Helical gears and herringbone gears are both types of gears used in machinery, each with its unique features and applications. Let’s compare them:
Helical Gears
- Design: Helical gears have angled teeth, which engage more gradually than straight teeth as in spur gears. This angle is known as the helix angle.
- Load Distribution: The load is distributed over several teeth, resulting in smoother and quieter operation compared to spur gears.
- Axial Thrust: They produce axial thrust, a force that acts parallel to the axis of rotation, requiring the use of thrust bearings to manage this force.
- Applications: Commonly used in automotive transmissions, conveyors, and other machinery where noise reduction is important.
- Efficiency: Generally more efficient than spur gears, but less so than herringbone gears due to the additional bearing load from the axial thrust.
Herringbone Gears
- Design: Herringbone gears consist of two helical gears placed side by side, but with the helix angles in opposite directions, resembling a herringbone pattern.
- Load Distribution: Like helical gears, the load is distributed over several teeth, ensuring smooth operation.
- Axial Thrust Cancellation: The unique design cancels out axial thrust, as the opposing teeth exert forces in opposite directions, negating each other.
- Applications: Typically found in heavy machinery, high power applications, such as in rolling mills and gear pumps, where axial thrust needs to be minimized.
- Efficiency: They are more efficient than helical gears due to the lack of axial thrust, allowing for better power transmission.
Summary
- Noise and Vibration: Both gears are quieter and vibrate less than spur gears, with herringbone gears being slightly superior due to better load balancing.
- Complexity and Cost: Herringbone gears are more complex to manufacture, making them more expensive compared to helical gears.
- Application Suitability: Helical gears are suitable for a wide range of applications, particularly where noise is a concern. Herringbone gears are preferred in high-power and high-torque applications, especially where axial thrust is a concern.
In choosing between them, it usually comes down to the specific requirements of the application, considering factors like load, noise, power transmission efficiency, and cost.