In the later there is a belt sometimes more than one connecting the motor to move the fan.
Direct drive vs belt drive fan.
Unlike the belt driven fans in case of a direct drive fan there is lesser energy loss.
Direct drive or belt drive.
The second pulley is connected to a shaft that drives the fan propeller.
Direct drive fans have no power transmission loss since the propeller is directly connected to the motor shaft.
On both direct drive and belt drive fans the motor has two bearings.
Deciding between a direct drive fan and a belt drive fan is fairly straightforward once you know all of your other variables like fan size application space fan speed needs and likely wear and tear in your application.
Where on a belt drive fan the fan motor shaft has a pulley connected by a belt to a second pulley.
Belt drive fans have two additional bearings.
Because of the fewer parts involved they can often be more compact in design.
Greater efficiency is the biggest pro of direct drive fan configurations.
There s also no belt residue and these fans cost less to maintain generally speaking because belts don t wear down and break.
The environmental conditions in which the fan is installed may dictate a preference toward a belt or direct drive fan.
Extreme hot cold dirty or humid conditions may favor a direct drive fan as it reduces the environmental impact on the drive belts and fan bearings.
It s a motor connected to your fan in one of only two ways.
The two bearings on direct drive fan motors which are 7 horsepower and larger are typically regreaseable.
In the former the motor connects to the fan wheel with nothing in between.
Unlike belt driven fans there s less energy loss because there s a reduced amount of friction as the fan operates.
Direct drive advantages direct drive fans are typically lower maintenance since there are no bearings belts or sheaves to maintain.
Direct drive fans should be designed for acceptable bearing life.