Two important ideas in gearing are pitch surface area and pitch angle. The pitch surface area of a gear is the imaginary toothless surface that you would have got by averaging out the peaks and valleys of the average person teeth. The pitch surface area of a typical gear is the form of a cylinder. The pitch angle of a equipment is the angle between the encounter of the pitch surface and the axis.

The most familiar kinds of bevel gears have pitch angles of less than 90 degrees and therefore are cone-shaped. This type of bevel gear is named external because the gear teeth point outward. The pitch surfaces of meshed exterior bevel gears are coaxial with the gear shafts; the apexes of the two surfaces are at the idea of intersection of the shaft axes.

Bevel gears that have pitch angles of greater than beval gear china ninety degrees have teeth that point inward and so are called internal bevel gears.

Bevel gears which have pitch angles of specifically 90 degrees possess teeth that point outward parallel with the axis and resemble the factors on a crown. That is why this kind of bevel gear is called a crown gear.

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

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