Traction

“ Horse traction, however, limited the weight of the car and the speed of travelling. The substitution Advantages of Different Systems.of steam traction for horse traction was a great advance. Higher speeds and quicker acceleration were obtained, and larger and more comfortable cars could be worked. The power, however, was limited, and the locomotives, built as light as possible, were expensive in first cost and maintenance. Cable traction, owing to the heavy first cost of the track, requires a great density of traffic to make it pay. ”

“ The traction may act as "tension," as it does in the case of a horizontal section of a bar supported at its upper end and hanging vertically, or as "pressure," as it does in the case of a horizontal section of a block resting on a horizontal plane, or again it may act obliquely or even tangentially to the separating plane. Normal tractions are reckoned as positive when they are tensions, negative when they are pressures. ”

“ The line of traction is mechanically best disposed when it lies exactly parallel to the direction of motion, and its power is diminished at any inclination of that line in the proportions of the cosine of the angle to radius. When obstacles frequently occur, it had better perhaps receive a small inclination upwards, for the purpose of acting with most advantage when those are to be overcome. ”

“ Do there not remain, even with the best carriages, other vibrations and other shocks which must be pursued and destroyed in order to render more perfect the conditions of traction? You have all experienced, at the moment of the sudden start of a carriage, and even at each stroke of the whip on a living horse, horizontal shocks which sometimes throw you to the bottom of the carriage. In a less degree, shocks of the same kind are produced at each instant of traction, for the speed of the horse is far from being uniform, and the traces are subjected to alternate tension and slackness. ”

“ The power of traction necessary to sustain the progressive motion of a boat floating on a liquid arises from the resistance of the liquid lying immediately before the boat. It is necessary that the vessel should divide the fluid which lies in its way; and the force necessary to move this with the speed of the vessel must be supplied by the power of traction or impulsion, whatever that power may be. ”

“ Oblique tractions can always be resolved, by the vector law, into normal and tangential tractions. In a fluid at rest the traction across any plane at any point is normal to the plane, and acts as pressure. For the complete specification of the “state of stress” at any point of a body, we should require to know the normal and tangential components of the traction across every plane drawn through the point. ”

“ Fig. 2.—Tracing of the dynamograph for a vehicle drawn by a horse.
To obviate suffering of men and animals is unfortunately not a motive sufficient to induce everybody to modify the old system of harnessing. To certain minds known as positive, it is necessary to prove that elastic traction has economical advantages, and that a horse thus harnessed is able to draw heavier loads. ”

“ Traction engines carrying hoops twenty feet in height, or at any rate as high as may be found compatible with stability when referred to the available width on the road, will be capable of transporting goods at a cost much below that of horse traction. ”

“ By this means the track is laid in front of the wheels, and passes over from the rear of the same in an endless belt, as shown.
“The guide-rails G are supported above the traction-wheels, by means of arms e, as shown, and prevent the jointed track from leaving the flanges.
“When a level pavement is available, or the ordinary road is of sufficient evenness, the jointed track may be dispensed with, and the traction-wheels used directly upon the ground or pavement. ”

“ The principle on which the feat was performed was, that the man on the bicycle, rushing down the incline, would get momentum enough to shoot across the gap. To prevent the wheel and rider from falling from the attraction of gravitation while it was flying across the space, the end of the incline was curved upward. ”

“ Already I knew well enough that tens of thousands who could never afford to own, feed, and stable a horse, had by this bright invention enjoyed the swiftness of motion which is perhaps the most fascinating feature of material life, the charm of a wide outlook upon the natural world, and that sense of mastery which is probably the greatest attraction in horseback-riding. ”

“ It seems safe to look forward to the time when the conception of attractive and repulsive forces, having served its purpose as a useful piece of scientific scaffolding, will be replaced by the deduction of the phenomena known as attraction and repulsion, from the general laws of motion. ”

“ Exquisite motion! more maddening than the smooth floating stride of the race-horse, or the crash of the thorn-hedges before the stalwart hunter, or the swaying of the fir-boughs in the gale, when we used to climb as schoolboys after the lofty hawk’s nest; but not so maddening as the new motion of our age—the rush of the express-train, when the live iron pants and leaps and roars through the long chalk cutting; and white mounds gleam cold a moment against the sky and vanish ”

“ You travel along for many rods over excellent, dry, solid sleighing where the road is perfectly level, not thinking but you are within a foot of the ground, then suddenly descend four or five feet, and find, to your surprise, that you had been traversing the broad back of a drift. ”

“ If we observe two men endeavouring to move a railway carriage upon the line, we shall notice that they do not at the first exert all their strength in one powerful, and what would probably prove exhaustive and futile, effort, but placing their backs against the carriage, they will push with a continuous and gradually increasing effort for several seconds, or even longer, when a slight movement will be perceived in the carriage, [149] and a slight additional exercise of force will set it in motion. ”

“ Imagine a track some six feet in width, formed of snow turned to ice by the process of constant watering, and so smooth and slippery that a burnished mirror would be rough and dull in comparison. Imagine this track inclined at a steep angle, walled in on both sides with low ice-banks, and trailing a long and sinuous course for a length of over a mile! Here we have the potentialities of speed when we remember that racing "bobs" are just low frameworks of wood whose steel runners glide over the polished track with as little friction as a flash of lightning traversing a thunder-cloud. ”

“ Have you ever felt the shuddering of a wagon with brake hard on, as it poised in air the instant before it dropped a foot or two to the next level, from hard rock to hard rock? Have you ever tried to keep four horses away from under a wagon, and yet sufficiently near it not to precipitate the crash? ”

“ A STRIDE is an act of progressive animal motion, which, for its completion, requires all of the supporting members of the body, in the exercise of their proper functions, to be consecutively and regularly thrust in the direction of the movement until they hold the same relative positions in respect to each other as they did at the commencement of the notation. In the bipedal walk or run a step is one-half of a stride or full round movement. ”

“ If a carriage, a horse, or a boat, moving with speed, be suddenly retarded or stopped, by any cause which does not at the same time affect passengers, riders, or any loose bodies which are carried, they will be precipitated in the direction of the motion; because by reason of their inertia, they persevere in the motion which they shared in common with that which transported them, and are not deprived of that motion by the same cause. ”

“ Stage Coaches, therefore, carrying heavy weights, moving with great velocity, and presenting to the road a narrow tire of wheel, must of necessity drag in a greater degree than any other carriage, as combining in themselves every cause by which dragging is produced. ”

“ Whoever has seen a runaway carriage strike another vehicle, and has beheld the breaking up, can realize 261 for the first time the tremendous force of an object in motion. The little Ralli cart can become a battering-ram of prodigious force. ”

“ Whether the road be one mile or one hundred miles in length, the effect of diurnal rotation is the same; and, whether the road be long or short, the tendency to run off, as you cross a given parallel at a stated rate of speed, is the same; for the tendency to fly off the track is in proportion to the speed of the train, and not at all in proportion to the length of the road. ”

“ As each mule and each rider had a distinct opinion of his own as to how the race ought to be run, and which side of the track was best in certain circumstances, and how often the track ought to be crossed, and when a collision ought to be accomplished, and when it ought to be avoided, these twenty-six conflicting opinions created a most fantastic and picturesque confusion, and the resulting spectacle was killingly comical. ”

“ Certainly, whoever has ridden down this long descent at breakneck speed, on a small hand-car, or railway velocipede, while the alternating rock cuts, high embankments, and trestles or bridges of dizzy height fly by in rapid succession, must feel at the same time a grand conception of the glories of nature and the triumphs of man. ”

“ You can’t stop, if you would;—you may die, but you can’t stop; the engine may explode upon the road, and up you go along with it; or, may be a bolter, and take a fancy to go down a hill, or into a river: all this you must bear, for the privilege of travelling twenty miles an hour. ”

“ The chase lay through the brake for perhaps a quarter of a mile, and then plunged into a dense thicket, which retarded our movements exceedingly, though we went through it in a crowd together,—fronds flicking into our faces, ropy creepers catching us under the chin or gripping our ankles, thorny plants hooking into and tearing cloth and flesh together. ”

“ If the angle be large that means the path of the fly be long, then the striking train will move slowly; but if the teeth of the escape wheel R can just pass by without causing the lever to describe a supplementary or extended arc, the striking work will run off rapidly. ”

“ No pretext of convenience in locomotion, whether by horseback, rail, steamer, velocipede, or mangle, can rub out of our preference the lines which trace the reserve that protects our youthful dream. And how can this being, only half suggested yet clearly not ourselves, put a scrawl of crudity in place of those fluent curves that describe something less angular than we are? ”

“ Riding along at a hard trot, we required to be ever on the alert, and to maintain an incessant motion of the feet, in order to avoid collision with the irregular surface and the projecting stones on either side of us. ”

“ But when a carriage is drawn or impelled along a hard and level road, the motion which it receives from the first impulse would continue undiminished for a short time, if the road and the faces of the wheels were perfectly smooth, and no resistance of the air. ”

“ The escapement is that part of the clock in which the rotary motion of the wheels is converted into the vibratory motion of the balance or pendulum, which by some contrivance or other is made to let one tooth of the quickest wheel in the train escape at each vibration ”

“ All the other roads were nothing but mere horse-tracks, in the most wretched state imaginable, full of holes and great stones, so that you could seldom go faster than a walking pace without danger of breaking your neck at every step, except in those parts where the track lay through forests and open plains. ”

“ The principle on which the roads were mended was to spend a great number of months on one spot, improving a tract of two or three miles, and then to remove the men to a distance, it may be of twenty, leaving the improved bit as an oasis that allowed the driver of a dog-cart the luxury of half an hour's fast trotting. ”

“ The whole effort was to overcome as much as possible the primary forward momentum the train had imparted to my body. When my feet hit the grit, my body was lying backward on the air at an angle of forty-five degrees. I had reduced the forward momentum some, for when my feet struck, I did not immediately pitch forward on my face. Instead, my body rose to the perpendicular and began to incline forward. In point of fact, my body proper still retained much momentum, while my feet, through contact with the earth, had lost all their momentum. ”

“ By having only two wheels, we have only two tracks, so that we can travel at a fair speed along those places in the country called roads, which consist of alternate lines of ruts and stones, where a three-track machine could not be driven, and where, from the quantity of loose limestone in the ruts, a little wheel of a two-track tricycle would be likely to suffer. ”

“ To explain this subject more fully, I may point out, that if a person is standing on the foot-board of the right side of a rapidly moving train which suddenly turns to the left, he or she would be far more inclined to fall off, than if a similar change of direction had been made to the right, in both of which instances the side of the train would play the part of the upper crutch. ”

“ Why does a person standing up in a wagon fall when the wagon is suddenly moved?
Because the feet, being in contact with the wagon, move with it before the motion extends to the rest of the body, thus throwing the line of gravity behind the feet; hence, the person must fall, unless supported. ”

“ Constantly in the long trains of animals descending to the coast, a slip of the foot or a charge from behind, for they all come down the steep track with a jolting shuffle, sends mule and its load over the ledge. ”