Spur or Helical Gear Boxes: Which Is The Ideal Option?

Gear boxes are an important part of many different vehicles and machines and are available in many different types. For proper operation, the gearboxes rely on gears, which are also available in an array of types. Spur and helical gears are the two most common types of gears and no matter how simple they seem, there is a lot to know about them. If you want gears that can maximize the torque density of your gearbox and extend its life, choose spur gears. If what you want is a smooth and quiet operation of your gearbox, helical gears are your obvious choice.

To make your choice between helical and spur gears easily, you only need to properly size your application and all its requirements. When choosing between helical and spur gears, you need to spend some time on considering all of their capabilities and features. First, you need to know that these two gears have much different loading characters. Spur gears are lacking of an axial load component, because they have a zero helix angle. Helical gears, on the other hand, create axial forces and have more sliding with the tooth. They also add friction forces into the gear mesh.

The smooth torque transmission depends on the number of teeth being in contact with the gears. With that said, you can get a smoother transmission of torque with the helical gears and helical gear boxes. The increased contact ratio of helical gears has a lower fluctuation of the gear, compared to spur gear. As a consequence of not generating any axial forces, the spur gears are used as a support in the gearboxes fluctuation. Therefore, they only need to provide a support to the rotating gear shafts, without playing an active and important role in the transmission of torque.

The axial forces available with helical gear boxes make everything different for the bearings of the helical gears. However, you must know the differences between fixed-axis and planetary gear boxes. The additional axial forces with fixed-axis gear boxes do not provide much more than an inconvenience, so the bearings used with these gearboxes’ bearings are especially modified to accommodate the additional forces.

With planetary helical gear boxes, on the other hand, handling the axial forces is much more difficult. The lack of room with these gear boxes for these bulky bearings is the first reason, while the second is that the planet gear bearings are expected to play an active role in torque transmission. These systems transmit the torque input from the sun gear to the planet gears, which then transfer the torque to a planet carried – directly connected to the helical gear boxes output.