US3022997A

US3022997A - Sheet transfer device

Info

Publication number: US3022997A
Application number: US775781A
Authority: US
Inventors: William Q Pendley
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-11-24
Filing date: 1958-11-24
Publication date: 1962-02-27
Anticipated expiration: 1979-02-27

Description

Feb. 27, 1962 w. Q. PENDLEY 3,022,997

SHEET TRANSFER DEVICE Filed Nov. 24, 1958 m Z1 .5 mi

66 mg i 94 76 90 o 5 g 33/ i /04 92 g s; 1 7 5 INVENTOR WILL/AM Q. PENDLE) BY faM ATTORNEY United States This invention relates to a sheet transfer device and especially to a pickup and transfer apparatus for use in handling sheets and signatures and particularly in the printing trade in collating parts of a finished group of sheets.

This is a continuation-in-part of my co-pending application Serial Number 625,140, filed November 29, 1956. As set forth in detail in this co-pending application, sheets of printed paper representing diiferent parts of a finished book are collated or collected in sequence, in order, by arranging the different sheets in individual stacks on a common base which is moved; and during movement of the common base, sheets are picked up in proper sequence and transferred to a central point where they are deposited in proper order. The particular structure used for this is a sheet pickup frame at each individual station which moves upwardly and downwardly in response to a track against which it is guided. On this frame are suction cups that engage the topsheet and adhere to it while suction is applied through them from a vacuum-producing means.

The present invention is an improvement on the sheet pickup station lifting frame apparatus by providing such things as an improved support for the sheets or signatures which assures substantially even, level top sheets even Where one side has accumulated and bunched due to heavier margins. A signature is a folded o-r assem bled group of individual sheets about a common edge or margin and this margin inherently is thicker than the thickness of the other edge of sheets. For this reason, a stack of signature sheets will lie higher on one side at the margin edge than on the other side, thereby presenting a top surface which is slanting from the margin side to the other edge. It is difficult for a sheet pickup device to engage the top sheet or signature evenly when the sheet or signature itself lies in a slanting plane to the horizontal. The present improvement provides a base for the stack of sheets or signatures which compensates for the unevenness or bunch or build-up of the stack at the margins and continuously and automatically compensates for this as the sheets are removed, since the accumulated build-up diminishes from the top as the sheets are removed.

In conjunction and cooperation with the compensating rack base of this device, the sheet engaging and transfer frame has been modified to present self-adjusting suction cups and also an adjustment which may be made manually to vary the contact distance between the frame and the top of the sheet stack thereby varying the contact of the suction cups with the top sheet.

A primary object of this invention is to present a sheet transfer frame device which has self-adjusting suction cups to fit the incline of the top sheet.

Another object is to provide on the transfer device,

in addition to the self-adjusting suction cups, a control device for varying the contact of the apparatus with the top sheet to permit the cups to engage freely. An additional object is to provide in conjunction with the transfer frame a base having a means thereon for compensating for stack build-up at the marginal edges of the sheets and as an additional feature a provision for compensating during the removal of the sheets.

Other and further objects and advantages of my invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

"ice

FIG. 1 is a perspective view of the entire sheet handling device with the movable base of the overall machine broken away.

FIG. 2 is a front side elevation view of the individual stack support base of the device shown in FIG. 1.

FIG. 3 is a perspective view of the compensating stack base of the device in FIG. 1.

FIG. 4 is a back side elevation view of the bottom portion of the stack transfer device in FIG. 1 showing an adjustment detail.

FIG. 5 is a cross-section view through one of the compensation plungers on the base of the device in FIG. 1.

The overall device itself is designated and presented as a single station 10 and is positioned as part of a composite collating or signature gathering machine having a common base 12 on which all identical stations 10 are located, each being the position for a stack of different sheets. Since the details of the overall collating machine are not herein involved, base 12 and the remainder of the machine have been broken away. Rigidly fastened on base 12 by any suitable means is a pair of upright support, slide rod members 14 on which the sheet transfer device moves in sliding engagement upwardly and downwardly thereon by means of a pair of tubular slide members 16, 18 connected by

rigid cross-bars

20, 22 and having fixed to member 22 a track guide support arm 24 with a track roller wheel 26 thereon. Member 2% is a hollow conduit. Normally the entire device is guided by engagement of wheel 26 with a guide track 27 to move the device upwardly and downwardly in sliding move ment on rods 14. As the members 16, 18 slide downwardly the entire device moves toward and eventually against the stack of sheets therebelow.

Protruding from and rigidly fixed on bottom member 20 is a pair of extension arms 23, 30 connected together and supporting a frame member 32 therebelow having a pair of suction cup support levers 34 mounted thereon. Each lever 34 is a straight flat bar with a journal end portion 36 loosely mounted on and for rotation about the frame member 32 so that the levers will move independently of each other on the member 32 and each lever has mounted thereon a suction cup, hollow conduit sup- 1 port 38 having a suction cup 40 sliding for limited move merit therein on a hollow rod 42. Suction cups 40 are in suction communication with the conduit 38 to have a vacuum produced therein in response to a vacuum produced through the line 38. Each conduit 38 is connected by a flexible hose 44 to the conduit 26 providing a central suction supply through which both air and suction are applied. Rigidly mounted on the respective levers 34 in front of each suction cup 40 is an air nozzle 46 connected by a flexible hose 48 to the central line 20. Through the operation of a valve timing device, not forming a part of this present invention and being shown in my co-pending application identified previously, the suction cups 40 are'supplied with the suction, and the nozzles 46 are suppliedwith air to blow against the stacked sheets and loosen them slightly to separate them for pickup by the cups 40.

Attached on each lever 34 is a respective upstanding post 50 with an adjustment tab 52 screwed thereon and resting on top of and against the arm 28 as each lever 34 hangs on its journal 36 to limit the downward travel of each lever 34 thereby maintaining the levers 34 in a slightly raised position. Since the engagement of tabs 52 against a respective arm 28 is a loose abutment by gravity, pressure against the levers 34, as when hitting against the top sheet, will cause the levers 34 to raise, each independently of the others.

Depending from and attached to arm 30 is an adjustment frame 54 (FIG. 4 in particular) which determines the point at which the suction cups 4a hit and consisting of a pair of spaced blocks 56 attached to the arm 30 supporting a respective member 58 each having a journal block 69 at the end thereof in which is journaled a shaft member 62. A pair of pivot blocks 64 on shaft 62 are connected by upper and lower arms 66,68. Rotation of blocks 64 on shaft 62 is prevented by a latch member 70 consisting of a cup-shaped retainer 72 fitting over one or the other of arms 66, 68 and fixed to a pin 74 sliding in a collar 76 attached on member 30. Accordingly, arm 66 is spaced further away'from shaft 62 than is arm 68 so that the distance of abutment from either one of the arms 66, 68 or shaft 62 may be adjusted by rotating the entire block assembly 64 on shaft 62 to one of three positions: arm 66 down; arm 68 down; or arms 66, 68 and shaft 62 in a horizontal line. This provides an adjustment of the point at which the device it) reaches its maximum travel downwardly and strikes the stack top, thereby lending an adjustment to the striking of the cups 40 against the stack top. By placing the short side 68 down, the cups 40 will lower less than if the middle shaft 62 were down, while having the long side 66 down will reduce the travel even more than with the side 68.

Cooperating with and co-acting with the device is the stack holding and positioning rack 80 consisting of a box-like base 82 of bent metal or the like attached to the moving base 12 of the overall machine beneath the device 18. As apparent in FIG. 2, the arrangement of this rack 80 maintains a stack of signature sheets 84 with the top sheet substantially level from side to side even though the outside marginal edges of the sheets 84 are thicker than the inside edges.

Sheets 84, which may be signature sheets folded from larger sheets, are stacked on the top 86 of base 82 and positioned in place by guide members consisting of front vertical guide bars 88 adjustably fastened by screws 90 on a front block 92, intermediate side positioning, vertical strips 24 having inturned bottom edges with elongated adjustment slots 96 receiving attachment screws 98; in base 82, and rear positioning strips 100 with bent bottom ends adjustably screwed to base 82. Removably positioned on base 82 about the rear strips 100 are stacked E-shaped adjustment platforms 102 of selected thickness. There may be as many or as few platforms 102 as needed to balance out the initial cumulative bunch or build-up of the front edge of sheets 84. Located at the front on base 82 are automatic compensating plungers 104 mounted in tubes 106 fastened on base 82 and confining inside the tubes 106 a respective spring 108.

Initially, in loading all stations adjacent devices 10, the

sheet stack guides

88, 94, 100 are adjusted by sight about the stack of sheet and platforms 102 are selected according to thickness and number to compensate for the cumulative bunch or build-up at the outer marginal edges (FIG. 2). By trial run, the suction cup 40 downward engagement and travel are adjusted against the top of the stack of sheets 84 to give the best engagement and pickup. Whenever more or less positive engagement against the top sheet 84 is needed, the frame arrangement blocks 6-4 are adjusted by lifting pin 74 with retainer 72 and turning blocks 64 about shaft 62 to the proper place. As stack 64 diminishes in size by the sheets being removed, the marginal bunch or build-up becomes less and less and gradually, if it were not for the plungers 164, the

, platforms 102 would cause a cumulative bunchon the opposite side. However, as the weight of stack 64 diminishes, plungers 104 are tendingto produce more and more effect on the stack front marginal edge and thereby compensate for the loss in build-up. at thetop by pushing upwardly from the bottom.

With this arrangement, once a stack 64 of sheets has been placed in the rack 80 in proper alignment and the initial front bunch compensated for by dropping the front from the rear platforms 102, the machine may be .operated to bring the device 10 in engagement with the stack top 64 and if necessary the stack engagement is adjusted at the frame '54. Then the machine may be run without regard'to the change in front build-up resulting from sheet 64 removal since the plungers 194 compensate for that. Any other curvature, slant or unevenness at the top of the sheets 64 is compensated for and the effect minimized by the adjustment of the frame 54 to give more or less positive engagement between the cups 40 and the sheet tops 64 and in addition each lever 34 is independent of any other so that even though there is not a straight line or plane between respective cups 40 each cup will nevertheless make suitable contact at its particularposition.

While I have shown and described a particular embodiment of my invention in detail herein and point out certain advantages thereof, this is not to be construed as the only advantages or as the only form of my invention since various alterations, substitutions, changes, eliminations, variations, and modifications may be made in the device shown without departing from the scope of my invention defined in the appended claims.

I claim:

1. In a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station in response to a machine control which also provides suction for engaging a sheet, station support means on said machine movable thereon to transfer a sheet, suction supports mounted for arcuate movement on said station support means, suction means on said suction supports having spaced suction surfaces independently operable against the top of the stack to adjust across any unevenness thereof, and adjustable means on said station for adjusting the point of contact with said stack to bring said suction means evenly into engagement with said stack top.

2. In a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station in response to machine control which also provides a timed vacuum to said station, a substantially fiat stack positioning surface adjacent said transfer station for holding a stack of sheets to be transferred therefrom, means on said surface for causing said stack to be substantially level at the top thereof even when said sheets are thicker on one side, said means on said surface compensating for the loss in build-up of the thicker side as said stack diminishes from sheets being removed therefrom to maintain the top of said stack substantially level from a full stack to a partly empty stack.

3. The device of claim 2 wherein there is an adjustable stack contact stop member for positioning said station against said stack.

4. in a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station'in response to machine control which also provides a timed vacuum and an independently timed air pressure to said station, station support means extending from said machine and base and being supported for movement thereon relative thereto as said station moves on said base to transfer sheetsfrom the stack thereon, suction supports mounted for arcuate movement on said station support means, suction cups mounted for independent movement on each said suction supports and being supported thereon above said stack to engage the top sheet thereof, each of said suctioncups being freely movable by contact with the stack top independently of the other so as to compensate for any unevenness of the stack top, and said suction supports moving arcuately and independently against said stack to adjust for any unevenness across said stack either longitudinally or transversely thereof' 5. In a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independently timed air pressure to said station, a substantially fiat stack positioning surface adjacent said transfer station for holding a stack of sheets to be transferred therefrom, means on said surface for compensating the accumulated buildup of one side of said stack to cause said stack to be substantially level at the top thereof, and spring loaded plunger means on said surface for compensating for the loss in build-up as said stack diminishes from sheets being removed therefrom to maintain the top of said stack substantially level from a full stack to a partly empty stack, said plungers normally being depressed when said stack is fuller and gradually pushing the stack as sheets are removed.

6. In a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independently timed air pressure to said station, station support means extending from said machine and base and being supported for movement thereon relative thereto as said station moves on said base to transfer sheets from the stack thereon, suction supports mounted for arcuate movement on said station support means, suction cups mounted for independent movement on said suction supports and being supported thereon above said stack to engage the top sheet thereof, each of said suction cups being freely movable by contact with the stack top independently of the other so as to compensate for any unevenness of the stack top, and adjustable stack stop means on said station adjustable to determine the contact of the entire station with the stack top whereby said suction cups yieldably engage the stack top to make suction engagement with the top sheet thereof, and said suction supports moving arcuately and independently against said stack to adjust for any unevenness across said stack both transversely and longitudinally thereof.

7. In a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independently timed air pressure to said station, a substantially fiat stack positioning surface adjacent said transfer station for holding a stack of sheets to be transferred therefrom, a plurality of selectively removable platform lifts on said surface for compensating the accumulated build-up of one side of said stack to cause said stack to be substantially level at the top thereof, and other compensating means on said surface for compensating the other side of said stack for the loss in build-up as the initially lifted side of said stack diminishes from sheets being removed therefrom to maintain the top of said stack substantially level from a full stack to a partly empty stack.

8. In a sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is'guided and moved on a moving machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independently timed air pressure to said station, station support means extending from said machine and base and being supported for movement thereon relative thereto as said station moves on said base to transfer sheets from the stack thereon, a plurality of suction cups pivotally mounted for independent movement on said station sup port means and being supported thereon above saidstack to engage the top sheet thereof, each of said suction cups being retained over said stack from downward movement and freely movable'by contact with .the stack top independently of the other so as to compensate for any unevenness of thelstack top, and an adjustable stack stop frame on said station having a plurality of contact members selectively adjustable to determine the contact of 6 the entire station with the stack top whereby said suction cups yieldably engage the stack top to make suction engagement with the top sheet thereof.

tially flat stack position ng surface adjacent said transfer station for holding a stack of sheets to be transferred therefrom, adjustable platform means on said surface for initially adjustably lifting one side of said stack for compensating the accumulated build-up at one side of said stack from any excess thickness of one side of said sheet compared to any other side to cause said stack to be substantially level at the top thereof, a plurality of spring loaded plungers on said surface compensating for the loss in build-up as said stack diminishes from sheets being removed therefrom to maintain the top of said stack substantially level from a full stack to a partly empty stack.

10. In a sheet transfer station for moving sheets from a stack of sheets wherein guide members are provided on a machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independent air pressure to said stations, station support members extending from said guide members, means supporting said support members for transfer movement on said base guide members, spaced suction cup levers mounted for pivotal movement on said station support members, each of said levers having a positioning means thereon normally yieldably positioning each thereof on said station supports, each of said levers being freely movable on its pivot upwardly and being limited in downward movement by said positioning means whereby contact of said lever with a stack will push said lever upwardly, each of said levers having a suction cup thereon in closed communication with a suction line attached thereto, a stack limiting means mounted on said station comprising a plurality of stack engagement members mounted on said support means each being positionable to a different stack engagement level, an adjustable means on said stack limiting means normally retaining one of said stack engagement members in set position, whereby said cups are yieldable and said station may be adjusted as to contact with said stack.

' 11. In a sheet transfer station for moving sheets from a stack of sheets wherein guide members are provided on a machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independent air pressure to said station, support means supporting said station movably for transfer movement on said base guide members, a plurality .of movable suction cups on said support movable both with and in limited relative distance on said support means, conduit means on said support means connecting said suction cups to said timed vacuum of said machine, a stack limiting meansmounte'd on said station comprising a pinrality of stack engagement members mounted on said sup- .port means each being positionable to a different stack engagement position, an adjustable means on said'stack limiting means normally retaining one of said stack engagement members in set position, a sheet stack base mounted on said machine below said station transfer device and having a raised base bottom with raised stack positioning members adjustably mounted on said base to be pre-arranged to locate and confine said stack thereon, adjustable means selectively positionable on said stack base at the rear thereof to compensate for accumulation of the stack edge at the front,. and means at the front of said base for adjusting said stack at the front thereof to maintain the proper level as sheets are removed therefrom and the front edge diminishes.

12. In a sheet transfer station for moving sheets frommoves the station in response to machine control which also provides a timed vacuum to said station, a substantially flat stack positioning surface adjacent said transfer station for holding a stack of sheets to be transferred therefrom, means on said surface for initially compensating the accumulated build-up at one side of said stack from any excess thickness of one side of said sheet compared to any other side to cause said stack to be substantially level at the top thereof, other means on said surface compensating for the loss in build-up as said stack, diminishes from sheets being removed therefrom to maintain the top of said stack substantially level from a full stack to a partly empty stack, station support means extending from said machine and base and being supported for movement thereon relative thereto in engagement with'said stack as said station moves on said base to transfer sheets from the stack, a plurality of suction cups mounted for independent movement on said station support'means and being supported thereon above said stack to engage the top sheet thereof, each of said suction cups being retained over said stack from downward movement freely movable by contact with the stack top independently of the other so as to compensate for any unevenness of the stack top.

l3. Ina sheet transfer station for moving sheets from a stack of sheets wherein the sheet station is guided and moved on a moving machine base and a control member moves the station in response to machine control which also provides a timed vacuum to said station, a substantially flat stack positioning surface adjacent said transfer station for holding a stack of sheets to' be transferred therefrom, means on said surface for initially ad-' justably lifting one side of said stack for compensating the accumulated build-up at one side of said stack from any excess thickness of one side of said sheet compared to any other side to cause said stack to be substantially level at the top thereof, other means on said surface compensating for the loss in build-up as said stack diminishes from sheets being removed therefrom to maintain the top of said stack substantially level from a full stack to a partly empty stack, station support means extending from said machine and base and being supported for movement thereon relative thereto in engagement with said stack as said station moves on said base to transfer sheets from the stack, a plurality of suction cups mountedfor "independent movement on said station support means and being supported thereon above said stack to engage 'the top sheet thereof, each of said suction cups being retained over said stack from downward movement freely movable by contact with the stack top independently of the other so as to compensate for any unevenness of the stack top, and adjustable stack stop means onsaid station adjustable to determine the contact of the entire station with the stack top whereby said suction cups yieldably engage the stack top to make suction engagement with the top sheet thereof.

14. In a sheet transfer station for moving sheets from a stack of sheets, wherein guide members are provided on a machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independent air pressure to said station, a station support means extending from said guide members, means supporting said support members movably for transfer movement on said base guide members, a stack limiting frame mounted on said station comprising a pair of spaced supports mounted belowone of'said station supports, a pivotal shaft member mounted on and between said supports, a pair of spaced block members mounted on said shaft for rotation thereon, a pair of stack engagement members mounted between said blocks on opposite sides of said shaft and being spaced different distances therefrom, an adjustable engagement member on said stack limiting frame normally retaining said stack engagement members in set position, said blocks being rotatable-about said shaft to select one of the positions diminishes.

of the stack engagement members, a sheet stack base mounted on said machine base below said station transfer device and, having a raised base bottom with a flat top surface, front, side, rear stack positioning members adjustably mounted on said base to be pre-arranged to locate and confine said stack thereon, a plurality of build-up blocks selectively positionable on said stack base at the rear thereof to compensate for accumulation of the stack edge at the front, and automatic compensating plungers spring mounted on said base to compensate for stack reduction as the stack diminishes.

15. In a sheet transfer station for moving sheets from a stack of sheets, wherein guide members are provided on a machine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independent air pressure to said station, a pair of station support members extending from said guide member, means supporting said support members movably for transfer movement on said base guide members, a suction lever support member fixedly mounted on said station supports, a pair of spaced suction cup levers mounted for pivotal movement on said suction lever support member, each of said levers having a position stop tab' thereon normally resting in engagement above one of said station support members, each of said levers being freely movable on its pivot upwardly and being limited in downward "movement by said stop tabs whereby contact of said lever with a stack will push said lever upwardly, each of saidlevers having a suction cup thereon in closed'communication with a suction line attached thereto, a movable connecting pipe supporting each of said suction'cups for limited movement on said respective levers, a sheet stack base mounted on said machine base below said station transfer device and having a raised base bottom with'a flat top surface, front, side, rear stack positioning'members adjustably mounted on said base to be pro-arranged to locate and confine said stack thereon, a plurality of build-up blocks selectively positionable on said stack base at the rear thereof to compensate for accumulation of the stack edge at the front, and automatic compensating plungers spring mounted on said base to compensate for stack reduction as the stack 16. In a sheet transfer station for moving sheets from a stack of sheets, wherein guide members are provided on a'rnachine base and a control member moves the station in response to machine control which also provides a timed vacuum and an independent air pressure to said station, a support means supporting said station movably for t'ransfer'movement on said base guide members, a

plurality of spaced suction cup supports mounted for pivotal movement on said station supports, each of said levers'being movable on its pivot upwardly and being positioned infstack contact position whereby contact of said lever with a stack will push said lever upwardly, each of said'levers having a suction cup thereon in closed communication'with a suction'line attached thereto, a stack limiting frame mounted'on' said station, a pivotal shaft member mounted on and between said station, a pair of stack engagement members mounted on'opposite sides of said shaft and being spaced different distances therefrom, an adjustable means on said stack limiting frame normally retaining said stack engagement members in'set position, a sheet'stack base mounted on said machine base below said station transfer device and having a raised'base' bottom with a flat top surface, front, side,

-rearstackpositioning members adjustably mounted on a stack-of sheets, wherein guide members are provided on amachinebase and a control member moves the station in response to machine control which also provides a timed vacuum and an independent air pressure to said station, a pair of station support members extending from said guide member, means supporting said support members movably for transfer movement on said base guide members, a suction lever support member fixedly mounted on said station supports, a pair of spaced suction cup levers mounted for pivotal movement on said suction lever support member, each of said levers having a position stop tab thereon normally resting in engagement above one of said station support members, each of said levers being freely movable on its pivot upwardly and being limited in downward movement by said stop tabs whereby contact of said lever with-a stack will push said lever upwardly, each of said levers having a suction cup thereon in closed communication with a suction line attached thereto, a movable connecting pipe supporting each of said suction cups for limited movement on said respective levers, a stack limiting frame mounted on said station comprising a pair of spaced supports mounted below one of said station supports, a pivotal shaft member mounted on and between said supports, a pair of spaced block members mounted on said shaft for rotation thereon, a pair of stack engagement members mounted between said blocks on opposite sides of said shaft and being spaced different distances therefrom, an adjustable engagement member on said stack limiting frame normally retaining said stack engagement members in set position, said blocks being rotatable about said shaft to select one of the positions of the stack engagement members.

18. In a sheet transfer station for moving sheets from a stack of sheets wherein guide members are provided on a machine base and a control member moves thestation in response to machine control which also provides a timed vacuum and an independent air pressure to said station, a pair of station support members extending from said guide members, means supporting said support members movably for transfer movement on said base guide members, a suction lever support member fixedly mounted on said station supports, a pair of spaced suction cup levers mounted for pivotal movement on said suction lever support member, each of said levers having a position stop tab thereon normally resting in engagement above one of said station support members, each of said 10 levers being freely movable on its pivot upwardly and being limited in downward movement by said stop tabs whereby contact of said lever with a stack will push said lever upwardly, each of said levers having a suction cup thereon in closed communication with a suction line attached thereto, a movable connecting pipe supporting each of said suction cups for limited movement on said respective levers, a stack limiting frame mounted on said station comprising a pair of spaced supports mounted below one of said station supports, a pivotal shaft member mounted on and between said supports, a pair of spaced block members mounted on said shaft for rotation thereon, a pair of stack engagement members mounted between said blocks on opposite sides of said shaft and being spaced different distances therefrom, an adjustable engagement member on said stack limiting frame normally retaining said stack engagement members in set position, said blocks being rotatable about said shaft to select one of thepositions of the stack engagement members, a sheet stack base mounted on said machine below said station transfer device and having a raised base bottom with a flat top surface, front, side and rear stack positioning members adjustably mounted on said base to be pre-arranged to locate and confine said stack thereon, a plurality of build-up blocks selectively positionable on 'said stack base at the rear thereof to compensate for accumulation of the stack edge at the front, and automatic compensating plungers spring mounted on said base to compensate for stack reduction as the stack diminishes.

References Cited in the file of this patent UNITED STATES PATENTS Dexter et a1. July 22, 1958