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Different Ways of Mounting Helical Gears

November 26, 2020

Helical gears, also called dry fixed gears, are sometimes regarded as the refined version of spur gears as they are also cylindrical, but their teeth are not made parallel to the rotation axis. Rather, their teeth are angled and look like a segment of a helix, hence the name. With such tooth inclinations, they run smoother and quieter than other gear types and can carry heavier loads more efficiently. They are also designed in a way that pressure is distributed gradually along all the teeth. However, they are subject to axial thrusts due to the gradience of their teeth and the application of pressure. Fortunately, this issue can be easily addressed by using thrust bearings and special lubricants.


Helical gears come in two teeth configurations: right hand and left hand.


They can transfer energy through two axial configurations as well, perpendicular, or parallel axes using their helical teeth. Parallel axis helical gears are mounted on two opposite hands to provide high load capacity and quiet operations while the perpendicular-axis gears, also referred to as skew gears, use two same-hand gears to transmit energy through a 90° angle. Compared to the other gear type, the limited contact of the teeth in the perpendicular-axis gear restricts workload capacity.


Lastly, helical gears can be attached to a shaft or a hub. Hubless ones are typically mounted through press fits or adhesives. Shaft mounting can be done in many ways including the following:


  • Keyway: there are square cutouts in the gear bore for exact attaching on the shaft. 
  • Simple bore: with this option, only a straight bore is designed for adhesive mounting.
  • Split: in this mounting style, the hub is split into pieces that are tightened down using a separate clamp to hold the shaft.
  • Set screw: the gear is mounted to the shaft by screwing through the hub.
  • Hub clamping screws: the gear is also attached by screwing but the screw used squeezes the inner diameter of the hub to fit tightly around the shaft.