Helical Inline Gear Motors Helical gears aren’t specifically comparable to worm or bevel gearbox systems. They are in fact an alternative to spur gears where the the teeth are parallel to the axis of the apparatus itself. For example, in an inline application, you can have either spur OR helical gears. An inline helical gearbox motor will usually be quieter and may bring higher loads than motors utilizing a spur gearbox. They can be more expensive in initial price, and manufacturers need to account for axial thrust. Nevertheless, the actual fact that the helix angle may differ from 15 to 30 degrees permits flexibility when it comes to design. They are used in in-line applications and also parallel shaft applications.

The benefit of helical gears is that it produces a rolling action, is quieter, and has less vibration in comparison to spur gears. In addition, it produces less friction and permits more teeth to be engaged simultaneously as the teeth roll across each other.
There are myriad types of gearing. Some manufactures make use of spur gears rather than helical gearing, for example. However, there is not as much surface contact, as mentioned above and consequently there is more noise and less helical spiral bevel gear motor torque transfer possible.

Another system where noise is definitely common are planetary equipment systems, where the one gear is completely within the other. They also require grease lubrication and they must be constructed with expensive materials to be able to maintain a long-life and bearing integrity. An easier variant, internal gearing, suffers from the same problems and can only be used with parallel shaft.

Finally, hypoid gearing may be best understood as similar to bevel gearing, but with the gear axes not intersecting. The sliding actions can create huge amounts of heat and the alignment needs great care.