Wheelbase

“ On the one hand you had coachbuilders and others filling the newspapers and publishing tracts, some very serious, some extraordinarily mathematical, others merely facetious, to prove that the roads could be preserved only by using very broad wheels—some,179 indeed, advocated rollers, which, as we shall see, were actually tried—and on the other hand you had people filling more columns, and very dull columns some of them were, to show that a low broad wheel was the one thing which no really satisfactory vehicle could possibly possess. ”

“ On the other hand, if one wheel should be loose, then, as power is applied to the shaft, the tractive action would be on one wheel only, and this would be bad practice, and frequently cause the wheel to slip, and thus unduly increase the wear of the tire.
The differential is made up of a system of gears, which are so arranged that one wheel may turn independently of the other, and at the same time the effective driving power is utilized by each. ”

“ 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. ”

“ When a load is resting upon a two-wheeled vehicle it is very seldom placed so as to balance just right. If correct for level ground, as soon as it ascends a hill, or descends, the balance is unsettled. When the wheels come to a hole, or a big stone, all the load must be raised with two wheels and only half when on four wheels. Again, an uneven road twists the horse that is between the shafts from side to side, when the load is on two wheels, more than when, on four wheels, the fore-carriage rotates on the perch-box. ”

“ This heavy wheel, which weighs five hundredweight, flies up the track with a terrific momentum, and, in consequence of its centrifugal force, presses against the track with a force of seventeen times its own weight.
When the wheel has passed the highest point of the loop it flies down the other side, and leaves the loop again by another trap-door which has in the meantime been opened. The downward movement, being still very rapid at the point of exit, is then retarded by means of outlet-rails which adjust themselves exactly to the wheel, and the mad ride ends at length in a net. ”

“ You do not think it will be necessary to limit Steam Carriages to any particular number of passengers, provided the wheels were of the dimensions stated?—If the wheels were of the dimensions and the description stated. I should, in reason, be regardless of weight, experience having completely proved, with properly constructed wheels, we sustain little or no injury from weight.
What is the maximum weight a road would bear upon each wheel?—The injury done by weight upon a road in a Carriage with proper wheels is principally. ”

“ Supposing the width of the wheel to be the same on a Carriage and Steam Engine, and the weight of the Carriage the same, do you consider that a wheel perfectly cylindrical, with a horizontal axle, preferable to a wheel dished like that of a common stage coach, with a common axle?—You cannot have a dished wheel to a great width, without its dragging as I have described, unless you alter the system. ”

“ When you are certain the structure is firm and can stand the strain and weight of a loaded car, lay the two-by-four rails upon the ground, and fit them to the car-wheels by pushing the car over them, to see that they are just the right distance apart. If you make your track too wide the car-wheels will slip off the rails and run between them, and if you lay your track with too narrow a gauge the rails will pinch the flanges of the wheels so tightly that the car will stop, or the rails spread. ”

“ Portugal the old classic bullock-cart on this principle is still to be seen, and it has been reasonably guessed that such carts tell the story how wheel-carriages came to be invented. Rollers were early used, on which a block of stone or other heavy weight was trundled. Suppose such a roller made of a smoothed tree-trunk to be improved by cutting the middle part smaller, so that it became an axle and pair of broad wheels in one piece, then by making this axle work underneath the rudest framework, the simplest imaginable wheel-carriage is made. ”

“ I think a waggon wheel of six inches in breadth, if standing fairly on the road with any weight whatever, would do very little material injury to a road well made, and perfectly smooth. The injury done to roads is by these immense weights striking against materials, and in the present mode of shaping the wheels they drive the materials before them, instead of passing over them, because I think if a carriage passes fairly over a smooth surface, that cannot hurt the road, but must rather be an advantage to it, upon the principle of the roller. ”

“ I think there would be very little increase of wear from the effect of the carriage wheels by an increase of velocity; but if the road should be uneven or rough, there would be an increase of wear, in consequence of the impetus or blow with which the wheels would strike the road, after passing over the inequalities in its surface, particularly if the Carriages were made without springs; but whether the road be a good or a bad one, the wear occasioned by the feet of the horses will be greater when they travel with an increased velocity ”

“ The wheels will, undoubtedly, be as safely guided in the shallow as in the deeper channels, and the rails will be equally durable with those of greater weight. When rails of this description are sunk into a channel in a rail of stone or wood, the base being wider than their upper sides, the pressure of sand into the seams on each side of the iron, caused by the running of common carriage wheels over them, will effectually confine the iron plates between the jambs of the stone or wood. ”

“ On our home and continental lines, the modern express locomotive, with a four-wheel bogie truck in front, is a much longer vehicle than its predecessors, and its total weight is distributed over a greater wheel-base; but the actual weight placed upon the driving-wheels, or on the coupled wheels, is now very much in excess of former practice, and must be taken into consideration when working out the details of girders and cross-girders of under-line bridges. ”

“ IT has been suggested that although in a generality of cases nature has forestalled the ingenious mechanician, man for his wheel has had to evolve an apparatus which has no counterpart in his primitive environment—in other words, that there is nothing in nature which corresponds to the wheel. Yet even the most superficial inquiry into the nature of the earliest vehicles must do much to refute such a suggestion. Primitive wheels were simply thick logs cut from a tree-trunk, probably for firewood. ”

“ Do you think it essential that the wheels of Steam Carriages should follow in the same track, provided they have a proper breadth of tire?—Not at all, as regards the injury to the road; it would require more power to work them if the wheels did not follow in the same track. ”

“ There is a particular width of wheel in which no injury will be done to the road, but rather good?—It will be rather good after the road has been mended to settle it down; there will be wear in it as at other times; but in certain states of the roads to settle them down they will be doing good, but at no state of the road could it do good with narrow wheels. ”

“ There is a singular addition to their vehicles outside the wheels; a piece of wood curved to the shape of the wheel is placed above it, frequently supported by two straight uprights from the end of the axle-tree outside the wheel; this acts as a wing or guard to keep any one from falling out of the vehicle, and also the dress of the passengers from becoming entangled in the wheel. ”

“ I have no doubt, save four out of five, if not nine out of ten stones that are crushed at present, and reduce the road expences in the same proportion; but while the fancy of having carriage-wheels out of upright with crooked axles is continued, wide wheels would be a serious objection; the inside and outside of the wheel being of different diameters, and going different speeds, must cause an increase of load to the horses, because their rubbing on the road and tendency to twist move the stones out of their bed in the road, and, instead of bedding them firmly, has the contrary effect ”

“ Steering and Turning Ability. —It has been mentioned several times that steering is a matter of importance in the prevention of accidents. Designing engineers should, therefore, take that into account. It was formerly thought that turning ability is a function of the length of wheel base, but there are other things to be taken into account and some late designs with reasonably long wheel bases are able to turn in half the radius that was required for some of the older designs with shorter wheel bases. ”

“ When they meet wagons, whether heavily loaded or not, they ought to yield as much of the road as they can conveniently,—certainly more than half, as they do not need that much of the road to pass conveniently,—but when they meet a vehicle in the form of a bicycle there seems to be no good reason why they should yield more than half the road. ”

“ The study of wheels in the market made with front-driving mechanism, on the plan of Fig. 4, suggests an incontrovertible argument in favor of getting over the work, in spite of the difficulty noticed in respect to dead centres; such machines actually have a creditable reputation as powerful hill-climbers and rough-road machines, which can only be explained on the theory that the vertical application of power more than makes up the deficiency caused by the arc of no power at all. ”

“ If you keep the present dish, you must have a narrow wheel, or it is rubbing; but if it is a straight axle, it ought to be as wide as that where there is no more friction, and then the wide wheel will not do half the mischief that the coach-wheel does. The present stage coach-wheel will do a great deal more mischief, working as it does, than if it had been perpendicular. ”

“ Waggons and carts with wheels of a cylindrical form and upright bearing, running on a breadth of tire of five and six inches, cannot injure a well made road, at the slow pace with which such carriages travel; at least, in any proportion beyond the toll they pay. On the contrary, it is certain, that Stage Coaches, with their present system of loading, and velocity of travelling upon very narrow wheels, damage the roads in a much greater proportion than the compensation derived from the toll. ”

“ To execute this movement, of course, the motor wheels for the guide-tracks must be mounted on entirely different principles from those adapted for railroad traffic. The broad and soft tyred wheels which bear upon the [Pg 102] asphalt track will be entrusted with the duty of carrying the machine without extraneous aid; but there will be two extra wheels, one in front and one at the rear, capable of being lifted at any time by means of a lever controlled by the driver. ”

“ Wheels provide the best form of transportation over a smooth, hard road, but if the road is soft, the wheel will sink into the surface and will be greatly impeded. In traveling over mud or sand runners are preferable to wheels because they have a broader and longer bearing surface. In the snowy regions of the north and the sandy regions of Africa and Asia [215] Minor, sledges are used in place of wheeled vehicles. Sliding friction is less than rolling friction under such conditions. In fact, only where man has constructed special roads is it possible to use wheeled locomotion. ”

“ The Verbiest model was for a four-wheeled carriage, on which an aeolipile was mounted with a pan of burning coals beneath it. A jet of steam from the aeolipile impinged upon the vanes of a wheel on a vertical axle, the lower end of the spindle being geared to the front axle. An additional wheel, larger than the supporting wheels, was mounted on an adjustable arm in a manner to adapt the vehicle to moving in a circular path. ”

“ As a method of controlling and changing the rate of rotation of the wheel, the rivers of water had already proven themselves; and as a method of static balancing to compensate for off-center weights, masses of it could be stopped and held in counterbalance tanks around the rim, thus assuring that the observatory, in its stationary position on the hub, would not suddenly take up an oscillatory pattern of motion as the balance within the wheel was shifted either by moving equipment or personnel. ”

“ 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. ”

“ Even should two bands be destroyed at a distance from each other and on the same side of the track, its action would not be destroyed, for although the isolated portion of wheels would be dead, those on the other side of the track would be in action, which, with the horizontal guide-wheels, would move forward the carriage, although, on such portion, at a diminished speed. ”