For ultrafine vertical mill driven by multiple motors, if Y-type motor + torque limiting hydraulic coupling + reducer is selected as the driving mode, the torque limiting hydraulic coupling with rear auxiliary chamber is recommended as the hydraulic coupling. Because the torque limiting hydraulic coupling is limited by heat dissipation conditions, the drive mode of Y-type motor + torque limiting hydraulic coupling + reducer is generally used on the ultrafine vertical mill with single power less than 630kw and length less than 1500m.

Advantages: high cost performance, simple and compact structure, small maintenance workload, low maintenance cost, protection of motor overload, when multiple motors are driven, it can balance motor power, delay starting in different stages, reduce the impact of ultrafine vertical mill on power grid when starting, high reliability and low price, so it is the preferred driving mode for ultrafine vertical mill with length less than 1500m.

Disadvantages: the soft start performance is poor, so it is not suitable for the down transport of ultrafine vertical mill and ultrafine vertical mill with speed regulation function.