Roll′er.
1. (Husbandry.) A clod-crusher or ground-leveler. An implement of a cylindrical form to roll over arable ground to break clods, cover seed, and press in plants which are thrown out of the ground by frost. The roller is mentioned as an implement for breaking the clods of arable ground by Googe, in his “Heresbachius,” published in 1578.
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| Land-roller. |
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| Land-roller. |
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| A, cutting-roller; b, clod-crusher. |
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| Harrow and roller. |
3. (Nautical.) A cylindrical anti-friction bar which revolves as a hawser or rope traverses against it, and thus saves the rope from wear.
4. (Ordnance.) a. A cylinder of wood, used as a winch in mounting and dismounting guns. b. For mechanical maneuvers in the ordnance department, rollers are used for mounting and dismounting cannon, or for transporting them to short distances. Long and short rollers are circular in section, being slightly hollowed out at their midlength, the better to prevent the gun from slipping off. The half-roller is semicircular in section, but is similarly hollowed out on top.
5. (Metal-working). A circular object in a machine acting as a carrier, as a cutter, as a die, as an impression-cylinder, or as a flattener, e. g., a. The carrier has an example in the rotating bearers on which the bed of a printing-machine traverses. It is common in other machines also, as the drawing rollers of spinning-machines, the fancy rollers and fly rollers of scribbling-machines, the tinsel roller of a lace-machine. b. The cutter is shown in some forms of rotary shears and slitting-machines, in which the edge of a roller laps past another roller or a plate and makes a shear cut. c. The die is found in the hub or roller die of the bank-note engraver's transferring-machine (Fig. 4403). Examples are also to be seen in many kinds of embossing-machines. d. The impression-cylinder is found in copperplate printing-presses, some forms of printing-machines, and in calico-printing machines. e. The flattener is found in rolling-mills, etc.
6. (Hardware.) A broad-faced wheel having gudgeons, and used as an anti-friction device to facilitate transportation of the object resting upon it. A caster. May be cited, —
| Barn-door roller. | Sash-cord roller. |
| Chest-roller. | Trunk-roller. |
7. (Music.) The studded barrel of the musical box or chime-ringing machine.
8. (Stationery.) A rolling blotter. 9. The printer's inking-cylinder. A cylinder of wood covered with a composition of glue and molasses, which is poured around it in a mold. The cylinder revolves on an iron axis as the roller runs over the face of the form. 10. Paper-making machines require cylinders of great accuracy, and their preparation involves several processes. Abradants are dispensed with, and the required accuracy of contact is attained by the friction of the surfaces of the rollers on each other, water being plentifully supplied to prevent their heating and tearing each other. They are first turned as truly cylindrical as possible in the lathe, and tested for parallelism by a thin copper wire applied around the circumference at various parts. The journals are turned at the same time to insure their concentricity with the cylinder. They are then mounted on their own bearings in a frame similar to that in which they are to be employed, and their surfaces carefully adjusted to each other, the bearings of one being fixed, and those of the other provided with a screw adjustment, so that they may be closed upon each other until their highest points just touch. They are then examined to see how they correspond to each other. Having been turned in the same lathe, their errors are usually alike, that is, they are either both convex or both concave; long rollers generally have the latter defect, in consequence of the middle part of the slide being more worn from turning short pieces of work. When there is a considerable want of correspondence between the two it is reduced by grinding each separately with a lead grinder mounted on the end of a long lever and supplied with emery. When reduced nearly to correspondence with each other, they are adjusted so as to revolve in contact, and the face of one is marked with chalk lines at intervals of a few inches; the manner of transferrence of these from one to the other indicates which parts do and which do not come in contact. The projecting parts are then farther ground away. When all the lines are transferred with considerable regularity, showing that the two surfaces nearly fit each other, they are adjusted by bringing their highest points into contact, and are then, by belt and pulley connections, caused to revolve in opposite directions and at different speeds, a constant stream of water being meanwhile directed upon them. By this means fresh points on each are continually brought in contact with each other, causing an equal and uniform abrasion, and gradually reducing both to a truly cylindrical surface. As the most projecting parts are gradually brought into correspondence, the two are pressed together by the adjusting screws, bringing a greater proportion of their surfaces into contact, and the operation is thus continued until both are gradually reduced to their true form, care being taken to avoid too great friction between them, which might heat and tear the surfaces. The process is tedious, and requires several days for its completion. See also Fig. 4405. Sometimes the rollers are ground under a pressure equal to that which they will have to sustain when at work, in order to ensure their not bending when actually required to perform their duty in the machine. In this case the two are driven in the same direction, but with slightly differing velocities.
11. (Saddlery.) The broad, padded surcingle used as a girth to hold a heavy blanket in its proper position, generally made of twilled web with leather billets and chapes.
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| Roller-barrow. |
