Spur Gear Vs Helical Gear

Spur Gear Vs Helical Gear

Spur Gear	Helical Gear
In spur gear, the teeth are parallel to the axis of the gear.	In helical gear, teeth are inclined at an angle (called helix angle) with the gear axis.
Spur gear imposes only radial load on bearings.	Helical gear imposes radial load and axial thrust load on bearings.
Radial bearings that can handle radial load only can be employed here.	Bearings that can handle both radial and axial load must be employed here.
Spur gear can be used for parallel shafts only.	Helical gears can be used for parallel shafts or crossed shafts.
At the time of engagement, entire face of the tooth comes in contact with the mating tooth.	Here engagement initiates with a point on tooth face and gradually extends across the tooth.
Mating teeth are subjected to impact loading.	Load on the mating teeth builds up gradually.
Sudden application of load increases vibration, especially in high speed condition.	Gradual loading on teeth minimizes vibration.
Spur gear produces noticeable noise due to sudden loading and vibration.	Operation of helical gear is noise free, even at high speed.
Teeth of the spur gear can be cut easily as it requires only two dimensional motion.	Making teeth for helical gear is comparatively difficult as it requires three dimensional motion.