Gear (mechanism)

“ The driving pulley b, Fig. 3189, for operating the feed mechanism, receives motion by belt connection from the countershaft, and drives the shaft on which are the bevel gears b and d, and from these gears the feed motion and quick return are derived, while from gear e and pulley r the cutter head may be raised and lowered by belt power as occasion may require. Beginning with the feed motion, the gear d drives gears e and f, which are a working fit on the shaft s. ”

“ By means of these it is possible to change the gear of the machine so as to have a high gear under favourable conditions and a low gear when mud, wind, or an ascent make travelling difficult. Although chain gearing is used in nearly every machine made, connecting rods, wheels, or bands are fitted instead to some machines. ”

“ Self-reversing gear, with one belt, two fast and one loose pulleys. The large spur wheel is driven from the bevil gear, and carries the weighted lever past the vertical position by a stop on the face-plate or disc, when it falls over and reverses the belt fork. ”

“ The imported gear cases are clumsy and heavy, and, being made mostly of metal, are apt to be noisy. The 1898 gear cases of American make are made of a combination of rubber, leather and metal, and are light, noiseless and graceful, and most of the leading makes of the chain cycles for the coming season are built with sufficient clearance to take a gear case. ”

“ Chain and sprocket act on each other much as the teeth of gears act, and in effect they are a peculiar form of gears, for if you can imagine one of a pair of gear wheels flexible and flattened out like a chain, and thus running, it is evident that this action is really that of gearing. ”

“ 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. ”

“ As a large gear reduction is thus rendered possible on the back axle, it will readily be understood that the change-speed gear-box may be made considerably smaller than would be necessary for a bevel-driven live axle, where a large gear reduction is not permissible, both on account of its size and because such a gear would be very noisy in its working. ”

“ 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 gear on the armature shaft should be as small, and that on the axle as large, as practicable. The intermediate gear should be of such a size that it will close the space between the small gear on the armature shaft and the large one on the axle. ”

“ 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. ”

“ 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. ”

“ To accurately divide off the pitch circle of a gear-wheel by hand, requires both patience and skilful manipulation, but it is time and trouble that well repays its cost, for in the accuracy of spaces lies the first requisite of a good gear-wheel. ”

“ On account of the first-named advantage, they are largely employed upon small gears, having their teeth cut true in a gear-cutting machine; while on account of the second advantage, interchangeable wheels, which are merely required to transmit motion, may be put in gear without a fine adjustment of the pitch circle, in which case the wear of the teeth will not prove destructive to the curves of the teeth. ”

“ At first sight, it might appear that sand and mud might create a disturbance by edging themselves into these small gears, but the makers maintain that a gear case is unnecessary, because the gears practically clean themselves, in consequence of each gear wheel running in direction opposite to that of its neighbor. ”

“ But by far the most interesting part of the machine is that which is underneath the frame. At one end we see a pair of ordinary-looking wheels and between them the gear for swinging them to right or left for steering purposes, but even they are somewhat unusual, since they will be seen to have flanges or rims round the edge for the purpose of biting into [Pg 279] the earth, so that they may be able to guide the machine the better in soft ground. ”

“ By multiplying both numerator and denominator by 4, we obtain two available gears having 24 and 40 teeth, respectively. The 24-tooth gear goes on the spindle stud and, the 40-tooth gear on the lead-screw. The number of teeth in the intermediate or “idler” gear b, which connects the stud and lead-screw gears, is not considered as it does not affect the ratios between gears a and c, but is used simply to transmit motion from one gear to the other. ”

“ The intermediate gears are securely locked to each end of the tubular gear shaft by a simple locking device, which makes it possible to remove and replace the gears conveniently and without the necessity of any special tools and appliances. The tubular gear shaft rotates on ball bearings specially constructed and designed to receive the thrust of the driving gear, and transmits the power to the rear hub. ”

“ Gear-case.—The modern roller chain by makers of repute is so durable that the necessity for a gear-case is not so great as when chains were of inferior quality. But if the bicycle is to require the minimum amount of care and attention a gear-case should be fitted. The Sunbeam gear-case is built into the frame and is oil-retaining, and the chain, chain-wheels, free-wheel and two-speed gear are continually lubricated by an oil-bath. A detachable gear-case is not usually oil-retaining, but serves to exclude grit and mud from the chain. ”

“ At each machine sat a human being working with hand, foot, and eye, watching the flashing needle, guarding the margin of the seams, jerking the cloth hither and thither quickly, accurately, watching the spool to see that the thread ran freely, oiling the gear with one hand while the other continued to push the garment rapidly under the needle, the whole body swaying, bending, twisting this way and that to keep time and pace with the work. ”

“ The sparking gears are driven by means of a gear formed on a sleeve which telescopes over the hub of the starboard drum, and has a bearing thereon, the end of the sleeve terminating in a ring which is fastened to the crank shaft. ”

“ 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. ”

“ Moore’s patent differential epicycloidal gear. The pinion and wheel are loose on the shaft and eccentric. One wheel has one tooth more than the other.
1546. Multiplying bevil gear. A is a fixed wheel, the cross C is keyed to shaft, B loose on ditto, D and E loose on C; then B is driven at a speed greater than the shaft in proportion to the diameters of the gear. See Patent No. 12,696, 1884.
1547. Double worm gear, right and left hand threads. Neutralises the end thrust on shaft. A and B may be geared together.
1548. Pointed gear; used for light work and for minimum of friction. ”

“ 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. ”

“ Gear Casing.—Push forward and remove receiver lock pin and unhook gear casing from gear case hinge pin.
Mainspring Group. To strip completely the parts assembled in gear casing, raise the gear stop with the point of a bullet, and allow mainspring to unwind. ”

“ 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. ”

“ By a belt on the fly-wheel of the prime mover the power is transmitted to the line shaft, and pulleys suitably placed along the line shaft by means of other belts transmit power, first, to small counter shafts carrying fast and loose pulleys and striking gear for starting or stopping each engine at will, and then to the driving pulleys of the several machines. ”

“ Furthermore, belt connections are lighter and cheaper than gear-wheel or other rigid and positive connections, and hence the wide application of leather belts for the transmission of power, notwithstanding the slight variations of pulley velocity ratio due to the unequal elasticity of the various parts of the leather composing the belt. ”

“ We now have uniformity in height and contour to insure perfect contact between all classes of equipment, and a positively locked knuckle. The design and attachments to car body are prescribed of a strength in excess of the power of locomotives, and in modern friction draft gear the strength reaches 250,000 pounds. ”

“ When the teeth of bevel gears form an angle of 45° they are called miter wheels.
Miter wheels to gear must be of equal sizes.
A crown wheel is a disc that has teeth which are on its side face; that is, teeth on a flat circular surface all parallel to the axis of the wheel.
A rack has teeth on a flat surface or plane all parallel to one another.
A gear cut by machine is called a cut gear. It has teeth with less clearance than cast wheels, which are not so true or perfect, and therefore require more clearance. ”

“ The link motion may be moved from full gear forward to full gear backward or to any intermediate position, whether the engine is running or at rest, but is, when the engine is running, harder to move from full gear forward toward back gear, and easier to move from full gear backward toward mid and forward gears, which occurs because of the friction of the eccentrics in the straps, and it follows that this will be the case to a greater extent in proportion as the revolutions of the eccentrics are increased. ”

“ The gearing is attached to the axle and countershaft which extend across the engine. The compensating gear is strong and well covered from dirt. The gearing is the gear type, axle turning with the drivers. There is an independent pump; also injector, and all attachments. The band wheel being on the steering wheel or right side of the engine, makes it easy to line up to a threshing machine. ”

“ Great care should be taken to see that both gear and bearings are kept properly lubricated, or worn surfaces will result, with much extra friction to be overcome, and if not quickly attended to other things may happen of a serious character. ”

“ This is a proper place to explain gear ratio or “gear,” which is a phrase not generally well understood, although in constant use; for instance, women have been known to ask dealers for a wheel with low gear, because they liked to be seated near the ground. The term gear, which is an adaptation from the old high wheel, expresses the ratio of forward travel of the bicycle for each pedal revolution, and yet this has nothing to do with either the height of the rider or the length of his leg, or the length of the crank. ”

“ Low and reverse are always opposite each other on the same core. High and intermediate are located on another core, and are controlled by another individual [201] shifting fork. The gear box arrangement (Fig. A) shows the cast gear box which contains the gears, shafts, and bearings, and a roomy compartment below the gears in which grease is carried, as the gears in this type of transmission always operate in an oil bath which prevents excessive wear and causes them to operate noiselessly. ”