US 3721377 A
For variation of the lateral positions of pairs of paper tractors, each tractor is slidable on a separate rack which is itself axially slidable. Coarse adjustment is according to preset positions of the tractors on the racks. Fine adjustment is by driving both racks of a pair of tractors together or driving only one of those racks.
Description (OCR text may contain errors)
limited States Patent 1 1 Atkinson 1Mmt3l1 2@, i973 1 1 WEB 1F EEDING APPARATUS  Inventor: Cyril John Atkinson, Royston, En-
gland  Assignee: international Computers Limited,
London, England 22 Filed: Nov. 23, 1971 21 App1.No.:201,304
[30 Foreign Application Priority Data March 26, 1971 Great Britain ..08,235/71  US. Cl ..226/74, 226/179  lint. Cl. "5.116511 17/38.  Field of Search ..226/179, 74, 75
 Relerences Cited UNITED STATES PATENTS 3,448,906 6/ 1969 Walsh et al ..226/179 X 3,407,981 10/1968 Staugaard ..226/179 X 3,152,742 10/1964 Wright ..226/74 5/1971 Cantwell ..226/74 Primary Examiner-Allen N. Knowles Attorney-Plane, Baxley & Spiecens [5 7 ABSTRACT For variation of the lateral positions of pairs of paper tractors, each tractor is slidable on a separate rack which is itself axially slidable. Coarse adjustment is according to, preset positions of the tractors on the racks. Fine adjustment is by driving both racks of a pair of tractors together or driving only one of those racks.
5 Claims, 1 Drawing Figure WEB FEEDING APPARATUS BACKGROUND OF THE INVENTION The invention relates to web feeding apparatus having at least one pair of simultaneously drivable tractors for engaging opposite edges, respectively, of a web to be driven.
It is often desired to accommodate different web widths, for example in using different paper widths on a high-speed printer which will generally have two pairs of tractors one on each side of the printing position. Provision has been made previously to drive the tractors of each such pair separately for lateral adjustment.
SUMMARY OF THE INVENTION Rather than compromise sensitivity in providing for full traverse drive of the tractors of a pair, it is proposed herein to have direct manual tractor positioning in coarse steps with final, more delicate drive for fine adjustment using separate tractor supports. For the fine adjustment, it is also of advantage to allow for separating the operations of achieving the right spacing and the final positions of the tractors, if desired.
According to the invention there is provided web feeding apparatus comprising at least one pairof simultaneously driveable tractors for engaging opposite edges, respectively, of a web to be driven, each tractor being slidable on a different one of a pair of axially movable elongated members, means for locating each tractor at any one of a number of predetermined positions along its'associated elongated member, and drive means including a first coupling for producing similar axial movement of both said members together and a second-coupling for producing axial movement of one of said members separately.
Coarse positioning is according to the predetermined positions. Fine adjustment is by the second drive coupling for width, and by the first drive coupling for position.
Preferably the drive means includes arotatable axially movable shaft of which a first portion has spaced circular grooves and a second portion has a spiral groove the portions meshing with a cooperatingly cut first pinion and second pinion, respectively. Rack and pinion action at the second portion on rotation of the second pinion causes axial movement of the shaft which by rack-and-pinion action at the first portion, causes simultaneous rotation of the first pinion. This causes movement of both tractors. Straight out of the second pinion and cooperating second portion grooves allows rotation of the shaft to drive only the first pinion if the shaft is locked against axial movement.
BRIEF DESCRIPTION OF TI-IE DRAWING One embodiment willnow be described, by way of example, with reference to the drawing which shows, diagrammatically, a mechanism for simultaneously adjusting two pairs of tractors.
DESCRIPTION OF PREFERRED EMBODIMENT cooperating pulleys or sprockets at least one of which is keyed and driven bya splined shaft. In the drawing one such splined shaft is shown at M with a smooth shaft shown at for the other pulleys.
An identical pair of paper tractors for out-feed is shown with the same reference numerals primed.
The tractor band shafts 114, I5 and 114', 115' are rotatable in the machine frame at l6, 17. The splined shafts M, M have one end extending through the machine frame at E6 and carry fixed pulleys or sprockets 18, I8 driven by a cooperating notched belt or chain 19 from a suitable motor unit indicated at 20 and linked to the shaft 114 in any convenient way.
Printing will take place between the pairs of tractors.
The tractors of each pair are slidable relative to the tractor band shafts to permit adjustment to accommodate different widths of paper. Such sliding is also relative to a pair of elongated members, 21, 22 for the in-feed tractors and 21, 22' for the out-feed tractors.
Each of the elongated members or bars 21, 22 and 211' 22' is itself axially slidable in suitable mounts, for example in slots in the machine frame at 16 and 17.
Between the machine frame parts 16 and 117, where the tractors are, the bars 21, 22 and 21', 22 have positions 23 for locating an associated one of the tractors. The left-hand tractors 10, Ill) are located on the bars 22, 22', and the right-hand tractors Ill, 11' are located on the bars 21, 21.
The precise mechanism for effective location of a tractor at the cooperating positions 23 is optional. Slots, grooves or holes in the bars at the. positions 23 and a cooperative spring-loaded tooth or lever on the tractor releasable from the front or side of the tractor is envisaged. In every case, the positions 23 are such that each hand, left or right, of tractors can be aligned together during coarse positioning.
The bars extend at 21a, 22a, 21'a, 22'a beyond the machine frame part 117 and have toothed racks at those ends. To show the teeth of these racks an element of perspective is introduced in this part of the figure. It is .by means of these racks that the bars are slidable axially for fine positioning of the tractors.
Two couplings are provided for driving the racks, one for driving one rack only of each pair andv the other for driving both racks of each pair together and equally.
The former coupling is by way of the straight cut pinions 24, 25 fixedly mounted on a rotatable shaft 26. Rotation of the shaft 26 will thus cause movement of the bars 22 and 22' to adjust the position of the left hand tractors l0 and 10' only. This rotation of the shaft 26 is imparted by a worm-and-wheel action involving a spirally grooved portion 27 of a shaft 2% rotatable in the machine frame between parts 17 and 29. This spirally grooved portion 27 cooperates with a cooperatively cut wheel or pinion 30 fixed on the shaft 26. Conveniently, such drive is initiated by rotation of a knob 31 keyed to the shaft 28.
The other coupling utilizes another portion 32 of the shaft 28 that is straight cut with a plurality of parallel circular grooves. The shaft 28 is slidable axially in its mounts in the machine frame at 17 and 29 and such sliding will impart rotation to the shaft 26 by rack-andpinion action between the spirally grooved shaft portion 27 and the meshing wheel 39.
Such axial movement of the shaft 28 is imparted by rotation of a straight cut wheel or pinion 33 meshing with the shaft portion 32. The pinion 33 is keyed on a further shaft 34 rotatable by worm-and-wheel action involving another pinion 35 keyed to the shaft 34 and cut to correspond with a meshing spirally grooved portion 36 of a shaft 37 axially fixed but rotatable in the machine parts 17 and 29. Rotation of the shaft 37, say by a knob 38, therefore causes rotation of both of the shafts 26 and 34 at the same time.
The shaft 34 also has two more pinions 39, 40 keyed thereto. These are straight cut and mesh with the racks of the bars 21 and 21', respectively. Simultaneous rotation of the shafts 26 and 34 thus causes similar movement of both racks 21, 22 and 21', 22' associated with each pair oftractors 10, 11 and 11' respectively.
Axial movement of the bars 21, 22 and 21', 22' should allow adjustment in either direction at least as far as the next of the positions 23. The clearance for permitted movement at the ends of the bars is sufficient to permit this. It may prove useful in practice to allow adjustment for two of the positions 23 in either direction, without requiring that the grooved portions 27 and 32 of the shaft 28 are undesirably long.
For the worm-and-wheel action between the portion 27 and the pinion 30 to effect movement of the lefthand tractor only, the shaft 28 requires locking against axial movement. Those components of reaction to rotation of the shaft 26 from the pinions 24 and will be about equal to those from pinions 39 and 40 in respect of rotation of the' shaft 34. Assuming comparability of the respective reaction components from pinions and 32, it is clear that if the reaction due to inefficiency from the pinion is high enough, the shaft 28 should be locked.
Alternatively or additionally,-suitable forms of braking or clutching may be incorporated for the shaft 28 and/or others of the illustrated shafts.
Bearings for mounting the shafts 26 and 34 for rotation may be at extensions of those shafts beyond the pinions 24, 30 and 39, 35 and/or above the rack bars for each pair of tractors.
The knob 31 is keyed to the shaft 28 by means of a pin 41 on the shaft and a slot 42 in the knob to allow sliding of the shaft relative to the knob.
1. Web feeding apparatus comprising at least one pair of simultaneously drivable tractors for engaging opposite edges, respectively, of a web to be driven, each tractor being slidable on a different one of a pair of axially movable elongated members, means for locating each tractor at any one of a number of predetermined positions along its associated elongated member, and drive means including a first coupling for producing similar axial movement of both said members together and a second coupling for producing axial movement of one of said members separately.
2. Apparatus according to claim 1, wherein the drive means includes a rotatable axially movable shaft of which a first portion has spaced circular grooves and a second portion has a spiral groove the portions meshing with a cooperatingly cut first pinion and second pinion, respectively.
3. Apparatus according to claim 2, comprising means for locking said shaft against axial movement when it is rotated. h
4. Apparatus according to claim 3, wherein said means for locking comprises a geared drive coupling of predetermined inefficiency to a rotatable drive shaft bearing the second pinion.
5. Apparatus according to claim 4, wherein said drive shaft and another drive shaft bearing the first pinion each have a pinion meshing with a toothed rack portion of said other and said one of the elongated members, respectively.