Types Of Bevel Gears
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There exists a special kind of gear, called the bevel gear. Bevel gears have two shafts intersect with their splines shaped as cones. These kinds of bevel gears are often used on shafts and are spaced at 90 degrees from each other.
As can be seen, bevel gears come in different designs according to the geometry of the splines and the gear plane. The straight bevel gear is similar to the zerol bevel gear except for the shape of the teeth or spline. The hypoid bevel gear is similar to the bevel gear except for the pitch surface of the latter. Clearly, the adaptation of the geometric shape is dictated by what the bevel gear is needed for, and which its function should be within a machine.
Bevel gears are most often used to transmit power at a 90° right angle. The axes of the two bevel gear shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart. Bevel gears are generally divided into 2 types, straight bevel gears and spiral bevel gears.
Straight bevel gearsIn Straight bevel gears, the teeth are straight and parallel to the generators of the pitch cone. Compared with spiral miter gears, straight bevel gears can be made in smaller sizes. We standardized Straight bevel gears as small as module 0.5 in various materials.
Spiral bevel gearsSpiral bevel gears have their teeth formed along spiral lines. They are somewhat analogous to cylindrical type helical gears in that the teeth are angled; however, with spiral gears the teeth are also curved. Spiral bevel gears have a strength, oscillation and noise level advantage over straight bevel gears. The disadvantage of Spiral bevel gears is that they produce an axial thrust load. Therefore proper bearing location and firm support are required for their assembly. Our standard Spiral bevel gears offer 1:5 , 1, 2:1 and 3:1 gear ratios.
Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well. The pitch surface of bevel gears is a cone, known as a pitch cone. Bevel gears transfer the energy from linear to vertical power, making it very useful in machines widely used in mechanical settings.
The most familiar kinds of bevel gears have pitch angles of less than 90 degrees and therefore are cone-shaped. This type of bevel gear is called external because the gear teeth point outward. The pitch surfaces of meshed external bevel gears are coaxial with the gear shafts; the apexes of the two surfaces are at the point of intersection of the shaft axes.
The use of a genuine bevel gear has even greater importance for the reliability of the axle than any other spare part.Bevel gears that have pitch angles of greater than ninety degrees have teeth that point inward and are called internal bevel gears.
Mitre gears are a special case of bevel gears that have equal numbers of teeth. The shafts are positioned at right angles from each other, and the gears have matching pitch surfaces and angles, with a conically-shaped pitch surface.
The cylindrical gear tooth profile corresponds to an involute (i.e. a triangle wave projected on the circumference of a circle), whereas the bevel gear tooth profile is an octoid[definition needed] (i.e. a triangle wave projected on the normal path of a circle of a sphere).All traditional bevel gear generators (such as Gleason, Klingelnberg, Heidenreich & Harbeck, WMW Modul) manufacture bevel gears with an octoidal tooth profile.IMPORTANT: For 5-axis milled bevel gear sets it is important to choose the same calculation / layout like the conventional manufacturing method.Simplified calculated bevel gears on the basis of an equivalent cylindrical gear in normal section with an involute tooth form show a deviant tooth form with reduced tooth strength by 10-28% without offset and 45% with offset [Diss. Hünecke, TU Dresden].Furthermore, those "involute bevel gear sets" cause more noise.
There are two issues regarding tooth shape. One is the cross-sectional profile of the individual tooth. The other is the line or curve on which the tooth is set on the face of the gear: in other words the line or curve along which the cross-sectional profile is projected to form the actual three-dimensional shape of the tooth. The primary effect of both the cross-sectional profile and the tooth line or curve is on the smoothness of operation of the gears. Some result in a smoother gear action than others.
In straight bevel gears, the teeth are straight and parallel to the generators of the cone. This is the simplest form of bevel gear. It resembles a spur gear, only conical rather than cylindrical. The gears in the floodgate picture are straight bevel gears. In straight bevel gear sets, when each tooth engages, it impacts the corresponding tooth and simply curving the gear teeth can solve the problem.
Spiral bevel gears have their teeth formed along spiral lines. They are somewhat analogous to cylindrical type helical gears in that the teeth are angled; however, with spiral gears, the teeth are also curved.
The advantage of the spiral tooth over the straight tooth is that they engage more gradually. The contact between the teeth starts at one end of the gear and then spreads across the whole tooth. This results in a less abrupt transfer of force when a new pair of teeth come into play. With straight bevel gears, the abrupt tooth engagement causes noise, especially at high speeds, and impact stress on the teeth which makes them unable to take heavy loads at high speeds without breaking. For these reasons, straight bevel gears are generally limited to use at linear speeds less than 1000 feet/min; or, for small gears, under 1000 rpm.
Zerol bevel gears are an intermediate type between straight and spiral bevel gears. Their teeth are curved, but not angled. Zerol bevel gears are designed with the intent of duplicating the characteristics of a straight bevel gear, but they are produced using a spiral bevel cutting process.
The bevel gear has many diverse applications such as locomotives, marine applications, automobiles, printing presses, cooling towers, power plants, steel plants, railway track inspection machines, etc.
Bevel gears are a special class of gear, where the axes of two different shafts intersect, but the faces of each gear are shaped like cones. In most applications, bevel gears are mounted on shafts that are 90 degrees apart, but other angles are also possible; regardless, the pitch surface is always a cone. Bevel gears are frequently used in differential drives, which can transmit power to two axes rotating at different speeds, and are also a common component of hand drills and rotorcrafts.
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Looking at bevel gears from the differences in helix angles, they can be generally classified into straight bevel gears, which do not have helix angles, and spiral bevel gears (including zerol bevel gears), which do have helix angles. However, because of the fact that manufacture facilities for straight bevel gears are becoming rare and the fact that straight bevel gears teeth cannot be polished, making spiral bevel gears which can be polished superior in terms of noise reduction, spiral bevel gears are likely to become more common in the future.
Bevel gears can be generally classified by their manufacturing methods, namely the Gleason method and Klingelnberg method, which each have differing teeth shapes, and presently most gears use the Gleason method. Incidentally, all gears manufactured by KHK use the Gleason method.
Furthermore, there are also variations in gears in terms of teeth pitch (modules, etc.), whether polished or not, and materials used. For example in the case of materials, S45C of machine structural carbon steel, SCM415 of machine structual alloy steel and MC901 of engineering plastic, etc. are often used, and duracon, etc. are used for plastic molded parts.
The gears used when two shafts intersect are based on two cones in rolling contact with apexes meeting at the point of intersection of the two axes and having teeth at the same distance from the apexes. These are called bevel gears. Above mentioned cones are called pitch cones and their half peak angles are called pitch cone angles.
Bevel gears are divided into straight bevel gears and spiral bevel gears based on their tooth lines at the pitch cone. Conical gears and face gears can also be considered as belonging to the spiral bevel gear group. Because they are not based on a pitch cone and rely on a specialized tooth cutting method however, they are discussed separately from spiral bevel gears.
Bevel gears are cone shaped gears which transmit motion between two intersecting shafts. Straight bevel gears are the simplest of these bevel gears with their teeth being straight and pointing toward the apex of the cone. They are easier than spiral bevel gears to make and do not produce inward thrust (in the minus direction), simplifying bearing construction. On the other hand, they have the disadvantage of not being able to grind teeth after heat treatment.
Straight bevel gears are generally used in relatively slow speed applications (less than 2m/s circumferential speed). They are often not used when it is necessary to transmit large forces. Generally they are utilized in machine tool equipment, printing machines and differentials.
Bevel gears are cone shaped gears which transmit motion between two intersecting shafts. Spiral bevel gears are one type in which the teeth are curved spirally. Unlike straight bevel gears, these teeth contact each other gradually and smoothly from one end to the other. The meshing of teeth are, as in straight bevel gears, rolling contacts on the pitch cone surface. 2b1af7f3a8