Gear wheel

“ 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. ”

“ 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. ”

“ 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. ”

“ For the benefit of those of our readers, who have no previous acquaintance with mechanism, we shall merely premise that a gear is a wheel with a toothed circumference, like watch-wheels, or what in ruder mechanism are known as cogged-wheels; and those gears, known as level gears, are such as have the toothing on the circumference not perpendicular to the plane of the diameter, but at an acute angle to it, so that when two gears of a peculiar degree of bevil are set in contact, a horizontal rotatory movement may be communicated to one by a corresponding perpendicular rotation of the other. ”

“ With a three-speed gear the low and high gears should be chosen respectively below and above the single gear which suits the rider, the middle gear being about the same as the rider’s usual single gear.
All the variable speed gears at present made consist of toothed wheel mechanism either at the hub or crank-bracket, and nearly all are based on the same epicyclic train of toothed wheels. At one speed there is no relative motion of the toothed wheels, the whole mechanism revolving as one solid piece ”

“ The pinions mesh with two wheels that are mounted on a countershaft, on which is also fixed a chain-sprocket, from which the drive is transmitted, through a long chain, to a chain-wheel surrounding the differential gear mounted on the back axle. Traction-engine type of steering gear, with revolving fore-carriage, is most generally adopted, and is rendered sufficiently rapid in its movement by suitable gear, operated by a diagonal shaft and wheel, from the driver’s footplate. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ In the majority of American vehicles the motion of the motor is transmitted to the wheels by means of spur gearing. In some cases a single motor is used, in others two; and in one or two designs that have come to public notice, four motors are employed, one for each wheel of the carriage. Fig. 2 illustrates what is commonly called a double reduction gear for single motor equipment. The outline A represents the motor, B being the shaft. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ A pinion C on a shaft D is so journaled that during one half of the rotation of the wheel A, it engages with the rim teeth, and during the other half with the hub teeth. As the hub B and gear C are the same diameter, one half turn of the pinion C will give a half turn to the wheel A.
As the rim teeth of the wheel A are three times the diameter of the pinion C, the latter must turn once and a half around to make a half revolution of the wheel A.
Scroll Gearing.—This is a type of gearing [190] whereby at the close of each revolution the speed may be greater or less than at the beginning. ”

“ 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. ”

“ At each side of the spur gear are placed bevel gears, meshing into the bevel pinions, one of which is keyed fast to the shaft or axle, while the other is firmly bolted to small pinion that drives the traction wheel, or to hub of the traction wheel, which also runs loosely on its axle. ”

“ The gearing by which the traction wheels of a traction engine are made to drive the engine is an important item. Of course, it is desirable to apply the power of the engine to both traction wheels; yet if both hind wheels were geared stiff, the engine could not turn from a straight line, since in turning one wheel must move faster than the other. The differential or compensating gear is a device to leave both wheels free to move one ahead of the other if occasion requires. ”

“ By connecting any one member of a gear of this character with the engine shafting, and another with the wheels, and locking the third to the frame of the car, a great variety of adaptations can be made to meet special needs, this arrangement having the advantage of neatness and compactness, and having all the gear wheels in constant engagement with each other all the time. ”

“ 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. ”

“ In the high gear position the epicyclic toothed wheels are to the extreme left position. The chain-wheel is mounted by a free-wheel on a drive-ring, with which the ends of the spindles of the planet wheels engage at high gear. The sun-wheel, not shown in the figure, is held stationary, and the annular wheel engages with a ring screwed to the hub-shell, by means of keys engaging in notches. ”

“ It receives in addition a cog-wheel, L, which transmits its motion to the decorticating cylinder through, the intermedium of a large wooden-toothed gear wheel, L'. The shaft, a, whose diameter is 228 mm., actuates in its turn, through the pinions, M' and M, the pitch pinion, N, upon whose prolonged hub is keyed the pinion, M. This latter is mounted loosely upon the intermediate axle, m. Motion is transmitted to the driving shaft, h, of the endless chain, I, by an ordinary pitch chain, through a gearing which is shown in Fig. ”

“ 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. ”

“ A tell-tale mark on the surface of the fly-wheel showed friction against something, and we found that while the wheel ran freely if we were out of the machine, with the load in, and especially on up grades with the chain drawing the framework closer to the running gear, the rim of the wheel just grazed a bolt-head in a small brace underneath, thereby producing the peculiar grating noise we had heard and materially checking the motor. ”

“ In the operation of the differential gear, the power is first transmitted to spur gear, containing cushion springs, from thence by the springs to a center ring and four bevel pinions which bear equally upon both bevel gears. The whole differential consequently will move together as but one wheel when engine is moving straight forward or backward ”

“ Screw and worm wheel gear, for the same purpose as 445.
447. The driven wheel A has a limited travel up and down the slot, the idle wheel B being kept in gear by the link suspension.
448. Idle wheel and slot. A common device for changing direction or speed in driving gear by connecting or disconnecting it with intermediate gearing between a fixed driving and a driven shaft.
449. Parallel motion radiating driving device, with a limited vertical travel and a radial motion.
450. Motion by belt is conveyed to a driven shaft having a radial motion in a vertical plane. ”

“ By putting on different-sized sprockets on the ends of the countershaft the ratio between the revolutions of engine and road wheels, so far as the top speed is concerned, may be varied to suit requirements, and by shifting the gear wheels, g, h, and i, so that they engage with either k, l, or m, this speed may be maintained or reductions made from it. Thus it will be seen that the different-sized gear wheels are arranged on their respective shafts at such intervals that when one pair are in gear, the others are out of gear. ”

“ 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. ”

“ Gear-wheels therefore form a convenient method of either simply transmitting motion or power, as when the wheels are all of equal diameter, or of transmitting it and simultaneously varying its velocity of motion, as when the wheels are compounded either to reduce or increase the speed or velocity in feet per second of the prime mover or first driver of the train or pair, as the case may be. ”

“ Section 87.—THROWING IN AND OUT OF GEAR. 1574. The driving wheel is loose on shaft, and is locked to its shaft by the hand wheel nut (see No. 945) , or by a ratchet wheel and locking pawl.
1575. Two half-nuts are lifted in or out of gear with the screw by cam or lever motion. See No. 942.
1576. One shaft runs in eccentric bearings, which can be revolved so as to throw it out of gear with the other shaft.
[193]
Larger plate.
[194]
1577. Radius bar and slot. The stud wheel can be shifted in or out of gear along the slot.
1578. Sliding back shaft, slides out of gear. See dotted lines. ”