With the development of skills and the widespread application of computers, the development of international transmission skills tends to use hard-tooth surface reducers. According to statistics, the selection of hard-tooth surface reducer gears makes the weight and volume of the machine lighter, the quality continues to improve, and the operating speed has also increased by a level.

According to the hardness of the tooth surface, generally people divide gear transmission into two types, namely hard-tooth-surface gear transmission and soft-tooth-surface gear transmission. There are also three types, namely adding a type of medium-hard-tooth surface gear transmission. Gears whose working surface hardness is greater than 350HB or 38HRC are called hardened gears; those whose gear working surface's hardness is less than or equal to 280HB are called soft toothed gears; those in between are called medium-hard gears. The corresponding reducer is called hard tooth surface reducer or medium hard tooth surface reducer, soft tooth surface reducer.

First, the soft tooth surface reducer, related to the hard tooth surface reducer, has always been the best choice for domestic traditional crane planning due to its simple structure and relatively low price. However, due to the unreasonable basic parameters and the backward skill level, it will definitely be replaced by a variety of new reducers, especially the lifting reducers that are not suitable for use as important components.