Abstract: A sheet feeding apparatus for feeding sheets from the top or bottom of a stack of sheets which includes a sheet stack supporting tray, a vacuum plenum and feed belt sheet separating and feeding assembly with at least one feed belt having a vacuum plenum disposed within the run of the belt, the vacuum plenum and the belt assembly being positioned adjacent a sheet to be fed such that a rear portion of the plenum and belt assembly lies opposite a portion of a stack of sheets to be fed and is adjacent and substantially parallel to the plane of the sheet to be fed and a front portion of the plenum and belt assembly which lies opposite the front portion of a stack of sheets to be fed and in a plane angled away from the plane of the sheet to be fed.

Abstract: A bill packet discharging apparatus is disclosed, in which bill packets can be automatically supplied to an outlet from a bill packet storage section in which bill packets are accommodated in a stacked form. Bill packets can be successively fed out from the lowermost bill packet in the stack in the storage section to a transport path by a bill packet feeding mechanism. When the bill packet being fed out is a defective bill packet with the band thereof broken so that the bills are released, this state is detected optically, and the defective bill packet is automatically collected in a recovery section.

Abstract: Apparatus is provided for taking a stack of flat articles such as folded newspapers, and delivering them successively to a conveyor in an overlapped or shingled arrangement to move to a processing station for labeling or addressing or for opening them to receive inserts. A rectangular hopper or gate is located over a traveling belt means to hold a stack of such flat articles with its converging angle pointing downstream. Each bottom article is gripped by the belt means, which is vacuumized in the area under the stack, and is pulled under the gate and downstream.When a given article is only partially through the gate, the succeeding article is gripped primarily by its side portions and pulled under the gate in overlapping or shingled relation with the preceding one, each article being arranged with its side edges at a substantial angle to the direction of travel.

Abstract: An apparatus for positioning an interleave on a finished sheet product prior to transferring and depositing the latter in a stacked relation. The apparatus includes a stripper means for removing the lowermost interleave from a stack of such interleaves and advancing the same on a conveyor arrangement to a pick-up station whereat the interleave is raised into engagement with a pair of gripping arms of a reciprocal shuttle. The shuttle transports the interleave to a forward position in vertically spaced relation to the sheet product for subsequent deposit thereon prior to removal of the sheet article along with the overlying interleave by a transfer apparatus.

Abstract: A bottom sheet feeding apparatus including a sheet separator and feeder and a sheet stacking tray which has a planar base portion defining a base plane, the front of the base portion having an opening within which said bottom sheet separator is positioned, the tray further including two sloping planar side wings, one at each side of said opening in the base portion. The sloping planar side wings are angled upward from the base plane and are angled outward from front to rear of the tray and intersect the base plane such that the intersection at the rear of the tray is in the approximate location of the rear corners of a rectangle the size of a sheet to be fed and the intersection of the planar wings and the base plane at the front of the tray is approximately midway between the front corners of a sheet to be fed and the centerline of a sheet to be fed. In a preferred embodiment the sheet separator feeder comprises a plurality of vacuum belts having a vacuum plenum disposed within the run of the belts.

Abstract: At one side of a stack of printed products or the like there are provided entrainment elements which are mounted at a revolving or orbiting driven chain or equivalent structure. Each entrainment element is inserted at one side of the momentarily lowermost printed product of the stack between the sheets of such printed product and comes into contact with the folding edge or spine of such printed product. By further moving the entrainment element the lowermost product is pulled out from beneath the stack while turning or rotating the same at the region of the product corner at which engages the entrainment element. The thus freely exposed region of the folding edge or spine of the lowermost product then comes to lie between two rolls or rollers of a product removal device, one of these removal rolls being driven. Both of these rolls pull the seized product out of the bottom of the stack in the product removal direction and place such upon two outfeed conveyor belts or bands.

Abstract: The apparatus comprises a continuous path, divided into a first rising section and a second substantially horizontal section, having a conveyor extending there along and carrying one or more pushers adapted to withdraw individually folded and flattened cartons from a container magazine provided and arranged at the top of the rising section. At the junction location between the two sections, movable supports are provided which receive, when at a first position arranged in continuation of the rising section, individually folded and flattened cartons and transfers the latter, when arranged at a second position in which said supports are arranged parallel to the conveying along the substantially horizontal section, again on the conveyor without said cartons being left by the one or more pushers. This assures a correct arrangement of said cartons on said conveyor downstream of the junction location.

Abstract: A sheet feed machine comprising guides for holding sheets in a stack at a sheet input station, a first conveyor for successively feeding sheets from the bottom of the stack at the sheet input station into a stream with adjacent sheets in an overlapped configuration, and an inverter for inverting the stream of sheets at a sheet inversion station. A stop is located at a sheet output station for stopping the stream and accumulating sheets in a stack, and a second conveyor is provided for conveying the stream of sheets from the inversion station to the sheet output station.

Abstract: An apparatus for the withdrawal of flat carton blanks made of paperboard, boxboard or corrugated board from a stack located in back of a retaining mechanism, which comprises conveyor belts and belt guides disposed beneath the stack of blanks for the controlled withdrawal of the lowermost blank and, directly adjacent to such takeoff conveyor and driven in synchronism therewith, a conveyor for the onward transportation of the individually withdrawn blanks. The belts of the takeoff conveyor under the stack are carried downwardly at an acute angle relative to the belt guides starting in the vicinity of retaining mechanism and there is disposed below said conveyor belts, in the vicinity of said retaining mechanism an eccentrically mounted roll whose eccentric shaft is driven by a drive controlled in synchronism with the drive of the takeoff conveyor.

Abstract: A feeder has an endless belt conveyer which removes flat articles one-by-one from the bottom of a stack and transports them downstream to a delivery point. A chamber is connected to a vacuum source in timed sequence to apply a vacuum through apertures in the belt to pull the underside face of the lowermost article against the upper surface of the moving belt. Further, restraining chambers are connected to a vacuum source to engage the article next thereabove and prevent its premature downstream travel.

Abstract: An improved conveyor for signatures, loose sheets, gathered sheets, and the like, with a device for picking them up. The improved conveyor achieves fast signature transport capabilities in overlapped relationship. A mechanism is also provided for entraining the signatures which are operative on each signature prior to a preceding signature moving fully away from the following one. Advantageously, the entrainment members have an outer surface with a high friction coefficient. The initial section of the elevator conveyor belts follows a path which deviates from the oblique plane of lay thereof, preferably a substantially vertical path.

Abstract: A sheet feeder for separating and feeding the bottom sheet in a stack, a biased corrugating ramp being provided to provide a large corrugation in light weight papers for maximum feeder reliability. The corrugating ramp is adapted to be depressed by heavy weight, stiff sheets to allow the sheets to more closely approach the vacuum feed belts and assure adequate acquisition thereby.

Abstract: A method and apparatus for selectively increasing the effective frictional force between a retard member and a feed member by making both the feed member and retard member from conductive elastomers, and providing a source of electrical potential to produce an electrical potential between them. A sensor is located downstream of the retard member that will sense a multi-feed of sheets between the pad and retard member. The sensor effects the production of electrical potential thereby increasing the friction between the two members and causing separation of the multi-feed of sheets. The potential is then removed and the frictional forces returned to the original level.

Abstract: An automatic document handler adapted to receive a stack of documents to be copied for feeding the documents seriatum to the platen of a copy machine and returning the copied documents to the stack. The combination of a vacuum-belt document corrugator/feed assembly and an air knife is provided to assure positive feeding of each document to the platen without misfeeds or multifeeds.

Abstract: A bottom sheet feeder employing a vacuum feed assembly in conjunction with an air knife for separating and feeding sheets from a sheet stack. A self regulating blower input and output bleed valve assembly utilized in conjunction with a single blower regulates air flow through the blower to the air knife irrespective of the degree of air flow through the vacuum feed assembly caused by blockage thereof by the acquired sheets.

Abstract: An automatic document handler adapted to receive a stack of documents to be copied for feeding the documents seriatim to the platen of a copy machine and returning the copied documents to the stack. A combination vacuum-document separator in conjunction with a precisely located air knife in relation to the vacuum belts and a document tray having a "U" shaped pocket therein is provided to assure positive feeding of each document to the platen without misfeeds or multifeeds.

Abstract: An automatic document handler employing a bottom vacuum sheet separator in conjunction with an air knife, a single blower with a cyclically operated air valve being utilized to provide sub-atmospheric air for the separator and pressurized air for the air knife to provide enhanced feeder performance and automatically compensate for variable paper weights.

Abstract: A blank feeding apparatus for feeding blanks one after another from a stack of blanks to the next processing rolls. Blanks are pushed by kickers attached to an endless conveyor. The motor for driving the conveyor is electronically controlled so that one cycle of kicker operation will be completed while the processing rolls make a full rotation, said one cycle including the acceleration tuned-run and deceleration steps.

Abstract: An automatic document disintegrator has a stand-by chamber into which waste documents to be processed are placed and a paper feed mechanism having engaging members for feeding to a shredding section the waste documents placed in said stand-by chamber. The stand-by chamber is divided by detachable partitioning members into a plurality of compartments corresponding to the sizes of the waste documents, and the engaging members project into each of the compartments and simultaneously feed a prescribed number of sheets of the waste documents placed in each of the compartments to the shredding section in a batch-wise manner.

Abstract: A machine for counting flat articles includes a sequence of conveyor belts driven at successively increasing speeds from input to output. At the input end the articles are stacked and withdrawn from the stack from the bottom. A separator above the conveyor isolates the bodies from each other and spaces them, the spacing being increased by the increasing speed of the conveyors as the articles move toward the output end. The articles are counted by a photocell device or feeler. A receiver arranges the articles in a layered arrangement. Band-shaped resilient, curved clamping members are mounted on the separator to assure separation of articles of varying thicknesses, a first set of clamping members being mounted on the outside of the separator and curving in the direction of conveyance and a second set being mounted on the inside and curving in the direction of conveyance under the separator. An eccentric adjusts the curvature and tension of the first set of clamping members.

Abstract: A document feeding apparatus has a deck that is placed at an angle such that the incline of the deck is sufficiently large so as to overcome the friction of documents placed thereupon. The deck has an opening at the bottom thereof through which a vacuum type conveyor extends to engage the bottommost document of the stack of documents to transport the bottommost document generally upwardly. With this feeding of the bottommost document the balance of the documents will remain in position due to the effect of gravity whereas the next-to-bottom sheet will be released from the bottommost sheet since the angle of incline is sufficiently great to overcome the frictional forces acting between these two documents.

Abstract: A right angle folder-gluer for folding paper boxes from box blanks has a mechanically actuated, timed, bumper-type magazine feed which feeds flat box blanks individually and successively onto an untimed conveyor in a flap folding zone. The folded blanks are then delivered to a right angle transfer zone in which a mechanically actuated pusher bar transfers each blank onto an untimed conveyor for advance through a glueing and folding zone. The bumper feed and transfer bar are positively, mechanically connected and powered for semi-automatic operation and the pattern glue wheel in the glueing zone is also synchronized with the feed and transfer for full automatic operation.

Abstract: Apparatus for receiving a stack of case blank sheets from a source of supply and delivering the sheets in shingled arrangement, for further processing, by receiving the stack at a first level, elevating the stack intact vertically to a second level above the first level, where the stack is transferred to a feeder located at the second level for operation in association with a stripper to feed the sheets forward in shingled arrangement from the bottom of the stack, while stabilizing the stack against toppling backward during feeding of the sheets forward from the bottom of the stack.

Abstract: An automatic sheet feeder, connected to an automatic writing system, for feeding the fresh sheets to a printing station from a first container after a separation in a separate device. After the printing operation, each printed sheet is sent to a driving roller which, in cooperation with a curved guide, reverses the sheet for piling it in a second container positioned above the first container, so that the printed sheets are piled in the same order of printing and upsidedown.

Abstract: A copy reproduction machine having an automatic document handler adapted for top feeding or botton feeding documents from the document supply tray. An inverter is also provided so that, depending on the machine operating mode selected, i.e. simplex (one sided) document to simplex copy, simplex document to duplex (two sided) copy, duplex document to simplex copy and duplex document to duplex copy; the documents are returned to the stacking tray in the proper page order.

Abstract: In a device for the synchronized introduction of sheets into a treatment machine, e.g. a printer-slotter or cutter for processing corrugated cardboard sheets, in which a reciprocating pusher pushes forward the lowermost sheet of a stack in a magazine between two stops and into engagement with feed rollers, the stack rests on the upper run of a set of endless belts, which upper run extends over a suction box which is maintained continuously under suction during forward movement of the pusher, the belts are driven forwardly to facilitate movement of the lowermost sheet from the bottom of the stack, and belts being immobile during the return movement of the pusher.

Abstract: Improved sheet separating and feeding apparatus that opens or partially opens the retard nip after the sheet has partially passed through the retard nip.

Abstract: A sheet stacking and feeding system for a copier with an integral normal force/jogger unit allowing continuous and simultaneous top loading and bottom feeding from opposite or common directions from a stack of documents or copy sheets. Disclosed are continuously rotating foraminous spaced counterbalanced jogging rollers engaging the top of the stack to provide lead edge or trail edge sheet pull-down and stacking registration against the front stack stop, and to provide a controlled uninterrupted normal force to edges of the feed belt of a bottom sheet retard feeder. This system is disclosed in a copying system for copying either duplex or simplex original document sets as pre-collated copy sets. A document handling system provides automatic recirculative pre-collation copying of duplex or simplex document sheets with selective different sheet inversion and different sheet restacking directions.

Abstract: In an envelope edge slitter having a base, apparatus for feeding the envelopes one-by-one from the bottom of a stack at an input station to slitter blades in which an endless elastic belt extending around an eccentric pulley has an upper reach disposed in a slot n the base at the input station. The eccentricity of the pulley alternately brings the belt into and out of engagement with the lowermost envelope in the stack while the elasticity of the belt, the eccentricity of the pulley and the speed with which the belt is driven are such as to produce a whipping action of the upper reach of the belt which ensures that adjacent envelopes of the stack are separated and are fed one-by-one to the slitter blades.

Abstract: A machine for counting flat articles includes a sequence of conveyor belts driven at successively increasing speeds from input to output. At the input end the articles are stacked and withdrawn from the stack from the bottom. A separator above the conveyor isolates the bodies from each other and spaces them, the spacing being increased by the increasing speed of the conveyors as the articles move toward the output end. The articles are counted by a photocell device or feeler. A receiver arranges the articles in a layered arrangement. In one embodiment the input conveyor belt is inclined and has spaced groups of holes with a suction box below the belt to grip and move the articles in spaced relationship.

Abstract: Folded signatures of lightweight stock are fed in a direction parallel to the backbone of the signatures and deposited in sets of predetermined number and in shingled relation onto a main conveyor moving transverse to the direction of feed from the supply stack. The main conveyor deposits the signatures on the top of a stack in the hopper of a gathering machine. The height of the stack in the hopper is sensed, and this is used to control feeding from the supply stack. Preferably, the supply stack is held in a hopper with the signatures resting on a second or supply conveyor which extends upwardly and outwardly from the main conveyor so that adjacent loading machines can be nested to reduce space requirements.

Abstract: An apparatus piles a continuous stream of booklets in a stack, with a succeeding booklet in the stream being piled atop a preceding booklet. When the stack attains a predetermined size, the stack is ejected from the apparatus without stopping delivery to the apparatus of the continuous stream of booklets which are accumulated in a temporary holding stack, during ejection of the other stack. The temporary holding stack is depleted at a rate faster than it formed, following the ejection of the other stack.

Abstract: Apparatus for removing sheets one at a time from a face of a stack of sheets wherein a flow-line is established between a primary feed roller or belt and sheet seizing means downstream thereof defining a nip, a lever system downstream of the nip for creating relative separation between the face and the feed roller or belt, the lever system including first and second levers each having first and second portions and first and second fixed pivots, the first portion of the first lever being disposed downstream of the nip and located normally to obstruct the flow-line but being movable from the flow-line by the passage of a sheet therealong, the first portion of the second lever being effective for effecting relative separation between the face and the feed roller or belt, and the second portion of the first lever controlling pivoting of the second lever about the second fixed pivot in direct mechanical repsonse to the movement of the first lever first portion by a sheet moving downstream of the nip.

Abstract: An apparatus for destacking a stack of flexible flat structures, especially unfolded or folded sheets or printed products, comprising a stack support composed of revolving driven rolls and contact rails disposed above the stack support for defining a stack support surface. A separation device is arranged below the stack support and revolvingly driven in cycle or rhythm with the arriving rolls in order to continuously downwardly remove an edge of the momentarily lowermost flat structure between the arriving rolls. A conveyor device engages below the stack support for the removal of the printed products which have arrived beneath the stack support. The stack support surface is arranged to be at an inclination or directed obliquely at one of its corners towards the direction of movement of the rolls.

Abstract: A document handling and counting device in which documents arranged in a stack within an infeed tray are bottom-fed through a document stripping and separating means so as to be fed at spaced intervals and in a one-at-a-time fashion through a document processing stage whereupon the documents are then restacked in their original order. Document stripping and separating is performed by cooperating stripper means and feed means imparting counteracting forces upon documents fed therebetween.

Abstract: A cardboard sheet-feeding device used for feeding corrugated cardboard one sheet after another, such as to an automatic box-making machine. The cardboard-feeding device has a frictional conveyor belt driven in one direction, a control plate located above the frictional conveyor belt, and a positioning device for stacking sheets of cardboard upon the frictional conveyor belt behind the control plate, whereby upon movement of the frictional conveyor belt the bottom most cardboard sheet in the stack stacked on the friction conveyor belt is fed forward, slipping under the control plate. There is also provided a cardboard-holding device which is supported and driven by a pair of endless movable loops, the loops being driven via a sliding clutch, and which exerts pressure on the stack of sheets to correct warping of the sheets regardless of the height of the stack.

Abstract: A discriminator supporting assembly for a discriminator plate which is mounted above a conveyor belt course. The assembly includes a lengthwise adjustment screw for moving the discriminator plate lengthwise of the conveyor belt toward and away from patter members, an upright adjustment screw for moving the discriminator plate toward and away from the conveyor belt course, and a plate swinging adjustment screw for swinging the discriminator plate with relation to the plane of the conveyor belt course.

Abstract: A method and apparatus are disclosed for automatically delivering discrete pieces of stationery, particularly envelopes, serially at a controlled rate from a stack of stationery into a programmable printing machine such as an automatic or a manual typewriter. Simultaneously, discrete pieces of stationery which have been printed by the typewriter are automatically fed back into the stack at the same rate at which they were delivered therefrom. The speed of operation of this automatic stationery handling apparatus is automatically coordinated to the speed at which discrete pieces of stationary can be processed by the programmable typewriter.

Abstract: Apparatus for feeding and transporting blanks of corrugated paperboard and the like is disclosed wherein a stack of blanks is received on a blank feeding station having a first belt-over-roller conveyor which cooperates with an angularly inclined control gate of a gate assembly to feed blanks from the bottom of the stack beneath the control gate and effect shingling of the blanks, whereafter the blanks are transported to a receiving station such as the feed hopper of a printing press or the like. The control gate is adjustable to vary the shingling relationship of the blanks fed from the bottom of the stack and has a low friction surface thereon facilitating optimum operation.

Abstract: A sheet delivery apparatus includes a sheet delivering revolving member in abutting relationship with a sheet separating member, which members cooperate to deliver the lowermost one of sheets in a stack through a nip therebetween while maintaining the forward edge face of the sheets in an inclined position.

Abstract: Apparatus for feeding, separating, counting and stacking documents at high speed. Documents are stacked in the infeed conveyor and are bottom fed preferably by closed loop belts and an eccentric wheel which continuously jogs the stack. Drive rollers support the closed loop belts which serve to feed the bottom-most documents beneath cooperative stripper means which assures the feeding of only one document at a time towards acceleration rollers and a cooperating platen roller for accelerating documents fed therebetween to provide a gap between succeeding documents to enable a sensor to accurately count the documents. Counted documents are driven from an outfeed location into a stacker having a floor positioned beneath the outfeed location by a distance selected to prevent incoming documents from being interleaved in their improper order and from interfering with the documents being fed into the stacker. The platen roller also serves as a backing roller for endorsing means.

Abstract: A device for separating, scanning and sorting publications bearing the Universal Product Code. The device comprises a flat bed extending horizontally but inclined to one side, along which move parallel belts at high speed. A loading bit or hopper at one end receives magazines stacked in random sequence. These are separated by means of the synchronized movement of stack lifting bars at the bottom of the bin and movable separating fingers downstream. The fingers drop on each magazine as it begins to pass beneath them, and the stack lifters are simultaneously raised to lift the remaining magazines off the belts. The fingers are lifted a short time after the trailing edge of the magazine passes them to ensure a gap between adjacent magazines. The stack lifters to drop as the trailing edge passes the fingers, without a time delay.

Abstract: Apparatus for removing sheets from a stack of sheets and feeding the sheets one at a time to an output flow-path, said apparatus comprising a feeding nip formed by a frictional drive adapted to engage and propel a sheet in a forward direction in combination with a pressure member adapted to press a sheet against the drive means, a stripper adapted to restrain plural sheets from being fed along the flow-path and a traction nip comprising a roller disposed downstream of the feeding nip, the roller being biased to obstruct said flow-path but being movable by the passage of a sheet and adapted, upon such movement, to open the feeding nip.

Abstract: This disclosure relates to a machine for dispensing a predetermined number of banknotes in bundle form with the banknotes being removed from a stack in sequence and there being counting apparatus for counting banknotes passing along a flow-path and a double note detector for detecting the simultaneous passage of plural banknotes along the same flow-path. The banknotes, as they are dispensed, are collected in a collecting compartment and if the proper number is dispensed without double notes being detected, the collected banknotes are delivered to a customer. However, if double banknotes are detected or there is an error in counting, the dispensing of notes from the stack ceases and all notes in the collecting department are diverted into a storage compartment and the machine is recycled.

Abstract: A sheet feeding device adapted for feeding sheets individually from the bottom of a stack of sheets. An air floatation stacking tray is provided to minimize sheet-to-tray and inter-sheet friction to assure positive feeding of individual sheets from the bottom of the stack irrespective of stack height.

Abstract: A facsimile transceiver apparatus is described which includes means for advancing a document to a station at which location the document is line scanned by a laser light beam. A video signal thus formed is transmitted to a remote facsimile apparatus for reproduction of the document. The transceiver further includes an electrostatographic printing station at which station a latent electrostatic image is formed by line scanning a laser light beam over a uniformly charged photoreceptor surface. A means for line scanning at the document scanning station and at the photoreceptor surface includes a laser light source and means for alternatively sweeping the laser light beam across the document at the scanning station or across a charged image retention surface at the printing station. Means are also described for enhancing document feed, resolution, and speed of reproduction.

Abstract: The end of a movable belt adjoins a supporting surface for removing a bottom sheet from a stack of sheets sitting on the supporting surface. A wall structure over the conveyor belt prevents those sheets other than the bottom sheet from being removed from the stack. The sheet supporting surface may be a transparent plate with a document reader located thereunder, thus allowing sheets containing information thereon to be placed face down on the glass plate and optically read automatically before removal by the movable belt.

Abstract: Sheet separating apparatus for separating the bottom sheet from a sheet stack while at the same time adapted to adjust to any non-uniformity in thickness of portions of the sheet as each sheet enters a nip between a friction member and a sheet conveyor of substantial breadth. The sheet separating apparatus includes a broad friction member which is biased toward engagement with a broad, load distributing conveyor which transports the sheet material. The friction member is supported in such a manner that it can tilt about an axis which is parallel to the sheet path, and thus adjust itself in accordance with any variations in thickness of that portion of the sheet which the conveyor encounters as it enters the nip between the friction member and the conveyor. This arrangement causes a uniform pressure to be generated by the various portions of the friction member upon the various portions of the conveyor, and thereby to have a more uniform effect upon the portions of the sheets as they enter the nip.

Abstract: For feeding blanks into, for example, a carton folding machine, blank feeder apparatus that includes a frame, blank support members having rear and intermediate portions that are forwardly and upwardly inclined and front portions that extend generally horizontally; a magazine for retaining the blanks in generally vertical stacked relationship on the support members, including hold down assemblies for resiliently urging the blank rear edge portions downwardly, and front escape bars; kicker assemblies for feeding the lowermost blank in the magazine forwardly, including endless chains having wedges thereon for lifting the adjacent part of the blank and a ledge adjacent the wedge to engage the blank rear edge to positively move the blank; feed rolls adjacent the front of the magazine to aid in moving the lowermost blank forwardly; and solenoid operated clutch mechanism for starting and stopping the drive to the feed rolls and the kicker assemblies.

Abstract: A belt type separator contacts a stack to feed a sheet to a retard nip formed between the belt and a retard member. The belt is supported by a first pulley downstream of the stack and a second pulley adjacent the stack which is pivotable relative to the first pulley. Frictional resistance encountered by the belt at the nip will cause the normal force with which the belt bears against the stack to increase. Oppositely skewed rolls are used to tension sheets fed to a sheet aligning abutment. When the separator is positioned below the stack, a pivotable lever may be used to hold the stack against the separator. The pressing effect of the lever may be overridden upon an increase of the force with which the separator engages the stack.