In the process of transporting goods, we need to carry out the process of frequency conversion and speed change, which can be divided into throttling speed change and volumetric speed change. Throttling speed change changes the cross-section size of the flow control elements in the control circuit, which can effectively control the flow of the elements, and then more effectively adjust the running speed of the electric forklift. Because the adjustment of movement speed is mainly completed by the transformation of flow section, the energy consumption will be damaged to a certain extent.

而电动叉车的容积变速将控制回路中的变量柱塞泵排量进行改变，这样可对实行元器件进行调整过程。泵控容积变速一方面将电动叉车电机转速比进行变化，也可更进一步对液压泵輸出流量进行改变。此外还可利用变量组织对液压泵排量进行转变，这样便可对液压泵的輸出流量进行改变。

The displacement of the variable piston pump in the control circuit is changed by the volume variable speed of the electric forklift, which can adjust the components. On the one hand, the pump controlled volume variable speed can change the motor speed ratio of the electric forklift, and also further change the output flow of the hydraulic pump. In addition, the variable organization can be used to change the displacement of the hydraulic pump, so that the output flow of the hydraulic pump can be changed.
               

电动叉车的泵源是利用压力反馈式变量柱塞泵完成。在对电机转速进行控制时，通过变频完成，可更进一步完成容积变速。随着持续变动的负荷运行，会逐渐转变为电动叉车的工作压力，进而将工作效率得到进一步提升。根据相关研究数据表示，电动叉车的工作压力通常与反馈压力维持在平衡位置状态中。

The pump source of electric forklift is pressure feedback variable piston pump. In the motor speed control, through the frequency conversion to complete, can further complete the volume variable speed. With the continuous change of load operation, it will gradually change into the working pressure of electric forklift, and further improve the work efficiency. According to the relevant research data, the working pressure and feedback pressure of electric forklift are usually maintained in a balanced position.

随着电动叉车交流电动机当代控制理论的不断发展，交流变频变速技术也在整个电动叉车行业中得到了更为普遍的使用。

With the continuous development of modern control theory of electric forklift AC motor, AC frequency conversion and variable speed technology has been more widely used in the whole electric forklift industry.