One’s teeth of a helical gear are set at an angle (in accordance with axis of the apparatus) and take the form of a helix. This enables the teeth to mesh gradually, starting as point contact and developing into line get in touch with as engagement progresses. One of the most noticeable advantages of helical gears over spur gears can be much less noise, especially at moderate- to high-speeds. Also, with helical gears, multiple teeth are often in mesh, which means much less load on every individual tooth. This outcomes in a smoother changeover of forces in one tooth to another, to ensure that vibrations, shock loads, 
and wear are reduced.
But the inclined angle of one’s teeth also causes sliding get in touch with between the teeth, which produces axial forces and heat, decreasing performance. These axial forces play a significant part in bearing selection for helical gears. As the bearings have to withstand both radial and axial forces, helical gears need thrust or roller bearings, which are typically larger (and more expensive) 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 bigger helix angles offer higher quickness and smoother helical gear china motion, the helix position is typically limited to 45 degrees due to the production of axial forces.