NEMA Motor Frame Dimensions and Mounting Reference
Compare selected NEMA frame shaft heights and diameters, interpret mounting suffixes, and locate the exact motor drawing before checking a replacement.
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Selected frame dimensions
Use the frame designation to locate the appropriate dimensional drawing. The selected conventional frame values below provide a quick shaft-height and shaft-diameter comparison. They are not a complete mounting drawing or a motor interchangeability approval.
| Frame designation | D: shaft center height (in.) | U: shaft diameter (in.) |
|---|---|---|
| 56 | 3.500 | 0.625 |
| 143T / 145T | 3.500 | 0.875 |
| 182T / 184T | 4.500 | 1.125 |
| 213T / 215T | 5.250 | 1.375 |
| 254T / 256T | 6.250 | 1.625 |
| 284T / 286T | 7.000 | 1.875 |
Two frames grouped in a row share the displayed dimensions, not necessarily mounting-hole spacing, overall length, shaft extension, key details, or accessory clearances. The actual motor drawing controls.
Read the dimension references
For a replacement, check the mounting-hole layout, shaft extension and key, mounting face/pilot where present, overall envelope, conduit-box position, and access space. A matching horsepower or shaft height does not establish a mechanical fit.
Suffixes and replacement checks
| Designation context | What to investigate |
|---|---|
| C | A C-face mounting interface; verify pilot, bolt pattern, shaft, and whether feet are present. |
| D | A D-flange mounting interface; do not treat it as a C-face dimension. |
| T | A NEMA T-frame designation; verify the entire frame, not just the first digits. |
| TS | A short-shaft designation in the relevant frame family; use the specified shaft/application details. |
| Z / other nonstandard or special suffix | Special features or nonstandard dimensions require the product drawing. |
Read the motor nameplate guide for electrical and duty data. Retain the exact frame drawing and the driven-equipment requirements in the job record. Environmental and drive suitability remain separate checks.