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Allen-Bradley MPL-B420P-RJ74AA Servo Motor — Detailed Product Information, Specifications, Applications, Advantages and Related Models

Below is a structured English-language product profile for the MPL-B420P-RJ74AA, including its technical parameters, product introduction, applications, advantages, series information, five closely related models, and five other popular models from the same brand family.

Note: The dimensions and weight shown for the main product and comparison models should be treated as practical reference values. For mechanical replacement, enclosure design, shaft coupling, and shipping calculations, the exact motor drawing and configuration should always be checked against the physical unit.

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1. Basic Product Information

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2. Product Introduction

The MPL-B420P-RJ74AA is a high-speed, low-inertia rotary servo motor belonging to the MP-Series MPL servo motor family.

It is designed for motion-control applications where accurate positioning, rapid acceleration and deceleration, repeatable movement, and controlled torque are important.

The motor uses a 5000 RPM rated speed, combined with approximately 4.74 N·m continuous torque and 13.5 N·m peak torque. This makes it suitable for machinery that needs relatively high rotational speed while maintaining controlled servo performance.

A major characteristic of this particular configuration is its resolver feedback system. Resolver feedback is commonly selected in industrial environments where robust feedback operation and reliable position information are important.

The motor also incorporates a 24 V DC holding brake. The brake is particularly useful in applications where the load needs to be held when servo power is removed, especially in vertical-axis or gravity-loaded mechanisms.

The motor uses a keyed shaft, which provides a conventional mechanical connection between the motor shaft and the driven mechanism. This makes it suitable for applications using compatible couplings, pulleys, gearboxes, belt drives, and other mechanical transmission components.

The right-angle DIN connector helps keep the electrical connection close to the motor body and can be advantageous where installation space around the rear of the motor is limited.

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3. Understanding the Model Number

The model number can be viewed as a combination of motor family, frame/stack configuration, feedback configuration, shaft configuration, brake configuration, and other construction details.

MPL-B420P-RJ74AA

The most important practical point is that the final characters of an MPL model number should not be ignored.

Two motors that look very similar externally can have different feedback systems, shaft arrangements, brake configurations, or connector arrangements.

For this reason, when selecting a replacement motor, it is better to match the complete catalog number rather than selecting a motor only according to power or frame size.

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4. Detailed Technical Parameters

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5. Performance Characteristics

The MPL-B420P-RJ74AA is positioned in the medium-output range of the MPL low-inertia servo motor family.

Its approximately 1.9 kW continuous power rating provides a useful balance between motor size and output capability.

The 4.74 N·m continuous torque is the more important figure for continuously loaded applications. The approximately 13.5 N·m peak torque provides additional short-duration torque capacity during acceleration, deceleration, rapid positioning, or transient load conditions.

The 5000 RPM speed rating makes the motor suitable for applications where high rotational speed is required.

The low-inertia rotor design is particularly useful when the machine needs to change speed rapidly. Lower motor inertia can help a servo system accelerate and decelerate the motor more quickly, provided that the load inertia and servo tuning are appropriately matched.

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6. Resolver Feedback

One of the defining characteristics of the MPL-B420P-RJ74AA is its resolver feedback.

A resolver is an electromechanical position feedback device that provides rotor position information to the servo control system.

Resolver feedback is often valued for its ruggedness and suitability for industrial environments.

Compared with some high-resolution digital feedback technologies, resolver systems can be attractive in applications where environmental robustness, temperature tolerance, vibration resistance, and dependable position feedback are priorities.

For machine builders, the important consideration is that the servo drive must support the specific feedback configuration.

Therefore, replacing a resolver-equipped motor with an encoder-equipped motor is not necessarily a direct plug-and-play replacement, even if the motor has the same frame size and power.

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7. Integral 24 V DC Brake

The 24 V DC brake is another important feature of this model.

The brake is primarily intended as a holding mechanism rather than as the normal method for controlling the motor during motion.

Typical applications include:

• Vertical lifting mechanisms
• Z-axis machine tools
• Pick-and-place equipment
• Vertical positioning systems
• Material-handling equipment
• Robotic mechanisms
• Assembly machinery
• Machines where the load must remain stationary after servo power is removed

The brake can help prevent a vertical load from moving downward when the servo is disabled.

However, brake control should be designed correctly. The brake should not normally be treated as a substitute for the servo’s dynamic braking or controlled deceleration function.

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8. Keyed Shaft Design

The motor has a keyed shaft.

A keyed shaft provides a mechanical means of transmitting torque between the motor shaft and the connected machine component.

It is commonly used with:

• Flexible couplings
• Gearboxes
• Pulleys
• Belt-driven mechanisms
• Screw mechanisms
• Rotary indexing systems
• Mechanical transmission assemblies

The shaft and coupling must be correctly matched in terms of shaft diameter, key dimensions, allowable radial load, axial load, alignment, and maximum rotational speed.

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9. Right-Angle DIN Connector

The motor uses a SpeedTEC DIN right-angle connector configuration.

The right-angle connector design can be advantageous when the machine has limited clearance behind the motor.

Compared with a straight connector, a right-angle arrangement can help keep the cable routing closer to the motor body.

The connector arrangement also provides flexibility in machine layout because the connector orientation can be adjusted within its designed range.

This is particularly useful in compact automation equipment where cable routing and mechanical clearance are important design considerations.

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10. Product Advantages

10.1 High-Speed Operation

The motor provides a rated speed of approximately 5000 RPM.

This makes it suitable for high-speed servo applications where conventional lower-speed motors may not provide sufficient rotational speed.

High speed is particularly useful in:

• High-speed indexing
• Spindle-like rotary motion
• Packaging machinery
• Material handling
• High-speed cutting or processing mechanisms
• Rotary automation equipment

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10.2 Strong Torque-to-Size Ratio

With approximately 4.74 N·m continuous torque and 13.5 N·m peak torque, the motor provides substantial output for its physical size.

This allows machine designers to obtain useful servo performance without moving immediately to a much larger motor frame.

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10.3 Low Rotor Inertia

The low-inertia construction is one of the main advantages of the MPL family.

Lower rotor inertia can improve:

• Acceleration response
• Deceleration response
• Positioning performance
• Dynamic response
• Cycle time
• Servo tuning flexibility

For machines with frequent start-stop cycles, the benefit can be particularly noticeable.

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10.4 Integrated Holding Brake

The integral 24 V DC brake makes the motor especially useful for vertical axes.

Instead of requiring a separate mechanical holding device in certain applications, the motor’s integrated brake can provide a compact holding solution.

This can simplify machine construction and reduce the number of separate components.

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10.5 Resolver Feedback

Resolver feedback offers a robust approach to motor position feedback.

It can be useful in industrial environments where the equipment is exposed to:

• Vibration
• Temperature variation
• Industrial electrical noise
• Long operating cycles
• Repetitive motion

The exact performance depends on the complete motor-drive-feedback system.

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10.6 Metric Mounting

The motor uses a metric mounting arrangement.

This is convenient for machines designed around IEC metric mechanical standards.

It can simplify integration into equipment using metric mounting hardware and mechanical components.

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10.7 Flexible Connector Arrangement

The right-angle DIN connector can improve cable management in compact machines.

This is especially useful when the motor is installed close to:

• Machine frames
• Covers
• Linear slides
• Gearboxes
• Safety guards
• Other motors

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11. Typical Product Applications

11.1 Packaging Machinery

The motor can be used for high-speed positioning in packaging systems.

Typical applications include:

• Film handling
• Feed mechanisms
• Cutting mechanisms
• Rotary indexing
• Conveyor synchronization
• Labeling systems
• Sealing mechanisms

Servo control allows the machine to synchronize motor movement with product position.

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11.2 Material Handling

The motor is suitable for controlled movement in material-handling machinery.

Examples include:

• Conveyor positioning
• Transfer mechanisms
• Lift axes
• Indexing units
• Automated sorting equipment
• Pick-and-place systems

The integrated brake can be particularly useful when the motor drives a vertical load.

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11.3 Machine Tools

Servo motors are commonly used for controlled axes in machine tools.

Potential applications include:

• Feed axes
• Positioning axes
• Tool movement
• Indexing mechanisms
• Rotary positioning
• Auxiliary machine mechanisms

The high-speed capability and closed-loop positioning make this type of motor suitable for precision movement.

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11.4 Assembly Equipment

Automated assembly systems frequently require accurate positioning and repeatable movement.

Potential applications include:

• Component insertion
• Screw-driving mechanisms
• Indexing tables
• Transfer mechanisms
• Part positioning
• Automated tooling

The servo system can coordinate motor movement with sensors, controllers, and other machine axes.

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11.5 Robotics and Pick-and-Place Machinery

The motor can be used in industrial automation mechanisms where rapid acceleration and deceleration are required.

Low rotor inertia is beneficial for repeated movement cycles.

Applications may include:

• Pick-and-place axes
• Rotary axes
• Transfer systems
• Positioning modules
• Automated handling mechanisms

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12. Recommended Related Models — Same B420P Configuration

The following models are particularly useful for comparison because they remain within the same B420P motor class while changing feedback, shaft, or brake configuration.

Related Model Selection Explanation

MPL-B420P-RJ72AA is the closest basic alternative if the resolver feedback and keyed shaft are required but the brake is not necessary.

MPL-B420P-RK74AA is suitable when resolver feedback and an integral 24 V DC brake are required but a keyless shaft is preferred.

MPL-B420P-MJ72AA changes the feedback technology from resolver to multi-turn absolute feedback while retaining the keyed shaft.

MPL-B420P-MJ74AA is one of the closest alternatives to the main model because it retains the keyed shaft and 24 V DC brake but uses multi-turn absolute feedback.

MPL-B420P-MK74AA combines multi-turn absolute feedback, keyless shaft construction, and an integral 24 V DC brake.

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13. Same-Series Model Comparison

The MPL family extends beyond the B420P frame and includes several different motor sizes.

The B310P and B320P are more compact choices when the application requires less torque.

The B330P provides a step up in torque while remaining in a relatively compact motor class.

The B420P provides a useful transition to a larger 115 mm frame and higher torque capability.

The B430P is appropriate when the machine requires additional continuous and peak torque beyond the B420P.

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14. Five Popular Models from the Same Brand Family

The following five models are useful examples from the same general automation and motion-control product ecosystem.

The five models above are intended as practical comparison choices rather than direct replacements. Exact connector, brake, feedback, shaft and drive compatibility should be checked from the complete catalog number.

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15. Main Model vs. Related Models

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16. Why Choose MPL-B420P-RJ74AA?

The MPL-B420P-RJ74AA is particularly attractive when the application requires a combination of:

• 5000 RPM operation
• Approximately 1.9 kW continuous power
• 4.74 N·m continuous torque
• 13.5 N·m peak torque
• Low rotor inertia
• Resolver feedback
• Keyed shaft
• Integral 24 V DC brake
• Metric flange mounting
• Right-angle DIN connector
• Compact industrial servo-motor construction

The combination is useful because the motor does not simply provide rotational power; it is designed as part of a closed-loop motion system.

For example, in a vertical positioning axis, the servo can provide controlled acceleration and deceleration while the integral brake can provide holding capability when the axis is stopped.

For a high-speed indexing application, the low-inertia rotor and 5000 RPM operating capability can help the machine achieve short movement cycles.

For automated machinery, the keyed shaft provides a conventional mechanical interface, while the right-angle connector can make cable routing easier.

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17. Application Selection Guide

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18. Important Points When Selecting a Replacement

When replacing an MPL-B420P-RJ74AA, the motor power alone should not be used as the selection criterion.

The following characteristics should all be checked:

1. Feedback Type

The original motor uses a resolver.

If the machine’s servo drive is configured for resolver feedback, changing to an absolute encoder version may require different drive hardware or configuration.

2. Brake

The original motor includes a 24 V DC brake.

If the machine depends on the brake for holding a vertical load, selecting a no-brake version can create a serious mechanical and safety problem.

3. Shaft

The original motor uses a keyed shaft.

A keyless version may have the same power and torque characteristics but cannot necessarily be installed using the same coupling arrangement.

4. Connector

The right-angle DIN connector is part of the physical installation configuration.

Cable clearance should therefore be checked before selecting an alternative.

5. Frame and Stack

The 115 mm frame and 50.8 mm stack dimensions should be matched when the motor is being used as a direct mechanical replacement.

6. Servo Drive Compatibility

The motor and drive form a complete servo system.

A motor with the same voltage and power rating is not automatically compatible with every servo drive.

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19. Product Advantages in Practical Machine Design

From a machine-builder’s perspective, the biggest advantage of this motor is its balance.

It is not simply a high-power motor, nor is it intended only for low-load precision positioning.

Instead, it combines moderate continuous power, relatively high rotational speed, substantial peak torque, low inertia, resolver feedback and an integral brake.

This combination makes it suitable for machinery where the motor repeatedly accelerates, decelerates and changes position.

The integral brake also helps reduce the need for an additional holding mechanism in suitable applications.

The metric mounting arrangement is convenient for international machine construction, while the right-angle connector helps with mechanical packaging.

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20. Overall Product Evaluation

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21. Final Summary

The MPL-B420P-RJ74AA is a MP-Series MPL low-inertia brushless rotary servo motor designed for industrial motion-control applications requiring high speed, controlled torque, accurate feedback and dynamic response.

Its principal specifications include approximately 5000 RPM, 4.74 N·m continuous torque, 13.5 N·m peak torque, and approximately 1.9 kW continuous power.

The motor uses resolver feedback, a keyed shaft, a 24 V DC integral brake, a 115 mm frame, a 50.8 mm magnet stack, and a right-angle DIN connector.

The approximate physical size is 133 × 187 × 98 mm, with an approximate weight of 5.5–5.8 kg depending on the exact configuration and physical measurement convention.

The biggest practical strengths are its low-inertia design, 5000 RPM speed, good torque density, resolver feedback, integrated brake, keyed shaft and flexible connector arrangement.

For applications involving rapid positioning, indexing, packaging, assembly, material handling, vertical axes and other industrial automation machinery, this motor represents a balanced servo solution.

For users who need to stay as close as possible to the original motor specification, the MPL-B420P-RJ72AA is a logical resolver/keyed-shaft alternative without the brake, while the MPL-B420P-RK74AA changes the shaft to keyless. If higher-resolution absolute feedback is preferred, the MPL-B420P-MJ74AA and MPL-B420P-MK74AA are particularly relevant alternatives.

Among the broader MPL family, the B310P, B320P and B330P are useful when a smaller motor is sufficient, while the B430P becomes attractive when additional torque is required.

Overall, the MPL-B420P-RJ74AA is best viewed as a 5000-RPM, approximately 1.9-kW, 115-mm-frame low-inertia servo motor with resolver feedback, keyed shaft and 24 V DC holding brake, intended for demanding industrial motion-control applications.