The History of Coaches

by George Athelstane Thrupp

There has been much controversy about the difference in the length of the front and hind axle-trees. It has been usual to make no greater difference than will allow the higher wheel to follow in the same track as the lower. In France it has been the practice, from the year 1846, to make the front axle-tree of broughams six inches shorter. The object has been to allow the front wheel to be placed nearer to the body. As the front wheel of a brougham must turn entirely in front of the body, the additional gain of three inches was very desirable. Some English Coachbuilders have followed the example of the French. There is a decided gain. The eye is pleased with the proportions. The horse is eased, and upon hard roads the difference of track is of no consequence. On the other hand, in country roads, the well-worn ruts make the running of the carriage uneasy, whilst in town the driver often forgets that the curbstones will strike his hind wheels sooner than the front wheels, and lastly more mud is thrown upon the panels. It is probable that the French style will not find favour.

In coaches built in 1750 it was customary to lower the hind part of the inside seats about two inches, by degrees this was changed to a level seat; recently the seat has been again lowered behind, and the back squabs made more upright than formerly. The height of the top of the cushion to the bottom of the body has varied during the same period from fourteen to eighteen inches. These slight changes belong more to the taste of the individual who uses the carriage. It is useless to lay down any general rule on these subjects.

If carriages had always to move along perfectly smooth roads, such as a tramway of wood, iron, or stone, the use of wheels in overcoming friction would be their sole utility, and the height of the wheels would be of small consequence. But as carriages are drawn along roads with loose stones and uneven surfaces, wheels are further useful in mounting over these obstacles, and it is plain that a high wheel does this more easily than a low one. To demonstrate this, let us suppose a shallow ditch or gulley of a foot wide and two inches deep, a wheel two feet high would sink into this and touch the bottom, but a wheel three feet high would only sink an inch, and a wheel four feet six inches high would sink only half an inch, on account of their greater diameters. Consequently, whilst the large wheel would have to be lifted by force of pulling only half an inch, the smallest wheel must be lifted two inches, and with the wheel must also be lifted a portion of the load of the entire carriage. Again, the long spoke acts as a longer lever, the point of draught being the axle, which is higher from the ground in the higher wheel, and again assists in overcoming the obstacle, as the angle of incidence is so much less.

To learn that the leverage power of a high wheel is very great we need only consider the advantages gained by a large wheel in locomotives and in bicycles. In practice we find that wheels from 4 feet to 5 feet are sufficient for large carriages, and from 3 feet upwards for ordinary vehicles.

The present method of constructing all wheels which have to carry considerable weight will doubtless continue to prevail. The timbers of which they are composed, viz., elm for the stocks, ash and hickory for the rims, and oak or acacia for the spokes in Europe and America, have been found the best for many years. Wheels of the present make must also be dished. The tendency of a wheel is always to become upright, and when it becomes so by the gradual hammering out of the tyre to a greater length, and the gradual sinking of the spokes further into the nave and rim by wear and tear, then the wheel goes to pieces. If any one will watch the manner in which the materials of a mop become straight as it is twirled round, he will understand that the same centrifugal force compels wheels to become upright. Secondly, as a wheel runs along a road it is forced from side to side by the uneven surface, the uneven draught of the horses, and the rapid motion, which latter frequently causes the wheel to jump over the road instead of pressing equally over all its circumference. Then we dish our wheels, not only to keep the tyre tight as long as possible, but also to resist the lateral thrust, which in a perfectly upright wheel would soon force the spokes out of the naves. There is one exception to this rule in the American spider wheel; in this the spokes are not larger than a man’s finger, and being of elastic wood, bend like a reed under the lateral thrust, and recovering themselves again will endure, whilst the unbending oaken spoke would be unrooted.

The late Lord Palmerston, whose vigorous common sense grappled many a problem which would be supposed quite out of his line, was fond of talking about carriages. He considered that wheels should have the spokes dished, but that the arm of an axle-tree should be nearly straight, so that the outside rim of the wheel should be upright; and would illustrate the soundness of his views by quoting the wheels of artillery waggons and pony phaetons. It became necessary to remind his Lordship that we pitch the arms of the axles for two reasons; first, in order to keep the box of the axle pressing against the strong shoulder instead of against the weak linch-pin; and secondly, because the wheels, when they are wider at the top of the tyres than at the bottom on the road, will throw the mud away from, instead of into the carriage, or on the panels.

There is no absolute rule for the dish of the wheel or the pitch of the arm of an axle. Experience and custom point out to a builder what is best for different carriages and different countries. It is sufficient to say that a spoke two feet in length will last longest when not dished more than its own width in its length, and that the pitch of the axle arms, to ensure chiefly the duration of the wheels, should not be more than will leave the spokes pointing towards the ground, not upright, but narrower at the naves than at the rims by three-quarters of an inch when the spokes are two feet long. This rule is simply for the duration of the wheel as long as possible, without reference to any other consideration, which the Coachbuilder, however, may find overrule what I have said.

If the axles of a carriage are rather stronger than is necessary—having regard to their length between the shoulders, and the weight they have to carry—it will be found to have a considerable influence upon the carriage, which will follow more steadily and quietly for the additional strength.

I do not propose to enter in this series of lectures at any length upon the subject of Springs. I think we are far from having attained perfection either in the manufacture or shape of springs for carriages.

It may have been remarked that the first springs were all elbow springs, placed in different positions, for different carriages. A double elbow or horizontal spring of a length of four feet seems to give the most easy play of any shape, and if made nearly straight at first wears little in the course of time compared with the elliptical shape.