What Is A C-Face Motor?
August 21, 2024
Motor Minute™ Technical Tip – What is a C-Face Motor?
Hi, Chris from Regal Rexnord here with your Motor Minute technical tip. Helping you become an HVAC motor pro one minute at a time.
Today’s Motor Minute topic is about C-face motors.
C-face motors are built with a machined face for mounting directly to the equipment of various applications. This is often referred to as directly coupled. The examples below show C-face motors in pump applications.
C-face motors are built in multiple frame sizes. The NEMA®* frame size listed on the motor rating plate contains the suffix letter (C) to denote that it is built with a C-face mount.
In the NEMA Frame Dimensions chart, we see that the mounting hole dimensions for C-face motors are standardized by frame size. The letters (AJ) denote the hole dimension related to the center of the shaft in the motor.
The NEMA Frame Dimensions chart also lists the “tap” values of the mounting holes for C-face motors, which are also standardized by frame size. “Tap” denotes the thread size of the holes.
The tap size and mounting hole dimensions are very important since the mounting bolts thread directly into the motor.
C-face motors can also be built with rigid base mounts to meet the original OEM specification.
The frame size of rigid base motors also denotes the dimensions (location) of the mounting holes in the base.
- The letter (E) denotes the dimension between the mounting holes and the center of the shaft.
- The letter (F) denotes the dimension between the mounting holes and the center of the base.
To summarize, the NEMA®* frame size in rigid base motors denotes the dimensions of:
- the center of the shaft to the base
- the mounting holes in the base
To summarize, the suffix letter (C) in the NEMA frame size denotes that the motor is built with a C-face mount. However, we discussed examples of C-face motors that are also built with a rigid base mount. It’s important to pay attention to the application the motor is used in to determine the type of mount needed for the replacement motor.
If the motor is built with a C-face mount and is directly coupled to the equipment, the replacement motor must also be built with a C-face mount.
However, a replacement motor built with a C-Face and rigid base mount can be mounted:
- direct coupled with the C-face mount
- directed coupled with the C-face mount and rigid base
- rigid base mounted in a belt drive application
The LEESON® Flex-in-1® motor is an example of a universal replacement for 56 frame motors built with C-face and rigid base mounts. This versatile motor can be mounted C-face or rigid base in all angles. Scan this QR code for more information on Flex-in-1 motors.
And that’s a wrap on this segment of Motor Minute technical tips. Remember that we provide motor training and product information in multiple formats including videos, literature, podcasts, articles, of course Motor Minute technical tips and classroom education both online and face to face. All of this industry leading training is available at no charge to HVAC professionals at regalmmu.com. Thank you for taking the time to build your motor knowledge.
*NEMA is the trademark of the National Electrical Manufacturers Association and is not owned or controlled by Regal Rexnord Corporation.
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