The involute gear profile is important in machine design, since unlike with or gear systems, involute gear tooth profile depends on only number of teeth on gear, pitch and pressure angle but does not depend on gear it mates with.

Base pitch is distance which is measured around base circle from origin of involute on tooth to origin of a involute (similar) on next tooth.
Base pitch = Base circumference / Number of teeth
= ? x Base circle diameter / N = ? x D cos? / N = ? x m x cos?.

High power gears are operated at low speeds generally but it has to transmit large force. Therefore for this purpose gear teeth should specify fullest possible contact along tooth length.

Smoothness of gear operation is important to provide for noiseless engagement and longer service life of gearing. The smoothness of gear operation can be ensured by limiting maximum permissible deviations in basic pitch.

Bearing contact for mating gears is represented by relative size of bearing contact pattern in % and along length of tool it is represented by ratio of traces of contact, subtracting gaps larger than size of module, to full tooth length.

Involute gears are used for general purpose in precision engineering. The cycloidal gears are not used in modern engineering generally, but can be used for some crude purposes where impact and heavy loads come on machine.

Undulation is a departure of actual tooth surface from design surface and undulation height is normal distance between 2 surfaces that contain crests and troughs of tooth undulation.

The analytical inspection of gears consists in determination of se Profile, Spacing, Pitch, Backlash, Runout or eccentricity or concentricity, thickness of tooth and Lead. These teeth elements in which errors are caused due to manufacturing errors are determined by analytical inspection.

The straight teeth are present in involute rack. Only a simple cutter is needed to form complex involute form on gear. It is an advantage which is associated with involute curve or profile.

The angle between line of action and common tangent to pitch circles is called as pressure angle. The standard values of pressure angle are 14.5 degree and 20 degree. Pressure angle is generally represented by ?.