Helical Inline Gear Motors Helical gears are not specifically much like worm or bevel gearbox systems. They are actually an helical spiral bevel gear motor alternative solution to spur gears where the tooth are parallel to the axis of the gear itself. For example, in an inline application, you can have either spur OR helical gears. An inline helical gearbox engine will usually be quieter and will carry higher loads than motors utilizing a spur gearbox. They may be more costly in initial cost, and manufacturers need to account for axial thrust. Nevertheless, the actual fact that the helix position can vary from 15 to 30 degrees allows for flexibility when it comes to design. They are found in in-line applications and also parallel shaft applications.

The advantage of helical gears is that it produces a rolling action, is quieter, and has less vibration in comparison to spur gears. It also produces less friction and allows for more the teeth to be engaged simultaneously as one's teeth roll across one another.
There are myriad types of gearing. Some manufactures use spur gears rather than helical gearing, for example. However, there isn't as much surface contact, as mentioned above and as a result there is more noise and less torque transfer possible.

Another program where noise can be common are planetary gear systems, where in fact the one gear is totally within the other. In addition they require grease lubrication plus 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 issues and can only be used with parallel shaft.

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