The most obvious benefits of using a helical gear over a spur gear is its less noise and smoother transition of forces from one tooth to another. These advantages also mean reduced vibrations, shock loads, and wear. However, on the down side, the inclined angle of their teeth also results in sliding contact between them, producing heat and axial forces. This, unfortunately, also decreases efficiency. It is this axial force that plays a vital role when it comes to selecting bearing for helical gears.
The gear’s bearings have to cope with both the radial and axial forces. This requires additional use of roller or thrust bearings which are often bigger and more expensive than regular bearings needed in spur gears. And while bigger helix angles offer higher speed and smoother motion, the helix angle is usually restricted to 45 degrees only because of the axial forces produced by the gear.
This concern can be countered with the use of double helical gears, also called herringbone gears. Essentially, they are two helical gears mounted back to back from each other, with a groove in the middle. This is to eliminate the axial forces so bigger helix angles are possible to use while also cancelling the need for thrust bearings. So, if you think your application can benefit from using either regular helical gear or double helical gear, reach out to our gear experts now.