Two important principles in gearing are pitch surface and pitch position. The pitch surface area of a gear may be the imaginary toothless surface area that you would Universal joint possess by averaging out the peaks and valleys of the individual teeth. The pitch surface of an ordinary gear is the shape of a cylinder. The pitch angle of a gear is the angle between your encounter of the pitch surface area and the axis.

The most familiar types of bevel gears have pitch angles of less than 90 degrees and therefore are cone-shaped. This type of bevel gear is named external since the gear teeth stage outward. The pitch areas of meshed external bevel gears are coaxial with the apparatus shafts; the apexes of both surfaces are at the point of intersection of the shaft axes.

Bevel gears which have pitch angles of greater than ninety degrees have teeth that time inward and are called internal bevel gears.

Bevel gears that have pitch angles of specifically 90 degrees have teeth that time outward parallel with the axis and resemble the points on a crown. That’s why this kind of bevel gear is called a crown gear.

Mitre gears are mating bevel gears with equivalent amounts of teeth and with axes in right angles.

Skew bevel gears are those that the corresponding crown gear has the teeth that are straight and oblique.