Read Ebook: A practical treatise on coach-building historical and descriptive by Burgess James W

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For this work the draughtsman requires a drawing-board and T square, and two set squares; as he never has to prepare very large drawings, a board of imperial size will be amply sufficient, and the T square to have a corresponding length of blade. T squares are made of a variety of woods, but the most serviceable is one made of mahogany, with an ebony edge; the most important consideration being that the edge should be truly "shot" from end to end. The set squares should either be vulcanite or skeleton mahogany with ebony edges; the latter are preferable, as they work more cleanly than the vulcanite, which, unless kept very clean, are apt to make black smears across the drawing. In order to fasten the paper down to the drawing board, drawing pins will be required; they are simple pins of iron or steel, with a large flat brass head; four is the number required for each sheet of paper, one at each corner. A very much better way to fix the paper down is to "strain" it to the board. It is done in the following way:--The sheet of paper to be fastened down is thoroughly well wetted, by means of a sponge or large flat brush, on one side ; it should then be left for five or ten minutes for the water to well soak into the pores of the paper; when this is done, the paper will be quite limp. Now take a perfectly clean straight edge, or the back edge of the T square, and turn up one of the edges of the paper 1/4 or 1/2 an inch against it; along this edge run a brush charged with glue from the glue pot, or a piece of ordinary glue dipped into boiling water and rubbed along the edge will do just as well, and when you think there is enough sticky matter to promote adhesion between the paper and the board, turn the edge of the paper back on the board , and quickly rub it with the tips of the fingers until it goes down flat all along without any air bubbles: do this to all four edges of the paper, and place in a perfectly flat position to dry; and if the operation has been carefully conducted the paper will be beautifully flat to draw upon, and there can be no fear of its shifting. When the drawing is finished, all that has to be done is to cut round the edges of the paper just inside the glued edge, and take it off. A little hot water will take off the glued strip, and take care to wash all the glue off at the same time, otherwise a smaller piece of paper might stick in some important part, and the drawing spoilt in order to detach it.

The draughtsman will do well to have a few French curves, for drawing the "sweeps" or curved lines of the carriage bodies, and scales of various sizes, which are slips of boxwood or ivory, on which are marked at the edges various scales, from ?/??th of an inch to a foot up to 3 inches to a foot; and last, though not by any means least, a good box of compasses or mathematical instruments. We shall not discuss the merits of the various kinds of instruments here, but any one wishing to go into the matter may do so by reading "Mathematical Instruments" in Weale's Series. But we should strongly advise the draughtsman to go to some good maker, as bad drawing instruments only lead to bad drawing.

The drawing paper used should be of a kind having a slight gloss on the surface, like "hot-pressed" paper, but without its granular texture. This kind of paper is usually called a "board," as Bristol board, and kept in various sizes, and sold by all colour dealers. Various names are given to it, but it is all pretty nearly alike.

The paper being fastened, the drawing is commenced by drawing the ground line A ; from that set off the height that the body is to be from the ground, indicated by the dotted line B, and draw the line C, which is the depth of the rocker. This latter is the real bottom of the vehicle, and from it is measured the height of the seat, about 12 inches, shown by the dotted lines on the body. Then from the seat measure 42 inches, the length of the roof D. Lay off 23 inches for the width of the door, and draw E and F. From F measure 28 inches, the depth of the back quarter G, and from E measure 25 inches, which will give the front quarter H. Now the curves or sweeps of the body can be put in by means of French curves. From the hinge pillar measure 26 inches, shown by dotted line I, and this is the centre of the hind wheel, which is 4 feet 3 inches high. The spring is 1 1/4 inches thick, and consists of 5 plates 42 inches long. The opening between the springs is 12 1/2 inches, the lower one being clipped beneath the axle. Measure 12 1/2 inches from the underside of the axle, which will give the underside of the top spring. 1 1/4 inches must also be allowed for the back bar J, and the pump-handle K will be 1/2 an inch thick. Then draw the boot L in such a position that the front wheels will lock or turn under it freely. This may be found by drawing a plan of the wheel as shown, and with the centre of the lock bolt produced to N, strike the lines M, and it will be seen that the wheels will just clear the body, which is all that is necessary. From this it will be noticed that the centre on which the fore carriage turns is not in the same plane as the axle. This is more particularly discussed in the chapter on wheel-plates. The front wheel is 42 inches high, the springs the same size as the back springs. The draught may be now completed from Fig. 7, after having settled on the various heights and sizes, and can be inked in with Indian ink. The dotted lines, being merely constructional, are rubbed out when the drawing is inked in. To complete the drawing, the spokes of the wheels must be shown. These should be neither too many nor too few, but there is no rule which regulates their number, except that there should be two to each felloe. Having inked the parts in and cleaned the pencil lines off, the drawing is ready to be coloured. The colours applied to the drawing are the same as will be used for painting the carriage, so we shall not detail them here.

From this drawing is constructed the full-size draught, which is prepared before a tool is touched. On the walls of the body-making shop are large black-boards, 10 or 12 feet square, and on these the draughts are prepared just in the same way as described for the scale drawing, except that all the heights are marked up a vertical line which runs through the centre of the doorway, and from this the various widths are also set off. This and the ground line are the first two lines drawn, and it is imperative that they should make a perfect right angle with each other, otherwise the draught will not be true, and the material worked from it will be wasted. This full-sized draught requires the greatest care in preparation, as all the patterns to which the materials are cut or shaped are taken from it, even to the smallest parts.

The full-size draught also differs from the scale draught, inasmuch as all the details of the construction of the vehicle are shown as in the accompanying cut , which shows the construction of a small doctor's brougham, and Fig. 9, which shows the construction of a landau. This latter is a representation of the working draught for the vehicle, and, in fact, is a reduced copy of what would be drawn upon the black-board in the shop, except that some of the minor details are omitted to avoid confusion.

VARIOUS MATERIALS USED IN COACH-BUILDING.

The materials employed in coach-building number a great many: various kinds of wood--ash, beech, elm, oak, mahogany, cedar, deal, pine, &c.; hides, skins, hair, wool, silk, glue, whalebone, ivory, &c.; iron, steel, copper, brass, lead, tin, glass, &c.

Beech is sometimes used by carriage-builders and by wheelwrights, on account of its cheapness; but it is very liable to warp and rot, and consequently unworthy of the attention of the conscientious manufacturer.

Elm is largely used for planking where strength is required. The grain is wavy, hard to work, brittle, and apt to split without care. It is not a good surface to paint on, as the grain shows through several coats of colour. It is also used for the naves or stocks of wheels.

Mahogany is largely used for panels, as when painted it shows a very even surface. There are two kinds, the "Spanish" and the "Honduras." The former is unfit for the purposes of the carriage-builder. It is heavy and very difficult to work, requiring special tools for this purpose, as the edges of ordinary tools are rapidly destroyed by it. The Honduras is very much lighter and cheaper than Spanish, and the grain and colour more even. It takes the sweeps and curves required for body-work very easily. It can be procured up to 4 feet in width, straight-grained, and free from knots and blemishes.

A coarse-grained species of cedar is brought from the same district as Honduras mahogany, and is sometimes used for panels which have to be covered with leather, &c. Its extreme porosity renders it unfit for the application of paint.

Deal is largely used for the flooring of carriages, and for covered panels, and for any rough work that is not exposed to great wear and tear.

The wide American pine is chiefly used in very thin boards to form the covered panels and roofing of carriages.

Lancewood is a straight-grained, elastic wood, but very brittle when its limit of elasticity is reached. It comes from the West Indies in taper poles about 20 feet long and 6 or 8 inches diameter at the largest end. It was formerly much used for shafts, but since curved forms have been fashionable it has fallen into disuse. It can be bent by boiling, but is a very unsafe material to trust to such an important office as the shafts.

American birch is a very valuable wood for flat boarding, as it can be procured up to 3 feet in width. It is of a perfectly homogeneous substance, free from rents, and with scarcely a perceptible pore. It works easily with the plane and yields a very smooth surface, and the grain does not show through the most delicate coat of paint. Its chief disadvantage is its brittleness, which will not permit of its being used for any but plane surfaces, and some care is required in nailing and screwing it.

Hides are used chiefly for coverings, but also in some parts strips are used for the purposes of suspension. The hides are those of horses and neat cattle. For covering they are converted into leather by the action of oak and other bark. They are afterwards smoothed and levelled by the currier, and sometimes split into two equal thicknesses by machinery. They are then rendered pliable by the action of oil and tallow, and finished to a clear black or brown colour as may be required. This is called dressed leather. For some purposes the hides are merely levelled, put on wet to the object they are intended to cover, and left to shrink and dry. Others are covered with a coat of elastic japan, which gives them a highly glazed surface, impermeable to water; in this state they are called patent leather. In a more perfectly elastic mode of japanning, which will permit folding without cracking the surface, they are called enamelled leather. They are generally black, but any colour desired may be given to them. All this japanned leather has the japan annealed, somewhat in the same mode as glass. The hides are laid between blankets, and are subjected to the heat of an oven raised to the proper temperature during several hours.

The skins used are those of the sheep and goat. The former are converted into leather by the action of oak bark. In one form of dressing them they are known as basil leather, which is of a light brown colour and very soft. Sometimes they are blacked, and occasionally japanned like the hides. In all these forms sheep skins are only used for inferior purposes, as mere coverings, where no strength is required.

Goat skins are used in the preparation of the leather known as "Spanish" and "Morocco." They are not tanned in oak bark like other leather, but very slightly in the bark of the sumach-tree. They pass through many processes previous to that of dyeing, for which purpose they are sewn up with the grain outwards and blown out like a bladder. This is to prevent the dye from getting access to the flesh side. This beautiful leather was originally manufactured by the Moors, who afterwards introduced the process into Spain, by which means it came to be known under two names. The English have greatly improved on the manufacture, so much so that few others can vie with it. These skins are used for the inside linings of carriages.

Hair is used as an article of stuffing. To give it the peculiar curl which renders it elastic, it is forcibly twisted up in small locks, and in that state baked in an oven to fix it. Horse-hair is the best, being the strongest and longest; but various other kinds are used. Sometimes it is adulterated with fibres of whalebone. Doe-hair is also much used as an article for stuffing, but as it is very short it cannot be curled, and there is not much elasticity in it.

Wool in its natural state is not used for carriage purposes. In the form of "flocks," which are the short combings and fibres produced in the process of manufacturing it, it is very largely used for stuffing. In its manufactured state wool is used in great quantities, as cloth, lace, fringe, carpeting, &c.

The iron used is that known as wrought iron. To judge of its quality break a piece over the anvil; if it breaks off brittle it is of no use for the purposes it is required for. If it is good wrought iron the fracture will present a bluish, fibrous, silky texture, without any crystalline portions. Inferior iron will either appear bright and glistening or dull and greyish in tone at the fracture.

It may also be tested by bringing it to a red heat and bending it, when any flaws, &c., will at once become apparent.

Cast iron is also used in the shape of axle-boxes.

Great quantities of wrought iron are used in the construction of modern carriages. One of the best qualities is that known as the "King and Queen," so called from its brand. This iron is manufactured from pieces of old iron, called scrap iron, which are placed in furnaces and welded under a heavy tilt-hammer, after which it is passed between rollers and converted into bars.

Steel also enters largely into carriage construction in the shape of springs, &c. Axles are made of Bessemer steel, and are found to wear very well. Steel consists of iron in which is combined a large proportion of carbon; the more carbon the higher the elasticity of the steel. If steel is over-heated, it gives up a portion of its carbon and approaches once again its original form of iron.

POINTS TO BE CONSIDERED BEFORE COMMENCING THE CONSTRUCTION OF A CARRIAGE.--COMPONENT PARTS OF THE BODY.--SMITH'S WORK.--GLUE.

As previously remarked the vehicle is divided into two parts--the carriage and the body. After the drawing or draught is carefully worked out to full-size on the black-board in the shop, with all the curves and sweeps developed, and shown in elevation and plan, patterns or templates are made from the draught, and from these the construction of the body proceeds.

In commencing the construction of a vehicle there are several things to be borne in mind; such as the purpose to which the vehicle is to be applied, the size of horses to draw it, and other considerations arising from these two. It is popularly believed that the shorter the carriage the lighter it will run; in ascending an incline this may be true, but on ordinary level ground a long carriage and short one must be alike in friction, provided the total amount of weight and other circumstances be equally balanced.

Another consideration is the height of the wheels. On level ground, draught is easiest when the centre of the wheel is a little lower than the point of draught, viz. the point where the traces are affixed to the collar; but this in practice would be found rather inconvenient, as very high wheels would be required, and consequently the height of the whole vehicle would have to be increased, causing great trouble and annoyance in getting in and out of the vehicle, and the driver's seat would have to be raised to a corresponding height. Under equal circumstances a high wheel is more efficient than a low one, and requires less power to draw it; though it may be mentioned that a low wheel on a good and level road will do its work far better than a very much higher wheel on a rougher road. The sizes of the wheels of two-wheeled vehicles vary from 3 feet to 4 feet 6 inches.

It would be a very good thing if four-wheeled vehicles were to have the wheels of equal size, in order that the friction and power might be equal. But with the present mode of construction this is an impossibility, as we have only one mode of making the lock or turn. Therefore the height of the fore wheels must be regulated by the height at which the body hangs, so that the wheels may pass beneath it without striking, when the springs play. In practice this height varies from 2 feet to 3 feet 8 inches, according to the kind of carriage the wheels are intended for. The hind wheels vary from 3 feet to 4 feet 8 inches.

The next point is the dishing of the wheel, which is necessary for strength to take the strain off the nuts, to throw off the mud and prevent it clogging either the wheel or the body, and to give greater room for the body between the wheels without increasing the track on the ground. Whatever be the amount of dishing or coning, which varies from 1 1/2 to 2 1/2 inches, one rule should always be observed, viz. so to form the wheel that when running the lower spokes should maintain a true vertical position both in the fore and hind wheels. This is mainly accomplished by the dip of the axle, but if the fore and hind wheels have the same dish, they will take the same track along the ground. The dish of a wheel will be understood by referring to Fig. 10, in which it will be seen that the extremities of the spokes are not in the same plane, thus forming a dish or hollow in the surface of the wheel.

Some ingenious persons have deduced from the foregoing that a wheel runs best on an axle having a conical arm , in which case the axle would not dip, but the wheel would be put on to a perfectly horizontal axle. The motion of a wheel thus placed would be anything but artistic, though there would not be so much friction on an arm of this sort as on an arm of the dipped axle. Dipping the axle is shown at Fig. 10. It merely consists in bending it so far out of the horizontal as to give the lower spokes a vertical position. But in practice this theory of the conical arm will not answer, inasmuch as curving the arm will reduce the front bearing surface so much that the oil would be squeezed out, and it would run dry, and the total amount of friction would be greatly increased. Long practice has shown that a cylindrical or slightly conical arm is the best that can be used.

We have now to settle the form, combination, and proportion of the springs. Springs which are laid on the axle at right angles have to carry the whole of the weight of the carriage, save only the wheels and axles. Where other springs are used in addition it is not necessary that the axle-springs should have much play. It will be sufficient to give them just so much play as will intercept the concussion caused by moving over a road. The strength of the springs must of course be adjusted to the weight they have to carry, for it is evident that if they be made sufficiently elastic to carry the weight of six persons, they will be found hard if only three enter the carriage. This is a disadvantage all carriages must labour under, for it is ridiculous to suppose that if a carriage is constructed to hold six that number will always want to use it at the same time. There would seem to be room for some improvement in the way of introducing springs adjustable to any weight, though, to give spring-makers their due, they do turn out really a first-class article in this respect; this is more noticeable because it is so recent. Light carriages are never so easy to ride as heavy ones, even when the springs are well adjusted, because on meeting with an obstacle there is not a sufficient resistance to the bound or jerk upwards of the spring, which makes riding in a light carriage over a rough road rather unpleasant.

The position of the front wheels next demands attention. As these have to turn under the body it requires some skill to fix them, and the play of the springs, the height of the axletree, and the height of the arch have all to be considered. This will be more particularly described when dealing with wheel-plates.

The rule for the height of the splinter-bar, to which the traces or shafts are fixed, is that it should fall on a line drawn from the horse's shoulder to the centre of the hind wheel. This, however, is not always convenient in practice, as the fore wheels regulate the height of the framing of the under carriage, to which the splinter-bar is fixed. The distance of the splinter-bar from the central pin, on which the wheel-plate and fore carriage turn, is regulated by the size of the wheels and the projection of the driving seat footboard.

All the above particulars are considered when setting out the full-sized draught, and all points capable of delineation are put on the board in some convenient part. In Fig. 9 the outline is simply given, as to show everything would only confuse the reader. Such other details as are required are filled in after the draught has reached the stage shown in the figure.

It is most necessary for the safe conduct of a coach and carriage builder's business that there should be a goodly stack of well-seasoned timber of the various kinds required, otherwise great trouble and vexation will arise in the course of business from a good piece of timber being perhaps spoilt in working, and there not being another piece in the factory to replace it.

Where there is sufficient accommodation it is usual for makers to season their own timber in specially constructed sheds, which are kept from bad weather, but at the same time thoroughly well ventilated. In these the timber is stacked, with small fillets between each plank or board, to insure a free current of air circulating all round. One year should be allowed for seasoning for every inch of thickness in the timber, and none should be used in which this rule has not been observed.

Thin portions of timber, such as panel stuff and the like, should be treated in the same way, and in addition the ends should be secured to prevent splitting. The panel stuff undergoes another process of seasoning after it is planed up; in fact, all the thin timber required for roofs, sides, &c., does. And about the first thing done in commencing to build a carriage is for the body-maker to get his thin stuff ready, as far as planing it up goes, and then to put it aside in some moderately dry place, with slips of wood between each board to allow a circulation of air round them. The other stuff that is likely to be required should also be selected and put aside. If all these things be strictly attended to, there is not likely to be much trouble about bad joints; and it will be to the employer's interest to look after such workmen who have not enough scientific knowledge to see the reason of things themselves, and put them in the right direction. But an intelligent workman will soon appreciate the advantage of getting his stuff ready at the commencement, instead of waiting till he wants to use it.

The parts composing the body may be thus enumerated:--

The frame or case.

The doors.

The glasses, which are fixed in thin frames of wainscot, covered with cloth or velvet. It is a very good thing to have india-rubber for these to fall on, and little india-rubber buffers would prevent them from rattling.

The blinds, which are sometimes panel, but more generally Venetian, so adjusted with springs that the bars may stand open at any required angle.

The curtains, of silk, which slide up and down on spring rollers.

The lining and cushions, of cloth, silk, or morocco, as the case may be, ornamented with lace, &c. The cushions are sometimes made elastic with small spiral springs.

The steps, which are made to fold up and fit into recesses in the doors, or in the bottom, when they are not in use.

The lamps, which are fixed to the fore part of the body by means of iron stays.

The boot, on which is carried the coachman's seat.

In carriages suspended from C springs we have in addition:--

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