Series of Reducers

Everyone is familiar with the four series of reducers, which are: R series coaxial helical gear reducers, F series parallel axis helical gear reducers, K series helical gear bevel gear reducers, and S series helical gear worm gear reducers.

But what exactly does R, F, K, S mean? Why is it defined this way? It is obvious that it is not the first letter of Chinese, but it does not seem to be the first letter described in English either. The corresponding English descriptions for the four major series are as follows:

R: Helical gear units

F: Parallel shaft mechanical gear units

K: Helical level gear units

S: Helical worm gear units

Further exploration revealed that these four letters originated from German. Specifically, the main reason for using these four letters is probably due to the profound influence of a gearbox product from a large German factory on a global scale. The specific German expressions represented are as follows:

Stirnradgetriebe (This initial letter is also S, which coincides with S below, so R is used?)

Flachgetriebe

Kegelradgetriebe

Schneckengetriebe