Common Drive Methods for Fans and Their Characteristics

Fan model traditional representation: Taking 4-72 No 10D as an example.

4 is the pressure coefficient, indicating the pressure series of the fan. It is obtained by multiplying the pressure coefficient at the highest efficiency point on the characteristic curve by 10 and then rounding.

72 is the specific speed of the series; the specific speed at the highest efficiency point on the characteristic curve is the specific speed of the fan series.

10 is the fan number (impeller diameter) in decimeters.

D is the drive method.

1.Type A Drive: Direct Drive

The fan impeller is mounted directly on the motor shaft.
Characteristics:The most compact structure, highest transmission efficiency (no additional losses), small footprint, stable operation, relatively low noise, and minimal maintenance. The impeller speed is the same as the motor speed and cannot be adjusted via a transmission mechanism. Fan performance is directly limited by motor power and speed. Typically used for small and medium-sized fans.
Applications: Most common in small to medium-sized, fixed-speed general-purpose fans, such as common axial fans and small centrifugal fans.

Type-A direct-connect fan

2.Type B Drive: Cantilever supported, Belt drive (pulley between bearings)

The impeller is cantilever-mounted, and the pulley is located between the two bearing housings. This places high demands on the bearings.
Characteristics:Structure is more compact than Type C. Speed can be easily adjusted by changing pulleys (thus adjusting airflow and pressure). Belt tension applies asymmetric forces to the two bearings, resulting in higher bearing requirements and less ideal force distribution compared to Type C.
Applications: Small and medium-sized fans requiring speed adjustment.

Type-B transmission type fan

3.Type C Drive: Cantilever supported, Belt drive (pulley outside bearings)

The impeller is cantilever-mounted, and the pulley is located outside the two bearing housings. This structure allows for speed/pressure adjustment, offers flexibility, and facilitates maintenance.
Characteristics:Bearing load distribution is better and more uniform than Type B, leading to longer service life. Speed adjustment via pulley change is very convenient. Maintenance and replacement of components like belts and bearings are easier. The structure is slightly longer than Type B, occupying slightly more space.
Applications: This is the most classic and widely used belt drive form, especially suitable for industrial applications requiring frequent speed adjustment or maintenance.

Type-C transmission type fan

4.Type D Drive: Cantilever supported, Coupling drive

The impeller is cantilever-mounted and connected to the motor via a coupling. It offers high efficiency, stable operation, and is commonly used. The motor and fan have independent bearing housings.
Characteristics:High transmission efficiency, very stable operation, capable of transmitting high torque. No belt slippage issues, precise speed transmission. Lacks the simple speed adjustment via pulley changes found in belt drives; requires a variable frequency drive for speed control. Requires high alignment accuracy between motor and fan during installation.
Applications: Medium to large fans requiring high power, high speed, and stable operation, such as large centrifugal compressors, boiler induced draft fans, etc.

Type-D transmission type fan

5.Type E Drive: Double support, Belt drive (without inlet box)

The impeller is located between two bearings (supported like a beam), and the pulley is on the fan side. It does not include an inlet box.
Characteristics:The support structure is very robust, capable of handling heavier impellers and higher loads. Operation is stable, and bearing life is long. The structure is complex and occupies relatively large space. The lack of an inlet box results in slightly inferior inlet conditions compared to Type F.
Applications: Suitable for medium-sized fans requiring structural stability and load capacity, where space and system intake requirements are less critical.

Type-E transmission type fan

6.Type F Drive: Double support, Coupling drive (with inlet box)

The impeller is located between two bearings, connected to the motor via a coupling, and equipped with a dedicated inlet box.
Characteristics:This is the most classic and robust structure for large centrifugal fans. The double support ensures stability, coupling drive offers high efficiency, and the inlet box guides airflow evenly into the impeller, significantly improving fan efficiency and performance. The structure is the most complex, bulky, and has the highest manufacturing cost and installation requirements.
Applications: Large, high-pressure, high-efficiency applications, such as power plant fans, mine main ventilation fans, large HVAC system centrifugal fans, etc.

Type-F transmission type fan

Classification Table of Drive Methods