You are here:

Electric Motors/Electric motors, shaft sizes and frame designations


I have got different size motor with different speeds, the frame size changes, where can I find the different shaft sizes for the different motors

If I understand what you are asking,  you have say two motors, one that runs at one speed, another that runs at another speed,     both have different frame sizes and with the change in frame size,  the shaft size is also different,  

Are you looking for a chart of frame/shaft sizes?   Or do you have existing motors and want to change the physical shaft sizes?

The standard shaft size should stay with the frame designation,   speed should have nothing to do with it,       if you are talking NEMA or even IEC  standards,

Example   motor 1 at 1200 RPM has a shaft size and frame number of X,   the HP will probably change but the shaft diameter should stay with the frame size,    this is for standard NEMA motors    and only the diameter is charted,   the length is a minimum,     so I have no idea if you are concerned about shaft size   being the diameter or both length and diameter,  

here is a standard shaft size/frame size chart:

If you have problems my shop is MEAR Services Inc,  Kansas City, Missouri,,    816-650-4030 phone number   USA central time    

Let me know if you still have questions  

Electric Motors

All Answers

Answers by Expert:

Ask Experts




Three phase/ AC DC single phase motors, controls, any problems or failures, motor installation, performance issues, connections. All other electric motors/gearboxes/apparatus. Specialty repair concerns, obsolete motors and solutions. Other mechanical or specialty equipment. See my profile under Home/electrical at this site


30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.

EASA, IBEW [retired], other specialty organizations, Lubrication, Vibration EDI, Tribo-electric Councils

Currently fielding concerns at this site under "Home Electrical"

4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.

©2017 All rights reserved.