Miter Gear

Miter Gears are a type of bevel gear designed to work in pairs. Miter gear sets are found in applications where the drives’ input and output rotational speed does not vary, but direction changes. A miter gear set has a 1:1 ratio, identical dimensions, and several teeth.

Miter Gear

What is a Miter Gear?

A miter gear is part of the bevel gear family designed to work in pairs and with both gears having identical dimensions and number of teeth. Miter gears are designed for applications where the rotational speed of the input and output drives remains constant, but the direction changes. Generally, the difference in drive/output orientation in miter gear sets is 90°, although groups are available which produce a selection of angular deviations. Miter gears are available in either spiral or straight-toothed configurations.

Miter gear sets are used in machinery designs requiring changes in drive direction while maintaining drive speeds. These criteria are achieved by employing a set of cone-shaped gears of identical size, profile, and tooth number. This design allows the gears to be positioned in an opposed orientation while maintaining a constant speed relationship between the two drives. In most cases, the miter gear turns the output drive at right angles to the input. Gear sets can, however, be designed to affect almost any directional deviation.

These gears fall into two basic categories: spiral or straight cut. This terminology refers to the angle at which the gear’s teeth cut at about the face or cone angle. Spiral cut gears are more appropriate for high-speed applications because the curve of the teeth allows for gradual engagement. This reduces the amount of “clashing” when the teeth of the two gears engage and make the gear train stronger and quieter. This type of gear is commonly used in high-speed applications such as lawn trimmers, where the motor and driveshaft are orientated at right angles to one another.

(1) Straight miter gears
In Straight miter 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 miter gears as small as module 0.5 in various materials.

(2) Spiral miter gears
Spiral miter gears have their teeth formed along spiral lines. They are somewhat analogous to cylindrical helical gears in that the teeth are angled; however, the teeth are also curved with spiral gears. Spiral Miter gears have a strength, oscillation, and noise level advantage over straight Miter gears. The disadvantage of Spiral miter gears is that they produce an axial thrust load. Therefore proper bearing location and firm support are required for their assembly.

A straight-cut miter gear is more suitable for slow-speed applications such as hand-operated door openers and hand tools. In these applications, the shortcomings of straight-cut gears are less noticeable, and the reduced cost of production makes their use attractive. Miter gear materials are dictated by their intended use with stern-faced, high carbon steel appropriate for high load and high-speed applications. Nylon and various injection molding resins are used for gears that don’t work as fast or hard. The close relationship between individual gears means that both gears in a set should ideally be replaced even if only one is worn or damaged.

Miter Gear Uses

Applications of miter gears are many and varied. They can be found in a variety of industries, and are used in many different ways. The cone shape of a miter gear creates an axial force that moves the shaft. These thrust forces can be different for different types of miter gears, and require bearings that can handle this force.

The composition of a miter gear will depend on its purpose, and is also influenced by its size and weight. For instance, if it is used for construction, it should be made of cast iron or alloy steel to provide durability. Carbon steels are a more affordable alternative, but are susceptible to corrosion. Aluminum is another popular material for gears, but is prone to corrosion and is not as durable as steel. Brass and copper are also inexpensive and easy to mold, although they may not be as corrosion resistant as steel.

There are two main types of miter gears. The first is the straight miter gear, which has the same number of teeth on both sides. The second is the spiral bevel gear, which features incremental interlock and quieter operation. Unlike straight-tooth miter gears, spiral bevel gears have a conical pitch cone, which allows them to transmit motion at any angle.

Spiral miter gears are better suited to high-speed applications such as power tools and machine drives. Straight-cut miter gears are suitable for low-speed applications such as door opener mechanisms and hand tools.

Miter Gear Design

Miter Gear VS Bevel Gear

The miter gear is of of the bevel gear types that have very similar mechanical properties. They are designed to transmit rotational power at a 90-degree angle, and both types of gears can be used in a wide range of applications. Outboard motors and automotive transmissions, for example, are common examples of bevel gears. However, there are some differences between the two types of gears.

Another difference between the two types of gears lies in their mounting distance. Ideally, the mounting distance of a gear is equal to the diametral pitch of the mating gear. If the mounting distance is too wide, the ends of the gears will not be in mesh, allowing excessive backlash. This can also lead to excessive wear and heat.

In addition to this difference, the differences between the two types of gears are largely determined by their end-use applications. For example, a high-speed application might call for a hard faced, high carbon steel miter gear. On the other hand, a low-speed application might need a gear made of nylon or injection-molded plastics.

Miter Gear VS Bevel Gear