Bevel Gear Types: Straight, Spiral, Zerol and Hypoid

The bevel gear is used to power transmission in between two interesting shaft or perpendicular shaft. It mostly used in automotive differential. When the gear teeth are formed by cutting teeth along with element of frustum of cone. The surface of pitch surface of gear are truncated cone, which one roll over to other roll. When the teeth are formed on cone together in straight shape, the gear is known as straight bevel gears, when inclined is called spiral helical gear.
The gear are mounted in intersecting shaft at desired angle, the most commonly 90 degree angle of shaft placed. It is not interchangeable because of bevel gears are designed and manufactured in pair.
The manufacturing process of gear such as cast, milled or generated. Which generated of method is more accurate than cast and milled teeth method.

Types of bevel gears:

The classification based on teeth shape:

Straight Bevel Gears

The gear are placed on parallel to line generating the pitch code, in this type of gear called as straight bevel gears.

straight bevel gear diagramThe teeth are straight or radial to the point of intersection of the shaft axes and varying cross section throughout the length. There are used to connect the shaft at right angle, which is run at low speed.

Spiral bevel gears:

The bevel gear teeth are inclined at an angle to face of bevel, there are known as spiral bevel gears. Helical type of gear used in bevel gears, Because of Which is used to reduce the noise during the operation. so provide smooth operation and quick than straight teeth bevel gears, also used to gradual load application and low impact stresses.

spiral bevel gear DiagramThe axial thrust are exited in spiral bevel gears, so it require strong bearing and supporting assembly. This types of bevel gears are used for drive to the differential shaft of an automobiles.

Zerol bevel gear:

The spiral bevel gear having curved teeth, but it should be having zero degree spiral angle is known as zerol bevel gear. The action of teeth and trust are same as straight bevel gear. The zero bevel gear are quicker in action than straight bevel gear, because the teeth are curved form.

Hypoid bevel gear or hypoid gear:

hypoid bevel gears diagramIt is similar to spiral bevel gears, but smaller difference from spiral gear is axis pinion is offset from axis of gear and the surface of pitch are hyperboloids rather than cone of gear.
The hypoid gear used to most of application involving large speed reduction ratios. They operate in mostly for smoothly and quietly than spiral bevel gear.

it Classification based on pitch angle

Grown gear:

The bevel gears having 90 degree pitch angle and plane for its pitch surface is called as Crown gear.

Internal bevel gear:

when the gear having pitch angle of bevel exceeds in 90 degree. This is known as internal bevel gears. which type of gear manufacturing method is difficult and internal bevel gear are rarely used.

Mitre Gear:

When the messing of two bevel gears having shaft angle of 90 degree and the number of teeth is almost same. This is called as mitre gear. It also having speed ratio is 1. Each two gears have 45 degrees pitch angle.


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