US1140883A

US1140883A - Stencil-duplicating machine.

Info

Publication number: US1140883A
Application number: US78064213A
Authority: US
Inventors: Albert B Dick
Original assignee: AB Dick Co
Current assignee: AB Dick Co
Priority date: 1913-07-23
Filing date: 1913-07-23
Publication date: 1915-05-25
Anticipated expiration: 1932-05-25

Description

A. B. DICK.

STENCIL DUPLICATING MACHINE.

APPLICATION men JULY 23. 1913.

Patented May 25, 1915.

4 SHEETSSHEET I.

A. B. DICK.

STENCIL DUPLICATING MACHINE.

APPLICATION FILED JULY23. 1913.

Patented May 25, 1915.

4 SHEE TSSHEET 2.

zuzzuzzzzzu- A. B. DICK.

STENCIL DUPLICATING MACHINE.

APPLICATION FILED JULY 23, I913.

191% 883e Patented May 25, 1915.

4 SHEETS-SHEET 3.

A. B. DICK.

STENCIL DUPLICATING MACHINE.

APPLICATION FILED JULY 23. 1913.

Patented May 25, 1915.

4 SHEETS-SHEET 4.

ATTO/V UB ITD @TATII AT" an an on.

ALBERT B. DICK, OF LAKE FOREST, ILLINOIS, ASSIGNOR TO A. B. DICK COMPANY, OF

CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

STENCIL-DUPLICATING MEGHINE.

Specification of Letters Patent.

Patented May 25, 1915.

Application fi1ed July 23, 1913: Serial no. 780,642.

To (ZZZ whom it may concern Be it known that I, ALBERT B. DICK, a citizen of the United States, residing at Lake Forest, in the county of Lake and State of Illinois, have invented certain new and useful Improvements in Stencil-Duplicating Machines, of which the following is a specification.

This invention relates to stencil-duplicating machines and is directed to the provision of certain improvements in the construction of machines of this type whereby greater convenience in the adjustment and operation of the machine is secured, whereby the printed sheets are properly removed from the drum and directed to a suitable receiver, whereby an adjustment may be made when necessary so that the impressions on the printed sheets will have the lines thereof parallel to the ends of the sheet and whereby greater reliability and efllciency in the operation of the machine is secured.

One of the features of the present invention resides in the provision of adjustable devices for use in insuring that the impressions will be received properly by the sheets. In stencihduplicating' machines having automatic paper-feeding devices, the sheets are arrested at a position adjacent to the line of coaction of the drum and pressure-roller so that the edges thereof will be brought to a definite line and thereafter the sheets are forwarded to the drum. If the stencil were secured upon the drum in a position slightly displaced angularly from its proper position, the lines of the impressions received by the sheets would not be parallel to the ends of the sheets and a very-undesirable appearance would be presented. A machine constructed in accordance with the present invention is provided with a capacity for adjustment whereby this objectionable characteristic is wholly overcome. In the present instance, this provision is in the form of a bar pivotally mounted upon the drum to which the forward end of the stencil-sheet is secured and which may be adjusted to various angular positions about its pivotal axis.

Another feature of the present invention resides in the means employed for stripping the sheets from the drum. This in-- volves the provision of guides on the drum adjustable toward and away from each other to coact' with sheets of different widths and adapted to incline the edges of the sheets downwardly so that they may be engaged by suitable strippers. These strippers are mounted upon a stationary bar adjacent to the drum of the machine and are so constructed as to greatly facilitate the proper positioning of the strippers and also of the guides. on the drum.

The invention further involves certain features in the construction of the mechanism employed in connection with the forwarding of the sheets to the drum and pressure-roller whereby smoother action of the machine requiring less power is attained. The sheets are fed to a suitable stop by the automatic sheet-feeding apparatus and from that point they are forwarded to the drum andpressure-roller by two coacting rollers one of which is movable toward and away from the other, these rollers being ar ranged to coact through a sheet s thal' they will rotate at the same surface speed as that of the drum at the proper times for feeding sheets to. the drum.

These and other features of the invention will be pointed out more in detail in the following description in connection with the accompanying drawings which show the preferred embodiment of the invention.

In these drawings, Figure 1 is a plan View of the machine with the drum removed, broken away in part, Fig. 2 is a central section of the machine, Figs. 3 and 4: are detail views of one of the guides, Fig. 5 is a vertical section of a portion of the machine inside one of the sideframes showing the gearing by which certain of the parts are actuated, Fig. 6 is a detail view of a portion of the operating mechanism, Fig. 7 is a detail view of a portion of the throw-off mechanism, Fig. 8 is a horizontal section through one of the side-frames showing the actuating gears, Fig. 9 is a detail view of a portion of the drum showing the stencil-securing device and Figs. 10 and 11 are detail views of the strippers.

Referring to these drawings, the drum of the stencil-duplicating machine is shown at 12 and this coacts with a pressure-roller 13. These parts are mounted between sideframes 1% which rise from a base 15. The roller is carried by the usual pivoted arms 16 normally pressed upwardly by springs 17.

The feedboardof the machine is in two

arts

18 and 19 whose upper surfaces are in substantial alinement. The part 19 of the feedboard may rock about a rod 20 to carry the top sheet of the pile into and out of contact witha sheet-feeding roller 21.

When the roller 21 is in contact with a sheet, it is rotated in the direction of the arrow of Fig-. 2 and buckles a sheet" between the roller and a bar 22 until the end of the sheet is caught by, a projection upon the surface of roller 21: and isfcarried around on top' of the roller." At that-time another -roller23 is lowered into contact with the sheet and the sheet is forwarded between these two rollers until its end engages stops 24 which )roject through openings in the )late 25.

hereafter the stops 24 are lowere and the sheet. is forwarded between the drum and pressure-roller b sheet-forwarding devices consisting o sectors 26 and a roller 27 c'oacting therewith."

The drum 12 is mounted upon trunnions in the side-frames 14 and has a gear 28 securedto one of its ends whereby it may be rotated by means'of a crank applied to'the shaft of a coacting gear 29. Extending tween the side-frames of the machine is a shaft 30 on which is a gear 31 driven from the gear 29 by 'a train ofv gearing 32. A gear 33 rotates with the gear 31 and this gear meshes with a gear 34 on an adjacent shaft 35. This shaft also carries a gear 36 meshing with a pinion 37 secured to a sleeve .38'which is rotatable upon the shaft 30. This sleeve 38 carries the sectors 26 as shown in Fig. 2. The shaft 30 also carries acam on which rides a roller secured to-the stops 24 as shown in Fig. 5 to effect the upward and "downward movement of the ends of the stops 24.

' The roller 27 is not positively driven.- Instead itis raised andlowered into and out of coaction with the sectors 26 and it is rotatedonly when coacting with the sectors through a sheet- For thisfpurpose, the shaft of :the roller 27 has its ends received in guide-ways formed in the side-frames 14 of which rides on the peripheryof a cam 42 is mounted upon the'shaft .30. The gearing above described-is such that thesectors 26 rotate at the samesurface speed as the drum and these sectorsare of such size that they a make preferably three revolutions for each revolution of. the drum. 1 The shaft 30 makes one revolution for each revolution of the drum and therefore the roller 27 is moved downwardly into coaction with the sectors 26 once during each revolution of the drum or once during three revolutions of the sectors 26. The cam 42' is soshaped that the roller 27 will coact with the sectors 26 while the entire length of those sectors. is passing under roller 27 once and there-' after the roller will be held up while the sectors pass under it twice. By this'constructionthe rotatable parts may be continuouslyv rotated but the sectors 26 will be operative to forward a sheet only every third revolution during which they coa'ct with the roller 27 and when asheet is forwarded by the coaction of roller 27 and sectors 26 that sheet will be moved forward at the same surface'spe'ed as that at which the drum is-rotating so that the sheet will be taken up by the drum andpressure-roller without such jar or strainin as would be apt to cause mal-alinement 0 the parts and result in improper registration.

It will be seenthat the-construction abovej described .for forwarding the sheets to thedrum requires that the stencil beplaced upon the drum with the lines of type'characters thereon parallel. to the axis of the drum.

If this'were not done, the impressions re ceived by the sheets would not have the lines thereof parallel to the ends of the sheets.

It sometimes happens that a stencil is not. placed on the drum accuratelyin this re spect anddiificulty is experienced in securing the proper positioning of the stencil.

In using machines of this character heretofore, it has been common to adjust certain of the parts against which the sheets are positioned prior to feeding them to the drum so that the sheets will be fed to the drum at a slight angle and thus receive the impressions thereon properly. But when automatic sheet-feeding apparatus is provided, thisexpedient cannot wellbe resorted to.

The drum 12has a sheet-metal strip or bar 43 secured thereto, as shown in Fig. 4,. which bar forms the support for the button bar 44 or otherdevice to which the forward edge of the stencil 45 is secured; This but ton-bar 44 is pivotallyfmounted upon the support 43. The pivot is shown at'46 in Fig. 9, this pivot passing through the button-bar 44 and support 43. The buttons on the bar 44 are shown at 47. Means are provided for adjusting the. bar 44 about its pivot 46-. as shown in Figs. 4 and -9. On they support 43 is a member 48 having a threaded opening therethrough to receive a screw 49 having a'knurled head. The end of this .screw 49 engages an abutment 50 which passes through a. slot'in the bar 43 :and is fixed to the button-bar 44. By turning the screw 49, the abutment 50 may be moved toward and away from the member 48, thus turning the button-bar 44 about its pivot 46. This construction is such that: if a stencil has been secured to the button-bar 44 and it is found that with the stencil thus positioned the impressions are not properly arranged with respect to the edges of the sheets, the stencil may be raised from the cylindrical surface of the drum and the angular position of the button-bar with respect to the drum changed slightly as may be necessary by manipulating the screw 49. When the proper angular disposition of the'button-bar has been obtained, the stencil may be again laid upon the cylindrical surface of the drum and the printing operation proceeded with. a

A bar 51 (Figs. -2, 3 and 4) is secured to the drum extending between the heads of the drum and forms the support for a pair of guides 52. Each of these guides is adapted to overlie the stencil. adjacent to theforw ward edge of the stencil and to extend between the stencil and the sheet which is printed upon so as to facilitate stripping the sheet from the drum after the printing operation. For this purpose, the bar 51 is.

located adjacent to-the periphery of the drum and adjacent .to the button-bar for securing the forward edge of the stencil .to

the drum. Each stripper 52 is secured to a' plate 53 lying on one side of the bar 51. On the other side of the bar is a sheet-metal strip 54 secured at one end to the strip 53 and at the other end provided with a screw 55 by which the

plates

53 and 54 may be drawn together to cause them to grip the bar 51 between them. The edges of the plate 53 are preferably flanged to cause them to embrace the bar 51. When the screw 55 is loosened, the guide 52 with its supporting

parts

53 and 54 may be moved along on bar 51 as desired and when'the proper position of the guide is found, it may be locked in that position by tightening up on screw 55. Each of the guides 52 istrough-shaped as shown in Figs. 10 and 11. These guides are normally placed so that they coact with the sheets to be printed upon close to the edges of the sheet and at points beyond the ends of the pressure-roller 13. This. relation of the parts is shown in Fig. 10. When so positioned theguides 52. will cause the edges of, the sheet being printed upon to be inclined downwardly beyond the ends of the roller 13 as is shown at 56 in Fig. 10. By thus deflecting the edges of the sheets, the guides 52 enable the strippers of the machine to .coact readily with the sheet for these strippers may be inserted between the drum and th portions 56 of the sheets.

The strippers are mounted upon a bar extending between the side-frames of the machine adjacent to the drum. This bar is shown at 57 and it is mounted upon the frame by having its ends secured to angular members 58 which are secured to the sideframes 14. Each stripper consists of a sheet-metal member 59 inclined downwardly as shown in Fig. 2 and having its upper end arranged vertically so as to lie fiat against the bar 57. At its lower end the plate-59 is cut so as to provide a projecting point 60. To

secure the stripper to the bar 57, an outer plate 61 is employed over which a fiat spring 62 is placed. A screw 63 passes through the flat spring 62 and the underlying portion of the plate 61. The plate 61 is secured to the engages bar 57:?gMe'ans are provided for facilitating the proper positioning of the parts of the stripping mechanism. For this purpose, a flat spring 64 issecured to the rear face .of the stripper and normallylies flat .against that face. This spring may, however, be deflected to the position in whichit is shown in Fig. 11 by a pin 65 secured to the spring and projecting through openings in the pieces 59 and 61. The guides 52 hav ing. been properly positioned, the pin 65 is pressed inwardly and the corresponding stripper is then moved along upon bar 57 until the end of spring 64 engages the guide whereuponthe screw 63 may be tightened up to hold the stripper-in the position thus posite the center line of the trough in guide 52 as shown in Fig. 10 so that it will be in position to be projected between the portion 56 of each sheet and the drum.

If desired the bar 57 may be provided with scale markings with which an index on the plate 61 may coact as shown in Fig.

10. When this is done, the stripper may be positioned by reference to these scale markings and the width of the sheets to be printed upon and the springs 64 may be employed in properly positioning the guides 52 with reference to the strippers. I 1

As will be seen from Figs. 1 and 10 the strippers are extended laterally toward each other and these extensions carry small starwheels 601 adapted to coact with the sheets at points distant from the edges of the sheets while the latter are engaged by the ends "30 of the strippers. This makes the operation of stripping the sheets from the drum much more reliable for if the central portion of a atpoints so far from the edges of the sheet as to insure that the sheet will be removed from the drum. v

The part 19 .of the feedboard is adapted to rock on the shaft 20 as above described. This rocking movement is effected by a cam 66 (Fig. 5) on the'shaft 30 which cam actuates a lever having a vertical arm 67 and a horizontal arm. 68 (Figs. 5 and. 8). This lever is loosely mounted upon a rock-shaft 69 which extends between the'side frames of the machine. The roller on the arm 67,

shown at 70 in Figs. 5 and 8, is held in engagement with the cam 66 by a spring 71 secured at one end to a suitable abutment 72 and at the other end to an arm of the lever 67, 68 depending below the shaft 69. Atits free end, the arm 68 of the lever above described has a member 73 piv'otally mounted thereon which. member carries a pawl 7A and a roller 75. This roller is adapted to engage a stationary abutment 76 upon the adjacent side-frame. A spring 77, tends to turn the member 73 in a clockwise direction as shown in Fig. 5. When the member 73 is so turned, the pawl 74: engages a rack 77 secured to and extending upwardly from an arm 78 of a lever which is secured to the rock-shaft 69. This lever has a downwardly extending arm 79 to which is secured one end of a spring 80 whose other end is socured to'the frame as shown in Fig. 5. The shaft 69 also has an arm 81 secured thereon whose free end carries a pm which lies in a slot in a piece 82 secured to the under side of the part 19 of the feedboard. By this mechanism as cam 66 rotates, arm 68 is raised and lowered by the cam and spring 71. As it is raised the roller engages the abutment 7 6 so that pawl 7 4c releases rack 7 7' whereuponthe spring is free to turn

lever

78, 79 and the rock-shaft 69 in a. clockwise direction so that arm 81 onthe shaft '69 will turnthe part 19 of the feed-board so as to carry the top of the sheet pile upwardly into contact with the feeder 21. As arm 68 moves downwardly, the pawl 7 4: will engage the rack 77so as to move the lever 78 with the lever 68 and thus carry the end 'of the feedboard downwardly again. By

this mechanism. the downward movement of arms 83 pivotally mounted at 81 upon thev si le-frames of the machine. These arms 83 are also pivotally

eonnected'to links

85 and 86 which linksform toggles. The links 86 are secured to a rock-shaft 87 which carries a crank 88 (Fig.6) having its end connected roller 23 is lowered upon the sheet.

to a link 89 provided with a roller 90 riding on the periphery of a cam 91 secured to the shaft 30, the link 89 being provided with a slot through which the shaft 30 extends. In the normal operation of the machine the rod 22 is raised by the parts just described'as the feedboard is lowered to carry the paper out ofcontact with feeder 21. It is desirable to have rod 22 so arranged that it may be supported in inoperative position while inserting a new pile of sheets; The toggle arrangement of the links-'85, 86 serves this purpose. By raising the arms 83 and bar 22 by means of the rod 92 provided therefor, the'toggle links are straightened to the position in which they are shown in Fig. 5 and support the bar 22 in this raised position. The lever 78 is provided with a handle 93 by which it may. be operated to depress the forward end of the feedboard while in serting a new pile of sheets. I therefore provide means whereby when this handle has been depressed to lower the feedb'oard and the bar 22 has been raised as above described, the raising of'the feedboard and with it the raising of arm 78 will automatically cause lowering of the bar 22. This is effected by means of a stop or roller 94 mounted upon the side of arm 78 and so positioned'that when the arm is raised,"this roller 94 will "engage the toggle links 85, 86 at the pivotal connection thereof and-force that pivot in a direction to cause buckling of the toggle. i

- After a sheet has been buckled'between the feeder 21 and bar 22 and the end of the sheet has been carried over thefeeder, the This roller 23 is'carried by arms 95 secured to a rock-shaft 96'which has an arm 97 (Fig. 6) secured thereto and carrying a roller which rides on the periphery of a cam 98 secured to the shaft 30. A spring 99- holds the roller always in-coaction with the cam. This cam therefore serves to raise and lower the roller 23 as is required for proper coaction of that roller with the feeder 21 in feeding the sheets between them" until the sheets arearrested by their forward edges engaging the stops 24. I

During the rotation of the drum,'the pressure-roller 'is moved away from the drum to inoperative position by a cam 100 fixed toone of the heads of the drum and coacting with a roller 101 carried by one of the arms 16 which support the pressure roller. If the pressure-roller werereturned' to operative position and no sheet were fed to the drum and pressure-roller, ink would be transferred from the stencil to the sur face of the roller which ink would be subsequently deposited upon the rear face of a sheet being printed upon. To avoid this, means are provided for holding the pressure-roller in its inoperative position after it has been moved there by cam 100 if no sheet is fed to the drum and pressure-roller. This locking of the pressure-roller in inoperative position is effected by a. stop coacting with a lever 102 (Figs. 2 and 7) pivoted upon the adjacent side-frame and having one end overlying the free end of one of the arms 16. As the pressure-roller moves down, this lever 102 rocks on its pivot and if the roller is to be held down, a stop is placed under the opposite end of lever 102 so as to prevent turning movement of that lever and turning movement of arms 16' carrying roller 13. This automatic stop mechanism is shown in Figs. 1 and 7. The stop consists of an arm 103 loosely mounted upon a stud 101 on the side-frame. This stud also carries a pivoted lever 105 having aroller at its end adapted to coact with a cam 106 on shaft 30. A spring 107 connects arms 105 and 103. A rock-shaft 108 extending between the side-frames has a lever 109 secured thereon and carrying a roller adaptedto ride on the surface of the cam 110 also secured on the shaft 30. Loose on shaft 108 is a lever 11.1 bifurcated at its end to embrace a pin 112 on the arm 103. The lever 111 has an extension 113 which may engage a pin 114; on the side-frame to limit the movement of arm 111. A spring 115 acts on lever 111 to turn it in a clockwise direction carrying extension 113 into engagement with a lateral projection 118 of arm 109. A spring 116 acts on arm 109 in a direction to holdits roller in engagement with cam 110. The pin 11 1 projects inwardly from the adjacent side-frame of the machine under the extension 113 of arm 111 to limit the turning movement of the arm 111 and support one end of spring 116.

Secured to shaft 108 are a plurality of feelers 117 whose ends are turned upwardly as shown in Fig. 2 and may be projected through openings in plate 25 so as to coact with a sheet, the movement ofthese feelers being arrested by a sheet if the latter is in position, but in the absence of such a sheet, being continued to the position in which the feelers are shown in Fig. 2.

The rotaton of shaft 30 and cam 110 thereon permits shaft 108 to be rocked by spring 110 so as to raise the free ends of the feelers. If the feelers engage a sheet, the rocking of shaft 108 in its bearings is arrested in position where the roller on arm 109 is away from the periphery of cam 110. At this time the lever 111 will be held by its spring 115 with its arir 113 engaging the projecting end 118 of the arm 109 and the position of arm 111 at this time is such that the arm 103 is retracted so that its end is out from under the end of lever 102. Consequently the lever 102 can rock on its pivot and allow the pressure-roller to be raised in operative position. But if no sheet has been in position when the feelers were raised, the roller on arm 109 would be permitted to follow the contour of cam 110 to the position in which it is shown in Fig. 7. As arm 109 moved so, its end 118 would depress the extension 113 of arm 111. This would cause the end of arm 103 to be carried under the end of lever 102 so that it would obstruct downward movement of this end of lever 102 nd hence upward movement of the opposite end of the lever and the pressure-roller.

If it should happen that the movement of arm 103 from its inoperative position to its operative or stopping position shown in Fig. 7 were obstructed by the end of lever 102 because this movement of arm 103 occurred in advance of the upward movement of the adjacent end of lever 102, the cam 106 would depress the free end of arm 105 so as to place the spring 107 under tension. Then when the adjacent end of lever 102 moved upwardly the arm 103 would be at once moved by spring 107 to the position in which it is shown in Fig. 7 for obstructing the upward movement of the pressureroller. v

Having now described my invention, what I claim as new therein and desire to secure by Letters Patent is as follows:

1. A stencil duplicating machine having a drum whose cylindrical surface is adapted to support a stencil, a pressure roller coacting with the drum, a strip extending lengthwise of the drum near the cylindrical surface of the drum, means for pivotally mounting the strip'upon the drum to turn about an axis radial to the drum, studs on the strip to coact with the edge of a stencil and means for turning said strip in different angular positions, substantially as set forth.

2.111 a stencil-duplicating machine, the combination of a drum, a member mounted on the drum near the cylindrical surface thereof and extending lengthwise of the drum, said member being pivoted to turn about an axis substantially radial to the drum, means on said member to coact with a stencil to secure the end of the stencil to the drum, and means for turning said member about its pivot, substantially as set forth.

3. A stencil duplicating machine comprising a drum, a coacting pressure roller, a support adjacent to the drum, strippers mount ed on the support and adapted to engage a sheet forwarded by the drum near the edges of the sheet and movable toward and away from each other, lateral extensions on the strippers projecting toward each other and forming auxiliary strippers for engaging the sheet at points intermediate the edge portions engaged by said strippers, and means for securing the strippers in any adjusted positions, substantially as set forth.

4. A stencil duplicating machine comprising a drum, a coacting pressure roller,v

guides mounted on the drum and movable toward and away from each other, strippers mounted-adjacent to-the drum and movable? toward and away from each other to positions corresponding to the guides, and auxiliary strippers mounted between said strippers and adapted to engage a sheet forwarded by the drum'at points distant from strippers, substan those engaged by said tially as set forth;

' 5. A stencil duplicating machine comprise ing a drum, a coacting pressure roller, guides mounted on the drum and movable toward and away from each other, strippers mounted adjacent to the drum and movable toward and away from each other to posi tions corresponding the guides, 'lateral' extensions on the strippers pro ect1ng to- 1 ward each other and forming auxiliary strippers for engagingsheets distant from the edges -of the sheets and means for securing the strippers-in any adjusted positions, substantially as set forth.

6. In a stencil-duplicating machine, the

combination of a frame, a drum, meansfor securing a stencllthereon, a. pressure-rolle srv coacting with the drum, guides mounted on the drum and ad ustable toward and away from each other, strippers mounted on the frame adjacent to the drum and movable torollerv movable toward and away from the. drum, means for moving the roller away from the drum, alever movable when the roller is somoved, a stop pivotally mounted upon a fixed pivot and movable about the fixed pivot to carry it into position for looking the lever and holding the pressure-roller away from the drum, and two means for moving the stop about said pivot into 1ocking position one of which is governed by a sheet in position for coactionlwith the drum and roller, substantially as set forth.

8. In a stencil-duplicating machine, the

luplicating they combination of a rotatable drum, a pressure roller movable toward and away fromthe.

drum, means for movingI-the'roller away from the drum, a lever movable when the roller is somoved, a stoppivotallymounted upon a fixed pivot andmovable' about the fixed pivot into coaction withjthe levertov obstruct movement. thereof and hold the t roller awayfrom the drum,-means for mov- 'ing the. stop including a feeler adapted" to coact with a sheet in positionto befed to the drum and roller, .a cam rotated a's'the drum isrotate'd, a pivotedlever actuated by named lever toq said stop, substantially vas set 'forth.- v-

9. In a stencil-duplicating machine, the combination of a'jdrum, a pressure-roller,

and means forlockingthe pressure roller in inoperative. position comprising a lever cooperating with the roller,cas'top coasting. with the lever, a pivoted arm controlling the stop, a feeler connected to the 'arm and coacting with a sheet in position to be fed. 7 to the drum, a shaft'rotating as the drum is rotated, a cam thereon'actuating said arm,

a second cam on said shaft, a pivoted arm] actuated thereby, and a spring connecting said last-named arm and, said stop, substantially-as set forth,

10; In a stencil-duplicating macl1ine,the:

combination of a drum, a pressure'roller movabletoward and away from the drum,

said cam and a spring connectingjs'aid last-1;

means for periodically moving the roller 7 away from the drum, a lever movable when the roller is so moved, a pivoted stop adapt- .ed to be moved into coaction with said lever to obstruct movement thereof and hold the roller away from the drum, means for mov-. ing'the stopintoobstructing position when there is no sheetin position to be fed to the drum and roller,,and additional means, including a springsecuredto said stop, and

periodically operated means for tensioning said spring, for exerting an additional pres-' sure on said stop in the direction of itsobstructing position, substantially as set forth. This specification signed and witnessed this 15 day of July, 1913. I ALBERT B; DICK. Witnesses:

W. G. ARNoLo, W.A. WATERBURY."