scope:

This Standard establishes the calculation procedures for determining tooth thickness measurements of external and internal cylindrical involute gearing.

The information is intended for use by the gear specifier or manufacturer in establishing values for tooth thickness measurement limits.

CAUTION: It is important that tooth thickness measurement limits be reasonable for the specified quality class of the gears, to permit economical manufacture. This Standard provides guidance in the selection of reasonable tooth thickness measurement limits.

The designed tooth thickness is established from engineering considerations. It is determined by gear geometry, gear tooth strength, and backlash. The methods for establishing designed tooth thickness for a given application are beyond the scope of this Standard.

This Standard assumes the designed tooth thickness is known in cases where the values for various measuring techniques are to be established.

It includes equarions and procedures for the following measuring methods:

(1) Chordal

(2) Fins (wires, rolls and balls)

(3) SPari

(4) Composite Action Test

This Standard also establishes methods of determining tooth thickness of a gear based upon measurement limits by means of pins, span, chordal thickness or composite action test. These methods are often used to convert a tooth thickness specified by one method, such as over pins to another more convenient method, such as span over X teeth.

CAUTION: The effect of tooth geometry variations on tooth thickness measurements made by different measuring methods may be significant. This must be considered if close control of backlash is required. When this is necessary the tooth thickness should be measured by the method specified on the drawing. Refer to 3.8 for additional discussion of the problem.

Examples included are for coarse pitch gears. The same mathematical principles apply to gear teeth of ah sizes. For information on fine pitch gears, see AGMA 370.01, Design Manual for Fine Pitch Gears.

This Standard does not contain tolerances on tooth thickness. See AGMA 2000-A@, Gear Classification and Inspection Handbook - Toierantes and Measuring Methods for Unassembled Spur and Helical Genrs {Including Metric Equivn- Zents), for tolerances.

AGMA 115.01, Reference Information - Basic Gear Geometry is a source for the derivations and detailed explanations of the geomeuical relationships used here.

AGMA 112.05, Gear Nomenclature (Geometry) Terms, Definitions, Symbols and Abbreviations is a source of definitions of common gear terms as used in this Standard