Countershaft

“ It was also old, and very common in machine shops and factories of various kinds, to provide an individual machine with a countershaft mounted directly in the machine frame, the counter-shaft being driven by a belt from the line-shaft, and the machine by a belt from the counter-shaft. ”

“ When the direction of rotation of the cone pulley on the countershaft requires to be occasionally reversed, there are two belts, an open one and a crossed one, from the line shaft to the countershaft, and there are three pulleys on the countershaft, their arrangement being as shown in Fig. 2596. l l′ are two loose pulleys, one receiving the open and the other the crossed belt, both these pulleys being a little more than twice the width of the belt; f is a fast pulley. ”

“ First discarding the old friction drum and shaft, and the shipper-fork carriage, he bolted a rawhide bevel gear to the lower surface of the flywheel. This turns two bevel gears, in opposite directions, on a countershaft directly underneath, approximately in the position of the old jackshaft. The right bevel gear is secured to the main countershaft on which two clutches are mounted, one on each side of the crankshaft. On a sleeve turning freely around the countershaft is mounted the reverse bevel gear and clutch. ”

“ The speed must be reduced and the torque increased before it will drive the car.
The countershaft consists of two grooved pulleys mounted upon an axle running in two bearings mounted upon the floor of the car. The bearings are made from a strip of heavy sheet-brass, bent at right angles and fastened to the car floor with small screws. The large pulley, A, is one inch and one half in diameter and the small pulley, B, is five-sixteenths of an inch in diameter. ”

“ It is in the earnest endeavor to properly locate these that the unaccustomed hand turns a wood ceiling into a sieve and a brick one into a wreck. To avoid kitchen and house razing effects, try the following recipe:
We will assume that line A B, Fig. 38, laid out by one of the methods previously described, is the center line of the proposed countershaft. The hanger's base length, lateral adjustment and individual foot length call for stringers 4Â3⁄4 inches wide, placed 5Â1⁄4 inches apart or 14Â3⁄4 inches outside (as per sketch) . ”

“ Shafting so run pretty nearly always gets out and keeps out of level.
In flanged bolt couplings (Fig. 1) no part of the bolt should project beyond the flanges. And where a belt runs in close proximity to such a coupling, split wood collars should be used to cover in the exposed coupling flanges, bolt heads and nuts. Countershafts have been torn out of place times innumerable by belts getting caught and winding up on the main line.
Whenever possible a space of 8 to 10 inches should be left between the end of a shaft line and the wall. ”

“ The shaft being both out of line and level does not, if both at the same point, aggravate matters, as might at first be supposed.
It is true that the full torsional strength of a shaft is only equal to the weakest portion of it, so that three weak spots more or less can, theoretically, make no difference one way or the other. But, practically, there is the undue strain and wear of the bearings at these points, and if a pulley transmitting any considerable amount of power is situated anywhere along the length A B it is sure to be unpleasantly in evidence at all times. ”

“ SECTION XXXII. LAW III. All shafts are to be solid. Wherever, by the smallness of the parts, we may be driven to abandon the incrusted structure at all, it must be abandoned altogether. The eye must never be left in the least doubt as to what is solid and what is coated. Whatever appears probably solid, must be assuredly so, and therefore it becomes an inviolable law that no shaft shall ever be incrusted. Not only does the whole virtue of a shaft depend on its consolidation, but the labor of cutting and adjusting an incrusted coat to it would be greater than the saving of material is worth. ”

“ If a place be not countermined before hand, a great deal may be done even after [441] the investment of the place, to prolong the siege by countermines. In this case, the first thing to be done immediately that the place is invested, is to sink a shaft in each of the places of arms of the covert way; one in each branch of the covert way opposite that part of the bastion where the breach will most probably be made; and one in the flanked angle of each bastion. Those on the covert way will be on the banquette, and sunk to about 18 inches below the bottom of the ditch. ”

“ There are others that are difficult of access—as in the case of bearings of screw-propeller shafts. Serious mischief may result before the heating of the bearing proclaims its dangerous condition. In some cases the timber work is set on fire, which may result in serious consequences.
In order to remove the cause of such serious mischief, I designed an arrangement of bearing, which enabled it, and the shaft working in it, to mutually accommodate themselves to each other under all circumstances, and thus to avoid the danger of a want of due and mutual parallelism in their respective axes. ”

“ If there is the slightest displacement of the centre of gravity of the system from the axis of revolution a force acts on the shaft tending to deflect it, and varies as the deflexion and as the square of the speed. If the shaft is therefore to revolve stably, this force must be balanced at any instant by the elastic resistance of the shaft to deflexion. ”

“ When very long lines of shafting are constructed of small or comparatively small diameter, such lines are liable to some irregularities in speed, owing to the torsion or twisting of the shaft as power is taken from it in more or less irregular manner. Shafts driving looms may at one time be under the strain of driving all the looms belted from them, but as some looms are stopped the strain on the shaft becomes relaxed, and the torsional strain drives some part of the line ahead, and again retards it when the looms are started up. ”

“ On the screw-shaft, above the top of the receptacle, is fixed a disk of wood or other suitable material, which catches the oil from the bearings of the power-shaft, and other foreign matters that otherwise would be liable to fall into the receptacle. The power-shaft is suspended in its bearings by suitable collars, which enable it to support the screw, and is driven from a horizontal shaft, through beveled gearing, or by other well-known or suitable mechanical means. ”

“ Considering the great labour necessary for securing the ground for the underlaying, the waste of planking, and of shores, and the time necessarily taken up in moving about, in securing and in baling out the water, and the many causes of interruption, and the imperfect way that things are done in underlaying, it is quite conclusive that the original plan of making a shaft, by sinking the structure, is the safest and the most economical. What is done is sound, and when once in place, may be secured with foundations in a very easy manner. The brickwork of the shaft is remarkably hard. ”

“ The point of excellence in the celebrated Sellers bearing for shafting is that it turns universally to accommodate itself to this flexure of the shaft, and the result is a durability almost perfect.
“The second requirement, when we have a shaft capable of maintaining perfect rigidity under all the strains it may be subjected to, is abundant extent of bearing surface both in length and circumference, a requirement, it will be seen, entirely consistent with the first. ”

“ Counter-shaft. Putting up the counter-shaft, when one is employed, is usually the first operation in installing a machine. It is generally placed directly over cone drive machines because of the interference of the driving belt with the upper part of the frame if it is located very far at either side. With constant speed drive machines, it is not necessary to place the counter-shaft directly overhead. ”

“ A standing balance is effected when the shaft being supported horizontally and with as little friction as possible, the pulley will remain at rest in any position in which it can be placed. Thus, in Fig. 2647 let c c represent the two centres of a lathe adjusted in their distance apart so as to sustain the shaft s with just sufficient force to prevent end movement or play of the shaft, and if the pulley p remains motionless when arrested at any point of rotation it is in standing balance. ”

“ The millowners understood this circular to convey an order that all shafts should be "permanently cased with wood or iron," Mr. Leonard Horner having repeatedly declared that sort of fencing to be the only secure one for vertical shafts, and for horizontal ones under seven feet in height; whereas he at the same time declared that rectangular hooks (of which more presently) are a security against one danger, "but not against other accidents;" while he stated in the same paragraph, that "adequate means must be adopted" "against all accidents from an horizontal shaft." ”

“ Shape of Shafts.-In Europe shafts are generally cylindrical, sometimes of elliptical cross-section, and are lined with masonry, concrete, cast iron or steel; in the United States and elsewhere throughout the mining regions of the world, rectangular cross sections are the rule for sinking in rock, the shaft walls being supported by limbering, occasionally by steel lining. For sinking in loose, water-bearing soils, the cross-section is almost invariably cylindrical, as this form best resists pressure tending to cause crushing or caving of the shaft walls. ”

“ A shaft with a centrifugal piece arranged on this principle has only one velocity of rotation without disturbance. If there be a small disturbance, the equations for the disturbance and may be written
The period of such small disturbances is revolutions of the shaft.
They will neither increase nor diminish if there are no other terms in the equations.
To convert this apparatus into a governor, let us assume viscosities and in the motions of the main shaft and the centrifugal piece, and a resistance applied to the main shaft. ”

“ There must always be danger caused from the necessity of suspending the fencing for shafts,—danger to those who had to put on the straps, and also from the possibility of the suspenders giving way. His decided conviction was that the best way of securely fencing a shaft 11 feet from the ground was to turn it truly, polish it brightly, and leave it open, so that its operation might be seen, and any attempt to tamper with straps and pulleys at once discovered."—Oldham Chronicle, February 10th, 1855. ”

“ The effect of this manipulation is to form a hard ring of close grain about one inch thick from the circumference of the shaft inward. The metal in this ring is much harder than that in the rest of the shaft, and takes all the strain the inner section gives; consequently, when strain is brought on, either in heavy weather or should the propeller strike any object at sea or in the Suez canal, a fracture is caused at the circumference. This, assisted by slight corrosion, has in my experience led in the course of four months to a screw shaft being seriously crippled. ”

“ The counter-shaft should be level and accurately aligned paralledl with the main, or driving, shaft. Where the beams are not uniform enough to bring the stringers to which the counter-shaft hangers are attached level, it will be necessary to shim between the feet of the hangers and the stringers to make the shaft level. The holes in the feet of the hangers are usually in the form of slots, which allow the hangers to be slightly adjusted when aligning the counter-shaft with
the driving shaft. ”

“ In sinking a shaft, danger is to be apprehended both from the falling in of loose and incoherent strata, and from the lateral springs, which sometimes empty themselves into the workings to an extent which it would at first appear hopeless to contend against. In such cases there is no safety to be obtained without walling the shaft with brick or stone, or securing it by timber or metal tubbing. ”

“ A crank or cross-arms may be placed on the turning-shaft, and, by means of connecting-rods, which connect the cranks or arms with the levers, the shaft may be turned, and the shoes thus thrown into a straight or zigzag line, as may be desired; or, instead of the crank-shaft to shift the shoes, the shoes may be united in sets to different bars, which may be straight, both bars being united to cross-bars or heads at their ends. ”

“ In order to avoid the great mischief arising sometimes from undue strain upon and the breaking of a shaft, a weak coupling composed of a link is sometimes employed between the shaft and the driven machine, whereby, should the force become suddenly too great, the link of weaker metal is broken, and the connection between the shaft thereby destroyed and the machine stopped. ”

“ I omitted to mention that built shafts, both of steel and iron, of large diameter, are now in general use, and with the excellent machines, and under special mechanics, are built up of five separate pieces in such a rigid manner that they possess all the solidity necessary for a crank shaft. The forgings of iron and steel being much smaller are capable of more careful treatment in the process of manufacture. These shafts, for large mail steamers, when coupled up, are 35 feet long, and weigh 45 tons. ”

“ Serious accidents have occurred through want of attention to the examination of this shaft; when working in salt water, with liners of gun metal, galvanic action ensues, and extensive corrosion takes place in the iron at the ends of the brass liners, more especially if they are faced up at right angles to the shaft. Some engineers have the uncovered part of the shaft between the liners, inside the tube, protected against the sea water by winding over it tarred line. ”