Pitch helix

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The pitch helix is the intersection of the tooth surface and the pitch cylinder of a helical gear or cylindrical worm.¹

Contents 1 Base Helix 2 Base Helix Angle 3 Base Lead Angle 4 Outside Helix 5 Outside Helix Angle 6 Outside Lead Angle 7 Normal Helix 8 Notes

[edit] Base Helix

The base helix of a helical, involute gear or involute worm lies on its base cylinder.

[edit] Base Helix Angle

Base helix angle is the helix angle on the base cylinder of involute helical teeth or threads.

[edit] Base Lead Angle

Base lead angle is the lead angle on the base cylinder. It is the complement of the base helix angle.

[edit] Outside Helix

The outside (tip or addendum) helix is the intersection of the tooth surface and the outside cylinder of a helical gear or cylindrical worm.

[edit] Outside Helix Angle

Outside helix angle is the helix angle on the outside cylinder.

[edit] Outside Lead Angle

Outside lead angle is the lead angle on the outside cylinder. It is the complement of the outside helix angle.

[edit] Normal Helix

A normal helix is a helix on the pitch cylinder, normal to the pitch helix.

[edit] Notes

1. ANSI/AGMA 1012-G05, "Gear Nomenclature, Definition of Terms with Symbols".