Abstract: A multiple product folder in a high speed rotary web printing machine for the production of signatures with various folds has a plurality of various operating cylinders, such as a pair of web cutting cylinders, a signature collecting cylinder, signature transfer and folding cylinders for one transversal and for a second parallel fold and signature delivering cylinders, wherein certain cylinders are driven by gear trains for accomplishing more than one slow-down speed, which gear trains have shiftable couplings for changing the speed of the transfer cylinders from a full speed to a slow-down speed according to the requirements of forwarding and delivering of certain signatures, whereas a shifting from a slow-down to a full speed can be performed for a certain folding action and the slow-down delivery yet can be maintained.

Abstract: A method for changing the direction of travel of a sheet includes the steps of providing a pocket, guiding a sheet traveling in a first direction into the pocket, and providing a fluid stream in the pocket to bias the sheet in a substantially opposite direction, thereby reversing the direction of travel of the sheet.

Abstract: This invention is directed to a collator and, in particular, a removable bin system in the collator. The purpose of this removable bin system is to make it possible to more, fully, utilize the printer and the collator. Prior to this invention, the printer and the collator could not operate after the collator bins had received the printed material. It was necessary to empty the collator bins before using the printer and the collator for another run of material. With this invention it is possible to more, fully, utilize the printer and the collator for printing and sorting the printed material.

Abstract: My pneumatically sustained, flexible exercise surface-and-platform, which I call a "Trampol-air," initially designed for foot-ease along with all the benefits of exercising in any jogging-like manner on a flexing-resilient mini-trampoline-like surface, consists of a flat, flexible exercise surface supported by pneumatic tubing located underneath the outer edge (and, optionally, beneath the surface across the center area) of the exercise surface. The surface consists of a sheet of woven polypropoline (or other suitable material) which covers the pneumatic tubing and fastens at the back of the exercise platform's base (which extends out several inches beyond the exercise surface). The base may be made of a sturdy substance, such as one-inch thick plywood, or of thinner metal with a one-inch upward-curving circular lip around the edge. On the underneath-area of the base there is an access hole (or doors) large enough for putting air into the pneumatic tubing.

Abstract: A protective cover for a video disc comprises an enclosure having an edge opening in communication with a record enclosing cavity and a record retaining member slidably mounted within the cavity for to-and-fro movement therein. The record retaining member includes a spine portion and an annular portion having an opening. The opening in the annular portion substantially encircles an enclosed record such that to-and-fro movement of the record retaining member is transmitted to the enclosed record. The spine portion substantially extends into the edge opening of the enclosure when it is fully inserted therein. The spine portion has a record extracting member receiving hole that is accessible in a direction substantially parallel to the direction of the to-and-fro movement of the record retaining member.

Abstract: A device for sealing the space between two surfaces comprising an elongated body portion made of a flexible, resilient material such as rubber. The body portion engages in a recess in one of said surfaces. The sealing device further includes at least two rigid plate members seating in a recess in the body portion and having a portion projecting therefrom defining a channel and a sealing member mounted in said channel and projecting therefrom to engage the other of the sealing surfaces to be sealed.

Abstract: An improved seal for closing the space between a pipe and the wall of an opening through which it passes, using a linear extrusion of elastomeric material, of predetermined length to form a gasket. The extrusion has a hollow, pear-shaped head formed integrally with a T-shaped anchoring flange. It is curled into the form of a right cylinder, and its mating ends are vulcanized together. The pear-shaped portion is deflected radially inwardly and the T-shaped anchoring flange outwardly, the latter being then embedded in concrete used to wall the opening for the pipe. The pear-shaped portion is free in space and provides a pneumatic cushion for the pipe.

Abstract: A wheel truck for a steerable platform such as a skateboard. The wheel truck includes a base frame mounted below the platform and carrying a vertical support shaft and downwardly inclined steering shaft. An axletree upon which wheels are mounted is carried from the frame by resilient support means. The support means includes pairs of elastomeric bushings mounted about both of the support and steering shafts. The bushings are seated in sockets formed in the axletree for positioning the latter with respect to the frame. Fasteners are provided to secure the bushings on the shaft. The fasteners are adapted to change the steering response or to vary angular orientation of the axletree for purposes of changing the turning radius.

Abstract: A mobile extra display cart is described. The cart includes a plurality of vertically adjustable shelves which slide in two vertical tracks located on the back wall of the cart. The plurality of vertically adjustable shelves are designed to pivot upwardly against the back of the cart when the stacked products are removed from the respective shelves. To facilitate the use of the mobile extra display cart as a delivery cart for the stacked products, each respective shelf is molded from plastic and contains an upper and lower lip to keep the stacked products from sliding off the shelves. In addition, there is provided a top cap which is adjustable in the vertical tracks and is hinged at the back of the cart. The top cap is designed to pivot downwardly covering the top layer of the stacked products and in combination with a pair of straps joined together in a Y configuration, the cap is maintained in compression with the stacked products to prevent them from falling out from between the shelves.

Abstract: A dirigible wheel of an automotive vehicle has its steering axis on the vertical center line of the wheel, and a brake disc is supported with annular braking surfaces in vertical planes adjacent to the center line and are engaged by caliper type brake shoes.

Abstract: An elongated horizontal channel member is mounted by means of a dual spring shock absorber in transverse position on one end of a towing vehicle. A pair of horizontal support arms have a first pair of corresponding ends pivotally mounted on the channel member for shifting along the channel member and swinging relative to the channel member about upstanding axes shiftable along the channel member with the first pair of arm ends between first outwardly convergent positions and second substantially aligned positions generally paralleling the channel member with the first pair of arm ends disposed remote from each other and the second other pair of arm ends disposed adjacent each other.

Abstract: A passive three-point lap and shoulder belt system has the outboard ends of the lap and shoulder belts mounted on the vehicle body door respectively adjacent the hip and shoulder of the occupant. A retractor mounted on the body generally adjacent the inboard hip of the occupant winds a control belt which is connected with the lap and shoulder belts at the juncture of their inboard ends to establish the lap and shoulder belts in their occupant restraining positions when the door is closed. A door mounted belt stiffener is encased within the lap belt and includes a plurality of stacked abutting elements normally hingedly movable relative one another to allow the lap belt to fall limp across the occupant lap.

Abstract: A protective frame for a vehicle for protecting the operator in the event of vehicle rollover. A protective frame having tubular uprights with a plurality of reinforcing members of variable length extending from the base upwardly internally of said tubular uprights to stiffen the frame.

Abstract: An apparatus with a holder body forming a flat surface with an angular support member to hold a printed publication at a convenient angle. The publication maintains intimate contact with the body being superimposed with a transparent fixably attached retaining plate. The retaining plate being vertically adjustable and removable with hairlines inscribed into the parent material extending horizontally and vertically. An opaque locator body is slideably attached to the retainer plate with an overlapping hem being horizontally movable with a rectangular window positioned in the center. The window displays the transparent retaining plate with the exposed hairline and the positioned indica. The holder body is supported on the back with a single leg at an oblique angle to the base and diagonally to the body being rotatable and folding against the back of the holder.

Abstract: The combination of a door stop and releasable latching device, whereby a keeper member is mounted to a conventional door and positioned thereon to engage a stationary door stop having a latching mechanism coupled therewith, wherein the door stop comprises a main supporting body to be mounted in a fixed position relative to the keeper member, the fixed body having a slidable bumper cover which is spring biased in an outwardly direction to engage the head of the keeper, and wherein a latching lever is pivotally mounted to the fixed body and arranged to be actuated by the movement of the slidable bumper cover for releasable latching over the head of the keeper when the door is positioned in an open mode.

Abstract: A door latch bolt locking device for use with a latch bolt having a transverse groove or kerf in its top surface and which will positively prevent the withdrawal of the latch bolt. The device comprises a slideable member adapted to be substantially flush with the intersecting edge surface of the door and the inner surface of the door. The slideable member will have a first portion which will be substantially flush with the inner surface of the door and an integral tongue portion at a right angle to the flat portion and adapted to be substantially flush with the edge surface of the door. The locking device is also provided with means for allowing the slideable member to be moved through a limited vertical distance in a substantially flush relationship with the door surfaces so that the tongue member can move into and out of the kerf provided in the latch bolt to thereby lock the door.

Abstract: An implement of tableware adapted to work in conjunction with conventional silverwave to clear all food from the plate. The tableware implement comprises a bowl head having a front scooped, pushing surface, peripherally defined by variously contoured scraping edges, and a handle attached to the rear of the bowl head. The variously contoured edges serve as scrapers, at least one edge is flat to maximally contact the surface of a flat plate, and at least one other edge is curved to maximally conform to the rounded bottom surface of cups and bowls.

Abstract: A load-carrying net comprises a network of interwoven belts provided with suspension rings for use in suspending the net from suspension tackle of an aircraft, particularly a helicopter. The net has a central load-supporting portion and opposed pairs of arms which are provided with the suspension rings and which radiate outwardly from the central portion. At least some load-carrying ones of the belts are each secured at their ends in an opposed pair of the arms and extend freely through the central portion so that they can make a sliding adjustment in the central portion for load equalization purposes.

Abstract: An integrally formed bottle carrier with a plurality of spaced split collars in which bottles can be locked into and supported by their neck-shoulders and removed, each collar supported by an individual frame interconnected to an adjoining frame by a ribbed member, and a plurality of flexible tabs attached to the sides of the bottle carrier to permit machine loading of bottles into the bottle carrier.

Abstract: In the art of supporting a glass sheet by self-closing metal tongs during the thermal treatment of the glass sheet, wherein the glass sheet is gripped between opposing glass gripping members of said self-closing tongs, the improvement comprising engaging said glass sheet surfaces with glass engaging members composed of a tungsten nickel composite essentially free of cobalt and iron during the thermal treatment.

Abstract: A pair of deflector segments are telescopingly interconnected to provide an air deflector of adjustable length. Each deflector segment includes a sloping forwardly facing portion, a relatively flat top, a vertical rear wall, and closed outer ends. The combined segments are fittingly received onto the top rear edge portion of the truck car and, after adjustment to accommodate the cab width, they are fixedly secured to the cab surface.

Abstract: A storage arrangement adapted to mobile homes and the like is disclosed comprised of a storage drawer which is supported beneath the under frame of such mobile home by means of a pair of support rails having a plurality of rollers mounted thereon which mate with corresponding roller tracks disposed in recesses formed in the sidewall of the drawer such that the storage drawer may be easily withdrawn from beneath the mobile home for access. The roller track extends about the entire periphery of the drawer so that the drawer may be installed with either its long sides or short sides extending into the clearance space. The drawer structure is made up of overlapping rolled aluminum panels which are adjustable in the degree of overlap such as to render the drawer depth adjustable for adaptation to differing ground clearances.

Abstract: An accessory mountable along a front of an automotive vehicle, so as to deflect air upwardly, and forming a curtain of air forwardly of the windshield, so that dust, bugs, rain or snow is lifted over the top of the vehicle, instead of being deposited upon the windshield; the accessory including a laterally extending inclined baffle, for thrusting the air upwardly, and also including a louver thereabove, which is pivoted by the force of air, in order to open a throat, and thrust the air at a desired angle and at a desired volume.

Abstract: A tablet arm attachment for a chair includes brackets with U-shaped channels and outwardly extending flanges to clamp the tablet arm to a support rod from which the tablet arm to a support rod from which the tablet arm is pivoted. A molded plastic bearing insert has a U-shaped channel portion complementary to the channel portion of the brackets to interfit therewith. A flap on the bearing insert permits the bearing insert to be folded over the support rod and provides a smooth, quiet, pivotal motion of the tablet arm which will not scratch the tablet arm.

Abstract: A spring loaded frame pivotably mounted in the backrest frame is easily unlocked by light pressure applied to a lever disposed at the side of the seat proper whereby the pressure of the seated person's back pressing against the backrest portion urges the pivotable frame to a new position, in which the pressure applied to the dorsal and lumbar regions of his or her back are substantially equal, and in which it is lockable.

Abstract: Mechanism for retracting a vehicle seat belt and locking the belt against extension includes a track mounted on the vehicle body and a belt carriage mounted on the track for movement in the belt extending and retracting directions. A locking pawl is mounted on the belt carriage and is selectively actuatable to a locked position engaging teeth on the track to lock the belt carriage against belt extending movement. A spring biases the carriage in the belt retracting direction. An actuating element extends alongside the track and is mounted for rotary movement into engagement with the locking pawl to move the locking pawl to the locked position. A pendulum supports the actuating element in a normal position and rotates the actuating element in response to a sensed condition of vehicle deceleration to actuate the locking means and thereby lock the carriage against belt extending movement along the track.

Abstract: A holding device for a chain is proposed, particularly for a chain associated with a coal cutter and having links located in two mutually transverse planes. The holding device has a chain block having two portions formed with a recess and bounding a slot. The recess is dimensioned for receiving an end portion of one of the chain links which is located in one of the planes, and the slot is dimensioned for receiving the other chain link which is located in the other of the planes. The recess may be U-shaped, and the slot extends in the direction of elongation of the chain block. Supporting portions may be provided for supporting one of the chain links which is located in a horizontal plane. Means may be provided for fastening the horizontal chain link to the supporting portions. Two additional such portions may be provided in the same chain block, spaced from the first two portions in the direction of elongation of the chain block.

Abstract: A mineral mining installation has a longwall conveyor provided with a guide at the face-side thereof. A drive frame is provided at each end of the conveyor, and a plough is movable along the guide to win material from the longwall face. The plough is driven by a chain passing round a pair of end sprockets associated with the drive frames. The plough is constituted by a pair of plough bodies joined together by an intermediate member pivotally connected therebetween. Each of the plough bodies is provided with cutter bits and the intermediate member may also have cutter bits. The two ends of the plough driving chain are connected to the intermediate member, and the plough is of sufficient length to enable material to be won at least as far as each end sprocket.

Abstract: A drive frame for the drive assembly of a mining installation has a pair of side plates and a connector. The mining installation is of the type having a winning machine and a conveyor. The connector is fastened to one of the side plates of the drive frame and constitutes means for mounting respective drive units for the winning machine and the conveyor. The connector is constituted by a respective mounting plate for each of the drive units. The two mounting plates are connected to one another in a tension-proof manner. The connector is provided with an annular collar which mates with an aperture in said one side plate to support and align the connector.

Abstract: A continuous mining machine has a rotatable cutter head which is slidably mounted on a feed bar which in turn is slidably mounted on a support bar carried by a movable carrier. A cable extends over a sheave which is mounted on one end of the feed bar where one end of the cable is connected to the cutter head and the other end fixed with respect to the support bar. Means are provided for sliding the feed bar longitudinally with respect to the support bar whereby the cutter head will slide along the feed bar at twice the velocity that the feed bar slides with respect to the support bar.

Abstract: There is disclosed a dual-circuit brake-force distributor wherein the control force of one circuit is transmitted to the other circuit through a floating intermediate piston. In order to achieve a highly sensitive control, the intermediate piston is provided with a large cross-sectional area. In the event of failure of the one circuit, the intermediate piston will become blocked and the control force will be transmitted through an auxiliary piston having a smaller cross-sectional area. By this arrangement upon failure of the one circuit a sufficient amount of braking pressure can still build up in the other intact braking circuit.

Abstract: A hydraulic brake system with pilot actuation for the braking of a vehicle is disclosed. The brake system includes a service brake valve, a park brake valve and a retard brake valve. The hydraulic brake system further includes an additional brake valve including two separate spools slidably disposed within a valve body, each being responsive to pilot pressure from the above-disclosed valves. The first of the spools in the additional brake valve communicates pilot pressure from a fluid pressure source to the rear brakes of the vehicle and from the rear brakes to a fluid pressure reservoir or sump. The second spool communicates fluid from the fluid pressure source to the front brakes and from the front brakes to the fluid pressure reservoir. The first spool of the additional brake valve is also independently responsive to pilot pressure from at least one of the above disclosed valves which responsiveness allows for a variance in braking force between the front and rear brakes.

Abstract: A valve for use in vehicle hydraulic brake systems for the purpose of limiting the rear wheel brake pressure relative to the front wheel brake pressure in order to reduce the potential for premature rear wheel lock. The valve includes a proportioning piston which operates to limit the fluid pressure delivered to the rear wheel brakes and an inertia member which senses changes in vehicle loading. When a vehicle is fully loaded, the inertia member remains in a position where it will disable the proportioning piston in its open position and, consequently, the rear wheel brake pressure will be equal to the front wheel brake pressure. When the same vehicle is unloaded, the inertia member moves in response to deceleration to a position where it will not disable the proportioning piston so that the rear wheel brake pressure will be reduced relative to the front wheel brake pressure.

Abstract: A running pad for an endless track is disclosed, including resilient retaining projections which extend away from opposite sides of the running pad and are adapted to enter into locking engagement, at their free ends, in recesses formed in the respective chain links. The retaining projections are formed by the ends of a unitary resilient plate that extends through said running pad and is designed to yield elastically in a direction toward and away from the recesses of the chain link in order to allow simple and quick assembly of the running pad at the chain link in a direction vertical to the tread surface without the need of disassembly of the chain link.

Abstract: A track assembly comprises a pair of laterally spaced links releasably secured to each track shoe thereof. A drive lug extends between the links and a rail is disposed on each link. A plurality of bolts provide common fasteners for releasably securing the links, track shoe, drive lug and rails together. A pair of such bolts are preferably disposed on each lateral side of each link to increase the lateral stability of the links and overall structure integrity of the track assembly.

Abstract: A cover plate to be positioned over an electrical receptacle and fastened to it and which plate includes a main plate with a pair of openings in registry with the electrical sockets of the receptacle and a pivotal cap normally in covering relation of each of the openings and energized sockets, the caps being pivotally connected to the main plate and including a ferrous metal keeper in blocking relation of pivotal movement of each of the caps and in a slot; the keeper is responsive to magnetic forces of attraction to slide in the slot out of blocking relation of pivotal movement of the cap so that a magnet can be used as a key to gain access to the energized receptacle.

Abstract: A grounding device includes an internally threaded collar having an end insulator bushing and provided in its outer peripheral face with a radial coupling socket which has regularly circumferentially spaced longitudinal grooves and a tapped axial bore in its base. A wire clamp includes an elongated base provided at an end thereof with a projecting polygonal shank which slideably engages the socket and grooves to permit the selective angular adjustment of and the angular locking of the wire clamp to the collar. A locking and fastening screw engages a bore coaxially formed in the shank and the tapped bore in the socket base. The wire clamp includes a stationary jaw integrally formed with the base and a screw advanced movable jaw.

Abstract: A high voltage cable coupler for releasably connecting together one or more high voltage cables having a concentrically located insulated conductor bounded by a semiconductive and/or metallic shield. The cable housing is provided to be in two moisture-proof halves, one-half for supporting the female connector assembly and the other half for supporting the male connector assembly. Each cable terminus includes a cable termination adaptor which provides a stress relief cone as well as insulative means in combination with an insulator tube assembly within which the conductor connector is secured. This combination also provides for proper positioning and support of the adaptor assembly within the housing as well as providing definitive means for the relationship separation of the termination of the cable shielding and the conductor connector which has an influence on the resultant creepage path.

Abstract: An electrical connector in which two rows of resilient contacts are mounted in a connector housing on opposite sides of a slot which is adapted to receive a printed circuit board or similar electrical component therein. The end portion of the spring contacting section of each contact is reversely bent in a direction away from the slot. A vertically movable contact shifting element is disposed between the spring contacting sections and the reversely bent end portions of the contacts in each row of contacts. A cam actuator is operated to move the contact shifting elements upwardly against the reverse bent end portions of the contacts thereby deflecting the spring contacting sections away from the slot so that a printed circuit board may be inserted therein with zero insertion force. Means is also disclosed for providing a wiping action between the contacts and the traces on the printed circuit board when the contacts are actuated to engage the board.

Abstract: A female guidance and polarizing means for either the male or female parts of a separable electrical connector which carry mating eletrical contacts. The polarizing and guide means is mounted in predetermined positions on either the male or female connector parts. The removable bushing has a portion which is keyed to the male polarizing pin to permit the connector parts to be mated only when the correct parts are presented to each other. The removable female polarizing guide bushing is made of resilient plastic material having a keyway, a flange, a polygonal body section, and a plurality of fingers with shoulders for engagement with the connector parts. The bushing is inserted into a bore in the connector body. The bore comprises a series of three axially aligned apertures. The fingers snap into one of these apertures and the bushing is thereby retained from moving longitudinally in one direction. The flange fits into an aperture which has a diameter greater than that of the flange.

Abstract: The end of a glass fibre of the graded or at least stepped, index type, or in the case of a clad fibre, the end of its core, is etched with an etchant which varies in etching power according to the composition, and thus in a graded or stepped - index fibre according to the index, of the fibre - core material, thereby producing at the end of the fibre a recess or "well" whose depth increases from the edge towards the axis of the fibre.

Abstract: An aperture stop control device for a zoom lens system includes a variable aperture stop, a first sensor for determining the diameter of the aperture stop and providing a first electrical signal representative of the diameter of the aperture stop means and a second sensor for generating a second electrical signal indicative of a designated F number. A signal generator provides a third electrical signal indicative of the focal length of the zoom lens system. A computing circuit computes an output electrical signal as a function of the second and third electrical signals to control the diameter of the aperture stop for automatically maintaining a designated F number during a zooming operation.

Abstract: A zoom lens system comprising from front to rear a first lens group of negative power and a second lens group of positive power with the axial separation therebetween being variable for zooming purposes. The first lens group is provided with a non-spherical surface to achieve minimization of the overall dimensions of the complete system without causing any decrease in the extent to which the corrections of various aberrations are maintained throughout the zooming range irrespective of a great increase in the photographable range extended toward the wide angle side.

Abstract: An adjusting device for rearview mirrors of vehicles for covering rearward and lateral traffic conditions. Mounted off-center on opposite sides in a mirror housing are a mirror plate and a controllable adjustment device by which the mirror plate is simultaneously pivotable about vertical and horizontal axes. In a rest position the mirror plate rests against stops in predetermined lateral and vertical positions.

Abstract: A device and method are disclosed for measuring the curvature of the cornea of the human eye. The device utilizes a continuous, curved surface plate positioned in front of the eye and having a telescope extending through the surface plate such that its optical axis is aligned with the eye. Several object points are generated on the surface plate within the field of vision of the eye and are formed also on the image plane of the eye. Detection devices, located within the telescope measure the positions of such image points in relation to the optical axis. The radius of curvature of the cornea can be determined from this measurement.

Abstract: A film loop size control is described for use in a camera in which the film s advanced intermittently past an image recording station by a first drive means and advanced continuously past a sound recording station by a second drive means. A detector which senses the size of the film loop between the image recording station and the sound recording station causes a control means to actuate only the second drive means whenever the detector senses a slack film loop when the film is stationary. The second drive means then advances the film past the sound recording station to remove the slack from the film loop. When the detector senses an absence of slack in the film, the control means de-actuates the second drive means. A switch is included which is adapted to be actuated when the film slack has been reduced for actuating both the first and the second drive means for advancing the film past the image recording station and the sound recording station.

Abstract: A microfilm reader includes a vertical rectangular projection screen surrounded by a rectangular frame. A cursor mechanism is separably provided which includes a vertical rail extending along a side edge of the screen between the frame top and bottom legs and slidably frictionally engaging a support member to which a cursor member is swingably mounted for angular adjustment in a plane parallel to the screen. The cursor member is releasably frictionally retained in its preset angular position and the support member is releasably frictionally retained in its preset vertical position. Cam means including a rotatable or slidable knob angularly adjusts the cursor member or the cursor member is directly turned by a knob attached to a pivot secured to the cursor member. The rail may be replaced by a side wall of the reader which is formed of magnetic material and the support member may carry a permanent magnet slidably securing it to the side wall.

Abstract: An exposure control circuit of the type adapted to produce an exposure termination signal after a time interval related to a time integral of light intensity includes general purpose lag compensation responsive to the absolute change in light intensity from the beginning to the end of exposure measurement for adjusting the time interval, whereby lag compensation is provided in ambient, flash, or fill-flash modes without the need for external mode switches.

Abstract: Apparatus for use in retouching both positive and negative photographic prints of various sizes. The apparatus includes a flat base member that is capable of being seated upon a desk or the like and a working board pivotally mounted upon the base at one end thereof by means of an adjustable slide mechanism whereby both the vertical and horizontal relationship of the board in reference to the base may be conveniently adjusted. An illuminated vibratory disc is recessed into the working surface of the board with the top surface of the disc being flush with the working surface of the board thereby allowing a photographic print having a larger surface area than that of the disc to be processed thereon.

Abstract: An optical distortion device which can make a contact copy of a photographic film image with one dimension of the copy lengthened or shortened while the perpendicular dimension is unchanged is comprised of a pair of cylindrical motor driven rollers, at least one of which can be driven at a very low speed. The axes of the rollers are disposed parallel to each other and to a narrow slit through which a beam of light is directed. A copy sheet such as a photographic negative and a sheet of photosensitive material are pressed into intimate contact as they pass over the slit by a jet of positive air pressure and each sheet is held to the circumference of a respective roller by negative air pressure selectively supplied to a plurality of grooves in the surface of the roller.