Home Mechanical Engineering Gear Terminology: Basic Terms Used In Gear & Calculation

Gear Terminology: Basic Terms Used In Gear & Calculation

In this article, you’ll learn what are the different Gear Terminology and Terms used in gear with calculation, And also you can download the PDF file of this post at end of it.

Gear Terminology:

Following are the gear terminology and gear terms used in the description of gears:

  1. Pitch circle
  2. Pitch circle diameter
  3. Pressure angle
  4. Pitch point
  5. Pitch surface
  6. Addendum
  7. Dedendum
  8. Addendum circle
  9. Dedendum circle
  10. Base circle
  11. Circular pitch
  12. Diameter pitch
  13. Module
  14. Clearance
  15. Total Depth
  16. Working Depth
  17. Tooth thickness
  18. Tooth space
  19. The face of the tooth
  20. The flank of the tooth
  21. Top land
  22. Face width
  23. Profile
  24. Backlash
Gear Terminology

Explanation of Gear Terms

1. Pitch circle

Pich circle is the imaginary circle that rolls without slipping with a pitch circle of a mating gear.

2. Pitch Circle Diameter

The pitch circle diameter is the diameter of the pitch circle. It is also known as pitch diameter.

3. Pressure angle

Pressure angle is the angle between the common normal at the point of tooth contact and the common tangent to the pitch circle. The usual pressure angles are 14½° and 20°.

4. Pitch point

It is a common point of contact between two pitch circles.

5. Pitch surface

It is the surface of the imaginary rolling cylinder that the toothed gear may be considered to replace.

6. Addendum

The addendum is the radial distance of a tooth from the pitch circle to the top of the tooth.

7. Dedendum

Dedendum is the circle drawn through the bottom of the teeth. It is also called “root circle”.

8. Addendum circle

It is the circle drawn through the top of the teeth and it is concentric with the pitch circle.

9. Dedendum circle

It is the circle drawn through the bottom of the tooth. It is also called “root circle”.

10. Base Circle

The base circle of involute gear is the circle from which involute tooth profiles are determined.

11. Circular pitch

The circular pitch is the distance measured on the circumference of the pitch circle from a point of one tooth to the corresponding point on the next tooth. It is denoted by Pc.

Pc = πd/T

  • D = diameter of the circle
  • T = No. of teeth on the wheel

12. Diametral Pitch

It is the ratio of a number of teeth to the pitch circle diameter. It is indicated by Pd.

Pd = T/d = π/Pc

Pc = πd/T

Where,

  • T= No. of teeth,
  • d= Pitch circle diameter.

13. Module

A module is the ratio of pitch circle diameter by m. m= d/T

14. Clearance

Clearance is the difference between the dedendum of one gear and the addendum of the mating gear.

15. Total Depth

Total depth is the radial distance between the addendum and the dedendum of a gear. It is equal to the sum of addendum and dedendum.

16. Working Depth

It is the radial distance from the addendum circle to the clearance circle. It is equal to the sum of the addendum of the two meshing gears.

17. Tooth thickness

Tooth thickness is the width of the tooth measured along the pitch circle.

18. Tooth space

Tooth space is the width of space between the two adjacent teeth measured along the pitch circle.

19. Face of the tooth

It is the surface of the tooth above the pitch surface.

20. Flank of the tooth

The flank of the tooth is the surface of the tooth below the pitch surface.

21. Top land

The top land is the surface of the top of the tooth.

22. Face width

Face width is the width of the gear tooth measured parallel to its axis.

23. Profile

It is the curve formed by the face and flank of the tooth.

24. Backlash

Backlash is the difference between the thickness of a tooth and the width of a tooth space on which it meshes.


Conclusion

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Download the PDF file of this article:

You may be interested in reading more articles on Gears:

  1. What Is Gear Ratio? It’s Formula and Calculation
  2. Types and Classification Of Gears and Gear Trains
  3. Four Types of Gearbox That Are Used In Modern Vehicles

References:

Saif M
Saif M. is a Mechanical Engineer by profession. He completed his engineering studies in 2014 and is currently working in a large firm as Mechanical Engineer. He is also an author and editor at theengineerspost.com