Hub (mechanics)

“ The wings for the wheel can be made of lath frames, say eight inches wide at the top, six inches at the bottom, and twenty-two inches long, covered the same as you decide to cover the mill house, and provision made for the lamps projecting through when the lamp sockets are screwed to the 1331 × 3-inch pieces behind. Next is the shaft, as shown in Fig. 3. Get a piece of gas pipe eight inches longer than your frame is square at the bearings, screw it securely into a 3-inch flange, which in turn is screwed to the center of the wheel and acts as a hub. ”

“ Then on faces C and D, lay off a distance of 1⁄2 inch on the center-line, measuring from the edge of face B, for the thickness of the propeller-hub, and draw diagonal lines from the upper and lower left-hand corners of faces C and D to the end of the hub center-line (Step B) . Then cut away the portions outside of these lines, as shown in Step C. Lay out the hub upon faces A and B of the block, with a 1⁄2-inch diameter, and bore a small hole through the center to receive the propeller-shaft (Step C) . Draw diagonals from the corners to the center-line of the hub (Step D) ”

“ The most common rotating pieces in machines are wheels of various kinds, and in these the centre of gravity is evidently identical with the centre of rotation; but if from any cause a wheel, which is to turn [Pg 64] rapidly, has an extra weight attached to one part, this weight must be counterpoised by one or more on other portions of the wheel, in order to keep the centre of gravity of the whole in its proper place. Thus it is that the driving wheels of a locomotive are always weighted so as to counteract the effect of the crank and restore the centre of gravity to the axis of rotation. ”

“ The hub is thus driven at a higher speed than the chain-wheel. For normal gear, the striking gear draws the internal mechanism of the hub towards a central position, compressing a spring, disengaging the sun-wheel and locking the drive-ring hub and annular wheel together. At low gear, the internal mechanism is drawn to the right-hand side, where the planet carrier engages with the end plate of the hub by means of claw-clutches. The annular wheel is still engaged with the drive-ring, and the sun-wheel is again locked to the spindle. The hub is thus driven at a lower speed. ”

“ This was an arrangement that tensioned the wheel by pulling a lever attached to the spokes so that they were strained in a direction tangential to their hub and held tight by locking the lever. Following the methods already described, the laced and tangent spoked wheels were introduced. This type of wheel is the modern one that has survived all the others, and reverses the process employed for straight spoked wheels in tension. The flanges of the hub are drilled at right angles, the headed spokes are bent close to the head, and threaded through the holes made in the hub flange. ”

“ The hub may be secured by putting two or three metal pins through hub and shaft. Adjust the spokes by boring holes for them and arrange them so that they extend from the center A, like B. The wheel is then ready for the blades. These blades should be of sheet metal or thin hardwood. The sizes may vary according to the capacity of the wheel and amount of room for the blades on the spokes. Each one is tilted so as to receive the force of the wind at an angle, which adjustment causes the wheel to revolve when the wind pressure is strong enough. ”

“ The hub for the revolving fan wheel is first constructed. One good way to get both the hub, lining, shaft and spokes for the blades, is to go to a wheelwright's and purchase the wheel and axle of some old rig. ”

“ We may suppose that A is the chain-ring, B a cog mounted on a pin projecting from the hub, and C a cog attached to the fixed axle. It is evident that B will not move so fast round C as A does. The amount by which A will get ahead of B can be calculated easily. We begin with the wheels in the position shown in Fig. 223. A point, I, on A is exactly over the topmost point of C. For the sake of convenience we will first assume that instead of B running round C, B is revolved on its axis for one complete revolution in a clockwise direction, and that A and C move as in Fig. ”

“ A very true method of securing a hub to a shaft is to bore it larger than the shaft and to a taper of one inch to the foot. A bushing is then bored to fit the shaft and turned to the same taper as the hub is turned, but left, say, 1⁄100 inch larger in diameter and 1⁄4 or 3⁄8 longer. ”

“ With a direct spoke screwed into the hub, the weight of the man is sustained by a direct end-pull, and a slight power is transmitted to the rim by the resistance to flexure or bending in the spoke tending to revolve the wheel, and it will be found in practice that any hub with a direct spoke will turn independently of the rim far enough to increase the distance slightly between the ends of the spokes so as to really make an end-pull as in the tangent spoke, but evidently the hub must revolve a great way in order to increase the length a very little. ”

“ The main object of this invention is to form a wheel hub for vehicles in such manner that the wheel will yield sufficiently when undue and sudden strains or jars may come upon it to receive the force of the blow and shield the other portions of the vehicle from the destructive effects of such action, as well as to afford ease and comfort of motion to the occupant ”

“ The wheel, C, which is graduated for the hours of the day, is fastened rigidly upon the hub, a, by means of the projection, b, and rotates with it. Loose on the same hub is the wheel, B, which may be fastened by friction to the wheel, C, in different positions, by the thumbscrew, Q, that is attached to, or forms part of, the wheel, B, and passes through the slot, c, of the wheel, C. p, p, p, p, p, designate pivots on which the several wheels revolve. The wheel, B, is cut away on its periphery, leaving the depression, d, and the cam projection, e ”

“ There are always a number of discarded carriages, wagons or parts thereof in the rear of the average blacksmith's shop. Sometimes for half a dollar, and often for nothing, you can get a wheel, an axle, and connected parts. Remove from the wheel, all but the four spokes needed for the fans as in Fig. 1. The same hub, axle and bearings will do. In case you cannot secure a wheel and shaft, the hub may be made from a piece of hardwood, about 4 in. in diameter and 6 in. long. A 2-in. hole should be bored through for a wooden shaft, or a 1-1/2-in. hole for a metal shaft. ”

“ If the direction of the force is vertical, and the beam is inclined, then the strain is increased by as much as the diagonal of inclination exceeds the vertical; for example, let one thousand pounds be suspended from the lower end of a beam ten feet long, inclined at an angle of 45°. The diagonal being ten, the vertical will be 7.07 feet, and the strain is increased as follows:—
7.07 to 10 as 1,000 to 1,414 lbs. As the angle of inclination, from the horizontal, increases, the strain from a given load decreases, until the beam is vertical, when a weight acts with its least power. ”

“ Hence the outer tip, travelling the fastest, is narrower than the middle of the blade, and it is also much thinner to lessen the centrifugal force acting upon it at great speeds. Near the hub, however, where the travel is slowest, the constructional problem demands that the blade contract in width and be made stout. ”

“ On the New York subways, it is interesting to note, every passenger who boards a train has his weight recorded by the brake mechanism, and allowance is automatically made for the inertia that his mass adds to the train when it is in motion. The weight operates through a system of levers to control the amount of pressure that is applied to the [133] brakes so that when the engineer operates the brake lever, he does not have to consider whether the cars are light or jammed full of passengers ”

“ The wheel builder laces the spokes through the holes in the hub flange, then through the holes in the rim and slips a washer and nipple on the end of each. When the wheel is loosely assembled it has to be trued. ”

“ When one end of the lever (A) goes down, the other end goes up, as shown in Fig. 129; and in Fig. 130, when the shaft (C) of one wheel turns in one direction, the shaft of the other wheel turns in the opposite direction.
It is plain that a gear, like a lever, may change direction as well as increase or decrease power. It is the thorough knowledge of these facts, and their application, which enables man to make the wonderful machinery we see on every hand. ”

“ The case was somewhat relieved by the fact that I always cored out a larger chamber in the middle of the hub for the purpose of getting rid of a mass of metal which would cause the hub to cool too slowly, finishing only a length of two inches at each end of the hub, which was 10 or 12 inches long. As the engine had been paid for on shipment and ran well when put together, there was no great harm done, but I was sorry for the poor fellows who had to do the work. ”

“ It also consists in the combination with a fixed plate, which confines the mainspring and supports the movement, of a rotating plate arranged in front of said fixed plate, and provided with a hub which extends through said fixed plate, and is connected to the winding end of the mainspring. It also consists in adapting to, and combining with, the hub thus constructed, a key having a screw-threaded winding part for engaging with said hub, and a recessed part for engaging with the prismatic end of the center shaft. ”

“ Sliding Contact: Forms of the Teeth of Spur-wheels and Racks.—A line of connexion of two pieces in sliding contact is a line perpendicular to their surfaces at a point where they touch. Bearing this in mind, the principle of the comparative motion of a pair of teeth belonging to a pair of spur-wheels, or to a spur-wheel and a rack, is found by applying the principles stated generally in §§ 36 and 37 to the case of parallel axes for a pair of spur-wheels, and to the case of an axis perpendicular to the direction of shifting for a wheel and a rack. ”

“ All members under tensile stress are open lattice girders.
Thus the bottom members-the vertical columns and the struts in cantilevers are always under compression and are tubular in form, while the top members, the inclined ties in cantilevers and vertical ties are invariably in tension, and are of open lattice-girder form. The diagonal struts in the central towers again, although always in compression from dead load or wind pressure, receive an alternate tensile or compressive stress, and vice versa, according to the direction from which the live load or train load enters on the pier. ”

“ A useful application of weighbridges is to ascertain the exact weights on the separate wheels of locomotive engines, so that they may be properly adjusted. For this purpose a number of separate weighbridges of simple construction are erected, one for each wheel of the engine, with their running surfaces in exactly the same horizontal plane. The engine is moved on to them, and the pressures of all the wheels are taken simultaneously, each by its own weighbridge. ”

“ Like the weighing machine for carriages, the fulcrum of each lever is at one end, and the force is diminished in passing to the spring, in the ratio of the length of its arms. The spring moves a pinion by means of a rack, upon which pinion a hand is placed, indicating by divisions upon a circular dial-plate, the amount of the force employed. ”

“ When w is 270 lbs. the compression on a b is 300 lbs., and the tension on b c is 405 lbs., so that both tie and strut attain their breaking loads together. The principle of duly apportioning the strength of each piece to the load it has to carry, involves the essence of sound engineering. In that greatest of mechanical feats, the construction of a mighty railway bridge across a wide span, attention to this principle is of vital importance. Such a bridge has to bear the occasional load of a passing train, but it has always to support the far greater load of the bridge materials. ”

“ The transmission H consists of a bicycle coaster-brake hub, shown in detail in Fig. 2. A split pulley, J, 6 in. in diameter, is bored out to fit over the center of the hub between the spoke flanges. The halves of the pulley are then clamped on the hub with two bolts, run through the holes in opposite directions. Their heads and nuts are let into countersunk holes so that no part will extend above the surface of the pulley. The supports for the hub axle consist of two pieces of bar iron, 4 in. ”

“ In the conical pendulum, or steam engine governor, which consists of two metal balls suspended on rods hung from the end of a vertical revolving shaft, the centrifugal force is manifested by the divergence of the balls, when the shaft is put into revolution; and the centripetal force, which in this instance is gravity, predominates so soon as the velocity is arrested; for the arms then collapse and hang by the side of the shaft. ”

“ Each arm of the wheel carries a segment of the rim, and is moved radially to increase or diminish the rim diameter by sliding in slots provided in the hub of the wheel, a radial screw operated by bevel gears receiving motion from the hand wheel and gear-wheels shown in the engraving. It is obvious that in this case the driving belt must be made long enough to embrace the pulley when expanded to its maximum diameter, the slack of the belt due to reduction of diameter being taken up by a belt tightener. ”