What Are the Common Types of Helical Gears?

What Are the Common Types of Helical Gears?

Helical gears commonly come in the following types:

I. Left-Hand Helical Gears and Right-Hand Helical Gears

They are classified according to the direction of the helix. When the axis of the helical gear is placed vertically and facing the gear, if the teeth rise from left to right, it is a right-hand helical gear; if the teeth rise from right to left, it is a left-hand helical gear. In the design of mechanical transmission systems, the appropriate helical direction of the helical gear needs to be selected according to factors such as the specific installation space, the power transmission direction, and the cooperation with other components.

For example, in some transmission devices with limited space, due to the layout and installation requirements of other components, helical gears with a specific helix direction may need to be selected to ensure the smooth progress of the transmission.

II. Herringbone Gears

It can be regarded as formed by combining two helical gears with equal helix angles but opposite helix directions. The axial forces of the left and right halves of the herringbone gear can cancel each other out, thereby reducing the axial force borne by the bearings and improving the stability and load-carrying capacity of the gear transmission.

It is commonly used in high-power and high-speed transmission occasions, such as the propulsion systems of large ships and the transmission devices of heavy machinery. The processing of herringbone gears is relatively complex and the cost is high, but it has an irreplaceable advantage in occasions with high requirements for transmission stability and reliability.

III. Spiral Bevel Gears (Also Called Spiral Bevel Pinions)

It is a special form of helical gears. The tooth shape is conical, and the tooth line is a helix. Spiral bevel gears can achieve power transmission between intersecting shafts, with accurate transmission ratios and strong load-carrying capacity, and are suitable for occasions where the transmission direction needs to be changed.

They are widely used in fields such as automobiles, aerospace, and construction machinery. For example, spiral bevel gears are usually used in the differential of automobiles to realize the power transmission from the transmission shaft to the wheels and allow the left and right wheels to rotate at different speeds to meet the driving requirements of the vehicle during turning.