MARATHON MOTORS

Rigid base mounting uses a foot-mounted design where the motor is bolted to a base or foundation, with the shaft parallel to the mounting surface. C-face with rigid base combines a foot mount with a C-face flange on the drive end, allowing direct coupling to a pump, gearbox, or other driven equipment while still providing foot support. The C-face flange has a specific bolt circle and register diameter that must match the driven equipment. Both configurations are available in Marathon Motors general-purpose and metric-frame lines, with the choice depending on the mechanical interface required by the application.

TEFC stands for totally enclosed fan-cooled. In a TEFC motor, the enclosure prevents outside air from flowing through the motor interior, and an external fan blows air over the exterior frame to dissipate heat. This design is suitable for dusty, damp, or dirty environments where open motors would be at risk of contamination. Marathon Motors TEFC motors in the 3G Electric catalog include ratings from 3 hp to 50 hp, with voltages such as 230/460V AC and 575V AC, and speeds from 1,180 RPM to 3,525 RPM at 60 Hz.

IEC metric frame motors and NEMA frame motors are not directly interchangeable in most cases. IEC frames, such as the 160M and 225S frames in the Marathon Motors line, have different mounting dimensions, shaft sizes, and flange dimensions compared to NEMA frames. When replacing a motor, the frame size, mounting configuration, shaft diameter, and keyway must match the driven equipment or be adapted with a suitable coupling or mounting plate. Marathon Motors offers both IEC metric and NEMA frame motors, so selection should be based on the original equipment specification or the mechanical interface of the replacement application.

The Marathon Motors 3-phase motors supplied by 3G Electric include full load current ratings that vary by horsepower and voltage. Examples include 6.2 A at 460V for a 5 hp motor, 8.6/4.3 A at 230/460V for a 3 hp motor, 13.6/6.8 A at 230/460V for a 5 hp motor, 37.5/18.7 A at 230/460V for a 15 hp motor, 47.5/23.7 A at 230/460V for a 20 hp motor, and 118.0/59.0 A at 230/460V for a 50 hp motor. These values are used for sizing overload protection, conductors, and starters.

Marathon Motors general-purpose AC motors are used in continuous-duty applications such as pumps, fans, conveyors, and compressors. The TEFC enclosure makes them suitable for indoor environments where dust, moisture, or other contaminants are present. Specific models in the 3G Electric catalog include rigid base and C-face with rigid base configurations, with ratings from 3 hp to 50 hp and speeds from 1,180 RPM to 3,525 RPM at 60 Hz. Selection depends on the driven equipment's torque and speed requirements, available voltage, and mounting interface.

To select a replacement, record the nameplate data from the existing motor: horsepower, voltage, phase, full load current, RPM, frame size, enclosure type, and mounting configuration. Also note the shaft diameter, keyway, and any C-face or flange dimensions. Compare these to the Marathon Motors catalog specifications, such as those listed for SKUs 19RX27, 55AY98, 44P065, and others. If the original motor is obsolete or unavailable, match the mechanical interface and electrical ratings as closely as possible, and verify that the replacement motor's speed and torque meet the driven equipment's requirements.