The method of measuring the tooth thickness of automobile gear parts is usually replaced by the method of measuring the span bar distance. This automobile gear method is more accurate and easy to operate than the tooth thickness gear method. An ordinary micrometer can be used to measure the span between rods. The only other thing you need is a steel ball or measuring rod whose size matches the module of the part.
The diameter of most automobile gear measuring rods and steel balls is generally 1.728 times of the module of parts, which can meet the measurement requirements of most parts. For parts with large tooth width or large pressure angle, 1.92 times of part modulus can also be selected.
It is determined from the measurement of span bar distance that the tooth thickness of automobile gear is equivalent to half of the normal circumferential pitch. However, if the measured value is greater than the theoretical value, the tooth thickness exceeds the upper difference; If it is less than, the tooth thickness exceeds the lower difference.