Bottom line
What this comparison can establish
Start with the complete family prefix and suffix. A shared frame number or similar appearance is never enough to select a replacement motor.
Motor-family comparison / synchronous servo systems
MKD vs MHD vs MSK Servo Motor Families
MKD, MHD and MSK are different synchronous-motor families with separate planning documentation. Similar frame numbers do not mean the winding, feedback, shaft, brake, connector, cooling or connected drive is compatible.
Side-by-side identity
What each product label must tell you
- Role
- Synchronous-motor family commonly documented with ECODRIVE-era system planning.
- Verify
- Frame, length, winding, encoder, shaft, brake, housing/connector and connected drive.
- Do not assume
- Do not compare only the numeric frame or housing dimensions.
- Role
- Separate synchronous-motor family with its own feedback, cooling, brake and type-code structure.
- Verify
- Complete MHD code, winding, feedback, shaft, brake, cooling, connector and drive.
- Do not assume
- An MHD and MKD with similar size remain different configured motor selections.
- Role
- IndraDyn S synchronous-motor family with edition-specific encoder and mechanical options.
- Verify
- Complete MSK code, winding, encoder, shaft, brake, connector, cooling and IndraDrive context.
- Do not assume
- Do not infer a migration path from torque or frame similarity without engineering review.
Decision path
Turn the cabinet into a useful evidence set
Which family prefix is on the tag?
Capture: Capture MKD, MHD or MSK plus every suffix character.
Then: Use the matching factory planning record and family page.
What feedback does the drive expect?
Capture: Record encoder or feedback fields, connectors and the connected controller.
Then: Reject a motor match that does not preserve the feedback system.
Will it fit and hold the load?
Capture: Measure only after recording shaft, flange, centering, brake and cooling codes.
Then: Verify electrical and mechanical configuration together.
Official manufacturer records
Use the edition that matches the installed hardware.
Verified downloads open on the manufacturer’s site. Other references open a library entry with assistance options. Confirm the applicable edition, physical nameplate and machine documentation.
R911272495Rexroth Synchronous Motors MKD - Project Planning Manual
Factory documentation for MKD windings, encoder, shaft, brake, dimensions, connections and operating limits.
View document reference →R911273697MHD Synchronous Motors - Project Planning ManualFactory documentation for MHD technical data, feedback, cooling, brake, type-code fields and installation planning.
View document reference →R911296289Rexroth IndraDyn S MSK Synchronous MotorsFactory documentation for MSK windings, encoders, shafts, brakes, connectors and cooling choices.
View document reference →Common questions
Before you request a configured match
Does the same frame number mean the motors interchange?
No. Family, winding, feedback, mechanical interface, brake, cooling and connected drive must all be compatible.
Can a newer MSK automatically replace an MKD or MHD?
No automatic migration should be assumed. A change of motor family can affect drive, feedback, cabling, mechanics, parameters and machine validation.
What is the best first photo?
Start with a straight-on nameplate, then add the complete motor, shaft/flange, connectors and installed drive.
Availability · repair · exchange
Send the complete code.
The suffix can change electrical and mechanical compatibility. Include every character and a clear nameplate photo.