Description
Bosch Rexroth MHD041B-144-PG1-UN | AC Servo Motor
Product Introduction
The Bosch Rexroth Indramat MHD041B-144-PG1-UN is an MHD-series synchronous AC servo motor designed for closed-loop motion applications. Its exact order number is R911274054, and the model designation specifies a 041 frame, B motor length, 144 winding, integrated multiturn absolute encoder, keyed shaft, and holding brake.
At the documented natural-cooling operating point, the motor is rated at 0.52 kW, 3,000 RPM, 1.4 Nm, and 2.8 A, with 2.7 Nm continuous torque at standstill and 7.5 A continuous standstill current. Maximum motor speed is specified at 7,500 RPM.
MHD041B-144-PG1-UN
Key Technical Specifications
- Model: MHD041B-144-PG1-UN
- Rexroth Order Number: R911274054
- Motor Family: MHD
- Motor Type: Synchronous AC servo motor
- Frame Size: 041B
- Winding Code: 144
- Rated Power: 0.52 kW
- Rated Speed: 3,000 RPM
- Maximum Speed: 7,500 RPM
- Rated Torque: 1.4 Nm
- Continuous Torque at Standstill: 2.7 Nm
- Rated Current: 2.8 A
- Continuous Standstill Current: 7.5 A
- Rated Voltage: 115 V
- Rated Frequency: 150 Hz
- Feedback: Digital servo feedback with integrated multiturn absolute encoder
- Shaft: Keyed shaft with shaft sealing ring
- Holding Brake: 2.2 Nm
- Brake Supply: 24 VDC ±10%; 0.34 A
- Flange Size: 82 mm
- Centering Diameter: 50 mm
- Protection: IP65
- Weight: Approximately 4.5 kg
- Connector Orientation: Power and feedback connectors rotatable through 270°
The 144 winding, PG1 encoder/shaft/brake configuration is important: Rexroth’s MHD designation system differentiates motors with otherwise similar frame sizes by winding, feedback, shaft, and brake options.
Application Scenarios & Pain Points
1. Legacy Indramat Motion Axes
The MHD041B-144-PG1-UN is applicable to legacy Bosch Rexroth Indramat servo axes where the existing motor, drive, feedback system, and mechanical interface must remain compatible.
The R911274054 order number should be matched against the installed motor rather than sourcing only by the MHD041B family.
2. Machine Tool and Precision Motion
MHD-series motors are used in applications such as machine tools, packaging, printing, paper processing, and other automated machinery requiring controlled rotary motion.
The integrated multiturn absolute encoder is particularly relevant where the control system requires absolute position information across multiple motor revolutions.
3. High-Frequency Start/Stop Motion
The electronically commutated synchronous motor design supports repeated acceleration and deceleration cycles. The integrated temperature monitoring also provides an additional means of protecting the motor against excessive thermal loading.
4. Legacy Motor Replacement
For an obsolete or difficult-to-source motion axis, replacing the exact MHD041B-144-PG1-UN can avoid mechanical changes to the mounting interface and changes to the servo-drive configuration.
Before replacement, verify the drive’s motor parameters and feedback compatibility.
QA & Live Testing SOP
For a used or surplus MHD041B-144-PG1-UN, acceptance testing should be performed with a compatible Rexroth drive or an approved motor test system.
- OEM Identity Verification
- Confirm on the motor nameplate.
- Verify order number R911274054 where present.
- Record serial number, date code, and motor revision.
- Photograph the complete nameplate before installation.
- Mechanical Inspection
- Inspect the 82 mm flange and 50 mm centering diameter.
- Check the keyed shaft and shaft sealing ring.
- Inspect bearings for abnormal play or noise.
- Check the housing for corrosion, impact damage, or contamination.
- Feedback Inspection
- Verify the integrated multiturn absolute encoder.
- Inspect the feedback connector for bent contacts or contamination.
- Check cable and connector compatibility with the existing Rexroth drive.
- Brake Test
- Verify the holding-brake circuit before enabling motor rotation.
- The documented brake is 2.2 Nm and uses 24 VDC ±10% with approximately 0.34 A current.
- Confirm brake release and engagement before performing a full-speed test.
- Electrical Test
- Check winding resistance and insulation according to the applicable Rexroth procedure.
- Confirm correct phase identification.
- Do not energize the motor from an arbitrary three-phase source; use a compatible servo amplifier.
- Controlled Motion Test
- Start at low speed.
- Verify encoder feedback and direction.
- Check acceleration, deceleration, abnormal noise, vibration, and temperature.
- Progress toward the application operating point only after feedback and brake behavior are confirmed.
- Thermal Test
- Monitor motor temperature during sustained operation.
- Confirm that temperature monitoring is recognized by the drive where applicable.
- Do not evaluate a used motor solely from a successful unloaded rotation test.
- ESD-Safe Packaging
- Protect encoder electronics and connectors from ESD.
- Secure the shaft against impact during shipment.
- Use protective packaging around the flange, connectors, and shaft.
Field Engineer’s Pitfall Guide
❗ Do not confuse PG1 with PG0. The MHD041B family contains multiple configurations. PG1 identifies the motor with an integrated multiturn absolute encoder and holding brake, while related variants can have different feedback and brake configurations.
❗ The shaft configuration matters. The PG configuration uses a shaft with key according to DIN 6885-1 and shaft sealing ring. Do not substitute a plain-shaft variant without checking the mechanical coupling.
❗ Do not size the motor from the 2.7 Nm figure alone. The 2.7 Nm value is continuous torque at standstill under the documented operating condition; the rated running torque is 1.4 Nm.
❗ Do not confuse brake torque with motor torque. The holding brake is rated at 2.2 Nm, while the motor’s continuous standstill torque is 2.7 Nm. These are different specifications with different functions.
❗ Verify the cooling condition when comparing specifications. Published sources for this exact motor identify natural/convection cooling for the rated operating data, while some aftermarket pages describe the housing differently. For procurement, the motor nameplate and applicable Rexroth project-planning documentation should control.
❗ Do not run this motor from a generic VFD as a substitute for the intended servo amplifier. The integrated digital feedback system and motor-specific parameters require a compatible closed-loop servo drive.
Intent-Driven FAQ
What is ch Rexroth ?
It is an MHD-series synchronous AC servo motor from Bosch Rexroth Indramat, with order number R911274054.
What is td power of ?
The documented rated performance is 0.52 kW, with a rated speed of 3,000 RPM and rated torque of 1.4 Nm.
What is the maximum speed?
The documented maximum motor speed is 7,500 RPM.
Does have an absolute encoder?
Yes. The PG1 configuration uses digital servo feedback with an integrated multiturn absolute encoder capable of absolute position detection over more than 4,096 revolutions.
Does the motor have a holding brake?
Yes. The has a 2.2 Nm holding brake. The brake specification calls for 24 VDC ±10% and approximately 0.34 A.
shaft does use?
The PG configuration uses a keyed shaft with shaft sealing ring. The exact mechanical coupling should be checked against the original motor before installation.
What is the motor’s continuous standstill torque?
The documented continuous standstill torque is 2.7 Nm, with a continuous standstill current of 7.5 A under the specified operating condition.
What is the protection rating?
The motor is documented with IP65 protection.
What should I verify befing a used ?
Verify the complete designation, R911274054 order number, encoder type, keyed shaft, 2.2 Nm brake, nameplate data, connector condition, shaft/bearing condition, and compatibility with the installed Rexroth servo amplifier.
Can be treated as a direct replacement for aMHD041B motor?
Not automatically. motors are available with different winding, feedback, shaft, and brake configurations. The complete order code must match the original application or be explicitly approved by the system engineer.
