaced downwardly below shaftll there is a further shaft 12 which is driven continuously from the feeding machine. 7

On shaft 11 there is keyed a cam 13 which engages a follower 14 on a comber supporting lever 15 thatis loosely mounted on shaft 12. Lever 15 is raised by cam action from its 'FIG'. 2 position where the comber is in contact with the pile to its FIG. 6 position" where it is well above the pile. It is caused todescend to itsFlG. 2 position'by a tensionsprin'g 16, FIG. 1, when the angular position of cam 13 permits. In the lever 15 there is a spindle 17 on'the free end of which'a conventional comber 18 is mounted. At itsopposite end this spindle carries a beveled pinion 19 which. meshes with a bevel gear 20 that is keyed to shaft 12, by means of which the comber is rapidly rotated. As shown in FIG.; 1 the power armoflever 15 may be bifurcated to form two spaced arms 15' between which the follower 14- is journaled. In theoperation ofrthe machine comber 18 descends to the pile, jcornbs up a group 10f. sheets at the top of the pile as indicated in FIG. 1 and then rises,fremaining oil thepile for the major portion of each cycle,

Referring now to FIGS. 1, 3 and 7, a, second cam 22 is keyed to shaft 11 at a point spaced from cam 13-; This cam 22 engages a roller follower 23 which is carried in the power arm'of a lever 2,4 that is loosely' mounted on shaft 12, the power end ofthe lever being bifurcated to formtwo spaced arms 24' between which the follower is journaled. On the work arm of lever 24 there is mounted the sheet separating and lifting sucker 25 and thelower portions 26 of the suction connections, the latter being of conventional formjand preferably embodying telescoping action when the mouth of the sucker is closed by its engagement with the sheet;

The cam 22 by means of its contact with the follower 23 serves to raise lever 24 and sucker 25 at the proper time in the cycle, while a tension spring 27 serves to depress the sucker to the critical point permitted by the automatic control now tobe described. Loosely mounted on shaft, 12 and which therefore turns with bell crank wand serves to assist in talking strain imposed upon' the rod. A projection 34 on lever 15 is so positioned as to contact rod 3 1 as the lever swings down to bring' the comberinto engagement withthe top of the pile, this condition being illustrated in FIG. 2. 0n the upper arm of bell crank there is a gear sector 35 which meshes with a sector 36. Integral with sector' 36 there is a stop cam 37 having an eccentric cam surface to" which is attached a hook 38 on the lower end of a tension spring 39 connected at its upper end to a fixed post 40 to which the spring 27 is also connected. A small leaf spring 41 mounted in the stop cam engages a bracket 42 fixed in the machine frame, to resiliently absorb the force as the stop cam swings counterclockwise to the limit of its motion in that direction under the inlluencc of spring 39. In the perimeter of the cam there is cut a groove 44 with inclined or beveled walls to receive a conical end 45 on a screw 46 which is threadably mounted in a block 47 attached to the lever 24'. Screw 46 may be threaded inwardly or outwardly in the block 47 for adjustment purposes. A nut 43 and a lock washer 49 on screw 46 may be turned down to tightly engage the top of block 47 and thus hold the screw in adjusted position. The taper on the conical end 45 of screw 46 corresponds substantially to the inclination of the sides of groove is in the stop cam. Hence, when these parts come together, as they do when the lever 24 is lowered by spring action, there is effected a wedging action resulting in a frictional interlock between these two step elements which not only prevents the lever 24 from descending further but also holds the stop cam 37 against any tendency toward movement due to inclination of the cam surface even though lever may have risen out of contact with rod 31 and therefore no longer acts upon stop cam 37 through the intcrmediacy of

gear sectors

35 and 36.

In the modification illustrated in FIG. 5, the frictional interlock is effected in a similar manner by step cam 37' having a plain ungrooved perimeter which is engaged by a stop screw 46 having a beveled groove 4 4. The block 47' carries a pin 51 which projects through a slot 52 in the screw 46' to permit vertical adjustment of the screw without turning, the adjustment being effected by the rotation of a nut 48 threaded upon the screw and engaging the top of block 47', while the screw is held in adjusted position by means of a lock nut 53 engaging the under side of block 47'.

In order to determine the setting of screw 46 for any given grade of stock, suction to the sucker is cut off and the machine is run to cause the comber to comb the sheets and the sucker to rise and descend as in the normal operation of the machine. The screw is then turned in one direction or the other until the sucker at its lowest point of travel just lightly touches the uppermost one of the combed sheets. The screw as is then locked in position, the suction turned on, and the device is ready for operation.

As indicated in the timing diagram of FIG. 8, the comber descends to the pile and efiects its combing action. As it swings down it swings rod 31 around shaft 12, which turns bell crank so counterclockwise. This motion of the bell crank functions through the

gear sectors

35 and 36 to swing stop cam 37 from the position of FIG. 3 to the position of FIG. 7. The combing action begins at about 35 after the start of the cycle and continues for something of the order of 45. In the meantime the sucker lever has begun to swing down under the influence of spring 27. Near the end of the combing action the sucker lever reache a position where the stop element 46 engages the stop cam 37, interrupting further descent of the sucker at precisely the elevation where it is most eifective for taking one sheet and one sheet only.

This position of the sucker is indicated in full lines in FIG. 3. At this time suction has been turned on, as 18 evident from FIG. 3. Now the uppermost sheet of the fiuifed pile is drawn against the sucker, closing its mouth. The sucker then telescopes in a conventional manner to the position indicated at 25a in FIG. 3. Under the action of

cams

13 and 22 the comber lever and the sucker lever start upwardly, the comber slightly in advance of the sucker. As soon as this occurs the stop element 46 is withdrawn from engagement with the stop cam and the latter swings counterclockwise under the influence of spring 39 until stopped by the engagement of leaf spring 41 with bracket 42, this movement causing

gear sectors

36 and 35 to swing bell crank 36 clockwise until rod 31 is in position to be engaged by lever 15 when it next descends. The sucker thus lifts to a predetermined height, indicated at 25b in FIG. 7, that portion of the sheet which it engages, after which the suction is cut off and sheet forwarding means, not herein shown, come into action and the comber and sucker dwell in raised position during the greater part of the cycle then remaining.

Although in the present embodiment of the invention the comber is employed as the feeler or pile-scnsing means which actuates the control mechanism for determining the minimum height of the sucker, and although this is a desirable feature of the invention, it is to be understood that other feeler means may be employed for the purpose if desired. It is also to be noted that the stop cam 37 need not necessarily be mounted upon the cam shaft a in the present disclosure, nor is it essential that the means for swinging the stop cam through a variable angle be that disclosed herein. Any other means for producing the desired movement controlled by the action of a feeler may be substituted.

Having thus described my invention, 2 claim:

1. In a sheet feeder oi the type in which sheets are removed one at a time from the top of a pile, a sucker, means for lowering the sucker once for each feed cycle from a point above the uppermost sheets, a rising and falling feeler engaging the top of the pile adjacent the sucker, and means actuated by the descent of said ieele toward the top of the pile to terminate the descent of the sucker at a predetermined elevation, whereby the sucker is caused to assume a given height relation to the uppermost sheet at each cycle.

2. in a sheet feeder of the type in which opposed corners of the uppermost sheets are preliminarily separated from the top of a pile, a sucker above one corner of the pile, means for lowering the sucker once for each feeding cycle from a point above the preliminarily separated portions of the uppermost sheets at that corner, a rising and falling fecler engaging the top of the pile, and means actuated by the descent of said fceler toward the top of the pile to terminate the descent of the sucker at a predetermined elevation above that of the pile proper, whereby the sucker is caused to assume a given height relation to the uppermost sheet at each cycle.

3. In a pile feeder, a comber, means for lowering the comber into contact with the pile once for each feeder cycle, a sucker, means for lowering the sucker once for each cycle from a position above the c mbed portions of the sheets, and means controlled by the position or the comber when in contact with the pile to terminate the descent of the sucker at a predetermined elevation above the pile, whereby the sucker is caused to assume a given height relation to the combed portion of the uppermost sheet at each cycle.

4. A sheet feeder as defined in claim 3, wherein the sucker is mounted upon a lever the downward movement of which is spring actuated and its upward movement is cam actuated, and wherein said means for terminating the downward movement of the sucker comprises a stop cam in the path of said lever and means actuated by the descent of the comber for turning said step cam through varying angles dependent upon the extent to which the height of the pile permits the comber to descend.

5. in a pile feeder of the type in which the sheets are combed upwardly for preliminary separation, a sucker, a lever upon which the sucker is mounted, a shaft, a cam on said shaft, a follower on said lever engaging said cam and causing said lever to rise and a spring causing it to descend, a stop cam mounted to oscillate upon a fixed axis, a feeler, means for lowering the feeier into engagement with the pile once for each cycle of "scrapes the machine, means actuated by the descent of the feeler forturning said stop cam through a variable angle de pendent upon the extent to which the height of the pile permits the feeler to descend, and means upon said lever engaging said stop cam to'limit the downward'swing of the lever.

6. in a pile feeder of the type in which opposed corners of the sheets are preliminarily separated, a sucker, a lever upon which the sucker is mounted, a cam shaft, a cam on said shaft, a follower on said lever engaging sai'd cam and causing said lever to riseand a spring causing it to descend, a stop cam loose on said shaft, afeeler, means for lowering said feeler into en- ,gagement with the pile adjacent the sucker once for each cycle, means controlled by the position of the feeler for turning said stop'ca'm through a variable angle dependent upon the extent to which the'he'ight of the pile permits the feeler to descend, and cooperating means upon the lever engaging said stop cam to limit the downward swing of the lever,

7. A pile feeder as defined in claim 5, wherein said stop cam and said c'ooperatingmeans on said lever corn- .prise inclined surfaces which produce a wedging effect and thereby cause frictional resistance to relative move- "ment between the 'lever and stop cam after their engagethem and before said lever is swung upwardly by cam action.

8. A pile feeder as defined in claim '5, wherein the means on said lever for engaging said Istop cam is adjustable toward and away from the stop cam to Corn- :pensatefdr different kinds and weights ofpaper stock.

9. A pile feeder as defined in claimS, wherein said stop cam and said c'ooperatingmeans on said lever are frictionally interlocked upon their engagemenntherebv preventing further turning movement of said stop cam 'or swin'ging of said lever in a downwarddirection and whereby the rising movement of the lever due'to the "action of said cam shaft releases said frictional interlock.

10. In apil'e feeder of the type in which opposed corners of the sheets are preliminarily separated, a sucker, a lever upon which the sucker is mounted, a cam shaft, a'cam'on said shaft,"a follower on'saidlever eniga'ging'said cam and causing said-lever to rise and a "spring causingiit to descend, a stop cam loose on'said shaft, afeeler, means for lowering "saidfeeler'into'engagement with the pile once for each cycle'of the machine, means actuated by the descent "of the feeler for turnin'g said stop cam througha'variable"angledependent uponthe'extent to which the height ofthepilepermits the feeler to descendymeans on said lever cooperating with said stop cam for eft'ectinga frictional interlock between them upon their interengagement as the lever descends, thereby preventing further turning movement of said std-p cam or 'downward'swinging of said lever,

j and whereby the rising movement of the lever due to theaction of said cam shaftreleases-said-frictionalinlljln a sheet feeder'of the type inwhich sheets are 'removed one at a time from the top of a pile, a rising and falling feeler engaging the' top of the pile in one 'part of eachcycle, a-sucker above the pile, means for {lowering the sucker to a predetermined elevation relative to the feeler ina laterpart of each cycle, and-means controlled by theposition of the feelervvhen engaged "with the pile for terminating the descentof" the sucker at itspredetermined"elevation, whereby the sucker is 13. A sheet feeder according to claim 11 in which means is provided for temporarily locking said sucker in its predetermined elevation to permit raising of saidfeeler independently of the sucker.

'14. In a sheet feeder of the type in which sheets are removed one at a time'from the top of a pile, sensing means'for gauging the top of the pile at least in one part of each cycle, a sucker above the pile, means for lowering the sucker toward the pile once for each sheet'fed, and means cooperating with saidsucker and controlled by the .saidsensing means according to'the detected level of the :pile for terminating the descent of said suckerat "a predetermined elevation, wherebythe sucker is caused to assurne'agiven height relation ,to the uppermost'sheet.

l5. In a sheet feeder of the type in which sheets are removed one at .a time from the ,top of apile,a sucker above Ithe-pile, means for lowering the sucker toward the ,pile once for each sheet fed, a feeler engaging the top of .a pile at .least at that time during which the sucker is lowered toward the pile, andmeans controlled by the position of the feeler according to the detected level of lthe pilefor terminating the descent of the sucker at a predetermined elevation above that of the feeler'to cause the sucker to assumea. given jheightrelation to-the upper- .most sheet. 7

1'6. in a sheet .feeder of the type in which sheets are removed one ata time from the'top of a pile, sensing means at spaced points nearthe rear of the pilefor gauging the top of thepile at least in one part'of each cycle, -a sucker above'and adjacent each of said points, means for lowering said suckers independently toward thepiIe, ence-for each] 'sheetfed, and meanscooperating with each ,of said suckers and controlledby the adjacent sensing means according to the detected level of thepile atthat point for terminating the descent of the sucker at a predetermined "elevation, whereby each sucker is caused to .assume aigiveniheight relation to the top of the pile at that point.

17. In a sheetfeeder of the type in which sheets are removed (meat at time'from the top of a pile, sensing means at each ofrthe rear corners of the pile forv gauging thelOp Of the pile atzleastinone part of each cycle, a sucker above each rear corner .of the pile, means for --lowering each of saidisuckers toward the pile, once for each sheet fed,-and meanscooperating'with each of said suckers and controlled by,,the-adjacent sensing means ac- .cordingto theldetected level ofithat cornerof the pile .for terminating the descent of the corresponding sucker at -,a, predetermined elevation, whereby each sucker is'caused toassumeua given heightrelation to that corner of the .uppermost sheet.

18.1In..a.- sheet. feederloflthe type in which sheets are removed one at a time from .the top of a pile',twosuckers spaced apart nearthe rear of the pile, means for lowering saidisuckersonce foreach. feed cycle from points above the uppermost sheet, a rising and falling feelerengaging the top of thepile adjacent each of,said suckers, and means controlled by ,theposition of each'feeler when in contactwith thepile-to terminate independently the descent of. the, adjacent r suckersv at predetermined elevations above the pile, whereby each of the su'ckersis tcausednto assume a. given height relation .to the pile at 'thatapoint.

-19..The..method of feeding sheets from the topof a pile to a sheet. handlingmachine comprising the steps of detecting the, elevation of the top of the pile in one part of afeed cycle, moving a sucker toward said pile from above in a later. part of the cycle, terminating the descent ofsaid. suckerat apredetermined elevation relative tothe, top level of the pile in response to vthe detected ,elevation-,of,the' pile, grasping the'top sheet with said sucker while at said predetermined elevation, and further handling said graspedv sheet for presentation to the sheet handling machine.

20. The method according to claim 19 including the additional step of preliminarily separating at least the uppermost sheet of the pile from the pile proper before moving the sucker to its predetermined elevation, said predetermined elevation being approximately at the level of the uppermost separated sheet.

21. The method according to claim 20 wherein said separation is accomplished by combing the sheets near a corner thereof.

22. In apparatus of the class described, a suction device arranged above a supply of sheets and movable downwardly toward and upwardly away from said sheet supply to grip the topmost sheet and lift at least a portion of said sheet from said sheet supply, mechanism for periodically moving said suction device downwardly and upwardly, means for determining the location of the top of said sheet supply, and stop means operable under the control of said last-named means to different positions in accordance with the location of the top of said sheet supply for limiting the downward movement of said suction device by said mechanism.

23. Apparatus as defined in claim 22 wherein said stop means functions in said positions to stop said suction device in a position spaced upwardly a predetermined distance from the top of said sheet supply.

24. In a sheet feeder, a suction device, means for periodicaliy moving said suction device downwardly toward and upwardly away from a supply of sheets to grip the topmost sheet of said sheet supply and lift at least a portion of said sheet from said sheet supply, a feeler element, means for periodically moving said feeler element downwardly into engagement with the top of said sheet supply in timed relation with the downward movement of said suction device, and means actuated variably in accordance with the extent of downward movement of said feeler element for controlling and determining the extent of downward movement of said suction device.

25. In a sheet feeder, a suction device arranged above a supply of sheets and mounted for movement toward and away from said sheet supply to grip the topmost sheet of said sheet supply and lift at least a portion of said sheet from said sheet supply, mechanism for periodically operating said suction device toward and away from said sheet supply, a feeler element arranged above said sheet supply, mechanism for periodically operating said feeler element toward and away from said sheet supply into and out of engagement, respectively, with the top of said sheet supply in timed relation with the operation of said suction device, and stop means operable in response to the movement of said feeler element toward said sheet supply and positioned in accordance with the extent of such movement for limiting the movement of said suction device by said first-named mechanism toward said sheet supply to a predetermined position with respect to the top of said sheet supply.

26. A sheet feeder as defined in claim 25, comprising means for releasably holding said stop means in the actuated position thereof.

27. A sheet feeder as defined in claim 25, comprising means for releasably locking said stop means in the actuated position thereof and against movement in either direction from said position.

28. A sheet feeder as defined in claim 25, comprising operable latch means responsive to the movement of said suction device toward said sheet supply for releasably holding said stop means in the actuated position thereof.

29. A sheet feeder as defined in claim 25, comprising latch means operable in response to the movement of said suction device toward said sheet supply for holding said stop means in the actuated position thereof and against movement in either direction from said position and operable in response to the movement of said suction device away from said sheet supply to release said stop means.

30. In apparatus of the class described, a suction device,

mechanism for periodically moving said suction device downwardly toward and upwardly away from a supply of sheets to grip the topmost sheet of said sheet supply and lift at least a portion of said sheet from said sheet supply, a movabiy mounted stop member arranged to be engaged by a part of said mechanism during downward movement of said suction device thereby for limiting such movement of said suction device, a feeler element operable from a fixed position spaced upwardly from said sheet supply toward and into engagement with the top of said sheet supply, mechanism operable periodically in timed relation with the operation of said suction device for moving said feeler element into engagement with said sheet supply prior to the downward movement of said suction device, and means operatively connected with said lastnamed mechanism for effecting movement of said stop member concurrently with downward movement of said feeler element and for positioning said stop member in accordance with the extent of such downward movement of said feeler element to bring the latter into engagement with said sheet supply.

31. In apparatus of the class described, a suction device, mechanism for periodically moving said suction device downwardly toward and upwardly away from a supply of sheets to grip the topmost sheet of said sheet supply and lift at least a portion of said sheet from said sheet supply, a movably mounted stop member arranged to be engaged by a part of said mechanism during downward movement of said suction device thereby for arresting the operation of said mechanism and thereby limiting such movement of said suction device, a pivotal arm associated with said stop member and operable to control the movement of said stop member to different operative positions, a feeler element mounted for movement toward and into engagement with the top of said sheet supply, mechanism operable periodically in timed relation with the operation of said suction device for moving said feeler element into engagement with the top of said sheet supply prior to the downward movement of said suction device, and means actuated by said last-named mechanism and operatively connected with said arm for operating the latter concurrently with the movement of said feeler element toward said sheet supply and for imparting movement to said arm of an extent commensurate with the extent of movement of said feeler element to bring the latter into engagement with said sheet supply.

32. In apparatus of the class described, a suction device, mechanism for periodically moving said suction device downwardly toward and upwardly away from a supply of sheets to grip the topmost sheet of said sheet supply and lift at least a portion of said sheet from said sheet supply, a movably mounted stop member arranged to be engaged by a part of said mechanism during downward movement of said suction device thereby for arresting the operation of said mechanism and thereby limiting such movement of said suction device, a pivotal arm associated with said stop member and operable to control the movement of said stop member to different operative positions, an operable feeler element arranged above said sheet supply and normally spaced therefrom, mechanism operable periodically in timed relation with the operation of said suction device for moving said feeler element downwardly toward and into engagement with the top of said sheet supply and upwardly away from and out of engagement with said sheet supply, said downward movement and engagement of said feeler element with said sheet supply occurring prior to the downward movement of said suction device, means including a lost-motion connection between said last-named mechanism and said arm for operating the latter concurrently with the downward movement of said feeler element and for imparting movement to said arm of an extent commensurate with the extent of such movement of said feeler element to bring the latter into engagement with said sheet supply, said lost-1notion connection allowing for operation of said last-named mechanism and upward movement of said feeler element independently of said arm, and latch means operable prior to the upward movement of said feeler element for releasably holding said arm in its actuated operative position.

33. Apparatus as defined in claim 32 wherein the operation of said latch means is responsive to the downward movement of said suction device.

34. Apparatus as defined in claim 32, comprising resilient means operably connected to said arm and tending at all times to move said arm in a direction opposite to the direction imparted thereto by said last-named mechanism.

35. Apparatus as defined in claim 34 wherein the operation of the latch means to hold the arm in its actuated operative position and to release said arm for movement by said resilient means is responsive to the downward and upward movements, respectively, of the suction device.

36. in a sheet feeder, a pair of suction devices arranged above a supply of sheets and mounted for movement in dependently of each other toward and away from said sheet supply to grip the topmost sheet at transversely spaced points and lift said sheet from said sheet supply, independent mechanisms for moving said suction devices in unison toward and away from said sheet supply, and means controlled by said sheet supply and actuated variably in accordance with the location of the top of said sheet supply for controlling and determining the extent of movement of said suction devices toward said sheet supply independently of each other.

37. In apparatus of the class described, a suction device, mechanism for periodically moving said suction device downwardly toward and upwardly away from a supply of sheets to grip the topmost sheet of said sheet supply and lift at least a portion of said sheet from said sheet supply, said mechanism including a downwardly and upwardly operable abutment adjustable downwardly and upwardly to different relative positions, a stop member arranged to be engaged by said abutment and movable to different operative positions with respect to said abutment, engagement of said abutment with said stop member occurring during downward movement of said suction device thereby limiting such movement of said suction device, a feeler element, mechanism operable periodically in timed relation with the operation of said suction device for moving said feeler element into engagement with the top of said sheet supply prior to downward movement of said suction device, and means under the control of said feeler element through movement thereof toward said sheet supply for variably positioning said stop member with respect to said abutment in accordance with the extent of such movement of said feeler element to bring the latter into engagement with said sheet supply.

38. in a sheet feeder, a sheet separating mechanism comprising frame means fixed against vertical up and down movement, a cam shaft journalled in said frame means, a sheet separating device pivotally mounted on said frame means and operable from a position spaced from a supply of sheets toward the latter to grip the first sheet of said sheet supply and move at least a portion of said sheet facewise away from said sheet supply to said position, means including a cam fixed on said shaft for operating said sheet separating device, and means carried by said frame means and controlled by said sheet supply and actuated variably in accordance with the location of said sheet supply from said sheet separating device in said position for controlling and determining the extent of move ment of said sheet separating device toward said sheet supply.

39. In a sheet feeder, a pair of suction devices arranged above a supply of sheets and mounted for movement independently of each other downwardly toward and upwardly away from said sheet supply to grip the topmost sheet at transversely spaced points and lift said sheet from said sheet supply, independent mechanisms for periodically moving said suction devices in unison toward and away from said sheet supply, said mechanisms providing for movement of said suction devices into engagement with the top of said sheet supply, a pair of members arranged above said sheet supply and adjacent said suction devices, independent mechanisms operable periodically in timed relation with the operation of said suction devices for moving said members in unison downwardly toward and upwardly away from said sheet supply into and out of engagement, respectively, with the top of said sheet supply, and independent stop means for said suction devices operable independently and variably under the con: trol of said members through downward movement thereof into engagement with said sheet supply for limiting the downward movement of said suction devices each to a position spaced upwardly from the top of said sheet supply.

References Cited in the file of this patent UNITED STATES PATENTS 1,061,526 Cortissoz May 13, 1913 1,545,492 Henderson July 14, 1925 1,625,578 Tremper Apr. 19, 1927 1,715,358 Harrold June 4, 1929 1,762,661 Low June 10, 1930 2,151,073 Belluche Mar. 21, 1939 FOREIGN PATENTS 652,530 Great Britain Apr. 25, 1951

Claims

1. IN A SHEET FEEDER OF THE TYPE IN WHICH SHEETS ARE REMOVED ONE AT A TIME FROM THE TOP OF A PILE, A SUCKER, MEANS FOR LOWERING THE SUCKER ONCE FOR EACH FEED CYCLE FROM A POINT ABOVE THE UPPERMOST SHEETS, A RISING AND FALLING FEELER ENGAGING THE TOP OF THE PILE ADJACENT THE SUCKER, AND MEANS ACTUATED BY THE DESCENT OF SAID FEELER TOWARD THE TOP OF THE PILE TO TERMINATE THE DESCENT OF THE SUCKER AT A PREDETERMINED ELEVATION, WHEREBY THE