Description
Bosch Rexroth MHD071B-035-PP1-UN | AC Servo Motor
Product Introduction
The Bosch Rexroth Indramat MHD071B-035-PP1-UN is an MHD-series synchronous servo motor intended for closed-loop industrial motion systems. Its exact Rexroth material number is R911283445, and the model code identifies the 071B frame, 035 winding, PP1 feedback/brake configuration, and UN version. Available technical references specify a 115 mm flange and 95 mm centering diameter.
This configuration combines digital servo feedback, an integrated multiturn absolute encoder, keyed output shaft, and a holding brake with a liquid-cooled motor housing. The documented continuous standstill torque is 8.0 Nm, while the holding brake is specified at 5.0 Nm. These values should not be confused: motor torque and brake holding torque serve different functions in the machine axis.
MHD071B-035-PP1-UN
Key Technical Specifications
- Model: MHD071B-035-PP1-UN
- Rexroth Material Number: R911283445
- Manufacturer: Bosch Rexroth Indramat
- Motor Family: MHD Synchronous Motor
- Motor Type: Synchronous AC servo motor
- Frame Size: 071B
- Flange Size: 115 mm
- Centering Diameter: 95 mm
- Winding Code: 035
- Continuous Standstill Torque: 8.0 Nm
- Feedback: Digital servo feedback
- Encoder: Integrated multiturn absolute encoder
- Output Shaft: Keyed shaft with shaft sealing ring
- Holding Brake: 5.0 Nm
- Cooling: Liquid cooling
- Power/Feedback Connectors: Rotatable through approximately 270°
- Protection Rating: IP65
- Maximum Speed: Approximately 4,500 RPM; verify against the specific drive/application documentation
The public references contain some inconsistent descriptions of the speed and brake values, including a 22 Nm figure on several reseller pages. The more specific MHD071B-035-PP1-UN comparison data identifies a 5 Nm holding brake, while the 22 Nm value appears to be an erroneous carryover in some product descriptions. For procurement, the physical nameplate and original Rexroth motor documentation should control.
Application Scenarios & Pain Points
1. Legacy Rexroth Motion-Axis Replacement
The MHD071B-035-PP1-UN is applicable to legacy Rexroth Indramat motion systems where the existing motor and servo amplifier must remain within the original mechanical and feedback architecture.
For replacement procurement, R911283445 should be matched rather than sourcing only an MHD071B motor.
2. High-Duty Machine Motion
The 8.0 Nm continuous standstill torque specification makes this motor relevant to machine axes requiring sustained torque at zero speed as well as controlled acceleration and deceleration. The actual continuous operating point must still be evaluated against the drive configuration and cooling arrangement.
3. Absolute-Position Motion Systems
The integrated multiturn absolute encoder provides absolute feedback over multiple motor revolutions. This is useful for machine axes where the control system is designed around absolute position feedback rather than a simple incremental encoder arrangement.
4. Liquid-Cooled Servo Applications
The PP1 configuration is associated with liquid cooling. This makes the cooling circuit part of the replacement-engineering check rather than treating the motor as a mechanically interchangeable air-cooled unit.
5. Obsolete Motion-System Maintenance
When an installed motor is no longer readily available through normal production channels, an exact legacy replacement can preserve the existing mounting, shaft coupling, feedback architecture, and brake arrangement.
The key requirement is matching the complete order code, not merely the frame.
QA & Live Testing SOP
For a used or surplus MHD071B-035-PP1-UN, acceptance testing should be performed with a compatible Rexroth servo drive or an approved motor test system.
- OEM Identity Verification
- Confirm on the nameplate.
- Verify R911283445 where shown.
- Record serial number, date code, and revision information.
- Photograph the complete nameplate before installation.
- Mechanical Inspection
- Verify the 115 mm flange and 95 mm centering diameter.
- Inspect the keyed shaft and shaft-sealing arrangement.
- Check shaft rotation for abnormal bearing noise or mechanical resistance.
- Inspect mounting surfaces for damage or corrosion.
- Feedback Verification
- Confirm the integrated multiturn absolute encoder configuration.
- Inspect feedback connector pins and locking hardware.
- Compare connector arrangement with the original motor.
- Verify the drive’s motor/encoder parameter set before enabling the axis.
- Brake Test
- Confirm the holding-brake circuit before attempting servo motion.
- The documented PP1 configuration uses a holding brake; available technical references identify the brake torque as 5.0 Nm.
- Verify brake release and engagement before full-speed operation.
- Electrical Test
- Check phase-to-phase winding characteristics according to the applicable Rexroth procedure.
- Perform insulation testing using the appropriate motor-test method.
- Do not connect the motor directly to an arbitrary AC source.
- Use a compatible servo amplifier with the correct motor parameters.
- Cooling-System Test
- Verify the liquid-cooling circuit before sustained operation.
- Check hoses, fittings, coolant flow, and leakage.
- Do not operate a liquid-cooled configuration under sustained load without the required cooling arrangement.
- Controlled Motion Test
- Start at low speed.
- Confirm encoder direction and position feedback.
- Verify brake release.
- Monitor vibration, bearing noise, current, temperature, and following error.
- Increase speed/load only after the initial test passes.
- ESD-Safe Packaging
- Protect feedback electronics and connectors from ESD.
- Protect the keyed shaft against impact.
- Seal and protect liquid-cooling ports during transport.
- Use rigid packaging to prevent flange and connector damage.
Field Engineer’s Pitfall Guide
❗ Do not confuse the PP1 configuration with PG1. Both configurations can use absolute feedback, but the complete ordering code must be matched. Bosch Rexroth motors are available with multiple feedback, shaft, brake, and cooling configurations.
❗ Verify the cooling arrangement. The PP1 configuration is documented with liquid cooling. Do not substitute a naturally cooled motor without checking thermal performance and the machine’s mechanical installation.
❗ Do not use the 22 Nm brake specification appearing on some reseller pages without verification. Multiple secondary listings reproduce that number, but other technical d the exact identifies a 5.0 Nm holding brake. This discrepancy should be resolved against the motor nameplate or original Rexroth documentation before publishing or engineering a replacement.
❗ Do not size the motor from the 8.0 Nm figure alone. The published 8.0 Nm specification is continuous standstill torque. It does not represent every permissible dynamic operating point.
❗ Verify the absolute encoder compatibility. An absolute encoder motor cannot automatically be substituted for a relative-feedback motor simply because the flange and shaft dimensions match.
❗ Protect the shaft and encoder connector during transport. Damage to the keyed shaft, sealing surface, or feedback connector can turn an otherwise serviceable motor into a commissioning problem.
❗ Do not energize the motor without the correct servo amplifier. The is a closed-loop servo motor requiring compatible drive electronics and correctly configured motor/feedback parameters.
Intent-Driven FAQ
What is ch Rexroth ?
It is an MHD-series synchronous AC servo motor manufactured by Bosch Rexroth Indramat. Its Rexroth material number is R911283445.
What is the winding code?
The winding code is 035. This is part of the motor’s complete ordering designation and should be matched when replacing an existing MHD motor.
What is the continuous standstill torque?
The documented continuous standstill torque is 8.0 Nm.
Does have an absolute encoder?
Yes. The PP1 configuration is documented with digital servo feedback and an integrated multiturn absolute encoder.
Does it have a holding brake?
Yes. The exact PP1 configuration is documented with a holding brake. The more specific technical reference identifies the brake torque as 5.0 Nm. Because some secondary listings incorrectly state 22 Nm, the physical nameplate should be used to resolve any procurement discrepancy.
What shaft does the motor use?
The motor uses a keyed shaft with shaft sealing ring. The shaft configuration is part of the PP1 motor specification and should be checked against the machine coupling before replacement.
What are the mounting dimensions?
The documented frame uses a 115 mm flange and 95 mm centering diameter.
Is liquid cooled?
Yes. The PP1 configuration is documented with liquid cooling. Cooling provisions should therefore be included in the replacement inspection and commissioning procedure.
What should I verify befing a used ?
Verify the complete designation, R911283445 material number, winding code, encoder type, keyed shaft, brake configuration, cooling arrangement, nameplate data, connector condition, shaft/bearing condition, and compatibility with the installed Rexroth servo amplifier.
Can another motor replace this model?
Not automatically. motors are available with different winding codes, feedback systems, shaft configurations, brakes, and cooling arrangements. The complete order code should be matched or explicitly approved by the motion-system engineer.
