Gears of first stage are changeable so that the operator can change the gearratio 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。
2
Change gearratio 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.