This is because of the fact that the amount of friction is greatly reduced in case of this fan when the fan is operating.
Direct drive fan vs belt driven fans.
You have a fan a motor and maybe a coupling.
In addition belt driven fans are less efficient than a direct driven fan of equivalent size due to transmission losses.
There s also no belt residue and these fans cost less to maintain generally speaking because belts don t wear down and break.
Direct driven fans mount the motor to the fan shaft in order to directly transmit energy.
More often than not the maintenance cost of this kind of fan is also comparatively lower.
Direct drive fans require fewer parts and thus usually less maintenance.
Belt drive fans have the two motor bearings similar to direct drive fans plus the two shaft bearings.
The second pulley is connected to a shaft that drives the fan propeller.
Because of the fewer parts involved they can often be more compact in design.
Direct drive fans have no power transmission loss since the propeller is directly connected to the motor shaft.
As energy costs increase it has become desirable to transition to a more efficient means of driving fan systems.
Direct drive fans with relubricable motor bearings must be lubricated as per the fan manufacturer s recommendations in terms of grease type and frequency.
Greater efficiency is the biggest pro of direct drive fan configurations.
Unlike the belt driven fans in case of a direct drive fan there is lesser energy loss.
Direct drive advantages direct drive fans are typically lower maintenance since there are no bearings belts or sheaves to maintain.
However a belt drive fan has power transmission loss due to the friction between the belt and sheaves and due to the drive shaft bearings.
When compared to belt drive fans which require belts sheaves and bushings direct drive is just plain simpler and maintenance folks tend to lean toward direct drive for daily maintenance.
Unlike belt driven fans there s less energy loss because there s a reduced amount of friction as the fan operates.