How to select the correct belly band or motor mounting kit for your direct drive blower motor

Choosing the correct belly band or motor mounting kit is vital for the smooth operation of your direct drive blower motor.

What is the purpose of a belly band or motor mounting kit?

Motor mounting kits are used to prop up your direct drive blower motor in your system. Furthermore, these motor mounts help to mitigate vibration and reduce noise.

What types of Belly Bands and Motor Mounting Kits are there?

There are a handful of different types of belly bands within the HVAC market. The difference between the different types of motor mounts include how many legs there are, the diameter size, and the bolt size.

Understanding the different Motor Mounting Kit sizes

The motor mounting kits are created in NEMA sizes based on the frame size of the motor. You'll need to know the frame size of the motor and therefore the dimension of the motor in order to select the correct motor mounting kit. Below you will find the standard belly band kit sizes matched with motor frame sizes:

As you can see above, the motor diameter correlates with the motor mounting kit's part number. For example, a motor with a 5 inch diameter would require a FM50 (5.0) and a motor with a 5.5 inch diameter would require a FM55 (5.5). But what do the additional letters and numbers mean? Continue on below...

Number of Legs and Bolt Sizes for Motor Mounting Kits

Now that you understand the first 4 characters of the motor mounting kit part number, we'll walk you through the additional characters. If there are no additional characters, this means that it is a standard belly band with 3 legs. For example, a FM55 bracket is for 48 frame, 5.5 inch diameter motors with only 3 legs. If you see a bracket with a 4 on the end (FM554A), this means that there are 4 legs.

The "S" and the "L" stand for "Small" and "Large" respectively in regards to the lug bolt size. For example, the FM55S has 3 legs and the bolt circle range is 6-7/8 to 8-1/8. In contrast, the FM55L has 3 legs and the bolt circle range is 8-1/8 to 12-1/8. You'll want to check the size of your bolts before ordering a replacement.

Do you need to replace your motor mounting kit when installing a new motor?

It is highly recommended to replace your motor mounting kit when installing a new motor. The reasoning is similar to why you should replace your condenser fan or blower wheel when installing a new motor. The fan blade, blower wheel, and motor kit may have been damaged when uninstalling the motor. It may just have wear and tear that pushes it out of tolerance. Ordering a new kit will help ensure that there is no unnecessary vibration in the set up which would increase the reliability and longevity of your motor.

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