Gears of first stage are changeable so that the operator can change the gear ratio based on current field condition.

第一级传动齿可变，驾驶员可根据电流与磁场情况来改变齿数比。

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Change gear ratio range, in particular, using planetary transmission, the transmission ratio can be up to 100 ~ 200 (single stage), the growth rate for slow down or drive.

传动比变化范围大，特别是采用行星传动时，传动比可到100 ~ 200(单级)，适用于减速或增速传动。

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