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Types Of Bevel Gears And Geometric Calculations With Calculators

Bevel gears are one of the most important mechanical elements in machinery. In the design phase of power transmission, there are lots of bevel gear mechanisms are used. In here you will find the information about;

  • Explanations of types of bevel gears,
  • Bevel gear geometry calculator.

What Are The Types Of Bevel Gears?

Bevel gears are used for the power transmission between non-parallel shafts. In general, shafts are in a 90-degree position. Cone-shaped bevel gears are produced for the power transmission between these shafts.

Bevel gears can be also used for only changing the rotation direction of power transmission which are called miter gears. For miter gears, input and output bevel gears have the same number of teeth.

There are four types of bevel gears are available in general mechanical design; Hypoid type, spiral type, zero spiral types, and straight type bevel gears. In general, when the concept of ‘bevel gear’ is spoken, people generally think of the straight type of bevel gears. But the situation is not like that.

The most general type of bevel gears is the hypoid type bevel gear. Other types of bevel gears are designed from hypoid type bevel gears in terms of several parameters.

  • Hypoid Type Bevel Gears: Hypoid type of bevel gear is the most general form of bevel gear. Other types of bevel gears are obtained with these parameters: Offset of pinion from the centerline, spiral angle of bevel gear teeth, and curving of teeth in spiral gear.
Hypoid type bevel gear(Image Source https://grabcad.com/library/hypoid-gear-set-for-automotive-drive-axle-1).

In the hypoid type of bevel gears, all the geometrical features are available. The offset position of the pinion provides power transmission between perpendicular shafts that are not placed in planar position. Other types of bevel gears must transmit power between planarly aligned shafts.

  • Spiral Type Bevel Gears: In this kind of bevel gears, there are not offset position teeth design like the hypoid type. But, teeth of spiral type is tapered as a spiral line over the cone. This teeth geometry provides a more smooth power transition between gears.
Spiral type bevel gear(Image Source:https://www.kggear.co.jp/en/kg-stock-gears/bevel-gears).

Spiral angles are generally between 20-45 degrees. But most generally used bevel gear spirals 35 degrees. The pressure angle of general spiral bevel gears is 20 degrees. Also, the minimum number of teeth is generally 12.

  • Zero Spiral Type Bevel Gears: In zero type of bevel gears, there is no offset teeth design and spiral geometry in teeth. But, teeth of zero spiral gears are tapered in a curve shape. They are generally operating more smoothly compared with the straight type of bevel gears.
Zerol bevel gear(Image Source: https://techminy.com/bevel-gear-types/).
  • Straight Type Bevel Gears: All the geometric features are stated above for different kinds of bevel gears do not exist in straight type bevel gears. Straight teeth are tapered on the cone. Typical pressure angles for straight type bevel gears are 20, 22,5, and 25 degrees. And the minimum number of teeth are used in pinion to avoid interference problems between mating gears.
Straight type bevel gear(Image Source:https://link.springer.com/article/10.1007/s42452-019-1171-3).

Geometrical Calculator For Straight Bevel Gears

Dimension of mating bevel gears(Image Source: Machine Elements in Mechanical Design-Book by Robert L. Mott).

Bevel Gear Geometric Calculations































































As you see above, there are lots of geometric variables available for calculation. You just need to enter the diameters of mating bevel gears and the number of teeth of these bevel gears. Diameters must be entered in inches because the diametral pitch is used in calculations.

After entering the required values inside brackets, click on the ‘Calculate!’ button to see all geometric results related to your bevel gear mates. If you want to do another calculation, just click on the ‘Reset’ button, then re-enter new values.

Take a look at the article about the difference between diametral pitch value and metric module value for gears. 

Conclusion For Bevel Gears

As you see in the above calculator, the geometries of bevel gears are a bit complex compared with other gear types.

Do not forget to leave your comments and questions below about the bevel gears and types and calculator of it.

Mechanical Base does not accept any responsibility for the calculations done by users, in calculators. A good engineer must check the solutions again and again.

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