The REXROTH R911311875 MSK050C-0300-NN-M2-UG1-RNNN is a compact synchronous servo motor from the Rexroth IndraDyn S MSK series. It is designed for precision motion-control applications where stable torque, accurate feedback, compact installation size, and dependable operation are required. This model is suitable for packaging machinery, small CNC axes, handling equipment, printing systems, assembly machines, laboratory automation, and other industrial equipment using high-response servo drive systems.
For correct identification, the full purchasing reference should include both the order number R911311875 and the complete motor type code MSK050C-0300-NN-M2-UG1-RNNN. The order number identifies the exact Rexroth configured product, while the type code describes the motor size, winding, cooling method, encoder, shaft, brake, and special design characteristics. Public product listings identify R911311875 as model MSK050C-0300-NN-M2-UG1-RNNN.
Basic Product Information
| Item | Description |
|---|---|
| Brand | REXROTH |
| Order Number | R911311875 |
| Model | MSK050C-0300-NN-M2-UG1-RNNN |
| Product Type | Synchronous Servo Motor |
| Product Family | IndraDyn S MSK Series |
| Motor Size | MSK050 |
| Motor Length | C |
| Winding Code | 0300 |
| Cooling Method | Natural Convection |
| Encoder Type | M2 Multiturn Absolute Encoder EnDat2.1 With 2048 Increments |
| Electrical Connection | Rotatable Plug 240 Degrees |
| Shaft Version | Plain Shaft With Shaft Sealing Ring |
| Holding Brake | Electrical Release Holding Brake 6 Nm |
| Other Design | Reduced Runout According To DIN 42955 |
| Protection Rating | IP65 |
| Insulation Class | 155 |
| Motor Net Weight | 6.3 kg With Holding Brake |
The MSK050C frame is a medium-small servo motor size within the MSK family. It provides higher torque capability than smaller MSK030 and MSK040 motors while remaining compact enough for machinery where installation space is limited. The 0300 winding version is designed for applications requiring moderate speed and stable torque behavior. According to Rexroth MSK050C technical data, the MSK050C-0300-NN version has 5.0 Nm continuous torque at standstill 60 K, 5.5 Nm continuous torque at standstill 100 K, and 15.0 Nm maximum torque. The maximum speed for the 0300 winding version is listed as 4,700 min-1.
The product weight needs to be read carefully. Rexroth technical data lists the MSK050C weight as 5.4 kg, with the bracketed value 6.3 kg applying to versions with a holding brake. Since the type code UG1 includes holding brake code 1, this specific configuration should be treated as approximately 6.3 kg motor weight, excluding export packaging, cable sets, carton, wooden case, and protective material.
Technical Specification Table
| Technical Parameter | Value |
|---|---|
| Continuous Torque At Standstill 60 K | 5.0 Nm |
| Continuous Current At Standstill 60 K | 3.1 A |
| Continuous Torque At Standstill 100 K | 5.5 Nm |
| Continuous Current At Standstill 100 K | 3.4 A |
| Maximum Torque | 15.0 Nm |
| Maximum Current | 12.4 A |
| Torque Constant At 20 °C | 1.77 Nm/A |
| Voltage Constant At 20 °C | 109.0 V/min-1 |
| Winding Resistance At 20 °C | 6.60 Ohm |
| Winding Inductivity | 46.100 mH |
| Discharge Capacity | 2.6 nF |
| Number Of Pole Pairs | 4 |
| Rotor Moment Of Inertia | 0.00033 kg*m2 |
| Thermal Time Constant | 14.0 min |
| Maximum Speed | 4,700 min-1 |
| Sound Pressure Level | Less Than 75 dB[A] |
| Protection Rating | IP65 |
| Insulation Class | 155 |
| Ambient Operating Temperature | 0 To 40 °C |
| Net Weight | 6.3 kg With Holding Brake |
Model Code Explanation
| Code Section | Meaning |
|---|---|
| MSK | Rexroth IndraDyn S Synchronous Servo Motor |
| 050 | Motor Size 050 |
| C | Motor Length C |
| 0300 | Winding Code 0300 |
| NN | Natural Convection Housing Design |
| M2 | Optical Multiturn Absolute Encoder EnDat2.1 With 2048 Increments |
| U | Plug Electrical Connection Rotatable 240 Degrees |
| G | Plain Shaft With Shaft Sealing Ring |
| 1 | Holding Brake Electrical Release 6 Nm |
| RNNN | Reduced Shaft Runout And Axial Runout According To DIN 42955 |
This configuration is different from standard NNNN versions because the final code RNNN indicates reduced runout. Reduced runout is useful for applications where shaft concentricity, mechanical precision, and smooth rotary motion are important. Examples include measuring machines, precision indexing systems, printing rollers, high-accuracy feed axes, and compact machine modules where the motor is directly coupled to a ballscrew, gearbox, belt pulley, or precision rotary mechanism.
The M2 encoder is another important feature. It is a multiturn absolute encoder with EnDat2.1 interface and 2048 increments. Compared with a simple singleturn feedback system, a multiturn absolute encoder can retain positional information across multiple rotations. This is valuable when an axis needs a known position after power restoration or when homing time must be reduced. In automated equipment, this helps improve machine readiness, repeatability, and production efficiency.
Application Areas
| Application Area | Typical Function |
|---|---|
| Packaging Machinery | Indexing, sealing, cutting, filling, and synchronized axis movement |
| CNC Equipment | Feed axis, tool changer axis, auxiliary rotary axis |
| Printing Machinery | Roller positioning, registration control, tension-related motion |
| Assembly Automation | Pick-and-place axis, screwdriving station, test fixture movement |
| Handling Systems | Transfer axis, small lifting unit, conveyor positioning |
| Medical And Laboratory Equipment | Precision positioning and controlled rotary motion |
| Electronic Manufacturing | Inspection module, component handling, dispensing machine axis |
| Textile And Converting Machinery | Winding, feeding, cutting, and material transport |
The REXROTH R911311875 MSK050C-0300-NN-M2-UG1-RNNN is particularly suitable for machines that require accurate control but cannot use large and heavy motors. Its compact motor frame, brake-equipped structure, reduced runout design, and absolute feedback system make it a strong choice for precision servo axes where performance and installation efficiency must be balanced.
The integrated holding brake is an important selection point. A holding brake is not normally intended to perform dynamic braking during normal movement. Its main function is to hold the axis when the drive is disabled or when the machine is stopped. This is useful for vertical axes, inclined axes, or equipment where load position must be maintained after shutdown. Because this model includes a 6 Nm electrically released holding brake, it may be more suitable than a no-brake variant for load-holding applications. However, the brake function and load safety margin should always be checked against the machine design.
Engineering And Procurement Notes
| Check Point | Why It Matters |
|---|---|
| Full Model Code | Prevents incorrect replacement with a similar MSK050C variant |
| Order Number | Confirms the exact Rexroth configuration |
| Encoder Type | Must match the drive feedback interface |
| Brake Configuration | Affects wiring, safety function, and mechanical holding behavior |
| Shaft Type | Determines coupling and mechanical compatibility |
| Reduced Runout Design | Important for precision rotary applications |
| Weight | Required for mounting, handling, and shipment planning |
| Drive Compatibility | Must be checked before replacing an existing motor |
When replacing an existing motor, it is not enough to match only MSK050C-0300. Several variants can share the same frame and winding but differ in encoder type, holding brake, shaft design, connection arrangement, or runout class. A wrong encoder or brake configuration may cause installation failure, drive alarm, incompatible parameter settings, or mechanical mismatch. Therefore, the safe replacement reference is the full code: R911311875 MSK050C-0300-NN-M2-UG1-RNNN.
Product Summary
The REXROTH R911311875 MSK050C-0300-NN-M2-UG1-RNNN is a compact high-precision synchronous servo motor for industrial automation and motion-control equipment. It combines the MSK050C frame, 0300 winding, natural convection cooling, M2 multiturn absolute EnDat2.1 encoder, rotatable plug connection, plain shaft with sealing ring, 6 Nm holding brake, and reduced runout design. With 5.0 Nm continuous torque at standstill 60 K, 15.0 Nm maximum torque, 4,700 min-1 maximum speed, IP65 protection, and an approximate motor weight of 6.3 kg with brake, this model is suitable for compact but demanding servo applications requiring accuracy, repeatability, and reliable mechanical integration.
