US2873116A

US2873116A - Paper-feeding mechanism

Info

Publication number: US2873116A
Application number: US693410A
Authority: US
Inventors: Lambert Donald Rudolf
Original assignee: Powers Samas Accounting Machines Ltd
Current assignee: Powers Samas Accounting Machines Ltd
Priority date: 1956-12-19
Filing date: 1957-10-30
Publication date: 1959-02-10
Anticipated expiration: 1976-02-10

Description

Feb- 10, l959 D. R. LAMBERT PAPER-FEEDING MECHANISM 5 Sheets-Sheet 1 Filed oo. 3o, 1957 I Il Feb- 10, 1959 D. R. LAMBERT 2,873,116 PAPER-FEEDING MECHANISM Filed Oct. 30, 1957 5 Sheets-Sheet 2 Feb. 10, 1959 D. R. LAMBERT 2,873,115

PAPER-FEEDING MECHANISM Filed oct. 5o, 1957 5 sheets-sheet 5 Inventor I O/VIAD fum-p r Feb. 1o, 1959 Filed Oct. 30, 1957 v D. R. LAMBERT PAPER-FEEDING MECHANISM 5 Sheets-'Sheet 4 Feb. 10, 1959 D, R LAMBERT 2,873,116

PAPER-FEEDING MECHANISM Filed oct; 3o, 1957 5 sheets-sheet 5 United States Patent O PAPER-annalisa MEcnANrsM i Donald Rudolf-Lambert, Carshaltom England, assignor to Powers-Saunas Accounting Machines Limited, Lon- This invention relates to paper-feeding mechanism and, 1n particular, to paper-feeding mechanism for use in machines in which imprinting is effected by styluses which determine one maximum dimension of a character and are moved axially to form character-defining dots on the paper, the paper being moved past the styluses during an imprinting operation at a constant linear speed which determines the other maximum dimension of the characters to be formed.

It will be understood that as the paper is not stationary, but is being moved continuously during imprinting operations, there is little time in which, when desired, to effect multiple spacing between successive lines of characters, particularly if it is desired not to retard the rate of printing by ensuring that the styluses are not operated for a predetermined period during which the paper can be moved at the said constant linear speed by a distance which is equal to a multiple of the normal, or single, line-spacing. v

It is a main object of the present invention to provide a paper-feeding mechanism which can be selectively operated to superimpose on, the paper-feeding elements a feeding movement whereby the paper-feeding elements will, for a predetermined interval of time as required 4by the space desired between successive lines of imprinting, move the paper with a linear speed greater than that of the constant linear speed at which the paper is moved continuously during imprinting operations.

According to the invention, paper-feeding mechanism comprises continuously operable driving means cooperating with paper-feeding elements to effect continuous feeding of paper at a constant linear speed, and auxiliary driving means adapted to co-operate with said continuously operable driving means temporarily to increase the rate of operation of said paper-feeding elements thereby to effect a temporary increase in the linear speed of paper fed by the paper-feeding elements to determine the spacing effected between successive lines of imprinting made on the paper. v

In order that the invention may be clearly understood one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which:

Figure l illustrates diagrammatically, and partly in section, paper-feeding elements and styluses for effecting marking on paper fed thereby,

Figure 2 is a top plan of Figure l,

Figure 3 is a top plan of auxiliary driving means for the feeding elements of Figures 1 and 2,

Figure 4 is an elevation, looking in the direction of arrow IV, Figure 3, of the mechanism shown in Figure 3,

Figure 5 is an elevation, partly in section, looking in the direction of arrow IV, Figure 3, and illustrating the mechanism which appears beneath the base plate of Figure 3.

Figure 6 is a plan, looking from below Figure 4,

2,873,116 Patented Feb. 10, 1959 Figure 7 illustrates a detail of the mechanism shown in Figure 6, and

Figure 8 is a circuit diagram showing electrical connections to certain of the parts shown in Figures 3 to 6.

Referring to the drawings, Figures 1 and 2 illustrate diagrammatically a paper-feeding device in which continuous stationery 1 is arranged to b'e fed in the direction of arrow 2 to and past an imprinting position at which printing is effected on the paper by imprinting elements, shown as styluses 3. The manner of effecting imprinting is known in the art and will be described only briey herein. The paper 1, during an imprinting operation, is moved continuously at a constant linear speed by paperfeeding elements 4 consisting of rotatable wheels provided with peripheral pins to engage in marginal perforations formed in the stationery. The linear speed of the paper 1 during imprinting operations is such that it will determine the height of characters to be defined on the paper and character definition is, in known manner, effected by the styluses 3, the marking ends of which are reciprocated as indicated by the double-headed arrow 5, Figure 2. The styluses, during character-definition, receive a succession of lengthwise impulses, as indicated by the double-headed arrow 6, Figure l, whereby the styluses 3, by impinging against a carbon or like tape 7, between which and a platen S the paper is passed effect imprinting on the paper by impressing carbon dots thereon to define the desired characters.

The paper-feeding elements 4 are rotated by gear wheels 9 which mesh with vgear wheels 10 rotatable with a drive shaft 11. The drive shaft 11 is rotated continuously from the main drive, not shown, of the machine, rotation being imparted to the shaft 11 through a differential gear consisting of -two bevel-

wheels

12, 13, carried respectively by worm-

wheels

14, 15, the

bevels

12, 13 and worm-

wheels

14, 15 being freely rotatable on shaft 11 and restrained against axial movement by collars 16 pinned to the shaft 11 and

byjplanet wheels

17, 13 which mesh with the

bevels

12, 13 and which are pinned to a cage 19, the cage being pinned to the shaft 11. The drive for shaft 11 from the main shaft of the machine is effected by a worm 20 which engages with the worm 14, the worm 20 being secured to a shaft 21 which is rotatedvfromthe main drive of the machine and imparts to the shaft 11 an angular velocity such that when the shaft 11 is driven under control of shaft 21 and worm 20, the paper feeding elements 4 feed the paper with the constant linear speed required during the definition of characters. When the paper 1 is to be fed with a linear speed greater than that at which it is fed during character definition in order to effect spacing between lines of characters, the shaft 11 is caused to rotate at a higher angular velocity by reason of a further driving movement imparted thereto by auxiliary driving means which includes a worm 22 meshing with the worm 15 secured to a shaft 23 which is rotatable as described below.

The auxiliary driving means is normally inactive and is brought into operation only when a line spacing operation is to be effected. Rotation of shaft 23 is effected by a ratchet wheel 24, Figures 3 and 4, Which is secured to the shaft 23 and is operable by a pawl 25 actuation of which is effected by control means to be described below. The pawl Z5 is pivotally mounted on an arm 26 secured to a gear wheel 27 freely mounted on the 'shaft 23. A spring 28 urges the pawl into engagement with the teeth of the ratchet wheel 24. The gear wheel 27 meshes with a toothed rack 29 which is supported, between a base plate 30 and guide elements 31 secured to the base plate, so as to be movable to and from a datum position, which position is illustrated in full lines in Figure 3.. The controlY means includes a cam-operated multi-pivot crank, the

pivots for which, as described below, determine themovement of the rack to and from the datum position thereof, and the pivots are selectively engageable with the crank in amanner such that on operation of the crank a selected one only of the pivots is operatively engaged with the crank.

Movement of the rack 29 to and from the datum position thereof is elected under control of a rack-actuating cam 32 secured to a shaft 33 which is rotated in 1:1 relation with the shaft 21, by means not shown, from the main drive of the machine. (Jo-operating with the rackactuating cam 32 is a follower roller 34 carried by a lever 35 pivoted at 36 to the base plate 30. One end of a link 37 is pivotally connected to the. lever 35. To the other end of the link 37 there is pivotally connected a rackactuating link 38 which is pivotally connected at 39 to the rack 29 and, at 4t), to a crank element 41. The follower roller 34 is maintained in co-operation with cam 32 by a spring 42.

As stated above, the crank element 41 is a multi-pivot crank and to this end one arm of the crank 41 is provided with a plurality of holes 43, Figure 3, located in spaced relation on one side of and along a line radial to the axis of a neutral pin 44, the axis of which is coincident with the axis of the pivotal connection 39 between the rack-actuating link 38 and the rack 29 when the rack is in the datum position thereof. The holes 43, when the pivotal axis of the neutral pivot pin 44 and pivotal connection 39 are co-incident, are aligned with retractable selectively operable secondary pivot pins 45, one of which is shown in Figure 4, and any one of which can be inserted into the crank hole 43 appropriate thereto so that, on withdrawal of the neutral pivot pin 44 from the crank element, the secondary pivot pin 45 which is engaged with the crank determines the extent of movement of the rack from the datum position thereof under control of the rack-actuating cam 32. Only one of the

pivot pins

44, 45 is engaged with the crank when the cam 32 is arranged to effect operation of the crank, and when the pivot pin which is engaged with the crank element 41 is the neutral pin 44, it will be understood that because the axis of the neutral pin is co-incident with the pivotal axis 39, there will be no linear displacement of the rack 29. If, however, the neutral pivot pin 44 is withdrawn and one of the secondary pins 45 is inserted into the hole 43 appropriate thereto then, on operation of the cam 32 to effect movement of the rack-actuating link 38, the crank element 41 which is connected to the rack-actuating link 38 will be moved about the pivot pin 4S and so effect lengthwise movement of the rack 29, to the right as viewed in Figure 3. In chain dotted lines in Figure 3 there is illustrated the position to which the rack Z9 is moved away from the datum position thereof when the link 38 is actuated by cam 32 and the pivot pin 45 most remote from the neutral pin 44 is inserted into its hole in the crank element 41. As shown in Figure 3, the crank element 41 is provided with seven holes 43 for co-operation with secondary pivot pins 45 and each of the holes 43 and secondary pins 45 is adapted to effect movement of ratchet Wheel 24 which is the equivalent of a multiple of the 'single line spacing which is effected when the neutral pin 44 is located' in thecrank so that no movement of the rack 29 is effected by cam 32. Thus, if the rack 29 is moved, as illustrated in chain dotted line in Figure 3, to

the furtherrnost position thereof from its datum position it will, when restored to the datum position, effect aueight-tooth movement of the ratchet wheel 24, this being the equivalent of eight line spacings.

As can be seen from Figures 3 and 4, there is provided an interruptor element consisting of a lever 46 having a step 47 formed at the free end thereof for engagement with the rack-actuating link 38. The interrupter element is normally retracted out of engagement with thev link '3S-and is retained in the retracted condition by an interrupter electro-magnet 4S. On de-energisation of'the elec- 75 tro-magnetA 48 a

spring

49,4 Figure 3, urges the step 47 into engagement with link 38 and thus prevents the cam follower 34 from following the cam 32 and effecting operation of link 38. It will be understood that when the interrupter element 46 co-operates with link 38 no multiple-line spacing can be effected.

The apparatus for selectively operating the pivot pins 44, will now be described with reference to Figures 5, 6 and 7. The neutral pivot pin 44, Figures 6 and 7, has appropriated thereto combined inserter and retractor means comprising a forked arm 50 which is engaged with the neutral pin 44, as shown in Figure 7, and which is secured to a rocking spindle 51 to which is also secured a lever 52 provided with a slot 53, Figure 7, in which is located a pin 54, lixed to one arm 55, Figure 6, of an actuating lever, indicated generically by the reference 56, Figure 6.

The actuating lever is pivoted at 57 to the base plate 38 and is rockable about its pivot, against the action of a spring 58, by an operating link 59' one end of which is pivotally connected to a cam follower arm 60 which, in turn, is pivoted at 61 to the base plate 30. The arm 60 carries a cam follower roller 62 which cooperates with an inserter/retractor cam 63 secured to the shaft 33 to be rotatable with the cam 32. On movement of arm 60 by cam 63 the operating link 59 is pulled thereby against the action of a spring 64, the free end of the opelating link being guided for lengthwise movement between the base plate 30 and a guide element 65 secured to the base plate. A latch 66 is pivoted at 67 to the free end of the operating link 59 and is urged by a leaf spring 63 into engagement with a stop 69 carried by the operating lever S9. As can be seen from Figure 6, the actuating lever 56 carries a lateral projection 70 which, when the latch 66 is moved to the active position thereof against the action of spring 68, is engaged by the latch so that length wise movement of the operating link 59, to the left as viewed in Figure 6, causes the actuating lever 56 to be rocked counter-clockwise about its pivot 57. The latch 66 is provided with a sloping face 71 which co-operates with a corresponding face formed on an interposer which is movable relative to the latch and which, in the drawings, is shown as an armature 72, pivoted at 73 to an interposer-actuating electro-magnet 74. It will be understood that, if desired, the interposer actuating electromagnet may be replaced by a Bowden wire or the like. With the arrangement as illustrated in Figure 6, when the electro-magnet 74 is de-energised movement of the operating link 59, to the left as viewed in Figure 6, will cause the armature 'l2 to rock about its pivot 73 so that the latch remains in the inactive position thereof and does not co-operate with the abutment 70. If, however, the electro-magnet 74 is energised the armature 72 is retained. thereby in a tixed condition so that, as the operatingV link 59 is moved to the left as viewed in Figure 6I thc latch, by co-operation with the armature, is caused to turn counter-clockwise about its pivot 67 so as to engage the abutment 7@ and effect rocking of the actuator lever 56.

The secondary pivot pins 4S are each provided, at the end thereof remote from the crank element 41, with a Idirnple 75, Figure 5, in which a selector lever 76 appropriated to thev secondary pivot pinis adapted to engage when it is moved to the active position thereof. A selector lever 76 is providedl for each pivot pin 45 and each selector lever is pivoted at 77 to a selector link '78 appropriate. thereto, the links 7S being secured to a selector spindle 79 rockable in bearings 80, Figure 6, by

actuator links

81, 82, of which the link S2 is a twisted link as shown in Figures 5 and 6, and has one end pivotally connected to the actuator lever 56.

The selector levers 76 are urged about their pivots 7'7 to the inactive positions thereof, as shown in Figure 5, by springs 83, but are movable to the active positions thereof by co-operation lof the tails of the selector levers With selector elements.y The selector elements may, if

desired, be flexible wires or the like but, as shown in the drawings,each selector element comprises a 'selector electro-magnet 84 having an armature 85 pivoted at 86 thereto. The armature is provided with a guide face, as shown in Figure 5, which co-operates with the tail of its selector lever. When the armature 85 is retained in the selector lever-actuating position thereof by energisation of its electro-magnet, counterclockwise movement of the selector link 78, as viewed in Figure 5, causes the selector lever 76 carried thereby to be turned about its pivot 77 so that the lever 76 is aligned with the appropriate pivot pin 45 and continued counter-clockwise movement of the selector link 78 causes its selector lever 76 to engage the secondary pivot pin appropriate thereto and to insert the pivot pin into the crank hole 43 appropriate thereto.

It will be understood that since the actuating lever 56 is commonv to the pivot pins 44, 45, as a pin 45 is introduced into the hole 43 appropriated thereto the neutral pivot pin 44 is retracted from its hole in the crank element 41. On the return movement of the actuating lever 56, the neutral pivot pin is restored into engagement with the crank element 41 and the active secondary pin 45 is withdrawn from engagementwith the crank element 41 by a retractor plate 87, Figure 5, which is common to all the pivot pins 45, the plate 87 being slotted to engage with the pins, as illustrated in Figure 5. The retractor plate 87 is pivoted to a spindle 88, Figure 5, about which it is rocked by retractor actuating links 89 pivoted to the outermost selector links 78 for movement therewith under control of the actuator links 81, 82.

Referring to Figure 8, it will be seen that the selector electro-magnets 84 are connected in an electric circuit fed from a D. C. supply. The circuit is opened and closed once during each operation of the main shaft of the machine by a cyclically operable timing switch consisting of a xed contact 90 and a movable contact 91 operated by a cam 92 secured to the main shaft of the machine. The selector electro-magnets are each connected to a predetermined position of a rst switch 93 and a second switch 94, the

switches

93, 94 being independently manually operable to condition a selector electro-magnet for energisation on closing of the timing switch. A normally inactive relay 95 is interposed between the selector electro-magnets and thev timing switch and is connected with a normally open contact 98 which contact is also connected with the second switch 94 by line 99. The. normally open switch 98 is arranged to be selectively closed by an automatically operable contact closer which co-operates therewith, the contact closer being diagrammatically illustrated as a Bowden wire 100 adapted for operation asA the result of a function of the machine, for example from an accumulator or as the result of the sensing of a statistical record card. On closing of the normally open contact 98 and of the timing switch contacts 90, 91,' the relay 95 is energised thereby opening the normally closed contact 96 so that the selector electro-magnet 84, as appropriate, and as conditioned by the second switch 94, is energised via line 99 and switch 94. From Figure 8 it will be understood that at any given time only one of the

switches

93, 94 will be effective to condition a selector electro-magnet 84, and the arrangement is such that the switch 93 remains operative until the contact closer 100 eects closing of the normally open contacts 98. Between the normally closed contact 96 and cyclic timing switch there is provided a manually operable switch 101, and this switch is closed when it is desired that a selector electro-magnet 84 be operated cyclically through switch 93, except when the operation is varied by an automatic signal initiated by the contact closer 190. As can be seen from Figure 8, switches 93 and 94 are provided with positions enumerated 2 to 8, respectively, each of these positions indicating a given line spacing which is a multiple of theV tinue to feed paper at a constant linear speed. Thus it will be understood that if the normal line spacing is JA inch, by setting either of the

switches

93 or 94 to the number 2 position thereof the auxiliary driving means will be caused to function and produce a double line spacing, that is a spacing of 1A inch. Similarly, if a

switch

93 or 94 is set to the number 8 position thereof, the spacing between the lines thus effected will be equal to one inch.

The interposer actuating electro-magnet 74, which operates during each machine cycle when switch 101 or 98 is closed is, as can be seen from Figure 8, connected in parallel with the selector electro-magnets 84. Similarly, the interrupter electro-magnet 48 is connected in parallel with the electro-

magnets

74 and 84.

I claim:

l. Paper-feeding mechanism comprising continuously operable driving means co-operating with paper-feeding elements to effect continuous feeding of paper at a constant linear speed, normally inactive auxiliary driving means co-operating with said continuously operable driving means, and control means co-operating with said auxiliary driving means to effect operation thereof and said control means being operable automatically to determine by lwhich of a number of predetermined time intervals the auxiliary driving means shall co-operate with said continuously operable driving means to increase the rate of operation of the paper-feeding elements thereby to effect a temporary increase in the linear speed of paper fed by the paper-feeding elements to determine the spacing effected between successive lines of imprinting made on the paper.

2. Paper-feeding mechanism comprising a differential gear coupled with paper-feeding elements to effect operation thereof, continuously operable driving means cooperating with the differential gear to cause the paperfeeding elements to feed paper at a constant linear speed, a normally inactive rotatable gear wheel co-operating with the dilferential gear and adapted when operative to effect temporary increases in the linear speed of paper fed by the paper-feeding elements, a ratchet wheel connected with said gear wheel to effect rotation thereof, a

pawl to effect rotation of the ratchet wheel, and selectively operable control means co-operating with the said pawl to effect operation thereof and to determine the interval during which said gear wheel is rendered active to cause a temporary increase of the linear speed of paper fed by the paper-feeding element.

3. Paper-feeding mechanism according to claim 2, wherein the pawl is carried by a gear wheel which is freely rotatable about theaxis of the ratchet wheel and which meshes with a toothed rack supported for lengthwise movement to and from a datum position thereof by the control means.

4. Paper-feeding mechanism according to claim 3, wherein the control means includes a cam-operated multipivot crank the pivots for which determine the movement of the rack to and from the datum position thereof and which are selectively engageable with the crank in a manner such that on operation of the crank a selected one only of the pivots is operatively engaged with the crank.

5. Paper-feeding mechanism according to claim 3, wherein the control means includes a rack-actuating cam, a rack-actuating link operable by the cam and pivotally connected to one end of the rack and to a crank element adapted normally to pivot about a retractable neutral pivot pin the axis of which is co-incident with that of the pivotal connection between the rack and rack-actuating link `when the rack i-s in the datum position thereof, said crank element being provided with a plurality ot holes located in spaced relation on one side of and along a line radial to the axis of the neutral pivot pin, said holes when said pivotal axes are co-incident being aligned with retractable selectively operable secondary pivot pins any one of which can be inserted into the crank hole appropriate thereto thereby on withdrawal of the neutral pivot pin from the, crank element to determine the eX- tent of movement of the rack from the datum position thereof under control of the rack-actuating cam.

6. Paper-feeding mechanism according to claim 5, including inserter and retractor members appropriated to the neutral pivot pin and to the secondary pivot pins and operable in synchronism so that as a secondary pivot pin is inserted into or retracted from the crank hole approvpriate thereto the neutral pivot pin is retracted from or inserted into the crank hole provided therefor.

7. Paper-feeding mechanism according to claim 6, wherein operation of the inserter and retractor means is effected by an actuator lever common thereto and actuated by an inserter/retractor cam movable with said rackactuating cam, a selectively operable connector device being arranged to connect the actuator lever to the inserter/retractor cam for operation thereby.

8. Paper-feeding mechanism according to claim 7, wherein the connector device comprises an operating link pivotally connected at one end to a cam-follower arm and having its free end guided for lengthwise movement by the inserter/retractor cam, a latch pivoted to the free end of the operating link and spring-urged to an inactive position thereof, and an interposer movable relative to the latch and co-operating therewith to move it into latching relation with the actuator lever.

9. Paper-feeding mechanism according to claim 7, wherein the interposer comprises an interposer-actuating electro-magnet having a pivoted armature which on energisation of the electro-magnet is retained thereby in a fixed position to cause movement of the latch into latching relation with the actuator lever.

10. Paper-feeding mechanism according to claim 8, wherein the interposer comprises an interposer-actuating electro-magnet having a pivoted armature which on energisation of the electro-magnet is retained thereby in a fixed position to cause movement of the latch into latching relation with the actuator lever.

11. Paper-feeding mechanism according to claim 9, wherein each secondary pivot pin is insertable into the crank hole appropriate thereto by a selector lever appropriated thereto, each selector lever being pivoted on a selector link therefor and secured to a rocking spindle rockable by an actuator link connected to the actuator lever, said selector levers being spring-urged to inactive positions thereof and movable by selector elements to their active positions for co-operation with the pivot pins appropriate to the selector levers.

12. Paper-feeding mechanism according to claim 10, wherein each secondary pivot pin is insertable into the crank hole appropriate thereto by a selector lever appro priated thereto, each selector lever being pivoted on a selector link therefor and secured to a rocking spindle rockable by an actuator link connected to the actuator lever, said selector levers being spring-urged to inactive positions thereof and movable by selector elements to their active positions for co-operation with the pivot pins appropriate to the selector levers.

13. Paper-feeding mechanism according to claim 11, wherein each selector element comprises a normally deenergised selector electro-magnet having a pivoted armature provided with a guide face to co-operate with a tail on the. selector lever, said armature being retained in the selector lever-actuating position thereof only on energisation of the electro-magnet,

14. Paper-feeding mechanism according to claim 12, wherein each selector element comprises a normally de-energised selector electro-magnet having a pivoted armature provided with a guide face to co-operate with a tail on the selector lever, said armature being retained in the selector lever-actuating position thereof only on energisation of the electro-magnet.

15. Paper-feeding mechanism according to claim 13, including a cyclically operable timing switch in circuit 8 with the selector electro-magnets to effect energisation of a conditioned one thereof, a first and a second presettable switch independently manually operable to condition a selector electro-magnet for energisation on closing of the timing switch, a normally inactive relay interposed between the selector electromagnets and timing switch and having a normally closed contact connected with said first switch, a normally open contact connected with the relay and the second switch, and an automatically operable contact closer co-operating with said normally open contact to effect closing thereof thereby on closing of the timing switch to cause energisation of the relay and opening of the normally closed contact.

16. Paper-feeding mechanism according to claim 14, including a cyclically operable timing switch in circuit with the selector electro-magnets to effect energisation of a conditioned one thereof, a first and a second presettable switch independently manually operable to condition a selector electro-magnet for energisation on closing of the timing switch, a normally inactive relay interposed between the selector eiectro-magnets and timing switch and having a normally closed contact connected with said first switch, a normally open contact connected with the relay and the second switch, and an automatically operable Contact closer co-operating with said normally open contact to effect closing thereof thereby on closing of the timing switch to cause energisation of the relay and opening of the normally closed contact.

17. Paper-feeding mechanism according to claim 15, wherein the interposer-actuating electro-magnet is connected in parallel with the selector electro-magnets.

18. Paper-feeding mechanism according to claim 16, wherein the interposer-actuating electro-magnet is connected in parallel with the selector electro-magnets.

19. Paper-feeding mechanism according to claim 11, wherein a retractor plate common to all secondary ypivot pins is engaged with the pins and is connected to a retractor-actuating link for movement with the selector link.

20. Paper-feeding mechanism according to claim 12, wherein a retractor plate common to all secondary pivot pins is engaged with the pins and is connected to a retractor-actuating link for movement with the selector link.

21. Paper-feeding mechanism comprising a differential gear coupled with paper-feeding elements to effect operation thereof, continuously operable driving means co-operating with the differential gear to cause the paperfeeding elements to fee/.l paper at a constant linear speed, normally inactive auxiliary driving means co-operating with the differential gear and adapted when operative to effect temporary increases in the linear speed of paper fed by the feeding elements, and control means cooperating with the auxiliary driving means to effect operation thereof, said control means including selector electro-magnets one for each interval during which the auxiliary driving means is to be rendered temporarily operative, a cyclically operable timing switch in circuit with the selector electro-magnets to effect energisation of a conditioned one thereof, a first and a second presettable switch independently manually operable to condition a selector electro-magnet for energisation on closing of the timing switch, a normally inactive relay interposedbetween the selector electro-magnets and timing switch and having a normally closed contact connected with said first switch, a normally open contact connected with the relay and the second switch, and an automatically operable contact closer co-operating with said normally open contact to effect closing thereof thereby on closing of the timing switch to cause energisation of the relay and opening of the normally closed contact.

22. Paper-feeding mechanism comprising a differential gear coupled with paper-feeding elements to effect operation thereof, continuously operable driving means cooperating with the differential gear to cause the paper- 10 feeding elements to feed paper at a constant linear thereby to permit automatic selection of the extent of speed, a normally mactrve rotatable gear wheel co-operlinear movement of the paper under control of the gear ating with the dierential gear and adapted when operawheel.

tive to effect temporary increases in the linear speed of paper fed by the paplr-feegiding elemntsl, tandcontrol 5 References Cited in the me of this patent means co-operatmg w1 1 sax gear w ee o e ect rotation thereof, said control means being operable auto- UNITED STATES PATENTS matically to determine by which of a number of prede- 1,537,594 ElSWOl'h et al May 12, 1925 termined angular extents said gear wheel shall be turned 2,259,139 Oesinghaus Oct. 14, 1941