Gear
Terminology
Addendum:
The radial distance between the Pitch Circle and the top of
the teeth.
Arc of Action:
That arc of the Pitch Circle between the first point of
contact between gear teeth and the last.
Arc of Approach:
That arc of the Pitch Circle between the first point of
contact between gear teeth and the the Pitch Point.
Arc of Recession:
That arc of the Pitch Circle between the Pitch Point and the
last point of contact between gear teeth.
Backlash:
Play between mating teeth.
Base Circle:
The circle from which is generated the involute curve upon
which the tooth profile is based.
Center Distance:
The distance between centers of two gears.
Chordal Addendum:
The distance between a chord, passing through the points
where the Pitch Circle crosses the tooth profile, and the tooth top.
Chordal Thickness:
The thickness of the tooth measured along a chord passing
through the points where the Pitch Circle crosses the tooth profile.
Circular Pitch:
Inches of Pitch Circle circumference per tooth.
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