Helical gears can be further classified into two types: single helical gears and double helical (or herringbone) gears.
- Single helical gears: These are the most common type of helical gears, where the teeth are slanted in one direction. They provide smoother and quieter operation compared to spur gears, but they produce axial thrust, which needs to be managed through additional components like thrust bearings.
- Double helical gears (Herringbone gears): These gears consist of two sets of helical teeth with opposite helix angles, effectively forming a V-shaped pattern that resembles a herringbone. The opposing helix angles of the gear teeth cancel out the axial thrust, eliminating the need for additional bearings or thrust washers to manage the force. Double helical gears provide even smoother and quieter operation than single helical gears, but their manufacturing process is more complex and expensive.
When choosing between helical gears and other types of gears, it’s essential to consider the specific application’s requirements. Helical gears are generally chosen for applications that require smooth, quiet operation and where higher loads need to be transmitted efficiently. Examples include automotive transmissions, power tools, and various types of industrial machinery.
On the other hand, if the primary concern is simplicity and cost, spur gears may be more suitable for the application. They are easier to manufacture and less expensive than helical gears, making them a popular choice for lower-speed, less demanding applications where noise and vibration are not significant concerns.
In summary, helical gears offer several advantages over spur gears, such as smoother and quieter operation, higher load capacity, and greater efficiency. However, they come with drawbacks like increased manufacturing cost and axial thrust. The choice between helical gears and other gear types depends on the specific needs of the application, balancing factors like performance, cost, and complexity.