The difference between helical gears and spur gears

The teeth of a spur gear are straight and parallel to the axis; the teeth of a helical gear are inclined and helically wrapped around the axis.

　　The directions of the teeth are different.

　　The teeth of a spur gear are straight and parallel to the axis; the teeth of a helical gear are inclined and helically wrapped around the axis.

　　Different loading conditions

　　When helical gears rotate, they generate thrust forces in both directions, requiring specialized bearings for support; spur gears, by contrast, do not produce such axial thrust and place lower demands on the bearings.

　　Stability and Noise

　　Helical gears engage gradually, resulting in low impact, reduced noise, and smooth operation; spur gears, by contrast, engage simultaneously, leading to higher impact and more noticeable noise.

　　Load-bearing capacity

　　Helical gears engage a greater number of teeth simultaneously, enabling them to handle heavier loads and making them well suited for high-speed, heavy-duty applications; spur gears, by contrast, have a lower load-carrying capacity and are more appropriate for low-speed, light-load conditions.

　　Processing cost

　　Spur gears are easy to manufacture and low in cost; helical gears are more complex to produce and relatively expensive.

　　Typical applications

　　Spur gears are commonly used in simple machinery or for reverse gear; helical gears are widely employed in automotive transmissions, industrial gear reducers, and other applications that demand high smoothness.