The teeth of a helical gear are set at an angle (in accordance with axis of the gear) and take the shape of a helix. This enables one’s teeth to mesh gradually, starting as point get in touch with and 
developing into series contact as engagement progresses. Probably the most noticeable benefits of helical gears over spur gears is certainly much less noise, especially at medium- to high-speeds. Also, with helical gears, multiple teeth are always in mesh, which means less load on each individual tooth. This outcomes in a smoother transition of gear rack forces in one tooth to another, to ensure that vibrations, shock loads, and wear are reduced.
However the inclined angle of one’s teeth also causes sliding contact between your teeth, which creates axial forces and heat, decreasing performance. These axial forces play a significant function in bearing selection for helical gears. As the bearings have to endure both radial and axial forces, helical gears require 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 in proportion to the magnitude of the tangent of the helix angle. Although larger helix angles provide higher rate and smoother movement, the helix angle is typically limited to 45 degrees due to the creation of axial forces.