Pole vaulting

“ This is a union of leaping and vaulting, in which the vaulter, instead of supporting himself upon a fixed object, carries with him a pole, which he applies to whatever spot he chooses. In supporting the body by a pole during the leap, a great deal also depends upon balancing, as well as on the strength of the arms and legs. ”

“ The vaulter then runs towards the bar at full speed, plants the spiked end of the pole in the ground about 18 in. in front of the bar and springs into the air, grasping the pole firmly as he rises. As he nears the bar he throws his legs forward, and, pushing with shoulders and arms, clears it, letting the pole fall backwards. In Great Britain the vaulter is allowed to climb the pole when it is at the perpendicular. Tom Ray, of Ulverston in Lancashire, who was champion of the world in 1887, was able to gain several feet in this manner. In the United States climbing is not allowed. ”

“ Fig. 15.—External View of Electric Railway Motor mounted upon Car-Wheel Axle.
To enable the motor to give a strong torque and run at a slow speed the number of poles in the field and armature is increased. The design of Fig. 10 has two poles in the field and two in the armature, and is what is known as the bipolar type. Machines having more than two poles in each part are called multipolar machines. The number of poles can be increased by pairs, but not by a single pole—that is, we can have four, six, eight, or any other even number of poles, but not five, seven, or any odd number. ”

“ The harder the multitude pulled, so long as they remained200 evenly distributed about the circle, the more rigid the pole would become. But if, on the other hand, all the men were to stop pulling and slacken the ropes, the pole would at once fall over. The pole, under such circumstances, would represent the axis of the revolving wheel, which acquired increased stability in exact proportion to the increased velocity of its revolutions, and therefore of the increased force with which its particles tend to fly off into space. ”

“ During the run the pole is held across the body, with the hands gripping the pole at proper spot; then the pole is placed in the hole in front of cross-bar and a spring is taken from the foot; the arm underneath should be straight, the one above bent; as the pole swings to a vertical position the body swings up, and if the vaulter is strong enough in the arms she should slide the lower hand up to the top one; an extra push is given to propel the body over the bar as the pole is released. While crossing the bar the body should be arched; in falling, the face should be downward. ”

“ By heading almost directly into the wind he could “shoot” the road, and by keeping his engine running at partial speed he could make a “power stall,” letting the craft settle very gradually instead of trying to glide down, guess at the correct height and then stall and drop. To do the latter in the comparative darkness of the highway might result in smashed landing gear or worse if he stalled too high and dropped, or it might happen that he would “put her on hot,” or at too great speed and without stalling, come against the ground. ”

“ When a rear wheel breaks down upon a march, the best method I know of for taking the vehicle to a place where it can be repaired is to take off the damaged wheel, and place a stout pole of three or four inches in diameter under the end of the axle, outside the wagon-bed, and extending forward above the front wheel, where it is firmly lashed with ropes, while the other end of the pole runs six or eight feet to the rear, and drags upon the ground. ”

“ The extending ends of the spokes are used to propel the wheel. Four children can ride in the wheel at one time.—Contributed by Maurice Baudier, New Orleans, La.
[162]
A Merry-Go-Round Pole
An inexpensive merry-go-round can be made of a single pole set in the ground where there is sufficient vacant space for the turning of the ropes. The pole may be of gas pipe or wood, long enough to extend about 12 ft. above the ground. An iron wheel is attached on the upper end so that it will revolve easily on an axle, which may be an iron pin driven into the post. ”

“ The motion down the incline by the force of gravity is accelerated; and if the train be not retarded, a descent of any considerable length, even at a small elevation, would produce a velocity which would be attended with great danger. The shoe used to retard the descent down hills on turnpike roads cannot be used upon railroads, and the application of brakes to the faces of the wheels is likewise attended with some uncertainty. The friction produced by the rapid motion of the wheel sometimes sets fire to wood, and iron would be inadmissible. ”

“ Sprinting is also as necessary an exercise for the pole vaulter as it is for the broad jumper. When the weather moderates, work should be begun and continued daily out-of-doors.
For practice the vaulter must have two square posts similar to those used by the high jumpers, only higher, bored with holes two inches apart above six feet, then one inch apart up to eight feet, and half an inch apart from there up. The pegs should be between two and three inches long, and the bar, of one-inch pine, should be about eleven feet long. ”

“ When running on any speed, if you allow the car to gain impetus and then put the change-speed lever in neutral position, the car will travel on in the same manner as a free-wheel bicycle, the action of the gear being neutral temporarily disconnecting the engine and gear.
If you see an obstacle in the road do not go up to it at full speed and suddenly put on the brake. The sudden application of the brake will hasten the end of the life of your tyres—and if you are not driving on non-skid tyres a bad accident may be the result if the road is at all wet. ”

“ The substance of the explanation is that the greater the force brought to bear on the roller R1 by the segment of the car that strikes against it, the stronger its precession, and hence the more powerful its lift. The oscillations and counter-oscillations thus brought about continue to operate powerfully on the roller R1 so long as the weight of the car is out of balance; and balance is restored only when the heavier side of the car rises, bringing the centre of gravity over the track, just as a man carrying a weight on the right shoulder leans toward the left, and vice-versa. ”

“ A, let there be hung by a pair of links of lengths equal to the pendulum arms, a load, B, capable of sliding up and down the spindle, and having its center of gravity on the axis of rotation. Then the centrifugal force is that due to A alone, and the effect of gravity that due to A + 2B; consequently the altitude for a given speed is increased in the ratio A + 2B : A, as compared with that of a simple revolving pendulum; and a given absolute variation of altitude in moving the regulating-valve produces a smaller proportionate variation of speed than in the common governor. ”

“ He stands in the middle of the runway, with the pole pointing straight at the uprights, and he fixes his eyes on the bar. From this moment he does not remove his gaze from that pine stick, or from the handkerchief which may be hanging from it, until he has made his leap. He should never look to see where he is placing the pole to vault, for this will interfere with the success of his leap. The pole will take care of itself. ”

“ All revolving wheels possess momentum, but momentum wheels, so called, as balance or fly wheels, are wheels whose momentum is utilized in the operation of machinery by a sufficient accumulation of force, through the weight and velocity of the wheel combined, to overcome the effects of temporary loss of power. ”

“ Resistless with its initial momentum, the big car was nevertheless gradually losing speed as it penetrated further into the drift and the passive but deadly resistance of the snow began more and more to make itself felt. The engine began to labor, and Bob was on the point of shifting speeds, when suddenly the car broke through the farther side of the drift, seemed to shake the clinging flakes from it, and began to pick up speed again. ”

“ Equation (3) indicates that the load, including its own weight, that a truck or an automobile can draw varies directly as the horse-power exerted effectively, and inversely as the velocity. Also it decreases as the coefficient of road resistance, μ, and the gradient g increases.
The resistance coefficient, μ may include axle or internal resistance of the vehicle plus road surface resistance plus air resistance. The axle resistance is nearly a constant, the road resistance likewise, but the air resistance depends upon the speed v, varying approximately as the square of the velocity. ”

“ They should not put any strain at all on the pole, for by doing so they obviously tend to counteract the efforts of the wheelers to keep back the coach. In order to carry the bars the traces should be slack, but not slack enough to let the whole weight of the bars weigh down on the pole, which would put so much extra weight on the wheelers’ necks. ”

“ If the wheels A and B be rotating at the same speed and a brake be applied, say to B, its speed will diminish and the spring will coil up, and if fairly flexible, more than the necessary amount to balance the load imposed by the brake; because when the position of proper torque is reached, B is still rotating slightly slower than A, and an additional torque is required to overcome the inertia of B and bring its speed up to synchronism with A. Now before the spring stops coiling up the wheels must be rotating at the same speed. ”

“ A slight unevenness in the rails, or a sharp flange on the wheel may supply all that is wanting to cause the engine to leave the track, and the probability that such risks are more common than is supposed, is far from satisfactory. The great weight of the engine doubtless tends to keep it on the track, but the rapid [Pg 312] wear of the tyres, and of the inside of the rail-heads clearly demonstrate the enormous amount of friction and abrasion that takes place. ”

“ The proper functioning of the interpoles is independent of the direction of rotation of the armature, also of the load carried over the whole speed range. In an ordinary motor without interpoles, commutation is assisted by a magnetic fringe emanating from the main poles, but as the value of this fringe is altered by the load of the motor and by rheostatic field weakening, if higher speeds be desired from such a machine, commutation becomes imperfect and sparking results, making a readjustment of the brushes necessary. ”

“ Considerable danger attaches to the running away of an engine, especially where it is provided with a heavy fly-wheel. This, if it is whirled round at an excessive speed, is liable to burst, and the consequences, in a crowded quarter, would be disastrous. The danger of bursting lies in the tremendous throwing-off power generated from the hub of the wheel, about the shaft; as the sections forming the circle of the wheel are brought rapidly over there is a strong tendency for them to be cast off in the same manner as a stone is thrown from a sling. ”

“ If the face of the wheel and the surface of the road were absolutely smooth and free from friction, so that the face of the wheel would slide without resistance upon the road, then the effect of the force thus applied would be merely to cause the wheel to turn round, the carriage being stationary, the surface of the wheel would slip or slide upon the road as the wheel is made to revolve. ”

“ In soft drift sand or wash gravel, slow down to from four to eight miles per hour, using the low or intermediate gear and maintaining an even, steady, constant torque on the rear wheels to keep the axle from jumping, and using the power sparingly to prevent the wheels from burying themselves. ”

“ On the top of each car were high geared fly wheels lying on their sides, which were so automatically adjusted that, as the speed of the car increased, the high speed of these fly wheels geometrically increased. Jules Galdea explained to us that these revolving fan-like wheels on top of the cars destroyed atmospheric pressure, or what is generally understood by the term gravitation, and with this force thus destroyed or rendered nugatory the car is as safe from falling to one side or the other from the single rail track as if it were in a vacuum ”

“ The fog was so thick that I could not tell by passing objects how fast we ran, but the dull, heavy and oppressive roar, as we shot through rock cuttings and tunnels, the rocking and straining of my engine, and the almost inconceivable velocity at which the driving-wheels revolved, told me that my speed was something absolutely awful. ”

“ The symptoms are a lag in the engine due to the exhaust valve not closing instantaneously, and as a result a certain per cent. of the charge under compression escapes, greatly diminishing the force of the explosion. Weakness in a valve spring can usually be detected by the following method: Remove the plate which encloses them at the side of the cylinder and insert a screw driver between the coils of the spring while the engine is running. If the extra tension thus produced causes the engine to pick up speed, the spring is obviously weak and should be replaced by a new one. ”

“ Side thrust of wheels often produces longitudinal waves in viscous road crusts.
In the classifications given no one seems to have considered the proportion of sprung and unsprung weight in the motor car. There can be no doubt but that the resiliency of the springs relieves the pavement of very much of the shock of impact. This is illustrated by an attempt to drive a nail into a springy board. It can hardly be done because the springiness of the board uses up, absorbs, the work of impact. ”