The teeth of a helical gear are set at an angle (relative to axis of the apparatus) and take the shape of a helix. This enables the teeth to mesh steadily, starting as point contact and developing into range get in touch with as engagement progresses. Probably the most noticeable benefits of helical gears over spur gears is certainly less noise, especially at moderate- to high-speeds. Also, with helical gears, multiple teeth are usually in mesh, which means less load on every individual tooth. This results in a smoother transition of forces from one tooth to the next, to ensure that vibrations, shock loads, and wear are planetary gearbox reduced.
However the inclined angle of the teeth also causes sliding contact between your teeth, which produces axial forces and heat, decreasing effectiveness. These axial forces perform a significant part in bearing selection for helical gears. Because the bearings have to endure both radial and axial forces, helical gears need thrust or roller bearings, which are usually larger (and more costly) compared to the simple bearings used in combination with spur gears. The axial forces vary compared to the magnitude of the tangent of the helix angle. Although larger helix angles offer higher swiftness and smoother motion, the helix position is typically limited by 45 degrees because of the production of axial forces.