Rexroth MHD112B-058-PG0-BN Servo Motor High Torque Output and Low Rotor Inertia for Dynamic Performance

Bosch Rexroth MHD112B-058-PG0-BN Synchronous Servo Motor
(Order Number: R911276798)

Overview

The Bosch Rexroth MHD112B-058-PG0-BN is a high-performance synchronous servo motor designed for demanding industrial applications requiring precision, dynamic response, and reliability. As part of the MHD series, this motor combines advanced electromagnetic design with robust construction to deliver exceptional torque density, smooth operation, and seamless integration with Rexroth’s digital drive systems. It is particularly suited for applications in machine tools, packaging machinery, robotics, and automation systems where accurate motion control is critical.

Key Features

• High Torque Density: Optimized design ensures high torque output relative to frame size.

• Dynamic Performance: Excellent acceleration and deceleration capabilities thanks to low rotor inertia.

• Digital Encoder System: Integrated high-resolution encoder (HSF type) for precise position feedback.

• Robust Construction: IP65 protection rating (standard) ensures resistance to dust and water jets.

• Flexible Cooling Options: Supports natural convection (IP65) or optional surface cooling (IP24 with blower).

• Holding Brake Option: Electrically released brake for safe holding of vertical axes or emergency stopping.

• Compliance: CE marked and cURus listed for use in North American and European markets.

Technical Specifications

The MHD112B-058-PG0-BN is engineered to deliver consistent performance under varying operational conditions. Below are its key technical parameters:

Design and Construction

The motor features a compact B05 flange design (according to DIN 42950) with a plain output shaft (without keyway) as standard, ensuring vibration-free operation and compatibility with clamp-type couplings. An optional featherkey (DIN 6885) is available for applications requiring positive torque transmission. The housing is coated with a black prime coat (RAL 9005) resistant to weathering, diluted acids, and lyes. Additional painting is not permitted to avoid affecting thermal performance.

The motor is equipped with a radial shaft sealing ring (DIN 3760, material FPM/Viton) to protect against oil and coolant ingress. For harsh environments, a sealing air connection (option) can be installed to maintain IP67 protection by creating an internal overpressure.

Cooling and Thermal Management

The MHD112B-058-PG0-BN is designed for natural convection cooling (IP65). For applications with high cyclic loads (e.g., frequent start-stop operations), an axial blower (e.g., LEMD-RB112B2XX) can be attached to enhance heat dissipation. Note: Motors with attached blowers are not suitable for high-shock applications (e.g., presses, punches).

Liquid cooling is not available for this model. Refer to MHD093 or MHD115 series for liquid-cooled variants.

Encoder and Feedback System

The motor includes a digital servo feedback (HSF) encoder with a resolution of 4,194,304 increments per revolution and a system accuracy of ±0.5 angular minutes. This ensures precise commutation and position control. The encoder stores motor parameters (e.g., type code, loop parameters) for automatic configuration with compatible Rexroth drives (e.g., HDC, HDS series), simplifying commissioning.

Installation and Mounting

The motor supports multiple mounting positions per EN 60034-7:

• IM B5: Flange-mounted, shaft horizontal

• IM V1: Flange-mounted, shaft vertical (downward)

• IM V3: Flange-mounted, shaft vertical (upward) — Note: Avoid fluid accumulation at the shaft seal.

Recommended mounting screws: M12 (4 pieces) with a tightening torque of 87 Nm (grade 8.8). Ensure the flange mating surface is clean and burr-free.

Electrical Connections

Power and encoder connectors are located on the motor flange. The power connector (INS0480 or INS0380, depending on cable cross-section) supports bayonet locking for secure connection. The encoder connector (INS0613) can be rotated in 90° increments to optimize cable routing. Pre-assembled cable sets are available from Rexroth to ensure compatibility and reduce installation time.

Application Notes

• Ambient Conditions: Rated for 0°C to +45°C and altitudes up to 1000m above sea level. Derating is required beyond these limits (refer to Fig. 16-1 in the documentation).

• Vibration/Shock: Complies with IEC 60721-3-3 for stationary use. Sinusoidal vibration limits: 20 m/s² (transverse), 1 m/s² (longitudinal). Shock load limits: 250 m/s² (transverse), 40 m/s² (longitudinal).

• Holding Brake: If equipped, the brake must be controlled with 24 VDC ±10%. It is designed for holding—not for operational braking. Grinding-in may be required initially and periodically (every 48 hours) to maintain torque.

• Bearing Life: Nominal bearing life is 30,000 hours (L₁₀ₕ) under rated radial/axial loads. Avoid redundant bearing arrangements to prevent premature failure.

Ordering Information

• Ordering Code: MHD112B-058-PG0-BN

• R911276798 (Complete motor unit)

• Optional Blower: LEMD-RB112B2XX (ordered separately or pre-mounted)

• Sealing Air Kit: Available via accessory sets (e.g., SUP-M01-MHD for INS0480 flange)

Conclusion

The Bosch Rexroth MHD112B-058-PG0-BN synchronous servo motor offers a blend of high torque, precision, and durability, making it ideal for advanced motion control applications. Its compatibility with Rexroth’s digital drive ecosystem ensures easy integration, reduced commissioning time, and reliable operation.