US3588106A

US3588106A - Sheet-feeding apparatus

Info

Publication number: US3588106A
Application number: US801014A
Authority: US
Inventors: Elmer L Csaba; Edward W Engel
Original assignee: SCM Corp
Current assignee: SCM Corp
Priority date: 1969-02-20
Filing date: 1969-02-20
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28
Also published as: CA927416A

Abstract

A PHOTOCOPYING MACHINE HAS A STORAGE COMPARTMENT WHICH IS COVERED BY A LID AND CONTAINS A STACK OF COPY PAPER SHEETS LATERALLY CONFINED BETWEEN GUIDE RAILS IN A FEEDING POSITION. ROTATABLY DRIVEN FEED ROLLERS ADVANCE THE TOPMOST SHEET FORWARDLY FROM THE FEEDING POSITION TOWARD AN EXIT THROAT, AND THE TOPMOST SHEET IS SEPARATED FROM THE REMAINDER OF THE STACK BY CORNER SEPARATORS ENGAGING THE FORWARD CORNERS OF THE STACK. FROM THE STACK, THE SHEET MOVES THROUGH THE EXIT THROAT WHICH GUIDES THE INCOMING SHEET INTO THE NIP OF A PAIR OF ROTATING ROLLERS WHICH REMOVE THE SHEET FROM THE COMPARTMENT FOR FURTHER PROCESSING. TO INSERT A FRESH STACK OF SHEETS INTO THE COMPARTMENT, THE FEED ROLLERS AND THE CORNER SEPARATORS ARE SUPPORTED FOR GENERALLY VERTICAL MOVEMENT AND MECHANICALLY CONNECTED TO THE LID SO AS TO MOVE UPWARDLY FROM THE FEEDING POSITION UPON MOVEMENT OF THE LID TO UNCOVER THE COMPARTMENT. THE FORWARD END OF THE STACK IS ALIGNED WITH THE CORNER SEPARATORS BY A PIVOTALLY SUPPORTED STOP MEMBER WHICH IS MECHANICALLY CONNECTED TO THE LID AND PIVOTALLY MOVED INTO AN UPRIGHT POSITION FOR ENGAGEMENT BY THE STACK UPON THE UNCOVERING MOVEMENT OF THE LID. AFTER THE STACK IS PROPERLY INSERTED, THE LID IS MOVED TO COVER THE COMPARTMENT AND MOVES THE STOP MEMBER FROM THE UPRIGHT POSITION AND MOVES THE SHEET ADVANCING MEANS AND THE CORNER SEPARATORS ONTO THE TOPMOST SHEET OF THE STACK.

Description

United States Patent [72] Inventors ElmerL.Csaba Highland Park;

Edward W. Engel, Northbrook, 11]. [2|] ApplNo 801,014 [22] Filed Feb. 20, 1969 [45] Patented June 28, 1971 [73] Assignee SCM Corporation New York, N.Y.

[54] SHEET-FEEDING APPARATUS 12 Claims, 6 Drawing Figs.

11in "nun" Primary Examiner]oseph Wegbreit Attorneys-Gerald S. Schur and Keith D. Moore ABSTRACT: A photocopying machine has a storage compartment which is covered by a lid and contains a stack of copy paper sheets laterally confined between guide rails in a feeding position. Rotatably driven feed rollers advance the topmost sheet forwardly from the feeding position toward an exit throat, and the topmost sheet is separated from the remainder of the stack by comer separators engaging the forward comers of the stack. From the stack, the sheet moves through the exit throat which guides the incoming sheet into the nip of a pair of rotating rollers which remove the sheet from the compartment for further processing. To insert a fresh stack of sheets into the compartment, the feed rollers and the comer separators are supported for generally vertical movement and mechanically connected to the lid so as to move upwardly from the feeding position upon movement of the lid to uncover the compartment. The forward end of the stack is aligned with the corner separators by a pivotally supported stop member which is mechanically connected to the lid and pivotally moved into an upright position for engagement by the stack upon the uncovering movement of the lid. After the stack is properly inserted, the lid is moved to cover the compartment and moves the stop member from the upright position and moves the sheet advancing means and the corner separators onto the topmost sheet of the stack.

PATENTEDJUH28I87I 3586 106 SHEU 1 BF 4 M EDWARD w- ENGEL ELMER L. CSABA wa is SHEET-FEEDING APPARATUS This invention relates to an apparatus for separately advancing a stack of sheets from a feeding position, and more particularly to a photocopying machine having a paper storage compartment containing a sheet-feeding apparatus for separating and advancing-the topmost sheet from the stack and moving it into the nip of a pair of rotating rollers which remove the sheet from the compartment for further processing. The compartment is normally covered with a lid, and to place a stack of paper in the feeding position, the lid must be moved to uncover the compartment and the apparatus must be moved from the feeding position. In addition, the stack must be aligned with the feeding position so that the stack of sheets may be properly engaged by the sheet-feeding apparatus. Finally, the sheet-feeding apparatus is moved into engagement with the properly positioned stack and the compartment is covered by the lid in preparation for subsequent operation.

Accordingly, an object of the present invention is to provide a photocopying machine having a sheet-feeding apparatus which may be easily moved relative to the feeding position to enable a fresh stack of paper to be placed into the storage compartment and aligned with the feeding position for subsequent processing by the photocopying machine.

Another object of the present invention is to provide a forward stop for aligning the forward end of the stack of the copy paper being inserted into the compartment with the feeding position, wherein the forward stop is separate from the apparatus for separating the advancing topmost sheet from the remainder of the stack.

An additional object of the present invention is to provide a forward stop which is movable into an upright position upon lifting of the lid covering the paper storage compartment, but which is moved out of engagement with a stack properly inserted into the compartment upon lowering of the lid.

A further object of the present invention is to provide a sheet-feeding apparatus having sheet-separating means and forward stop means which are separate from each other and independently movable'so as to provide a storage compartment having greater capacity than a sheet-feeding mechanism in which the forward stop and the corner separators are formed integrally.

Still other objects, features and advantages of the present invention will be apparent to those skilled in the art from a reading of the following detailed description of a single embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is fragmentary perspective view of a preferred embodiment of a photocopying machine having a sheet-feeding apparatus according to the present invention, and showing the topmost sheet being advanced forwardly from the stack;

FIG. 2 is a cross-sectional view of the sheet-feeding apparatus taken generally along the lines 2-2 in FIG. 1, illustrating the condition of the apparatus when all of the sheets of paper have been fed from the storage compartment;

FIG. 3 is a view of the sheet-feeding apparatus shown in FIG. 2, illustrating the condition of the sheet-feeding apparatus when the lid is lifted for inserting a stack of paper into the compartment;

FIG. 4 is a cross-sectional view of the sheet-feeding apparatus taken generally along the lines 44 in FIG. 1, showing a stack of copy paper sheets properly inserted into the compartment with the lid in a raised position;

FIG. 5 is a cross-sectional view taken generally along the lines 5-5 in FIG. 4, illustrating the mechanical connections between hingedly connected lid and the feed rollers, the corner separators, and the forward stop;

FIG. 6 is a view of the sheet-feeding apparatus shown in FIG. 4, illustrating the condition of the sheet-feeding apparatus with the stack of sheets properly inserted and the lid covering the compartment.

Referring generally to the figures in the drawings and particularly to FIG. 1, there is shown a photocopying machine,

generally indicated 11, for copying original documents onto sheets of copy paper. Except as indicated below, the machine 11 is generally of the type described in U.S. Pat. No 3,330,179, entitled Automatic Photocopying Machine. The machine 11 includes a housing 13 having an upper storage compartment, generally indicated 15, with an opening, generally indicated 16, which is covered by a lid 17 and contains a stack 19 of copy paper sheets in a feeding position. The

' sheets are advanced separately from the feeding position and through an exit throat, generally indicated at 21, which guides the incoming sheets into the nip of a pair of cooperating

rollers

23, 25. The

rollers

23, 25 are mounted on drive shafts, 27,

29 respectively, which are rotatably driven by suitable means, not shown, to remove the sheets from the storage compartment 15 for further processing in the machine 11. The means for rotatably driving

shafts

27, 29 have been omitted from the description, since they form no part of the present invention and are adequately described in the above-mentioned U.S. Patent.

Inside the housing 13, the stack 19 is supported on a substantially horizontal floor 31 of a tray 33 which is supported between two

sidewalls

35, 37 to form the storage compartment 15. The sheets forming the stack 19 are laterally confined in the feeding position between two

guide rails

39, 41 which are symmetrically opposite and carried by the tray 33. The

guide rails

39, 41 serve to align the stack 19 with the nip of the

rollers

23, 25, and are laterally movable to accommodate sheets of different widths therebetween. The

guide rails

39, 41 may be held in position on the floor 31 of the tray 33 by any suitable means. As more particularly shown in FIGS. 1 and 2, the

guide rails

39, 41 have depending lugs 43 extending downwardly through a lateral slot 45 in the floor 31 with heads 47 on the lower end thereof which engage the floor 31 of the tray 33 in a suitable friction fit.

As shown, the topmost sheet 49 is being advanced forwardly from the stack 19 by sheet-advancing means, generally indicated 51, including a pair of rubber-covered

feed rollers

53, 55 which are fixedly mounted on a rotating shaft 57. The shaft 57 is rotatably driven by the drive shaft 27 through a belt drive, generally indicated by 59, which is located at one end of the

shafts

27, 55. The belt drive 59, as shown, includes a conventional timing pulley belt 61 extending around timing pulleys 63, 65 which are fixedly mounted on the ends of the

shafts

27, 57 respectively, although other suitable belt drives may be used, for example a friction belt drive. The belt 61 is maintained taut and the shaft 57 is supported for generally vertical movement in parallel spaced relation to the shaft 27 by

arms

69, 71 which are pivotally connected to the drive shaft 27. The weight exerted on the stack 19 by the

rollers

53, 55, the shaft 57, and the pulley 65 is generally sufficient to provide the necessary frictional engagement between the rubber-covered

rollers

53, 55 and the topmost sheet 49, so as to enable the rotatably driven

rollers

53, 55 to forwardly advance the sheet 49. Although only a single belt drive 59 is illustrated in the preferred embodiment, it is to be understood that suitable belt drives may be located at both ends of the

shafts

27, 55. In addition, the belt drive 59 could be located at the opposite ends of the

shafts

27, 55 instead of as shown in FIG. 1. Also, additional weights may be suitably placed on the shaft 57 to increase the frictional engagement between the rubber-covered

rollers

53, 55 and the topmost sheet 49.

As the topmost sheet 49 is advanced, the adjacent sheets of the stack 19 move forward due to the frictional contact between the sheets of copy paper. The forward movement of the sheets may be retarded by suitable friction pads 73 placed on the inner sides of the

guide rails

39, 41 in engagement with the sides of the stack 19. To prevent more than one sheet at a time from being fed into the nip of the

rollers

23, 25, separator means, generally indicated at 75, are provided to separate the topmost sheet 49 from the remainder of the stack 19. In the preferred embodiment, the separator means 75 are in the form of

corner separators

77, 79 which are symmetrically opposite and engage the forward corners of the stack 19. The corner separator 77 includes a lip 81 resting on a corner of the topmost sheet 49 and a down-tumed forward portion 83, which is more clearly shown in FIG. 5, engaging the forward end of the stack 19. Since the other comer separator 79, engaging the other forward comer of the stack 19, is similar to comer separator 77, identical reference numerals have been placed on similar portions thereof.

Upon advancement of the topmost sheet 49 by the rotatably driven

feed rollers

53, 55, the lips 81 of the

corner separators

77, 79 hold the forward corners of the sheet 49 and cause them to buckle and bend as shown in P16. 1. As is known, the forward corners continue to bend until the resiliency of the advancing sheet 49 causes the forward comers thereof to move over the lips 81 of the

corner separators

77, 79, thereby separating the topmost sheet 49 from the remainder of the stack 19. Further advancement of the topmost sheet 49 moves it into the exit throat 21 which, in the preferred embodiment, is formed by an upwardly inclined forward portion 85 of the floor 31 in conjunction with a generally horizontal plate 87 which is suitably attached to the tray 33. The converging exit throat 21 guides the incoming sheet 49 into the nip of the rotatably driven

rollers

23, 25 which remove the sheet 47 from the compartment for further processing in the photocopying machine 11.

As the sheets forming the stack 19 are fed from the compartment 15, the stack 19 diminishes and the sheet-advancing means 51 move downwardly, with the shaft 57 being received in

notches

89, 91 formed in the

guide rails

39, 41 respectively. The

comer separators

77, 79 are supported for generally vertical movement so as to maintain engagement with the topmost sheet of the diminishing stack 19. Although the corner separators might be suitably supported for only vertical movement, in the preferred embodiment the corner separators are supported for generally vertical movement in an arcuate path by pivotally mounted

arms

93, 95. The

arms

93, 95 extend along the outer sides of the

guide rails

39, 41 and are pivotally mounted on the rearward portions thereof, although the

arms

93, 95 might be mounted on suitable independent pivots.

Due to the pivotal mounting of the

corner separators

77, 79, theymove downwardly through an arcuate path, and accordingly the forward end of the stack of sheets must be aligned in relation to the arcuate path so as to prevent the

corner separators

77, 79 from binding with the lower sheets of the stack 19. Also, it is necessary for the down-turned forward portion 83 of the

corner separators

77, 79 to move past the surface of the floor 31 of the tray 33 to enable the lower sheets to be fed from the compartment 15. As shown, the forward portions 83 of the

corner separators

77, 79 extend downwardly through openings 97, 99 respectively, provided in the floor 31 until the lips 81 rest on the floor 31 of the tray 33 after the last sheet of copy paper has been fed from the compartment 15.

When it is desirable to insert another stack 19 of copy paper sheets into the photocopying machine 11, it is first necessary to move the lid 17 covering the opening 16 of the compartment 15. As shown, to enable the compartment 15 to be easily uncovered, the lid 17 is hingedly connected to the machine by a pair of arcuate-shaped

brackets

101, 103, each having one end thereof connected to the lid 17 and the other end pivotally mounted on the

sidewalls

35, 37. in addition, the sheet advancing means 51, along with the

corner separators

77, 79 must be raised upwardly from the feeding position to enable the stack 19 to be placed on the floor 31 of the tray 33. Furthermore, as previously mentioned, the forward end of the stack 19 must be aligned relative to the arcuate path followed by the downwardly moving

corner separators

77, 79 so as to prevent the forward edges of the lower sheets of the stack 19 from interfering with the downward movement of the

corner separators

77, 79.

To enable a stack of sheets to be easily placed in the feeding position in the compartment 15, the

corner separators

77, 79 are provided with means for enabling them to be moved with the raising and lowering of the lid 17. As shown, the

arcuateshaped brackets

101, 103 are provided with inwardly protruding pins 105, 107 respectively, for engaging the pivotally mounted

arms

69, 71 respectively. Upon lifting the lid 17 upwardly to the position shown in FIG. 3, the pins 105, 107 engage the

arms

69, 71 respectivelyand move the sheet-advancing means 51 upwardly from the feeding position. The upwardly moving

arms

69, 71 and the shaft 57, along with the

brackets

101, 103 and the pins 105, 107 serve as lifting means for the

comer separators

77, 79. The arms 93, supporting the corner separators 77 79 are provided with carrying means in the fonn of

fingers

109, 111 respectively, for engagement by the shaft 57, so as to move the

corner separators

77, 79 upwardly and downwardly as the lid 17 is raised and lowered.

To align the forward end of the stack with the arcuate path followed by the downwardly moving

separators

77, 79, stop means must be provided for engagement by the forward end of the stack being placed on the floor 31 of the tray 33. In addition to properly aligning the forward end of the stack with the feeding position, the stop means must be movable from the path of the forwardly advancing sheet as the sheets are fed from the compartment 15. In the past, stop means have been provided by extending the down-turned forward portions 83 of the

corner separators

77, 79 to a length at least equal to the thickness of the stack of sheets being placed on the tray 33. To properly align the forward end of the stack so as to prevent binding, the extended portions 83 had an arcuate configuration which conformed to the arcuate path followed by the downwardly moving

separators

77, 79. Other arrangements used in the past have included a forward stop which is mechanically connected to the

corner separators

77, 79 but not integral with them. Such a forward stop is often in the form of a vertical post which is located between the

corner separators

77, 79 and descends through an opening formed in the floor 31 of the tray 33 as the

corner separators

77, 79 move downwardly.

Such prior arrangements are not always desirable because they necessitate a clearance beneath the floor 31 of the tray 33 substantially equal to the vertical length of the stop means. This clearance is necessary for receiving the stop means, whether in the form of an independent vertical post or extensions of the

corner separators

77, 79, beneath the floor 31 of the tray 33. Such prior art arrangements necessarily limit the space in the machine 11 available for the paper storage compartment 15, because space must be provided both above and below the floor 31 of the tray 33 for the forward stop means. Furthermore, the space beneath the tray 33 may be severely restricted by the location of other parts in the photocopying machine, and thus may prevent the stop means from descending substantially the full vertical length beneath the floor 31 of the tray 33.

According to the present invention, the photocopying machine 11 is provided with a forward stop means, generally indicated at 113, which is movable to and from an upright position for engagement by a stack of sheets in accordance with the raising and lowering of the lid 17. As more particularly shown in FIGS. 2--6, the forward stop means 113 is in the form of a stop member 115 which is located between the

corner separators

77, 79 and extends through an opening 117 formed in the inclined portion 85 of the fioor 31. The stop member 115 is supported for pivotal movement to and from the upright position by having the lower end thereof fixedly connected by suitable means to a shaft 119 which is rotatably supported beneath the floor 31 of the tray 33 by

brackets

121, 123 connected to the bottom side of the floor 31. The shaft 119 extends laterally to one side of the tray 33 and is rotated by a member 125 which, in the preferred embodiment, is in the form of an arm fixedly attached thereto. The arm 125 serves to move the stop member 115 in accordance with the raising and lowering of the lid 17 and has a slot 127 which receives the protruding pin for movement therein.

Although the stop member is pivotally supported in the preferred embodiment by the shaft 117 which is mounted beneath the floor 31 of the tray 33, it could also be pivotally supported by a shaft mounted above the floor 31 of the tray 33. In addition, the stop member 115 could be pivotally moved by another form of mechanical linkage instead of the pin 105 engaging the arm 125 which, in turn, is connected to the shaft 119. For example, a gear linkage could be used wherein a gear mounted on the shaft 119 is driven by another gear or portion thereof connected to the pivotal mounting of the arcuate-shaped bracket 101.

As the lid 17 is lifted to the position shown in FIGS. 3-5, the pin 105 follows an arcuate path and moves along the slot 127 formed in the arm 125 to pivotally move the stop member 115 to an upright position for aligning a stack of sheets in the feeding position in the compartment 15. As more particularly shown in FIG. 3, when the forward stop member 115 is in an upright or generally perpendicular position, it is spaced slightly rearward of the forward down-turned portion 83 of the

comer separators

77, 79 to compensate for the arcuate path of the

corner separators

77, 79. Accordingly, when a stack of sheets is inserted into the compartment in engagement with the forward stop member 115, as shown in FIG. 4, the lower sheets of the stack are rearward of the down-turned portions 85 of the

comer separators

77, 79 to enable them to move downwardly in an arcuate path without binding on the lower sheets of the stack. In addition, since the forward stop member 115 is separate from the

corner separators

77, 79, the downturned forward portions 85 need only extend a length sufficient to engage the topmost sheets of the stack, and therefore need not extend a substantial vertical distance beneath the floor of the tray.

After the stack of sheets has been placed on the floor 31 of the tray 33 in alignment with the feeding position, the lid 17 is lowered as shown in FIG.- 6 so as to cover the opening of the storage compartment and prepare the machine 11 for operation. As the lid is lowered, the pins 105, 107 supporting the sheet advancing means 51 move downwardly through an arcuate path and lower the rubber-covered

feed rollers

53,55 onto the topmost sheet of the stack. The corner separators 77, 79, which are supported by the

fingers

109, 111 engaging the shaft 57, likewise move downwardly until the lips 81 thereof rest on the corners of the topmost sheet. Further lowering of the lid 17 moves the pin 105 along the arcuate path and in the slot 127 of the arm 125, thereby pivotally moving the forward stop member 115 onto the upwardly inclined portion 85 of the floor 31, thus enabling the sheets to be forwardly advanced from the feeding position during subsequent operation of the machine.

When the photocopying machine is again operated for producing copies of original documents, the

rubber'covered feed rollers

53, 55 are rotatably driven to advance the topmost sheet 49. Due to the frictional contact between the sheets forming the stack, the advancement of the topmost sheet tends to move the stack forwardly. Although the friction pads 73 retard the forward movement of the stack, the adjacent topmost sheets move forwardly into engagement with the down-turned portions 83 of the

corner separators

77, 79. As previously described, further advancement of the topmost sheet by the rotatably driven rollers buckles and bends the forward corners thereof until the resiliency of the sheet moves the forward corners over the lips 81, thereby separating the topmost sheet from the remainder of the stack. The rotatably driven

rollers

53, 55 continue to advance the topmost sheet and move it into the converging exit throat 21. The exit throat 2] guides the incoming sheet into the nip of the rotatably driven

rollers

23, 25 which in turn remove the sheet from the storage compartment 15 for further processing.

While only a single embodiment has been illustrated and described, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the invention is not to be limited by the illustrative embodiment, but only by the scope of the depending claims.

We claim:

1. In a photocopying machine, the combination comprising a storage compartment for supporting a stack of generally in a feeding position from which they may be separately advanced from said compartment, stop means for aligning the stack of sheets in said feeding position in said compartment, said stop means being supported for movement in said feeding position, said storage compartment having an opening for inserting a stack of sheets into said compartment, a lid for covering said opening of said storage compartment and supported for movement relative thereto, said lid being movable in one direction for uncovering said opening of said storage compartment to enable a stack of sheets to be inserted therein, moving means operable upon the uncovering movement of said lid for moving said stop means to a generally upright position at said feeding position for engagement by the forward end of the stack, said lid being movable in another direction for covering said opening of said storage compartment, and said moving means being operable upon the covering movement of said lid for moving said stop means from said generally upright position in said compartment.

2. In a photocopying machine according to claim 1, said lid being supported for pivotal movement relative to said opening of said storage compartment, said moving means including a moving member connected to said pivotally .moving stop means for pivotally moving said stop means in response to movement of said lid, said moving means further including a bracket carried by said lid and movable therewith for engaging said member, said bracket being operable upon raising said lid for moving said stop means to said generally upright position for engagement with the forward end ofa stack of sheets being inserted into said compartment and being operable upon lowering said lid for moving said stop means from said generally upright position in said compartment.

3. In a photocopying machine according to claim 2, said moving member being an arm connected to said pivotally supported stop means, said bracket having a pin extending in a direction generally transverse to said arm, and said arm having a slot formed therein which receives said pin for movement in said slot, whereby raising said lid moves said pin along said slot in said arm to pivotally move said stop means to said generally upright position and lowering said lid moves said pin in another direction along said slot for moving said stop means from said generally upright position in said compartment.

4. Apparatus for advancing sheets from a stack comprising a substantially horizontal support for supporting a stack of sheets in a feeding position from which the sheets may be separately advanced, sheet-advancing means for advancing the sheets from said feeding position, stop means for aligning the stack of sheets with said feeding position on said horizontal support, said stop means being supported for movement to an upright position at said feeding position for engagement by a stack of sheets being placed on said horizontal support, said sheet-advancing means being movable from said feeding position to enable a stack of sheets to be placed on said horizontal support, moving means operable upon the movement of said sheet-advancing means from said feeding position for moving said stop means to said generally upright position for engagement by the forward end of the stack of sheets being placed on said horizontal support, said sheet-advancing means being movable to said feeding position in engagement with the topmost sheet of the stack, and said moving means being operable upon the movement of said sheet advancing means to said feeding position for moving said stop means from engagement with the forward end of the stack.

5. Apparatus for advancing sheets from a stack according to claim 4, said stop means being supported for pivotal movement, said moving means being operable upon the movement of said sheet-advancing means from said feeding position for pivotally moving said stop means to said generally upright position for engagement by the forward end of the stack of sheets being placed on said substantially horizontal support, and said moving means being operable upon the movement of said sheet advancing means to said feeding position for pivotally moving said stop means from said generally upright position.

6. Apparatus for advancing sheets from a stack according to claim 5, wherein said stop means includes a rotatably supported shaft, said stop means further including a stop member connected to said rotatably supported shaft for pivotal movement about the axis of said shaft, and said moving means in cluding a moving member for rotating said shaft, said moving member being connected to said shaft and laterally spaced from said stop member.

7. Apparatus for advancing sheets from a stack according to claim 6, said shaft being rotatably supported beneath said horizontal support, and said moving member being an arm connected to said rotatably supported shaft, said arm being pivotally movable about the axis of said shaft for pivotally moving said stop member to and from said upright position.

8. In a duplicating machine, the combination comprising a paper feed tray having a substantially horizontal floor for supporting a stack of sheets in a feeding position from which the sheets may be separately advanced, sheet-separating means for separating an advancing sheet from the remainder of the stack at the feeding position, said sheetseparating means being carried by said tray and supported for movement rela tive to said feeding position for engagement with the stack of sheets at said feeding position, stop means for aligning the stack of sheets with said sheet-separating means at said feeding position on said tray, said stop means being supported by said paper feed tray and movable to an upright position for engagement by the forward end of the stack of sheets being placed on said tray in said feeding position, said stop means being separate from said sheet-separating means and movable independently thereof, means for moving said stop means relative to said feeding position, said means being operable for moving said stop means to said upright position at said feeding position to enable a stack of sheets to be placed on said tray and aligned with said sheet separating means, and said means being operable for moving said stop means from said upright position at said feeding position with said sheet-separating means in engagement with the stack of sheets.

9. In a duplicating machine according to claim 8, said stop means including a stop member supported for pivotal movement to an upright position at said feeding position for engagement by the stack of sheets being placed on said feed tray.

10. In a duplicating machine according to claim 9, said stop means including a shaft rotatably supported by said tray beneath said feeding position, said stop member being connected to said shaft for pivotal movement about the axis thereof, and said means includes a moving member laterally spaced from said stop member and connected to said rotatably supported shaft for pivotally moving said stop member to and from said upright position.

11. A duplicating machine according to claim 10, said floor of said tray having a forward portion adjacent to said feeding position, said forward portion of said tray having an opening formed therein adjacent to said feeding position, said stop member extending through said opening in said forward portion of said tray and being pivotally supported by said tray beneath said feeding position.

12. In a duplicating machine according to claim 11, said forward portion of said tray being inclined from said floor to serve as a guide for sheets advanced from said feeding position and said stop member being pivotally movable from said upright position into engagement with said inclined forward portion.