Gearwheel

“ In action these bevelled wheels are similar to the gear wheels first described, but instead of revolving lightly on their bearings and pushing round the teeth of the opposite wheel as they come in contact, their shape causes a strong repelling action also to take place, the tendency of the bevelled faces of the gear wheels being to force themselves apart, which throws a considerable cross strain upon the bearings. The power, too, is deflected at right angles, which is another source of loss. ”

“ Under the latter conditions, viz., with the higher gears in use, the rider's feet revolve the crank axle slower, but the ratio of gearing being about one to two and a half turns of the road wheel on normal or middle, and three to three and a half turns of the road wheel on top gear, the machine moves faster with approximately the same exertion; or to explain it another way, the rider has no need with a high gear in use to exhaust himself with rapid pedalling as he would do if he wished to ride fast with a normal single gear. ”

“ A. A gear-wheel in the form of a continuous screw. (Fig. 10.)
Q. What is a sprocket-wheel?
A. A toothed wheel that engages the links of a chain. (Fig. 11.)
Q. What is a spur-wheel?
A. A gear-wheel with teeth parallel with the axle of the [43] wheel. If in Fig. 7 the rack were in form of a wheel, it would be a spur-wheel. (The pinion is also a spur-wheel.)
RACK AND PINION.
Fig. 7.
MITRE GEAR.
Fig. 9.
BEVEL GEAR.
Fig. 8.
WORM GEAR.
Fig. 10.
SPROCKET WHEEL AND CHAIN.
Fig. 11.
Q. Point out or describe the location of the following parts of a seacoast carriage:
Base-ring. ”

“ Now the simplest method possible would be the driving of the road wheels or wheel direct by the piston-rods of the engine, a plan only possible where a very small wheel is used, and only actually employed in the Holden bicycle as described in the chapter devoted to this type of machine. Next to this comes the use of gear wheels—'cog' wheels—as employed upon tricycles and some light forms of car where the motor is set close to the axle. In these we have one gear wheel fixed to the shaft of the motor, gearing into a similar one upon the axle. ”

“ The above cut represents a very cheap and simple gear-cutter. Its principal novelty consists in the use of the large gear-wheel instead of the common graduated table. It is extremely simple, and at the same time possesses all the advantages of the old machine. It will be observed that the crank is connected to the large wheel by a set of intermediate gears, every revolution of which is made to correspond with the number of teeth in the wheel to be cut. ”

“ A gear is primarily a toothed wheel; gearing is a train of toothed wheels for transmitting motions; there are two chief sorts of toothed gearing, viz., spur gearing and bevel gearing.
A spur wheel has teeth around the edge pointing to the center; commencing at the center, a spur wheel may be said to consist of a hole, square, octagonal or round, for its axle or shaft; a hub; the web, body or arms; a rim, and the teeth; see fig. 263.
A spur wheel has teeth on its circumference which run parallel to its shaft; wheels as shown in fig. ”

“ A primary gear wheel is propelled horizontally by a lever worked by a horse. The primary gear impels a pinion keyed to the shaft of a windlass, upon which is wound the elevating rope, whenever the clutch, A, is made to operate through the cord and lever, B. This cord runs over a pulley on the under side the wood framework at C, and its further end may be held in the hand of the workman on the hay load, who, when he has properly adjusted the fork, pulls the cord which operates the clutch, and the "fork-full" of hay is at once elevated. ”

“ When the water wheel is an iron one, it usually has light iron suspension arms incapable of resisting the bending action due to the transmission of the turning effort to the axle. In that case spur segments are bolted to one of the shrouds, and the pinion to which the power is transmitted is placed so that the teeth in gear are, as nearly as may be, on the line of action of the resultant of the weight of the water in the loaded arc of the wheel. ”

“ A foot piece or pedal, P, arranged at a convenient position, enables the attendant to depress the lever and brake-shoe by placing his foot thereon when he desires to throw off the brake for releasing the hand-wheel.
In lieu of connecting the hand-wheel and blade-lifting bar or lever by means of a toothed pinion and rack, said parts may be connected by a strap or chain (one or more) , one end whereof connects with the lift bar or lever, while the other end is arranged to wind onto the pinion or hub on the hand-wheel, or onto a sheave geared to the hand-wheel hub. ”

“ In order to travel fast over level country, and yet be able to mount hills without undue exertion, we must be able to do what the motorist does—change gear. Two-speed and three-speed gears are now very commonly fitted to cycles. They all work on the same principle, that of the epicyclic train of cog-wheels, the mechanisms being so devised that the hub turns more slowly than, at the same [Pg 443] speed as, or faster than the small chain-wheel, [42] according to the wish of the rider. ”

“ We have now arrived at the stage when a high bicycle was regarded as dangerous, and, if the front wheel were too small, it detracted from the rider’s speed owing to the shorter distance covered by each turn of the wheel. What was the next move? The engineer’s mind turned towards a method of gearing by cogs or chains, by which one turn of the crank axle would cause the driven wheel to turn more than once. That is where we get our method of describing the ratio of gearing between the crank and the wheel of a modern safety bicycle. ”

“ When a screw or worm revolves in the teeth of a wheel, the latter is termed a worm wheel or worm gear; see fig. 270. When a pinion acts with a rack having teeth, we speak of rack and pinion. When the teeth are on the inside of the rim, and not on the periphery, the wheel is termed an internal gear; see fig. 272.
Two wheels acting upon one another in the same plane are called spur gear; the teeth are parallel with the axis. When wheels act at an angle, they are called bevel gear. ”

“ 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. ”

“ The tractive power of the engine may be just doubled, trebled, or quadrupled to adapted to the grading of the road on which it is to be used. Another mode of changing the gearing by holding fast the two wheels B, and D, alternately, is by means of levers placed in a groove lengthwise the shaft, one arm of which being raised operates like a feather entering a notch or groove in the bush of the wheel, the arms of the levers are raised, depressed by a slide, and gage bar as shown in Fig. ”

“ Fig. 1505 represents a shaper that may be driven either by hand or by belt power. The cone pulley shaft has a pinion that drives the gear-wheel shown, and at the other end of this gear-wheel shaft is a slotted crank carrying a pin that drives a connecting rod that actuates the sliding bar, or ram, as it is sometimes termed. The fly-wheel also affords ready means of moving the ram to any required position when setting the tool or the work. ”

“ By gripping the endless rope between grip wheels (see 1208) the small wheel can be thrown into gear to grip the rope by a lever, cam or screw.
c. Differential gear may be driven from a shaft by belts or gearing. See Sections 84 and 3.
d. Screw gear. Ditto.
e. Rack gear. Ditto.
f. Worm and wheel gear. Ditto.
g. Friction gear is usually driven as No. 1211.
1211. Where the barrel shaft has a slight horizontal movement, so that, by the lever, it can be forced into gear with the friction pinion to raise the load, or into the brake block to sustain the load or lower it. ”

“ Considering that the railway-carriage builder gives up the coach-wheel principle, and returns to the primitive construction of the pair of wheels fixed to the axle turning in bearings, we see that our ordinary carriage-wheels turning independently on their axles are best suited to comparatively narrow wheels, and to smooth ground or made roads. Here they give greater lightness and speed, and especially have the advantage of easily changing direction and turning, which in the old block-wheel cart can only be done by gradually slewing round in a wide circuit. ”

“ The rider, therefore, pedalled by pushing the levers down alternately and releasing the pressure at the end of the strokes. The Facile was followed at a later date by the Geared Facile, which was the same design as the Facile and had the same lever motion for pedalling, but included a sun and planet gear on the hub. Briefly, this consisted of a large toothed wheel on the axle and a crank extending beyond the edge of the wheel. Working in a bearing on the crank end was a small planet pinion, or toothed wheel, which meshed with the larger toothed wheel. ”

“ A large internal toothed wheel was placed on the outer ends of the arms of the spider to which the windwheel arms were bolted, the internal gearing of which wheel engaged with a small gear wheel or pinion placed on an independent shaft, at the other end of which shaft a bevelled pinion was placed, interlacing with a corresponding bevel on the upper end of the upright revolving shaft. ”

“ The question of gearing is complicated by the fact that the frame of the car oscillates vertically with respect to the axles. Spur-wheels, worm-gear, friction gear, belts, multiple-band gear, and chain-gear are or have been used. ”

“ Connected with the fly-wheel was a powerful wooden brake, acting by pressure against its rim, something like the brake of a railway-carriage against its wheels. On catching sight of the chain attached to the ascending corve-cage, the brakesman, by pressing his foot upon a foot-step near him, was enabled, with great precision, to stop the revolutions of the wheel, and arrest the ascent of the corves at the pit mouth, when they were forthwith landed on the “settle board.” ”

“ So that all the wheels are connected with each other and the great rollers, and by turning one you can turn all, and work the hammers and shears into the bargain. All our Giant has to do, therefore, is to seize hold of that end of the balanced beam farthest from the arm, and to occupy himself in pulling it down and pushing it up continuously. By this means the arm, which hangs free to swing backwards and forwards, pulls the spoke of the wheel to which it is attached up one side, pushes it down the other, and thus sets its own and all the other wheels revolving. ”

“ The power is transmitted from one of the pulleys by a rubber belt to an intermediate shaft, which carries a toothed wheel that transmits the power to the axle by means of an endless chain. On this axle are three conical gear wheels, two of which are furnished with hooked teeth, and the third with wooden projections and fixed permanently in place. ”

“ Now, since the rider, by the action of his momentum107 and that of the machine, is rolled upon the obstacle or out of the rut, it is easily seen that if he is attending strictly to his work and is at all a skilful rider, he can, by a lively thrust upon the pedal at the opportune time, right himself and keep the drive-wheel rolling on, in which case the rear part of the machine will, in all ordinary cases, drop back upon the ground, from which, of course, it will have raised. ”

“ A single lever is usually employed for engaging any of the forward gears or the reverse, so that the mistake of simultaneously engaging a reverse and a forward gear is not possible. The spur-wheels are generally mounted in pairs on two sleeves, so that, by means of a selector mechanism that compels one sleeve to be brought to the neutral position before the other can be moved, no two gears can ever be engaged together. ”

“ Between the wheels is a crank-axle which the rider drives by means of the cranks and pedals, and its motion is transmitted to the rear or driving wheel either by a chain which passes over two chain wheels, one fixed on the crank-axle and the other on the hub of the rear wheel, or, in the chainless bicycle, by a tubular shaft and two pairs of bevel-wheels. ”

“ The driving power being transmitted from front sprocket or gear by shaft tube to rear gear or sprocket, all being suitably secured as above stated to frame upon rear fork rotatably supported by ball bearings connected to the frame and forks.
“This does precisely what has always been accounted to be out of the question and confutes both theoretical and practical mechanics. It is a gear that turns the corner by means of square cut teeth that mesh directly instead of by means of bevel teeth, and we call it a face gear. ”

“ The large wheel should be attached to an axle and one of the pedal-cranks made fast to it. Instead of the pedal a wooden handle will slip on the pedal axle where it can be secured by the nut that held the pedal in place. The relative positions 142of wheels, axles, and other parts of this reel can be seen at Fig. 33. A represents the crank, handle, and large wheel; B the axle that passes through the box; C the axle and flanges made fast to the small sprocket-wheel ”