240t焊接滾輪架設(shè)計-主動滾輪座設(shè)計(全套含CAD圖紙)
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Axle
Train wheels are affixed to a straight axle, such that both wheels rotate in unison. This is called a wheelset.
An axle is a central shaft for a rotating wheel or gear. In some cases the axle may be fixed in position with a bearing or bushing sitting inside the hole in the wheel or gear to allow the wheel or gear to rotate around the axle. In other cases the wheel or gear may be fixed to the axle, with bearings or bushings provided at the mounting points where the axle is supported. Sometimes, especially on bicycles, the latter type is referred to as a spindle.
Axles are an integral structural component of a wheeled vehicle. The axles maintain the position of the wheels relative to each other and to the vehicle body. Since for most vehicles the wheels are the only part touching the ground, the axles must bear the weight of the vehicle plus any cargo, as well as acceleration and braking forces. In addition to the structural purpose, axles may serve one or more of the following purposes depending on the design of the vehicle.
Drive: One or more axles may be an integral part of the drivetrain. A mechanical system (typically a motor) exerts a rotational force on the axle, which is transferred to the wheel(s) to accelerate the vehicle.
Braking: Conversely a vehicle may be slowed by applying force to brake the rotation of the axle. Consumer vehicles' brakes are part of the wheel assembly and therefore exert friction on the wheels directly, but engine braking may still be effected via the axle.
Steering: The front axle of most automobiles is a steering axle. The vehicle is maneuvered by controlling the direction of the front wheels' rotational axis relative to the body and rear wheels.
Structural features
0 Series Shinkansen Wheel
A straight axle is a single rigid shaft connecting a wheel on the left side of the vehicle to a wheel on the right side. The axis of rotation fixed by the axle is common to both wheels. Such a design can keep the wheel positions steady under heavy stress, and can therefore support heavy loads. Straight axles are used on trains, for the rear axles of commercial trucks, and on heavy duty off-road vehicles. The axle can be protected and further reinforced by enclosing the length of the axle in a housing.
In split-axle designs, the wheel on each side is attached to a separate shaft. Modern passenger cars have split drive axles. In some designs, this allows independent suspension of the left and right wheels, and therefore a smoother ride. Even when the suspension is not independent, split axles permit the use of a differential, allowing the left and right drive wheels to be driven at different speeds as the automobile turns, improving traction and extending tire life.
A tandem axle is a group of two or more axles situated close together. Trucks designs will use such a configuration to provide a greater weight capacity than a single axle. Semi trailers usually have a tandem axle at the rear.
Drive axles
Splines on a front drive axle.
An axle that is driven by the engine is called a drive axle.
Modern front wheel drive cars typically combine the transmission and front axle into a single unit called a transaxle. The drive axle is a split axle with a differential and universal joints between the two half axles. Each half axle connects to the wheel by use of a constant velocity (CV) joint which allows the wheel assembly to move freely vertically as well as to pivot when making turns.
In rear wheel drive cars and trucks, the engine turns a driveshaft which transmits rotational force to a drive axle at the rear of the vehicle. The drive axle may be a live axle, but modern automobiles generally use a split axle with a differential.
Some simple vehicle designs, such as go-karts, may have a single drive wheel. The drive axle is a split axle with only one of the two shafts driven by the engine.
Dead axles/lazy axles
This dump truck has an airlift pusher axle, shown in the raised position.
A dead axle, also called lazy axle, is not part of the drivetrain but is instead free-rotating. The rear axle of a front-wheel drive car may be considered a dead axle. Many trucks and trailers use dead axles for strictly load-bearing purposes. A dead axle located immediately in front of a drive axle is called a pusher axle. A tag axle is a dead axle situated behind a drive axle.
Some dump trucks and trailers are configured with airlift axles, which may be mechanically raised or lowered. The axle is lowered to increase the weight capacity, or to distribute the weight of the cargo over more wheels, for example to cross a weight restricted bridge. When not needed, the axle is lifted off the ground, to save wear on the tires and axle and increase traction in the remaining wheels. Lifting an axle also makes the vehicle perform better on tighter turns.
Several manufacturers offer computer-controlled airlift, so that the dead axles are automatically lowered when the main axle reaches its weight limit. The axles can still be lifted by the press of a button if needed.
Gear
Old clock with exposed gears.
modern single-stage planetary gearhead for use with small fractional horsepower motor
A gear is a component within a transmission device that transmits rotational torque by applying a force to the teeth of another gear or device. A gear is different from a pulley in that a gear is a round wheel that has linkages ("teeth" or "cogs") that mesh with other gear teeth, allowing force to be fully transferred without slippage. Depending on their construction and arrangement, geared devices can transmit forces at different speeds, torques, or in a different direction, from the power source.
The most common situation is for a gear to mesh with another gear, but a gear can mesh with any device having compatible teeth, such as linear moving racks.
The gear's most important feature is that gears of unequal sizes (diameters) can be combined to produce a mechanical advantage, so that the rotational speed and torque of the second gear are different from those of the first. In the context of a particular machine, the term "gear" also refers to one particular arrangement of gears among other arrangements (such as "first gear"). Such arrangements are often given as a ratio, using the number of teeth or gear diameter as units.
Mechanical advantage
Intermeshing gears in motion
The interlocking of the teeth in a pair of meshing gears means that their circumferences necessarily move at the same rate of linear motion (eg., metres per second, or feet per minute). Since rotational speed (eg. measured in revolutions per second, revolutions per minute, or radians per second) is proportional to a wheel's circumferential speed divided by its radius, we see that the larger the radius of a gear, the slower will be its rotational speed, when meshed with a gear of given size and speed. The same conclusion can also be reached by a different analytical process: counting teeth. Since the teeth of two meshing gears are locked in a one to one correspondence, when all of the teeth of the smaller gear have passed the point where the gears meet -- ie., when the smaller gear has made one revolution -- not all of the teeth of the larger gear will have passed that point -- the larger gear will have made less than one revolution. The smaller gear makes more revolutions in a given period of time; it turns faster. The speed ratio is simply the reciprocal ratio of the numbers of teeth on the two gears.
(Speed A * Number of teeth A) = (Speed B * Number of teeth B)
This ratio is known as the gear ratio.
The torque ratio can be determined by considering the force that a tooth of one gear exerts on a tooth of the other gear. Consider two teeth in contact at a point on the line joining the shaft axes of the two gears. In general, the force will have both a radial and a tangential component. The radial component can be ignored: it merely causes a sideways push on the shaft and does not contribute to turning. The tangential component causes turning. The torque is equal to the tangential component of the force times radius. Thus we see that the larger gear experiences greater torque; the smaller gear less. The torque ratio is equal to the ratio of the radii. This is exactly the inverse of the case with the velocity ratio. Higher torque implies lower velocity and vice versa. The fact that the torque ratio is the inverse of the velocity ratio could also be inferred from the law of conservation of energy. Here we have been neglecting the effect of friction on the torque ratio. The velocity ratio is truly given by the tooth or size ratio, but friction will cause the torque ratio to be actually somewhat less than the inverse of the velocity ratio.
In the above discussion we have made mention of the gear "radius". Since a gear is not a proper circle but a roughened circle, it does not have a radius. However, in a pair of meshing gears, each may be considered to have an effective radius, called the pitch radius, the pitch radii being such that smooth wheels of those radii would produce the same velocity ratio that the gears actually produce. The pitch radius can be considered sort of an "average" radius of the gear, somewhere between the outside radius of the gear and the radius at the base of the teeth.
The issue of pitch radius brings up the fact that the point on a gear tooth where it makes contact with a tooth on the mating gear varies during the time the pair of teeth are engaged; also the direction of force may vary. As a result, the velocity ratio (and torque ratio) is not, actually, in general, constant, if one considers the situation in detail, over the course of the period of engagement of a single pair of teeth. The velocity and torque ratios given at the beginning of this section are valid only "in bulk" -- as long-term averages; the values at some particular position of the teeth may be different.
It is in fact possible to choose tooth shapes that will result in the velocity ratio also being absolutely constant -- in the short term as well as the long term. In good quality gears this is usually done, since velocity ratio fluctuations cause undue vibration, and put additional stress on the teeth, which can cause tooth breakage under heavy loads at high speed. Constant velocity ratio may also be desirable for precision in instrumentation gearing, clocks and watches. The involute tooth shape is one that results in a constant velocity ratio, and is the most commonly used of such shapes today.
Comparison with other drive mechanisms
The definite velocity ratio which results from having teeth gives gears an advantage over other drives (such as traction drives and V-belts) in precision machines such as watches that depend upon an exact velocity ratio. In cases where driver and follower are in close proximity gears also have an advantage over other drives in the reduced number of parts required; the downside is that gears are more expensive to manufacture and their lubrication requirements may impose a higher operating cost.
The automobile transmission allows selection between gears to give various mechanical advantages.
Gear types
External vs. internal gears
Unlike most gears, an internal gear (shown here) does not cause direction reversal.
An external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, an internal gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, an internal gear is one with the pitch angle exceeding 90 degrees.
Spur gears
Spur gears are the simplest and most common type of gear. Their general form is a cylinder or disk. The teeth project radially, and with these "straight-cut gears", the leading edges of the teeth are aligned parallel to the axis of rotation. These gears can be meshed together correctly only if they are fitted to parallel axles.
Helical gears
Helical gears from a Meccano construction set.
Helical gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. The angled teeth engage more gradually than do spur gear teeth. This causes helical gears to run more smoothly and quietly than spur gears.
Helical gears also offer the possibility of using non-parallel shafts. A pair of helical gears can be meshed in two ways: with shafts oriented at either the sum or the difference of the helix angles of the gears. These configurations are referred to as parallel or crossed, respectively. The parallel configuration is the more mechanically sound. In it, the helices of a pair of meshing teeth meet at a common tangent, and the contact between the tooth surfaces will, generally, be a curve extending some distance across their face widths. In the crossed configuration, the helices do not meet tangentially, and only point contact is achieved between tooth surfaces. Because of the small area of contact, crossed helical gears can only be used with light loads.
Hypoid gears
Hypoid gears resemble spiral bevel gears, except that the shaft axes are offset, not intersecting. The pitch surfaces appear conical but, to compensate for the offset shaft, are in fact hyperboloids of revolution.Hypoid gears are almost always designed to operate with shafts at 90 degrees. Depending on which side the shaft is offset to, relative to the angling of the teeth, contact between hypoid gear teeth may be even smoother and more gradual than with spiral bevel gear teeth. Also, the pinion can be designed with fewer teeth than a spiral bevel pinion, with the result that gear ratios of 60:1 and higher are "entirely feasible" using a single set of hypoid gears.
A worm is a gear that resembles a screw. It is a species of helical gear, but its helix angle is usually somewhat large (ie., somewhat close to 90 degrees) and its body is usually fairly long in the axial direction; and it is these attributes which give it its screw like qualities. A worm is usually meshed with an ordinary looking, disk-shaped gear, which is called the "gear", the "wheel", the "worm gear", or the "worm wheel". The prime feature of a worm-and-gear set is that it allows the attainment of a high gear ratio with few parts, in a small space. Helical gears are, in practice, limited to gear ratios of less than 10:1; worm gear sets commonly have gear ratios between 10:1 and 100:1, and occasionally 500:1.In worm-and-gear sets, where the worm's helix angle is large, the sliding action between teeth can be considerable, and the resulting frictional loss causes the efficiency of the drive to be usually less than 90 percent, sometimes less than 50 percent, which is far less than other types of gears.
Rack and pinion
A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line. Such a mechanism is used in automobiles to convert the rotation of the steering wheel into the left-to-right motion of the tie rod(s). Racks also feature in the theory of gear geometry, where, for instance, the tooth shape of an interchangeable set of gears may be specified for the rack (infinite radius), and the tooth shapes for gears of particular actual radii then derived from that. The rack and pinion gear type is employed in a rack railway.
According to historical records, far from 400 BC to 200 years in ancient China has been started on the use of gears, unearthed in Shanxi Province in China's bronze gear have been found so far the oldest of the gear, as reflected in scientific and technological achievements of ancient cart is gearing mechanical devices at the core. End of the 17th century, people began to study transmission of movement to correct the shape of the tooth. The 18th century, the European industrial revolution, the gear drives the application of the increasingly widespread; first cycloid gear development, and the latter is the involute gear until the early 20th century, involute gear has been accounted for in the application of the advantage.
As early as 1694, the French scholar Philippe De La Hire first involute curve can be used as profile. In 1733, the French made M. Camus tooth contact point of the law center line connection through the node. Instantaneous center line of a supporting, respectively, along the large round and small round
The instantaneous center line (pitch) of pure rolling, the instantaneous center line and auxiliary aids together solid profile in the round and round on the small envelope formed by the two tooth profile curve is conjugate to each other, and this is the theorem Camus. It takes a two-tooth meshing state; clearly established the modern trajectory of contact point on
According to historical records, far from 400 BC to 200 years in ancient China has been started on the use of gears, unearthed in Shanxi Province in China's bronze gear have been found so far the oldest of the gear, as reflected in scientific and technological achievements of ancient cart is gearing mechanical devices at the core. End of the 17th century, people began to study transmission of movement to correct the shape of the tooth. The 18th century, the European industrial revolution, the gear drives the application of the increasingly widespread; first cycloid gear development, and the latter is the involute gear until the early 20th century, involute gear has been accounted for in the application of the advantage.
The late 19th century, show the principle of law into gear and use the principle of exclusive Cutting Machine Tool and Tool have emerged one after another, so that gear plus a more comprehensive tool for the military means, the involute profile of a great show of excellent walking. Just when Cutting Cutting Tools from the normal location of the mesh a little mobile, you can use the standard tool in machine cut gear shift accordingly. 1908, Switzerland MAAG variable method to study and create a show into gear processing machine, subsequently, the United Kingdom BSS, the United States AGMA, the German DIN have to shift gears to a variety of calculation methods.
In order to improve the power transmission gear life and reduce its size, with the exception from the material, heat treatment and to improve the structure, the arc of the gear tooth development was. In 1907, the British released the first Frank Humphris arc tooth profile. In 1926, Swiss natives of Laws Eruest Wildhaber helical gear tooth surface arc of the franchise. In 1955, the Soviet Union, M. L. Novikov gear tooth to complete the arc of the applied research and the Order of Lenin. In 1970, the British company Rolh-Royce engineer R. M. Studer made a double circular gear U.S. patents. This gear has been a growing importance for the people,
Gear is meshing with each other tooth of the mechanical parts, which in mechanical transmission and the machinery in the field of a wide range of applications. Modern technology has reached Gear: Gear modulus O.004 ~ 100 mm; gear diameter by 1 mm ~ 150 meters; transmission power up to 100,000 kilowatts; speed of up to 100,000 rev / min; the highest speeds of up to 300 meters circumference / seconds.
Gear in the transmission of applications have emerged very early on. 300 years BC, the ancient Greek philosopher Aristotle in the "mechanical problems", in relation to the use of cast iron bronze gear transmission or the issue of rotation. Guide to the ancient Chinese invented the car has been applied a comprehensive set of gear. However, the ancient wood of the gear is used to manufacture or use of cast metal and can only pass between the rotary axis mov
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