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Allen-Bradley MPL-B420P-SJ72AA Servo Motor
1. Product Overview
The MPL-B420P-SJ72AA is a high-speed, low-inertia rotary AC servo motor from the Allen-Bradley MP-Series MPL servo motor family.
It is designed for industrial motion-control systems where fast acceleration, rapid deceleration, accurate positioning, repeatable movement, and stable servo performance are important.
The motor operates in the 460 V AC class and uses a 115 mm frame with a 50.8 mm magnet stack. It has a rated speed of 5000 RPM and provides approximately 4.74 N·m of continuous output torque, with a peak torque capability of approximately 13.5 N·m.
One of the most important characteristics of the MPL-B420P-SJ72AA is its single-turn high-resolution encoder feedback system.
Unlike resolver-feedback versions of the B420P family, this model uses a high-resolution single-turn encoder to provide detailed rotor-position information to the servo control system.
The motor also has a keyed shaft extension, making it suitable for mechanical systems designed around keyed couplings, pulleys, gears, timing belts, or other compatible transmission components.
Another important feature is that this particular configuration does not include an integral brake.
This makes the model different from brake-equipped versions such as the MPL-B420P-SJ74AA. The absence of a brake can be advantageous in applications where a holding brake is unnecessary and where reducing unnecessary motor options or mechanical complexity is desirable.
The motor uses a right-angle SpeedTEC DIN connector that can be rotated through approximately 180 degrees. This gives machine designers additional flexibility when routing cables and positioning the motor inside a compact machine enclosure.
2. Basic Product Information
| Parameter | Specification |
|---|---|
| Brand | Allen-Bradley |
| Model | MPL-B420P-SJ72AA |
| Product Family | MP-Series |
| Product Series | MPL Low-Inertia Servo Motors |
| Product Type | Rotary AC Servo Motor |
| Motor Construction | Brushless Permanent-Magnet Servo Motor |
| Voltage Class | 460 V AC |
| Rated Power | 1.9 kW |
| Continuous Torque | 4.74 N·m |
| Peak Torque | 13.5 N·m |
| Rated Speed | 5000 RPM |
| Maximum Speed | 5000 RPM |
| Feedback | Single-turn High-resolution Encoder |
| Feedback Resolution | Sin/Cos, 1024 cycles/revolution class |
| Feedback Protocol | Hiperface protocol |
| Shaft Type | Keyed Shaft Extension |
| Brake | No Integral Brake |
| Connector | SpeedTEC DIN |
| Connector Style | Right Angle |
| Connector Rotation | 180° Rotatable |
| Frame Size | 115 mm |
| Magnet Stack Length | 50.8 mm |
| Mounting | IEC Metric Flange Mount |
| Mounting Hole Type | Free Mounting Holes, Type FF |
| Shaft Seal | No |
| Protection Rating | IP66 |
| Duty | S1 |
| Number of Phases | 3 Phase |
| Operating Temperature | Approximately 0 to 40 °C |
| Approximate Motor Weight | Approximately 5.0 kg |
| Approximate Overall Length | Approximately 190 mm |
| Approximate Overall Height | Approximately 140.1 mm |
| Frame Reference | 115 mm |
| Magnet Stack | 50.8 mm |
The electrical and mechanical specifications above describe the standard configuration of the MPL-B420P-SJ72AA. The 115 mm frame and 50.8 mm stack are directly associated with the model configuration, while the overall dimensions can vary slightly depending on the specific connector and mechanical arrangement.
For machine design, the motor’s mounting pattern, shaft dimensions, connector clearance, and cable bend radius should be checked against the actual mechanical drawing before manufacturing a mounting plate or replacement assembly.
3. Brand
Allen-Bradley
The MPL-B420P-SJ72AA belongs to the Allen-Bradley brand.
Allen-Bradley servo motors are widely associated with industrial automation and motion-control applications where accurate motor control, repeatable positioning, coordinated movement, and reliable operation are required.
The MPL-B420P-SJ72AA represents a high-speed, low-inertia servo configuration intended for machines that need more than simple motor rotation.
A servo motor is normally used as part of a complete motion-control system. The motor works together with a compatible servo drive, feedback system, controller, power cable, feedback cable, mechanical transmission, and machine control program.
For this reason, selecting the correct model configuration is important.
The complete model number identifies several characteristics of the motor, including its voltage class, frame size, stack length, speed class, feedback type, shaft configuration, connector configuration, and brake option.
4. Product Series
MP-Series MPL Low-Inertia Servo Motor Series
The MPL-B420P-SJ72AA belongs to the MP-Series MPL Low-Inertia Servo Motor series.
The MPL series is designed for industrial servo applications where fast response and precise motion are important.
The low-inertia design is particularly useful when a machine repeatedly accelerates and decelerates.
For example, a packaging machine may move a product into position, stop quickly, perform an operation, reverse direction, and then repeat the same cycle hundreds or thousands of times.
In this type of application, motor inertia has a direct influence on how quickly the servo system can change speed.
The B420P motor platform provides a useful balance between speed, torque, frame size, and dynamic response.
The P designation corresponds to the 5000 RPM speed class, while the S feedback designation identifies the single-turn high-resolution encoder configuration.
The J designation identifies the keyed shaft configuration.
The 7 identifies the right-angle SpeedTEC DIN connector configuration, and the 2 indicates the no-brake configuration.
5. Model Number Interpretation
The model number MPL-B420P-SJ72AA contains useful information about the motor.
| Model Section | Description |
|---|---|
| MPL | MPL low-inertia servo motor family |
| B | 460 V class |
| 4 | Frame size 4 / 115 mm |
| 20 | Magnet stack length 20 / 50.8 mm |
| P | 5000 RPM speed class |
| S | Single-turn high-resolution encoder |
| J | Keyed shaft extension |
| 7 | Right-angle SpeedTEC DIN connector |
| 2 | No integral brake |
| AA | Configuration suffix |
This model structure is useful when comparing the B420P-SJ72AA with other motors in the same family.
For example, changing the feedback letter from S to R changes the feedback technology, while changing J to K changes the shaft configuration.
Similarly, changing the brake designation from 2 to 4 changes the motor from a no-brake configuration to a 24 V DC brake configuration.
This is why two motors that look very similar externally may not be direct electrical or mechanical replacements.
6. Detailed Technical Parameters
Electrical Parameters
| Electrical Parameter | MPL-B420P-SJ72AA |
|---|---|
| Rated Voltage | 460 V AC |
| Voltage Class | 460 V |
| Rated Power | 1.9 kW |
| Continuous Torque | 4.74 N·m |
| Peak Torque | 13.5 N·m |
| Rated Speed | 5000 RPM |
| Maximum Speed | 5000 RPM |
| Phase | 3 Phase |
| Motor Type | AC Synchronous Servo Motor |
| Rotor Type | Permanent Magnet |
| Feedback | Single-turn High-resolution Encoder |
| Feedback Resolution | 1024 cycles/rev Sin/Cos class |
| Feedback Protocol | Hiperface |
| Duty Cycle | S1 |
| Rotor Inertia | Approximately 0.00026 kg·m² |
| Operating Temperature | 0 to 40 °C |
| Protection | IP66 |
The combination of 1.9 kW rated power and 5000 RPM operating speed makes this motor suitable for relatively fast industrial motion applications.
The 4.74 N·m continuous torque rating gives the motor a useful continuous-load capability, while the approximately 13.5 N·m peak torque allows the motor to handle short-duration acceleration and dynamic load requirements.
7. Mechanical Parameters
| Mechanical Parameter | Specification |
|---|---|
| Frame Size | 115 mm |
| Frame Classification | IEC Metric Frame 4 |
| Magnet Stack | 50.8 mm |
| Shaft Type | Keyed |
| Shaft Extension | Keyed Shaft Extension |
| Shaft Seal | No |
| Mounting Type | IEC Metric Flange |
| Mounting Holes | Free Mounting Holes, Type FF |
| Connector | SpeedTEC DIN |
| Connector Orientation | Right Angle |
| Connector Rotation | 180° |
| Brake | None |
| Approximate Weight | 5.0 kg |
| Approximate Length | 190 mm |
| Approximate Height | 140.1 mm |
| Frame Reference Dimension | 115 mm |
| Protection Rating | IP66 |
The 115 mm frame is one of the key physical characteristics of the B420P platform.
The 50.8 mm magnet stack is also important because it distinguishes this motor from other MPL motors with different stack lengths.
For replacement work, the frame size alone should not be used to determine mechanical compatibility.
The shaft diameter, shaft length, flange dimensions, pilot diameter, mounting-hole arrangement, connector position, and cable clearance should all be checked.
8. Dimensions and Weight
The dimensional information is especially important for customers using the MPL-B420P-SJ72AA as a replacement motor.
| Physical Parameter | Approximate Value |
|---|---|
| Frame Size | 115 mm |
| Magnet Stack Length | 50.8 mm |
| Overall Length | Approximately 190 mm |
| Overall Height | Approximately 140.1 mm |
| Frame Reference | 115 mm |
| Approximate Weight | 5.0 kg |
| Enclosure | IP66 |
| Shaft Configuration | Keyed |
| Connector | Right-angle DIN |
| Brake | None |
A practical weight figure for this model is approximately 5.0 kg.
Some commercial listings may show different shipping or packaged weights, so the approximate 5.0 kg figure should be treated as the motor reference value rather than a shipping weight.
The overall length and height figures should also be treated as reference dimensions. For precision mechanical installation, the actual mounting drawing should be used.
9. High-Speed Performance
One of the main advantages of the MPL-B420P-SJ72AA is its 5000 RPM speed rating.
A 5000 RPM servo motor can be particularly useful when the machine needs fast rotary movement without moving to a physically larger motor.
High-speed operation can reduce the time required for:
- Indexing
- Feeding
- Cutting
- Positioning
- Pick-and-place movement
- Conveyor synchronization
- Rotary table movement
- Packaging operations
- High-cycle assembly operations
The motor’s low-inertia design complements the high-speed rating because the motor is intended to respond quickly to changes in command speed.
10. Single-Turn High-Resolution Encoder
The MPL-B420P-SJ72AA uses a single-turn high-resolution encoder.
This feedback system provides the servo controller with detailed information about the motor’s position.
High-resolution feedback can be valuable when the machine requires accurate positioning and smooth motion.
Typical applications include:
- Precision positioning
- Electronic assembly
- Packaging
- Indexing
- Machine-tool auxiliary axes
- Automated inspection
- Material positioning
- High-speed pick-and-place
The single-turn configuration is different from a multi-turn encoder.
A single-turn feedback system is primarily concerned with accurate position within one revolution, while multi-turn systems add information concerning multiple revolutions.
Therefore, the correct feedback configuration should be selected according to the machine’s control requirements.
11. Keyed Shaft
The motor uses a keyed shaft extension.
This is an important mechanical characteristic.
A keyed shaft allows a compatible coupling or transmission component to mechanically engage with the motor shaft through a keyway arrangement.
It is commonly used with:
- Gearboxes
- Pulleys
- Timing-belt systems
- Couplings
- Rotary tables
- Rollers
- Mechanical indexing systems
The keyed shaft configuration also distinguishes this model from the keyless MPL-B420P-SK72AA and resolver/keyless models in the same general family.
When replacing an existing motor, the shaft type should be checked carefully.
A motor with the same torque and speed but a different shaft configuration may require a different coupling or mechanical adapter.
12. No Integral Brake
The MPL-B420P-SJ72AA is a no-brake configuration.
This can be an advantage in applications where the motor does not need to hold a vertical load when power is removed.
Removing the brake option can simplify the motor configuration and eliminate the need for brake wiring.
Typical applications where a brake may not be required include:
- Horizontal conveyors
- Rotary indexing
- Packaging rollers
- Horizontal positioning systems
- Belt-driven mechanisms
- Continuous rotary applications
- Certain assembly axes
For vertical or gravity-loaded axes, a brake-equipped model should normally be considered if mechanical holding is required when servo power is removed.
13. Connector Design
The motor uses a right-angle SpeedTEC DIN connector.
The connector is designed to provide a compact connection arrangement for industrial machinery.
Its approximately 180-degree rotation capability provides flexibility when the motor is installed in a confined machine area.
This can be especially useful where there is limited space between the motor and:
- Machine frames
- Safety guards
- Cable ducts
- Other servo motors
- Linear guides
- Gearboxes
- Protective enclosures
Good connector positioning can also improve cable routing and reduce unnecessary stress on cables.
14. IP66 Protection
The motor is specified with an IP66 protection rating.
This provides a useful level of protection against dust and water exposure in industrial environments.
This makes the motor suitable for many factory-floor applications where the motor may be exposed to dust, dirt, moisture, or incidental water.
Typical environments include:
- Packaging machinery
- Production lines
- Material handling
- Industrial assembly
- General factory automation
- Processing machinery
The IP66 rating should still be considered together with the actual installation environment.
Cable connections, connectors, cleaning methods, chemicals, temperature, and mechanical installation all influence the long-term reliability of the complete system.
15. Product Introduction
The MPL-B420P-SJ72AA is a high-speed servo motor designed around a low-inertia motor structure.
Its combination of 5000 RPM speed, 4.74 N·m continuous torque, 13.5 N·m peak torque, and high-resolution single-turn feedback makes it particularly useful for automated machinery that needs fast and repeatable movement.
The motor is not simply intended to rotate continuously like a conventional industrial motor.
Its primary purpose is controlled motion.
A servo system can command the motor to move to a specific position, accelerate to a specific speed, follow a programmed motion profile, stop at a defined location, and repeat the same movement with high consistency.
This makes the motor suitable for applications where production accuracy and cycle time are important.
The B420P size is also useful because it sits in a practical middle range of the MPL family.
Smaller motors may not provide enough torque for certain applications, while larger motors may add unnecessary cost, size, and mechanical weight.
The B420P provides a balanced solution for many medium-duty servo axes.
16. Main Product Advantages
16.1 5000 RPM High-Speed Operation
The 5000 RPM speed rating is one of the strongest characteristics of the motor.
High-speed operation allows the motor to perform rapid rotary movements and can contribute to shorter machine cycles.
For machines where every fraction of a second matters, this can have a direct impact on production throughput.
16.2 4.74 N·m Continuous Torque
The 4.74 N·m continuous torque rating gives the motor a useful continuous load capability.
It is suitable for many medium-duty servo applications without requiring the larger frame size associated with higher-torque motors.
16.3 13.5 N·m Peak Torque
The approximately 13.5 N·m peak torque capability allows the motor to handle short-duration acceleration loads.
This is especially useful for applications with frequent:
- Starts
- Stops
- Direction changes
- Rapid indexing
- Acceleration
- Deceleration
- Position corrections
16.4 Low-Inertia Design
The low-inertia design is particularly useful for dynamic motion.
When the machine repeatedly changes speed, a low-inertia motor can respond quickly to changes in the commanded motion profile.
This makes it suitable for high-cycle automation.
16.5 High-Resolution Encoder Feedback
The single-turn high-resolution encoder provides detailed position feedback.
This supports accurate servo control and can improve positioning performance in applications requiring repeatable motion.
16.6 Keyed Shaft
The keyed shaft is useful for conventional industrial mechanical transmission systems.
It can simplify integration with compatible couplings, pulleys, gears, and other mechanical components.
16.7 No-Brake Configuration
The absence of a brake can be an advantage for horizontal applications.
It avoids unnecessary brake wiring and eliminates the need to manage an integral holding brake when the application does not require one.
16.8 IP66 Protection
IP66 protection provides additional environmental resistance for industrial installations.
This makes the motor suitable for many demanding factory-floor environments.
16.9 Flexible Right-Angle Connector
The 180-degree rotatable right-angle connector provides additional freedom for cable routing.
This can be particularly valuable when machine space is restricted.
16.10 Compact 115 mm Frame
The 115 mm frame provides a useful balance between motor capacity and physical size.
The motor can provide approximately 1.9 kW while maintaining a relatively compact mechanical package.
17. Typical Applications
Packaging Machinery
The MPL-B420P-SJ72AA is well suited to packaging machines requiring fast and repeatable motion.
Possible applications include:
- Film feeding
- Product positioning
- Labeling
- Rotary indexing
- Cutting
- Sealing
- Conveyor synchronization
- Packaging material control
The 5000 RPM speed is especially useful where rapid machine cycles are required.
18. Automated Assembly
Automated assembly equipment often uses servo motors for accurate positioning.
The MPL-B420P-SJ72AA can be used for:
- Component positioning
- Rotary indexing
- Tool positioning
- Feeding systems
- Pick-and-place mechanisms
- Assembly stations
- Inspection mechanisms
The high-resolution encoder can provide the feedback required for accurate positioning.
19. Material Handling
Material-handling systems often require repeated acceleration and deceleration.
Typical applications include:
- Conveyor positioning
- Transfer units
- Sorting mechanisms
- Product alignment
- Rotary transfer
- Pallet positioning
- Automated loading
- Automated unloading
The motor’s high-speed capability can be beneficial for machines that need to move products quickly between stations.
20. Pick-and-Place Machinery
Pick-and-place machines depend heavily on rapid motion and repeatable positioning.
The low-inertia design can be beneficial for fast movement cycles.
Possible applications include:
- Electronic component handling
- Packaging product transfer
- Small-part handling
- Automated sorting
- Inspection equipment
- Assembly equipment
The high-resolution encoder provides useful feedback for accurate positioning.
21. Indexing Systems
Rotary indexing machines are another strong application area.
The motor can drive:
- Rotary tables
- Indexing plates
- Assembly stations
- Inspection stations
- Packaging wheels
- Product positioning mechanisms
The motor can accelerate to speed, move through the required position, decelerate, and stop under servo control.
22. Machine Tools
The motor can also be considered for machine-tool auxiliary motion.
Possible applications include:
- Positioning axes
- Rotary positioning
- Tool handling
- Feed mechanisms
- Indexing
- Automated workpiece positioning
The actual suitability depends on the required torque, inertia ratio, acceleration, duty cycle, and mechanical transmission.
23. Printing and Converting Machinery
High-speed servo motors are frequently used in printing and converting equipment.
Potential applications include:
- Roller synchronization
- Web handling
- Cutting
- Feeding
- Registration
- Indexing
- Material positioning
The 5000 RPM speed and low-inertia construction are useful characteristics for this type of machinery.
24. Five Related Models in the Same Series
The following five models are useful comparison choices within the same general B420P/MPL platform.
| Model | Feedback | Shaft | Brake | Speed | Continuous Torque | Peak Torque | Power | Frame |
|---|---|---|---|---|---|---|---|---|
| MPL-B420P-SJ72AA | Single-turn high-resolution encoder | Keyed | No Brake | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | 115 mm |
| MPL-B420P-SJ74AA | Single-turn high-resolution encoder | Keyed | 24 V DC | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | 115 mm |
| MPL-B420P-SK72AA | Single-turn high-resolution encoder | Keyless | No Brake | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | 115 mm |
| MPL-B420P-SK74AA | Single-turn high-resolution encoder | Keyless | 24 V DC | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | 115 mm |
| MPL-B420P-RJ72AA | Resolver | Keyed | No Brake | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | 115 mm |
These models are particularly useful to compare because they share the B420P platform while changing the feedback, shaft, or brake configuration.
25. Related Model Comparison
| Model | Voltage | Power | Speed | Continuous Torque | Peak Torque | Feedback | Shaft | Brake | Approx. Weight |
|---|---|---|---|---|---|---|---|---|---|
| MPL-B420P-SJ72AA | 460 V | 1.9 kW | 5000 RPM | 4.74 N·m | 13.5 N·m | Single-turn Encoder | Keyed | No | Approx. 5.0 kg |
| MPL-B420P-SJ74AA | 460 V | 1.9 kW | 5000 RPM | 4.74 N·m | 13.5 N·m | Single-turn Encoder | Keyed | 24 V DC | Approx. 6.8 kg |
| MPL-B420P-SK72AA | 460 V | 1.9 kW | 5000 RPM | 4.74 N·m | 13.5 N·m | Single-turn Encoder | Keyless | No | Approx. 5.0 kg |
| MPL-B420P-SK74AA | 460 V | 1.9 kW | 5000 RPM | 4.74 N·m | 13.5 N·m | Single-turn Encoder | Keyless | 24 V DC | Approx. 6.8 kg |
| MPL-B420P-RJ72AA | 460 V | 1.9 kW | 5000 RPM | 4.74 N·m | 13.5 N·m | Resolver | Keyed | No | Approx. 5.0 kg |
The brake-equipped models are heavier because of the additional integral brake assembly.
The SJ models are particularly close to the subject motor because they use the same single-turn high-resolution encoder family.
The SK models provide the same general servo performance but use a keyless shaft instead of a keyed shaft.
The RJ model changes the feedback system from a single-turn high-resolution encoder to resolver feedback.
26. Five Popular Allen-Bradley Models for Comparison
The following models are useful products to compare within the broader Allen-Bradley servo motor range.
| Model | Series | Voltage Class | Speed | Continuous Torque | Peak Torque | Power | Feedback | Shaft |
|---|---|---|---|---|---|---|---|---|
| MPL-B320P-SK74AA | MP-Series MPL | 460 V | 5000 RPM | Approx. 3.05 N·m | Approx. 7.91 N·m | Approx. 1.5 kW | High-resolution Encoder | Keyless |
| MPL-B330P-SK74AA | MP-Series MPL | 460 V | 5000 RPM | Approx. 4.18 N·m | Approx. 11.1 N·m | Approx. 1.8 kW | High-resolution Encoder | Keyless |
| MPL-B420P-SK74AA | MP-Series MPL | 460 V | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | High-resolution Encoder | Keyless |
| MPL-B420P-RK74AA | MP-Series MPL | 460 V | 5000 RPM | 4.74 N·m | 13.5 N·m | 1.9 kW | Resolver | Keyless |
| MPL-B430P-SJ74AA | MP-Series MPL | 460 V | 5000 RPM | Approx. 6.55 N·m | Approx. 19.8 N·m | Approx. 2.2 kW | High-resolution Encoder | Keyed |
These five models cover several practical choices for applications with different torque, feedback, and shaft requirements.
The MPL-B320P is a lower-output option.
The MPL-B330P provides a step upward in torque.
The MPL-B420P represents a useful medium-output 5000 RPM platform.
The MPL-B430P provides additional torque for applications where the B420P may not provide enough load capacity.
27. Popular Model Parameter Comparison
| Model | Rated Power | Continuous Torque | Peak Torque | Rated Speed | Feedback | Shaft | Brake | Approx. Weight |
|---|---|---|---|---|---|---|---|---|
| MPL-B320P-SK74AA | Approx. 1.5 kW | Approx. 3.05 N·m | Approx. 7.91 N·m | 5000 RPM | High-resolution Encoder | Keyless | 24 V DC | Approx. 4 kg |
| MPL-B330P-SK74AA | Approx. 1.8 kW | Approx. 4.18 N·m | Approx. 11.1 N·m | 5000 RPM | High-resolution Encoder | Keyless | 24 V DC | Approx. 4.5 kg |
| MPL-B420P-SK74AA | 1.9 kW | 4.74 N·m | 13.5 N·m | 5000 RPM | High-resolution Encoder | Keyless | 24 V DC | Approx. 6.8 kg |
| MPL-B420P-RK74AA | 1.9 kW | 4.74 N·m | 13.5 N·m | 5000 RPM | Resolver | Keyless | 24 V DC | Approx. 5.7 kg |
| MPL-B430P-SJ74AA | Approx. 2.2 kW | Approx. 6.55 N·m | Approx. 19.8 N·m | 5000 RPM | High-resolution Encoder | Keyed | 24 V DC | Approx. 7 kg |
Weight values for related models should be treated as approximate comparison figures because the final motor mass can change with shaft, brake, connector, and configuration options.
28. MPL-B420P-SJ72AA vs. MPL-B420P-SJ74AA
The two models are very similar electrically and mechanically.
| Parameter | MPL-B420P-SJ72AA | MPL-B420P-SJ74AA |
|---|---|---|
| Voltage | 460 V | 460 V |
| Power | 1.9 kW | 1.9 kW |
| Speed | 5000 RPM | 5000 RPM |
| Continuous Torque | 4.74 N·m | 4.74 N·m |
| Peak Torque | 13.5 N·m | 13.5 N·m |
| Feedback | Single-turn High-resolution Encoder | Single-turn High-resolution Encoder |
| Shaft | Keyed | Keyed |
| Connector | Right-angle SpeedTEC DIN | Right-angle SpeedTEC DIN |
| Brake | No Brake | 24 V DC Brake |
| Frame | 115 mm | 115 mm |
| Stack | 50.8 mm | 50.8 mm |
| IP Rating | IP66 | IP66 |
| Approx. Weight | Approx. 5.0 kg | Approx. 6.8 kg |
The major difference is the brake.
The MPL-B420P-SJ72AA is the no-brake version.
The MPL-B420P-SJ74AA includes a 24 V DC integral brake.
For a horizontal axis where no holding brake is required, the SJ72AA configuration can be a practical choice.
For a vertical axis where the load must be held when the servo is de-energized, the brake-equipped SJ74AA configuration may be more appropriate.
29. MPL-B420P-SJ72AA vs. MPL-B420P-SK72AA
These two models are also closely related.
| Parameter | MPL-B420P-SJ72AA | MPL-B420P-SK72AA |
|---|---|---|
| Voltage | 460 V | 460 V |
| Power | 1.9 kW | 1.9 kW |
| Speed | 5000 RPM | 5000 RPM |
| Continuous Torque | 4.74 N·m | 4.74 N·m |
| Peak Torque | 13.5 N·m | 13.5 N·m |
| Feedback | Single-turn High-resolution Encoder | Single-turn High-resolution Encoder |
| Shaft | Keyed | Keyless |
| Brake | No Brake | No Brake |
| Frame | 115 mm | 115 mm |
| Stack | 50.8 mm | 50.8 mm |
| Connector | Right-angle DIN | Right-angle DIN |
| IP Rating | IP66 | IP66 |
The major difference is the shaft.
The SJ72AA uses a keyed shaft.
The SK72AA uses a keyless shaft.
This difference can determine whether the motor can be installed directly into an existing machine.
30. Application Selection Table
| Application | Suitability of MPL-B420P-SJ72AA |
|---|---|
| Packaging machinery | Excellent |
| Rotary indexing | Excellent |
| High-speed positioning | Excellent |
| Pick-and-place | Excellent |
| Automated assembly | Excellent |
| Conveyor positioning | Very Good |
| Material handling | Very Good |
| Printing equipment | Very Good |
| Cutting equipment | Very Good |
| Horizontal axis | Excellent |
| Vertical axis | Requires consideration because this model has no brake |
| Machine tools | Good, depending on duty cycle |
| Rotary table | Excellent |
| Inspection equipment | Very Good |
| Electronic assembly | Very Good |
| High-cycle automation | Excellent |
31. Important Advantages for Machine Builders
For machine builders, the MPL-B420P-SJ72AA has several practical advantages.
First, the 115 mm frame gives a good balance between physical size and motor output.
Second, the 5000 RPM speed allows fast machine movement.
Third, the 4.74 N·m continuous torque is sufficient for many medium-duty servo applications.
Fourth, the high-resolution encoder provides detailed feedback for precise positioning.
Fifth, the keyed shaft is convenient for machines using conventional keyed mechanical transmission components.
Sixth, the no-brake configuration can be useful when the machine does not require a holding brake.
Seventh, the right-angle connector can help reduce the amount of installation space required around the motor.
Finally, IP66 protection makes the motor suitable for a broad range of industrial environments.
32. Installation Considerations
The motor should be installed on a rigid and properly aligned mounting surface.
The shaft coupling should be correctly aligned with the driven equipment.
Misalignment can produce excessive radial or axial forces on the motor shaft and bearings.
The motor should also have sufficient clearance around the connector.
Because the connector is a right-angle type, cable routing should be planned before the motor is permanently mounted.
The feedback cable should be routed appropriately to reduce the possibility of electrical interference.
The motor power cable and feedback wiring should be installed according to the requirements of the complete servo system.
33. Mechanical Replacement Considerations
When replacing an existing servo motor with the MPL-B420P-SJ72AA, the following characteristics should be checked.
| Replacement Check | Required Specification |
|---|---|
| Voltage | 460 V class |
| Power | 1.9 kW |
| Continuous Torque | 4.74 N·m |
| Peak Torque | 13.5 N·m |
| Speed | 5000 RPM |
| Feedback | Single-turn High-resolution Encoder |
| Shaft | Keyed |
| Brake | No Brake |
| Frame | 115 mm |
| Stack | 50.8 mm |
| Connector | Right-angle SpeedTEC DIN |
| Mounting | IEC Metric |
| Protection | IP66 |
| Approximate Weight | 5.0 kg |
| Approximate Length | 190 mm |
| Approximate Height | 140.1 mm |
Matching only the power rating is not enough.
A replacement motor should have compatible feedback, shaft, connector, brake, mounting dimensions, and servo-drive requirements.
For example, replacing an SJ72AA with an RK72AA changes the feedback technology.
Replacing an SJ72AA with an SK72AA changes the shaft from keyed to keyless.
Replacing an SJ72AA with an SJ74AA adds an integral brake.
Therefore, the full model number should always be compared before selecting a replacement.
34. Maintenance
Although the MPL-B420P-SJ72AA is designed for industrial operation, regular inspection is still recommended.
The motor should be checked for:
- Abnormal vibration
- Unusual bearing noise
- Excessive temperature
- Loose mounting bolts
- Damaged cables
- Damaged connectors
- Shaft-coupling problems
- Contamination
- Feedback faults
- Servo drive alarms
- Mechanical backlash
The motor should also be kept within its specified operating conditions.
The IP66 enclosure provides environmental protection, but the complete installation still needs appropriate protection from excessive chemicals, temperatures, mechanical impact, and improper cleaning procedures.
35. Overall Product Advantages
The main advantages of the MPL-B420P-SJ72AA can be summarized as follows:
| Advantage | Description |
|---|---|
| High Speed | 5000 RPM rated speed |
| Good Torque | 4.74 N·m continuous torque |
| High Peak Torque | Approximately 13.5 N·m |
| Fast Dynamic Response | Low-inertia construction |
| High-Resolution Feedback | Single-turn encoder |
| Mechanical Flexibility | Keyed shaft |
| Compact Frame | 115 mm |
| Standard Industrial Mounting | IEC metric flange |
| Environmental Protection | IP66 |
| Flexible Cabling | 180° rotatable right-angle connector |
| No Brake | Useful for applications without holding-brake requirements |
| 1.9 kW Output | Suitable for many medium-duty servo applications |
| High-Cycle Capability | Suitable for repeated acceleration and deceleration |
36. Final Product Summary
The MPL-B420P-SJ72AA is a 1.9 kW, 460 V class, 5000 RPM low-inertia rotary servo motor belonging to the Allen-Bradley MP-Series MPL family.
It provides approximately 4.74 N·m of continuous torque and approximately 13.5 N·m of peak torque.
Its 115 mm frame and 50.8 mm magnet stack provide a compact industrial servo-motor package.
The motor uses a single-turn high-resolution encoder, giving the servo system detailed position feedback for accurate and repeatable motion.
The keyed shaft makes it suitable for mechanical systems designed around keyed couplings and transmission components.
Unlike brake-equipped versions of the same B420P family, the MPL-B420P-SJ72AA does not include an integral brake.
This makes it particularly suitable for horizontal axes and other applications where a holding brake is not required.
The right-angle SpeedTEC DIN connector, combined with its 180-degree rotational capability, provides additional flexibility when designing cable routing and machine layouts.
The IP66 protection rating further improves its suitability for industrial environments.
Overall, the MPL-B420P-SJ72AA is a strong choice for high-speed automation applications that require a combination of 5000 RPM operation, approximately 4.74 N·m continuous torque, high-resolution feedback, low-inertia response, keyed-shaft construction, and a compact 115 mm frame.
It is particularly well suited to packaging machinery, automated assembly, indexing systems, pick-and-place equipment, material handling, rotary positioning, printing and converting machinery, inspection systems, and other industrial motion-control applications.
For replacement applications, the most important point is to verify the complete motor configuration rather than simply matching horsepower or torque.
The feedback type, shaft configuration, brake option, connector arrangement, mounting dimensions, motor weight, and drive compatibility should all be checked before installation.