Helical Gears, or "Dry Fixed" Gears, have teeth that are oriented at an angle to the shaft, unlike Spur Gears which are parallel. This causes more than one tooth to be in contact during operation and helical gears can carry more load than spur gears. The angled teeth engage more gradually than do spur gear teeth, causing them to run more smoothly and quietly.

A Herringbone Gear, a specific type of Double Helical Gear, is a special type of gear that is a side-to-side (not face-to-face) combination of two helical gears of opposite hands. From the top, each helical groove of this gear looks like the letter V, and many together form a herringbone pattern (resembling the bones of a fish such as a herring). Unlike helical gears, herringbone gears do not produce an additional axial load.

Like helical gears, they have the advantage of transferring power smoothly, because more than two teeth will be enmeshed at any moment in time. Their advantage over the helical gears is that the side-thrust of one half is balanced by that of the other half. This means that herringbone gears can be used in torque gearboxes without requiring a substantial thrust bearing. Because of this, herringbone gears were an important step in the introduction of the steam turbine to marine propulsion.

a Herringbone Gear in action

Herringbone gears are very similar to the double helical gear, but they do not have a gap separating the two helical faces. Herringbone gears are typically smaller than the comparable double helical and are ideally suited for high shock and vibration applications. Precision herringbone gears are more difficult to manufacture than equivalent spur or helical gears and consequently are more expensive, so typically they are used in heavy machinery.

Photos of Herringbone Gears (Double Helical Gears)

HOLK Bearing is a leading manufacturer of a wide range of power transmission products such as Gears, Chain Sprockets, Bearing Housings, Adapter Sleeves, Withdrawal Sleeves, Precision Lock Nuts, and many other bearing accessories.

We can produce a wide range of standard and bespoke gears like Spur Gears, Helical Gears, Internal Gears, Miter Gears, Bevel Gears, Worm Gears, Rack and Pinions and so on.

All HOLK's gears are made from top-notch quality steels and can be further adapted for high performance with coatings such as black oxide or zinc plating. 

To enhance the hardness and wear resistance of the tooth surface, the tooth surface can be subjected to high frequency quenching and heat treatment, thereby increasing the life of the chain sprockets and gears.

HOLK's helical gears grant high performances on a wide array of industrial applications. Their resistance to wear and fatigue is way above the standard requirements according to relevant ISO regulation. Thanks to our top-notch production capacity, we can offer many different series and also customised power transmission products. 

Aside from standard products, we can also produce special customized Chain Sprockets, Gears, Gear Racks, and many other industrial products according to customers' drawings and samples.