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 steadily, starting as point contact and developing into line get in touch with as engagement progresses. Probably the most noticeable benefits of helical gears over spur gears is definitely much less noise, especially at medium- to high-speeds. Also, with helical gears, multiple the teeth are often in mesh, which means less load on each 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 reduced.
But the inclined angle of the teeth also causes sliding get in touch with between the teeth, which generates axial forces and heat, decreasing efficiency. These axial forces enjoy a significant part in bearing selection for helical gears. As the helical gear china bearings have to endure both radial and axial forces, helical gears need thrust or roller bearings, which are typically larger (and more costly) compared to the simple bearings used with spur gears. The axial forces vary compared to the magnitude of the tangent of the helix angle. Although bigger helix angles provide higher rate and smoother motion, the helix angle is typically limited by 45 degrees because of 
the production of axial forces.