spiral bevel gear for electric power tool

What are bevel gears ?
The standard definition of a Bevel Gear is a cone-shaped gear which transmits power between 2 intersecting axels.
Looking at bevel gears from the differences in helix angles, they can be generally classified into straight bevel gears, which do not have helix angles, and spiral bevel gears (including zerol bevel gears), which do have helix angles. However, because of the fact that manufacture facilities for straight bevel gears are becoming rare and the fact that straight bevel gears teeth cannot be polished, making spiral bevel gears which can be polished superior in terms of noise reduction, spiral bevel gears are likely to become more common in the future.
Furthermore, there are also variations in gears in terms of teeth pitch (modules, etc.), whether polished or not, and materials used. For example in the case of materials, S45C of machine structural carbon steel, SCM415 of machine structual alloy steel and MC901 of engineering plastic, etc. are often used, and duracon, etc. are used for plastic molded parts.
BEVEL GEARS
RoHS Compliance
Bevel gears are most often used to transmit power at a 90° right angle. The axes of the two bevel gear shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart. Bevel gears are generally divided into 2 types, straight bevel gears and spiral bevel gears.
Straight bevel gears
In Straight bevel gears, the teeth are straight and parallel to the generators of the pitch cone. Compared with spiral miter gears, straight bevel gears can be made in smaller sizes. We standardized Straight bevel gears as small as module 0.5 in various materials(Brass, stainless steel, Titanium, nylon Delrin etc.).
Spiral bevel gears
Spiral bevel gears have their teeth formed along spiral lines. They are somewhat analogous to cylindrical type helical gears in that the teeth are angled; however, with spiral gears the teeth are also curved. Spiral bevel gears have a strength, oscillation and noise level advantage over straight bevel gears. The disadvantage of Spiral bevel gears is that they produce an axial thrust load. Therefore proper bearing location and firm support are required for their assembly. Our standard Spiral bevel gears offer 1:5 , 1, 2:1 and 3:1 gear ratios.