Description
Rexroth MKD025B-144-KP0-UN | Multiturn Encoder Motor
Product Introduction
The Bosch Rexroth Indramat MKD025B-144-KP0-UN is a compact MKD-series permanent-magnet synchronous servo motor designed for closed-loop industrial motion systems. The 025B frame uses winding code 144 and a keyed output shaft, while the KP0 configuration combines resolver feedback with an integrated multiturn absolute encoder. Rexroth’s MKD type-code documentation identifies P as the keyed-shaft option and 0 as the no-brake option.
The exact R911288059 configuration provides 0.9 Nm continuous standstill torque, a 3,000 RPM nominal speed, 115 V rated voltage, and 6.0 A rated current. Its 54 mm flange and 40 mm centering diameter make it suited to compact servo axes, while the absence of a holding brake is an important replacement constraint for vertical or gravity-loaded applications.
MKD025B-144-KP0-UN
Key Technical Specifications
- Manufacturer: Bosch Rexroth Indramat
- Series: MKD Synchronous Motors
- Exact Model: MKD025B-144-KP0-UN
- Material Number: R911288059
- Motor Type: Synchronous servo motor
- Motor Size: 025
- Motor Length: B
- Winding Code: 144
- Continuous Torque at Standstill: 0.9 Nm
- Nominal Speed: 3,000 RPM
- Rated Voltage: 115 V
- Rated Current: 6.0 A
- Feedback: Resolver feedback with integrated encoder
- Position Detection: Absolute, greater than 4,096 revolutions
- Output Shaft: Shaft with keyway
- Shaft Seal: Yes
- Holding Brake: None
- Flange Size: 54 mm
- Centering Diameter: 40 mm
- Connection Type: Power and encoder connectors
- Connection Direction: Rotatable through 270°
- Protection Rating: IP65
- Operating Temperature: -20°C to +40°C
The 0.9 Nm torque, 54 mm flange, 40 mm centering diameter, keyed shaft, no-brake configuration, and absolute multiturn feedback are supported by exact-model references.
The 3,000 RPM figure is the published nominal speed. Some MKD025B-144 technical documentation lists higher characteristic or maximum-speed values for particular cooling/configuration conditions, so a maximum-speed claim should be taken from the motor rating sheet and drive parameter set rather than inferred from the nominal speed.
Application Scenarios & Pain Points
1. Compact CNC and Machine-Tool Axes
The MKD025B-144-KP0-UN can be used for compact servo axes requiring controlled position and speed feedback.
Engineering pain point: Mechanical interchangeability is not enough. The replacement must match the 144 winding, KP feedback/shaft configuration, connector arrangement, and drive parameters.
2. Packaging and Indexing Equipment
The integrated multiturn absolute feedback provides absolute position information over more than 4,096 revolutions.
Pain point: The machine controller and drive must support the specific Rexroth feedback arrangement. A visually identical motor with different feedback coding should not be treated as an automatic substitute.
3. Small Rotary Positioning Axes
The 0.9 Nm continuous standstill torque provides a defined reference for compact indexing, positioning, and actuator applications.
Pain point: The motor has no holding brake. Any axis that must remain mechanically secured after servo power is removed requires an external holding or safety mechanism.
4. Legacy Indramat Machine Restoration
The MKD025B-144-KP0-UN is particularly relevant when maintaining an existing Rexroth/Indramat machine without changing its motor mounting, shaft coupling, and feedback architecture.
Procurement pain point: Do not purchase simply as an “.” The complete KP0-UN suffix determines important mechanical and electrical characteristics. Rexroth’s type-code documentation confirms that MKD motors were offered with different feedback, shaft, and brake combinations.
QA & Live Testing SOP
1. Identity Verification
Before accepting the motor:
- Photograph the complete nameplate.
- Confirm MKD025B-144-KP0-UN.
- Cross-check R911288059.
- Verify motor size 025.
- Verify length B.
- Verify winding code 144.
- Confirm KP0 configuration.
- Confirm there is no factory holding-brake assembly.
- Record serial and manufacturing information where available.
2. Mechanical Inspection
Inspect:
- 54 mm mounting flange.
- 40 mm centering diameter.
- Keyed shaft.
- Shaft keyway for deformation or wear.
- Shaft seal.
- Bearing condition.
- Motor housing.
- Power connector.
- Encoder connector.
- Connector orientation mechanism.
Rotate the shaft manually and check for:
- Bearing roughness.
- Abnormal noise.
- Radial play.
- Axial play.
- Mechanical binding.
- Shaft or keyway damage.
3. Feedback Verification
The KP0 configuration uses resolver feedback with an integrated multiturn absolute encoder.
Using a compatible Rexroth test system:
- Confirm resolver recognition.
- Confirm encoder recognition.
- Verify absolute position data.
- Verify multiturn position tracking.
- Check encoder fault status.
- Confirm stable position feedback during controlled rotation.
Do not apply uncontrolled voltage directly to the motor.
4. Electrical Motor Test
Perform appropriate controlled electrical checks:
- Phase-to-phase winding resistance comparison.
- Insulation resistance test using an appropriate motor procedure.
- Connector continuity.
- Resolver signal integrity.
- Motor current balance during controlled operation.
Compare measured values with the applicable Rexroth motor documentation rather than relying on generic MKD025 specifications.
5. Controlled Functional Test
Run the motor using a compatible Rexroth drive/test system.
Record:
- Initial motor temperature.
- Motor current.
- Speed.
- Feedback status.
- Position stability.
- Drive fault codes.
- Vibration.
- Bearing noise.
- Temperature rise.
The published nominal speed is 3,000 RPM. Any higher-speed testing should be authorized by the exact motor rating data and compatible drive configuration.
6. Packaging
- Protect the keyed shaft and keyway from impact.
- Prevent the shaft from carrying shipping loads.
- Protect power and feedback connectors.
- Protect the flange and centering surface.
- Use ESD-conscious handling around the feedback electronics.
- Prevent movement inside the shipping carton.
Field Engineer’s Pitfall Guide
❗ KP0 is not KG1. Both configurations use the K feedback designation, but the shaft and brake portions differ. P identifies the keyed shaft, while G identifies the plain-shaft option. The final 0 indicates no holding brake.
❗ There is no holding brake.se the on a vertical axis that depends on the motor itself to mechanically hold the load after power removal.
❗ Do not confuse the keyed shaft with the plain-shaft KG1 version. The KP0 model has a keyway according to the MKD type-code documentation.
❗ The 0.9 Nm figure is continuous standstill torque. It is not the same specification as peak torque, rated running torque, or brake torque.
❗ The 144 winding code must match. MKD motors use winding codes to define the motor’s electrical output characteristics. A motor from the same 025B frame with another winding should not be substituted without drive-parameter verification.
❗ Do not use 3,000 RPM as an assumed maximum speed. It is the published nominal speed for this exact configuration. Higher characteristic speeds appear in MKD technical documentation under specific operating conditions; verify the exact rating sheet before high-speed operation.
Intent-Driven FAQ
Q: What is the exact Rexrother for ?
A: The material/order number is R911288059.
Q: What is the continuous standstill torque?
A: The exact configuration is specified at 0.9 Nm continuous torque at standstill.
: Does have a holding brake?
A: No. The 0 brake designation indicates without holding brake, and exact-model references confirm that this motor is supplied without a brake.
Q: What feedback does the KP0 configuration use?
A: It uses resolver feedback with an integrated multiturn absolute encoder, with absolute position detection exceeding 4,096 revolutions.
Q: Does this motor have a keyed shaft?
A: Yes. The P shaft designation identifies the shaft-with-keyway configuration. The exact-model references also explicitly specify a keyed shaft.
Q: What are the mounting dimensions?
A: The exact configuration has a 54 mm flange and 40 mm centering diameter.
Q: What is the nominal speed?
A: The published nominal speed is 3,000 RPM at the stated rated conditions. Maximum permissible speed should be verified from the exact Rexroth motor rating data before commissioning.
Q: What is the rated voltage and current?
A: The exact-model reference lists 115 V rated voltage and 6.0 A rated current.
Q: Is interchangMKD025B-144-KG1-UN?
A: Not as a direct configuration substitution. Both belong to the family, but KP0 has a keyed shaft and no brake, while KG1 uses the corresponding different shaft/brake configuration. Mechanical coupling, brake requirements, and machine parameters must be checked before substitution.
Q: What condition should be specified when sourcing this motor?
A: Unless documented inspection results are provided, specify Legacy / Verify Condition and require nameplate verification, shaft/keyway inspection, winding checks, resolver/encoder testing, and controlled functional testing before acceptance.
