A Dictionary of Arts, Manufactures and Mines / containing a clear exposition of their principles and practice

by Andrew Ure

The bearings of the cylinders D and E are lodged also in slots of the frame A, which point obliquely upwards, towards the centre of B. The pressure of these two print cylinders C and F is produced by two screws c and d, which work in brass nuts, made fast to the frame, and very visible in the figure. The frame-work in which these bearings and screws are placed, has a curvilinear form, in order to permit the cylinders to be readily removed and replaced; and also to introduce a certain degree of elasticity. Hence the pressure applied to the cylinders C and F, partakes of the nature of a spring; a circumstance essential to their working smoothly, on account of the occasional inequalities in the thickness of the felt web and the calico.

The pressure upon the other two print cylinders D and E is produced by weights acting with levers against the bearings. The bearings of D are, at each of their ends, acted upon by cylindrical rods, which slide in long tubular bosses of the frame, and press with their nuts g at their under end upon the small arms of two strong levers G, which lie on each side of the machine, and whose fulcrum is at h (in the lower corner at the left hand). The long arms of these levers G, are loaded with weights H, whereby they are made to press up against the bearings of the roller D, with any degree of force, by screwing up the nut g, and hanging on the requisite weights.

The manner in which the cylinder E is pressed up against B, is by a similar construction to that just described. With each of its bearings, there is connected by the link k, a curved lever I, whose fulcrum or centre of motion is at the bolt l. To the outer end of this lever, a screw, m, is attached, which presses downwards upon the link n, connected with the small arm of the strong lever k, whose centre of motion is at o. By turning therefore the screw m, the weight L, laid upon the end of the long arm of the lever K (of which there is one upon each side of the machine), may be made to act or not at pleasure upon the bearings of the cylinder E.

In tracing the operation of this exquisite printing machine, we shall begin with the first engraved cylinder C. Its bearings or bushes shift, as was already stated, in slots of the frame A. Each of them consists of a round piece of iron, to which the end of the screw c is joined, in the same way as at d, in the opposite side. In each of these iron bearings, a concave brass is inserted to support the collar of the shaft, and in a dovetailed slit of this brass, a sliding piece is fitted, upon which a set or adjusting screw in the iron bearing acts, and which, being forced against the copper cylinder C, serves to adjust the line of its axis, and to keep it steady between its bearings, and true in its rotatory motion. Upon the iron bearing a plate is screwed, provided with two flanges, which support the colour trough q, and the colour roller M. This trough, as well as the others to be mentioned presently, is made of sheet copper in the sides and bottom, and fixed upon a board; but its ends are made of plates of cast copper or gun-metal to serve as bearings to the colour roller M. The trough and its roller may be shifted both together into contact with the printing cylinder C, by means of the screw r. Near s, seen above the roller, C, and t below it, are sections of the two doctors, which keep the engraved cylinders in sound working condition; the former being the colour doctor, and the latter the lint doctor. Their ends lie in brasses, which may be adjusted by the screws u and V, working in the respective brackets, which carry their brasses, and are made fast to the iron bearings of the cylinder.

The pressure of the colour doctor is produced by two weights w (see high up on the [frame work]), which act on a pair of small levers x, (one on each side of the machine,) and thus, by means of the chains, tend to lift the arms y, attached to the end axles of the doctor. The pressure of the lint doctor upon the cylinder C, is performed by the screw z, pressing upon an arm which projects downwards, and is attached to the axle of that doctor.

The bearings of the second printing cylinder D, consist at each end of a mass of iron (removed in the drawing to show the mechanism below it), which shifts in the slanting slot of the frame A. In each of these masses there is another piece of iron, which slides in the transverse direction, and may be shifted by the adjusting screw a′ fixed to it, and working in a nut cast upon the principal bearing above described. To the inner bearings, which carry the brasses in which the shaft lies, are screwed the two curved arms b′ b′ to which are attached the bearings, &c., for the colour trough, and the doctors. In these brasses there are also dovetailed pieces, which slide and are pressed by set screws furnished with square heads in the iron secondary bearings, which serve, as before said, to adjust the printing cylinder in the line of its axis, while other screws adjust the distance of the cloth upon which the second colour is printed, and the line of contact with the cylinder B.

N, is the colour roller of D, and d′ the colour trough, which rests by its board upon the lever e′; whose centres of motion f′, are made fast to the curved arms b′, fixed at the bearings of the cylinder, and whose ends are suspended by screws g′; whereby the colour roller N, may be pressed with greater or less force to the cylinder D. h′ and i′ are the two doctors of this cylinder; the former being the colour, the latter the lint doctor. They rest, as was said of the cylinder C, in brasses which are adjustable by means of screws, that work in the studs or brackets by which the brasses are supported. These brackets must of course be screwed to the secondary bearing-pieces, in order that they may keep their position, into whatever direction the bearings may be shifted. k′ and l′ are these set screws for the colour and lint doctors. The pressure of the former upon the cylinder D, is produced by weights m′, acting upon levers n′, and pressing by rods or links o′, upon arms attached to each end of the axis of the doctor. (See the left hand side of the [figure] near the bottom). The lint-doctor i′, is pressed in a similar way at the other side upon the cylinder D, by the weights acting upon levers p′, and by rods q′ upon arms fixed at each end of the axis of the doctor.

The bearings of the third printing cylinder E, are of exactly the same construction as that above described, and therefore require no particular detail. The lint doctor s, is here pressed upon the engraved cylinder by screws t′, working in the ends of studs or arms fixed upon each end of the axis of the doctor, and pressing upon flanges cast upon the brackets in which the brasses of the doctor’s axis lie, which are made fast to the bearings of the cylinder E.

The bearings of the fourth copper cylinder F, are also constructed in a similar way. Each consists of a first bearing, to which is joined the end of the screw d, by which it is made to slide in a slot of the frame. Another bearing, which contains the brass for the shaft of the cylinder, can be shifted up and down in a transverse direction by a screw z′, of the second bearing, working in a nut cast upon the first bearing. To this secondary bearing, plates are made fast by the screws v′ v′ to the inside, to carry the studs or brackets of the doctors x′ and y′. In the brasses of the cylinder shaft, dovetailed pieces are made to slide, being pressed by set screws w′, against the engraved cylinder F, similar to what has been described for adjusting the cylinders to one another. This cylinder has no separate colour roller, nor trough, properly speaking, but the colour doctor y′ is made concave to serve the purpose of a trough in supplying the engraved lines of the cylinder with colour. With this view the top plate of the doctor is curved to contain the coloured paste, and it is shut up at the ends by pieces of wood made to fit the curvature of the doctor. Its pressure against the engraved surface is produced by weights a′′, acting at the ends of arms b′′, attached to the ends of the axis of the doctor. The pressure of the lint doctor x′ is given by screws c′′, working in arms attached to the ends of the axis of the doctor, and pressing upon the flanges d′′, cast upon the brackets which carry the brasses for the axis of the doctor. These brasses are themselves adjustable, like those of all the other cylinders, by set screws in the brackets, which work in the nuts formed in the brasses.

e′′ e′′, is the endless web of felt stuff which goes round the cylinder B, and constitutes the soft elastic surface upon which the printing cylinders C, D, E, and F exercise their pressure. This endless felt is passed over a set of rollers at a certain distance from the machine, to give opportunity for the drying up of any colouring paste which it may have imbibed from the calico in the course of the impressions. In its return to the machine in the direction of the arrow, it is led over a guide roller o, which is thereby made to revolve. Upon the two ends of this, and outside of the bearings which are fixed upon the tops of the frame A, are two eccentrics, one of which serves to give a vibratory traverse movement to the colour doctors s′, h′, and r′ of the three cylinders, C, D, and E whilst the other causes the colour doctor y′ of the cylinder F, to make lateral vibrations.