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.
Following are the gear terminology and gear terms used in the description of gears:
- Pitch circle
- Pitch circle diameter
- Pressure angle
- Pitch point
- Pitch surface
- Addendum circle
- Dedendum circle
- Base circle
- Circular pitch
- Diameter pitch
- Total Depth
- Working Depth
- Tooth thickness
- Tooth space
- The face of the tooth
- The flank of the tooth
- Top land
- Face width
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.
The addendum is the radial distance of a tooth from the pitch circle to the top of the tooth.
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
- T= No. of teeth,
- d= Pitch circle diameter.
A module is the ratio of pitch circle diameter by m. m= d/T
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.
It is the curve formed by the face and flank of the tooth.
Backlash is the difference between the thickness of a tooth and the width of a tooth space on which it meshes.
So now, we hope that we have clear all your doubts about Gear Nomenclature. If you have still any doubts about the “Gear Terminology” you can contact us or ask in the comments.
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You may be interested in reading more articles on Gears:
- What Is Gear Ratio? It’s Formula and Calculation
- Types and Classification Of Gears and Gear Trains
- Four Types of Gearbox That Are Used In Modern Vehicles
6 thoughts on “Gear Terminology: Basic Terms Used In Gear & Calculation”
Important circle in gear terminology which one
All circles are important in gear terminology.
All definitions are very easily understand after one time reading any student easily understand to this after the reading .
Thank you so much
It is very useful for Be&btech, diploma students glad to using this tnqqq