What is Helical Gear – Different Types of Helical Gear and How Do They Work

Our gear machining services will provide a variety of custom gears with different specifications.

– Single helical gear: When two helical gears mesh, the helix angle on each gear must be the same, but one gear must have a right-hand helix and the other has a left-hand helix. The single helical gear is used to transfer power from one parallel shaft to another. If the surface of the helical gear is wide enough, multiple teeth will be engaged at the same time. These multiple meshing of the gear teeth allow the helical gear to carry more load on a single gear set. The inclination angle of the teeth allows the teeth to mesh gradually, but also causes sliding contact between the teeth, thus generating axial force and improving efficiency. The gear and the shaft try to move laterally, The direction of the thrust load acting on the axle is determined by applying the right or left rule to the driver. 

– Double helical gear: The axial load generated by helical gear can be offset by using double helical gear or herringbone gear. The double helical gear arrangement has the appearance of two helical gears, and the two helical gear heads are installed back-to-back, although they are actually machined from the same gear. The double helical gear has a groove in the middle between the teeth. This arrangement offsets the axial force on each group of teeth, so a larger angle can be used, and no thrust bearing is required.

– Herringbone gear: The unique tooth structure of herringbone gear is composed of two adjacent relative helices in the shape of the letter V. The main difference between herringbone gear and double helical gear is that in double helical gear, there is a groove between the two gears, but in herringbone gear, the groove is missing. Therefore, the manufacturing processes of these two gears are different. Herringbone gear sets are designed to transmit power through parallel shafts. Multiple teeth mesh during rotation to distribute workload and provide quiet operation. Herringbone gear overcomes the problem of axial thrust generated by single helical gear, and this arrangement can eliminate the demand for thrust bearing. 

– Crossed helical gear: The cross helical gear is a pair of helical gears with the same hand. The torsional angle is 45 degrees when non-parallel and non-cross shifting. Because the tooth contact of this configuration is limited, its bearing capacity is low, and it is not suitable for high-power transmission. 

– Helical rack & pinion: A helical rack is a linear gear that meshes with a helical gear. A helical rack can be considered part of a helical gear with an infinite radius. The helical gear rack has helical teeth cut into a surface of a square or circular cross-section rod, and its working principle is that the small cylindrical helical gear meshing with the rack ear rack will convert the rotary motion into linear motion.