Terminology of Gears: Pitch Circle, Pitch, Module & Others

Terminology of Gears

Hi guys, welcome to the third post of this blog. Different types of gear (which we have discussed in the previous post) have different terminologies, but some of the common terminologies used in every gear are covered in this post.

TERMINOLOGY  includes various parameters which are needed to define a gear.

                                              Terminology of gear or gear nomenclature

1)     c

3)      PITCH CIRCLE DIAMETER (P.C.D):  It is the diameter of the pitch circle.

4)      MODULE (m): It is defined as the ratio of pitch circle diameter to some teeth gear have. (Gears are designed based on pitch circle diameter and module).

5)      DIAMETRAL PITCH: It is defined as the ratio of a number of teeth to pitch circle diameter.

6)      Addendum (a): It is defined as the distance between pitch circle to the top land of teeth.

7)      DEDDENDUM (f): It is defined as a distance between pitch circle to the bottom area of teeth.

8)      ADDENDUM CIRCLE: A circle concentric to pitch circle and passes through the top land of all teeth.

9)      DEDDENDUM CIRCLE: A circle concentric to pitch circle and passes through the bottom area of teeth.

10)   TOTAL DEPTH: It is defined as the radial distance between addendum circle and dedendum circle     TOTALDEPTH =ADDENDUM +DEDDENDUM.

11)   CENTRE DISTANCE: It is a distance between an axis of two mating gear & can be given by the average of pitch circle diameter of two mating gears.

12)   CLEARANCE: It is defined as a difference between addendum of circle & addendum of circle .( addendum > addendum).

13) WORKING for DEPTH CIRCLE: It is defined as a circle concentric to pitch circle and tangent to addendum circle of the mating gear.

14)WORKING DEPTH: It is defined as the distance between addendum circle and working depth circle.

THESE ARE MOST PRIMARY PARAMETER CODESIGN A GEAR. EXCEPT THIS ALL   OTHER PARAMETERS  ARE ALSO USED FOR DESIGN OF A GEAR.