One’s teeth of a helical gear are set at an angle (in accordance with axis of the gear) and take the form of a helix. This enables one’s teeth to mesh gradually, starting as point contact and developing into range contact as engagement progresses. One of the most noticeable advantages of helical gears over spur gears is definitely much less noise, especially at medium- to high-speeds. Also, with helical gears, multiple teeth are constantly in mesh, this means much less load on each individual tooth. This outcomes in a smoother transition of forces in one tooth to the next, so that vibrations, shock loads, and wear are reduced.

However the inclined angle of one’s teeth also causes sliding get in touch with between the teeth, which produces axial forces and heat, decreasing efficiency. These axial forces play a significant role in bearing selection for helical gears. Because the planetary gearbox bearings have to endure both radial and axial forces, helical gears require thrust or roller bearings, which are usually larger (and more expensive) compared to the simple bearings used with spur gears. The axial forces vary in proportion to the magnitude of the tangent of the helix angle. Although larger helix angles provide higher acceleration and smoother motion, the helix position is typically limited to 45 degrees due to the production of axial forces.