The distribution of transmission ratio is one of the important problems in the design of gear transmission chain. Whether the distribution of the transmission ratio is reasonable will affect the structural layout of the entire transmission chain and its working performance, so the distribution of the transmission ratio must be carried out reasonably according to the requirements of use in the design.
The total transmission ratio of the gear chain is often given in advance according to specific requirements. After the total transmission ratio is given, the transmission series is determined and the transmission ratio is assigned.
Generally speaking, it is better to have fewer transmission stages of the gear drive chain. Because the more transmission series, the more complex the structure of the transmission chain. The fewer transmission series can not only simplify the structure, but also improve the transmission efficiency, reduce the transmission error and improve the working accuracy.
However, in the case of a certain total transmission ratio, due to the reduction of transmission series, it is bound to cause the increase of transmission ratio values at all levels. If the transmission ratio of all levels (single-stage transmission ratio) is too large, it will make the structure of the transmission chain is not compact. At the same time, when the single-stage transmission ratio is too large, the diameter of the driven wheel will be large, resulting in an increase in the moment of inertia of the gear, which is not desired for the gear transmission chain that requires a small moment of inertia. Therefore, its transmission series should be reasonably determined according to the specific working requirements of the gear transmission chain.
The following principles can be used to assign the transmission ratio when designing.
1. Distribute the transmission ratio according to the principle of first small and then large
2. Distribute the transmission ratio according to the principle of small volume
3. The transmission ratio is assigned according to the principle of small moment of inertia