Direct-drive fans couple the impeller straight to the motor shaft. With no belts or extra bearings they need less routine maintenance and run slightly more efficiently, but the fan speed is fixed at the motor speed, so the duty point can only be changed by swapping the motor or adding a VFD. They suit clean, stable duties where the requirement is well defined.
Belt-drive fans add a pulley and belt set, which need periodic tension checks and replacement, plus their own bearings. In return you can fine-tune fan speed by changing pulleys — valuable when the duty point is uncertain or may change, and convenient for field adjustment. We supply both; for variable or uncertain duties belt drive or a VFD gives the flexibility, while fixed continuous duties often favour direct drive.