Gear Terminology: Basic Terms Used In Gear | The Engineers Post

Gear Terminology: Basic Terms Used In Gear

Gear Terminology

Gear Terminology

Following are the gear terminology or gear terms used to about gears:

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

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

3. Pitch point

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

4. 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°.

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. 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

11. 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.

12. Module 

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

13. Clearance 

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

14. 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.

15. 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.

16. Tooth thickness 

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

17. Tooth space 

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

18. Face of the tooth 

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

19. Flank of the tooth 

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

20. Top land 

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

21. Face width 

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

22. Profile 

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

23. Backlash 

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


That’s It

Thanks for reading. Leave a comment if you have any question about gear terminology. Share with your friends if you find this article helpful. Subscribe to our website for more educational articles like this.

Read more articles about gears by clicking here.

Join our community by liking our Facebook Page. 

360 Shares

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.