c. This angle is obtained by subtracting the

5. Dedendum angle (

) from the pitch

dedendum angle (

a. This angle is formed by a line

addendum down on the tooth and a

cone angle (

drawn through the bottom tooth.

b. This angle cannot be measured, but

used in calculations.

4. Addendum angle

c. In the triangle shown in figure 14-16, view

a. This angle is formed by the top of the tooth

B, the side opposite the dedendum angle is

the dedendum and the hypotenuse is the

and a line one addendum down on the

pitch cone radius.

tooth.

b. This angle cannot be measured, but it is

Therefore, Cot

used in making calculations for the gear.

c. In the triangle shown in figure 14-16, view

6. Back cone angle (BCA or

A, the hypotenuse is the pitch cone radius

This angle is formed by the large end of the

and the side opposite is the addendum.

tooth and the pitch diameter of the gear. It is

equal in value to the pitch cone angle (PCA).

Therefore, Cot

14-17

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