APPENDIX III
FORMULAS FOR SPUR GEARING
Formula
To Get
Having
Rule
Diametral pitch
Circular pitch
Divide 3.1416 by the
diametral pitch.
Pitch diameter and
Circular pitch
Divide the pitch diameter by
number of teeth
the product of 0.3183 and
the number of teeth.
Outside diameter and
Circular pitch
Divide the outside diameter
number of teeth
by the product of 0.3183 and
the number of teeth plus 2.
Number of teeth and
Pitch diameter
The product of the number
circular pitch
of teeth, the circular pitch,
and 0.3183.
Number of teeth and
Pitch diameter
Divide the product of the
outside diameter
number of teeth and the
outside diameter by the
number of teeth plus 2.
Outside diameter and
Pitch diameter
Subtract from the outside
circular pitch
diameter the product of the
circular pitch and 0.6366.
Addendum and
Pitch diameter
Multiply the number of teeth
number of teeth
by the addendum.
Number of teeth and
Outside diameter
The product of the number
circular pitch
of teeth plus 2, the circular
pitch, and 0.3183.
Pitch diameter and
Outside diameter
Add to the pitch diameter
circular pitch
the product of the circular
pitch and 0.6366.
Number of teeth and
Outside diameter
Multiply the addendum by
addendum
the number of teeth plus 2.
Pitch diameter and
Divide the product of the
Number of teeth
circular pitch
pitch diameter and 3.1416
by the circular pitch.
Circular pitch
Chordal thickness
One-half the circular pitch.
AIII-1