Home » Press » Gear tooth modifications applied in wind turbine gears and pinion shafts

Gear tooth modifications applied in wind turbine gears and pinion shafts

Views: 38     Author: Site Editor     Publish Time: 2021-06-07      Origin: Site

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Our teams of engineers carefully consider the way to enforce the specified tooth flank modifications for the gearing of all types of gears and pinion shafts with new installations. These considerations include profile and lead correction– ensuring that NYY gears and pinion shafts are fit-for-purpose and deliver maximum output with minimal noise disruption. Through precise manufacturing strategies, we implement profile and longitudinal modifications as required by all kinds of customers.

We can also re-engineer gears and pinions that are already installed. If you need to replace existing gears and pinions with ones having better performance or different speeds, we know how to optimize the new gearing to satisfy your new demands.


Many factors result in the gears during operation not having optimal contact along with the complete tooth. This is partly because of static effects such as manufacturing inaccuracies in the gearbox, on the gears, and shafts/pinion shafts. And partly due to dynamic effects which lead to the shafts, teeth, gearbox, etc. to deflect in the operation process. We can partly compensate for this imprecision and deviations with tooth modifications.

Gear tooth modifications

In order to compensate for deviation of the teeth and to alleviate the tooth meshing, the tooth profile is usually adjusted by a tip relief and/or a root relief or by a smooth crown shape all over the tooth from bottom to top. A combination of all of these is also an option.

In order to compensate for non-parallelism and deflection of shafts and gearbox or torsion of the shaft, we can correct the tooth flanks by either an end relief, a smooth curve along the length of the whole tooth, a tapered tooth, or a combination of all of these.

It should be stated that tooth corrections are constantly a compromise due to the fact that the surface pressure also increases concurrently with the increased corrections. Therefore, the target is to maximize the engagement ratio throughout the biggest effect imposed on the gear by making some tooth modifications in order that the gears barely do not have edge contact.

In nearly all cases we have good experience of it being an advantage to utilize tooth modifications to a restrained extent. We can usually offer such tooth modifications without extra costs with our very precise CNC-controlled Höfler gear grinding machines. Only in case of very big modifications or very fine tolerances, it will have an effect on the cost.


Many sections of the wind turbines include gears/ ring gears and pinion shafts. For the pitch regulation, a drive pulls inside on internal ring gear, and to rotate the wind turbine against the wind so-called YAW-drives are used, in which a number of drives are pulling on a large ring gear that is fixed on the tower. The latter can be with either internal or external teeth.

Due to the slow speed, all the above gears are usually of rough quality. The gears are normally manufactured by hobbing and case hardened. During recent years, more and more manufacturers have however used ground teeth on the drives that allow you to acquire a better distribution of the surface pressures. Here, extremely large flank line modifications and tip reliefs are getting used to making up for deflection and non-parallelism.

The precision gears are in the generator equipment. We are talking about gear ratios of altogether up to over 1:100 and big torques which are being transmitted. In recent years, we are talking about up to three planetary gear stages and succeeding one or two normal gear stages.

NYY can provide the ground YAW-drive gears/ring gears and pinion shafts and some of the generator gears according to shape and dimension. Especial for planetary gears, they must not be magnetic because the gear will then run as a generator and produce power.