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Allen-Bradley MPL-B420P-SJ74AA Servo Motor

1. Product Overview

The MPL-B420P-SJ74AA is a high-speed, low-inertia rotary AC servo motor belonging to the Allen-Bradley MP-Series MPL servo motor family.

It is designed for industrial motion-control applications that require accurate positioning, fast acceleration and deceleration, repeatable movement, high operating speed, and reliable feedback.

The motor is part of 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 torque, with a peak torque capability of approximately 13.5 N·m.

One of the most important characteristics of the MPL-B420P-SJ74AA is its combination of a single-turn high-resolution encoder and an integral 24 V DC holding brake.

The high-resolution encoder provides detailed position feedback for the servo control system, while the integral brake provides a mechanical holding function when the motor is not energized.

The motor uses a keyed shaft extension, making it suitable for mechanical systems designed around keyed couplings and other compatible power-transmission components.

The connector is a right-angle SpeedTEC DIN type and can be rotated through approximately 180 degrees. This gives machine designers more flexibility when installing the motor in compact equipment and routing power and feedback cables.

The motor is also designed with an IP66 enclosure, providing a useful level of protection for many industrial environments.

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2. Basic Product Information

Parameter	Specification
Brand	Allen-Bradley
Model	MPL-B420P-SJ74AA
Product Family	MP-Series
Product Series	MPL Low-Inertia Servo Motors
Product Type	Rotary AC Servo Motor
Motor Construction	Low-Inertia Brushless 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 Type	Single-turn High-resolution Encoder
Feedback Resolution	1024 Sin/Cos cycles/revolution class
Feedback Protocol	Hiperface
Shaft Type	Keyed Shaft Extension
Shaft Seal	No
Brake	24 V DC Holding Brake
Connector	SpeedTEC DIN Connector
Connector Type	Right Angle
Connector Rotation	Approximately 180°
Frame Size	115 mm
Magnet Stack Length	50.8 mm
Mounting Type	IEC Metric Flange Mount
Mounting Hole Configuration	Free Mounting Holes, Type FF
Protection Rating	IP66
Duty Rating	S1
Number of Phases	3 Phase
Operating Temperature	Approximately 0 to 40 °C
Approximate Motor Weight	5.44 kg
Approximate Overall Length	Approximately 190 mm class
Approximate Overall Height	Approximately 140 mm class
Frame Reference	115 mm
Magnet Stack	50.8 mm

The motor weight is approximately 5.44 kg for the specified configuration. The exact overall dimensions should be treated as mechanical reference values because connector arrangement and installation geometry can affect the usable envelope.

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3. Brand

Allen-Bradley

The MPL-B420P-SJ74AA belongs to the Allen-Bradley brand.

The motor is intended for industrial automation and motion-control systems where a conventional induction motor would not provide the positioning accuracy or dynamic response required by the machine.

A servo motor is normally part of a complete motion-control system.

The motor, servo drive, motion controller, feedback system, cables, mechanical transmission, and machine software work together to control position, speed, acceleration, deceleration, and torque.

For this reason, the complete model number is important when selecting the correct motor.

The MPL-B420P-SJ74AA is not simply a 1.9 kW motor. Its complete configuration includes a particular feedback technology, shaft type, connector arrangement, and brake option.

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4. Product Series

MP-Series MPL Low-Inertia Servo Motor Series

The MPL-B420P-SJ74AA belongs to the MP-Series MPL Low-Inertia Servo Motor series.

The MPL series is designed for industrial motion-control applications where fast response and precise movement are important.

The low-inertia construction makes the motor particularly suitable for machines that repeatedly accelerate, decelerate, stop, reverse direction, or perform rapid positioning movements.

The B420P platform provides a useful balance between speed, torque, physical size, and dynamic performance.

The motor is rated for 5000 RPM, making it suitable for high-speed servo applications.

The B420P platform provides approximately 4.74 N·m of continuous torque and approximately 13.5 N·m of peak torque, placing it in a useful medium-output range within the MPL family.

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5. Model Number Interpretation

The model number MPL-B420P-SJ74AA provides useful information about the motor configuration.

Model Code	Meaning
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
4	24 V DC brake
AA	Configuration suffix

This model-code structure is particularly useful when comparing related B420P servo motors.

For example, an SJ72AA model has the same general encoder and keyed-shaft configuration but does not include the integral 24 V DC brake.

An SK74AA model uses a keyless shaft instead of the keyed shaft.

An RJ74AA model uses resolver feedback instead of the single-turn high-resolution encoder.

These differences can have a direct impact on electrical compatibility and mechanical interchangeability.

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6. Detailed Technical Specifications

Electrical and Performance Parameters

Parameter	MPL-B420P-SJ74AA
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
Number of Phases	3
Motor Type	AC Synchronous Servo Motor
Rotor Type	Permanent Magnet
Feedback	Single-turn High-resolution Encoder
Encoder Type	Absolute Single-turn
Encoder Resolution	1024 Sin/Cos cycles/revolution class
Feedback Protocol	Hiperface
Duty Rating	S1
Rotor Inertia	Approximately 0.00026 kg·m²
Operating Temperature	Approximately 0 to 40 °C
Enclosure	IP66

The 1.9 kW rated output gives the motor sufficient capacity for a broad range of medium-duty servo axes.

The 4.74 N·m continuous torque rating is important for applications where the motor must deliver a sustained load.

The approximately 13.5 N·m peak torque capability provides additional short-duration torque for acceleration, deceleration, rapid positioning, and transient load conditions.

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7. Mechanical Specifications

Mechanical Parameter	Specification
Frame Size	115 mm
Frame Classification	IEC Metric Frame 4
Magnet Stack Length	50.8 mm
Shaft Configuration	Keyed
Shaft Extension	Keyed Shaft Extension
Shaft Seal	No
Mounting	IEC Metric Flange
Mounting Hole Style	Free Mounting Holes, Type FF
Connector	SpeedTEC DIN
Connector Orientation	Right Angle
Connector Rotation	Approximately 180°
Integral Brake	24 V DC
Protection Rating	IP66
Approximate Weight	5.44 kg
Approximate Overall Length	Approximately 190 mm class
Approximate Overall Height	Approximately 140 mm class

The 115 mm frame is one of the most important mechanical dimensions of the B420P platform.

The 50.8 mm magnet stack is associated with the “20” stack designation in the model number.

The keyed shaft should also be considered carefully when selecting a replacement motor.

A keyless version may have similar electrical characteristics but cannot necessarily be installed directly into a machine designed for a keyed shaft.

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8. Dimensions and Weight

Dimensions and weight are especially important when the motor is being used as a replacement component.

Physical Parameter	Approximate Value
Frame Size	115 mm
Magnet Stack Length	50.8 mm
Approximate Overall Length	190 mm class
Approximate Overall Height	140 mm class
Frame Reference	115 mm
Approximate Motor Weight	5.44 kg
Enclosure Protection	IP66
Shaft Type	Keyed
Connector	Right-angle DIN
Brake	24 V DC

The approximate 5.44 kg motor weight should be considered when designing brackets, mounting plates, linear-axis structures, and machine frames.

The motor’s weight is also relevant when determining the load on a moving axis.

For example, if the servo motor is mounted directly onto a moving carriage, its mass becomes part of the moving load and should be included in the mechanical calculations.

The overall mechanical envelope should be checked before installation, particularly around the right-angle connector and motor cable routing.

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9. High-Speed 5000 RPM Operation

One of the most useful characteristics of the MPL-B420P-SJ74AA is its 5000 RPM operating speed.

High rotational speed allows the motor to perform rapid movements and can help reduce machine cycle time.

This is especially useful in:

• Packaging machinery
• Rotary indexing
• Pick-and-place equipment
• High-speed assembly
• Product feeding
• Cutting equipment
• Material handling
• Printing and converting
• Automated inspection

A 5000 RPM servo motor can be especially effective when the machine requires repeated short movements rather than simply continuous rotation.

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10. Continuous and Peak Torque

The motor provides approximately 4.74 N·m continuous torque.

This is the torque level that the motor can provide during continuous operation within its specified operating conditions.

The approximately 13.5 N·m peak torque provides additional torque capability for short-duration dynamic events.

This difference is important in servo applications.

A machine may normally require only 3 to 4 N·m while moving at a constant speed, but it may temporarily require much higher torque when accelerating a load.

The peak torque capability provides additional capacity for these transient conditions.

Typical examples include:

• Rapid acceleration
• Rapid deceleration
• Direction reversal
• High-speed indexing
• Position correction
• Load disturbance compensation
• Fast start-stop cycles

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11. Single-Turn High-Resolution Encoder

The MPL-B420P-SJ74AA uses a single-turn high-resolution encoder.

The encoder provides detailed feedback regarding the motor’s rotational position.

This feedback is important because the servo controller uses the motor position information to regulate movement accurately.

The encoder configuration is particularly useful in applications requiring:

• Accurate positioning
• Repeatable movement
• Controlled acceleration
• Controlled deceleration
• Electronic synchronization
• High-speed indexing
• Precise rotary movement

The single-turn configuration should not be confused with a multi-turn encoder.

A single-turn encoder provides high-resolution position information within a revolution, while multi-turn feedback is designed to retain or determine position across multiple revolutions.

The correct feedback type should therefore be selected according to the machine’s control requirements.

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12. Keyed Shaft Configuration

The motor uses a keyed shaft extension.

A keyed shaft provides a mechanical interface for compatible couplings and transmission components.

This configuration is commonly used with:

• Gearboxes
• Timing pulleys
• Belt drives
• Mechanical couplings
• Rotary tables
• Rollers
• Gear mechanisms
• Indexing systems

When selecting a replacement motor, the keyed shaft is an important specification.

A keyless version of the same B420P family may have identical torque and speed ratings, but the shaft interface is different.

Therefore, replacing a keyed motor with a keyless motor may require a different coupling or mechanical modification.

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13. Integral 24 V DC Holding Brake

The MPL-B420P-SJ74AA includes a 24 V DC integral holding brake.

This is one of the main differences between the SJ74AA and SJ72AA versions.

The brake can be useful when the motor is used on a vertical axis or another load where the machine must hold its position when servo power is removed.

Typical applications include:

• Vertical lifting systems
• Z-axis mechanisms
• Vertical slides
• Automated lifting equipment
• Pick-and-place vertical axes
• Material-handling elevators
• Gravity-loaded mechanisms

The brake is primarily a holding function and should not automatically be considered a substitute for the machine’s safety stopping system.

The brake, servo drive, mechanical transmission, and machine safety system should be designed as a complete system.

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14. Right-Angle SpeedTEC DIN Connector

The motor uses a right-angle SpeedTEC DIN connector.

This configuration helps reduce the amount of space required around the motor.

The connector can be rotated through approximately 180 degrees, which provides flexibility when routing cables.

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

• Machine frames
• Protective guards
• Gearboxes
• Linear rails
• Other motors
• Cable trays
• Machine covers

The flexible connector orientation can make machine wiring cleaner and reduce unnecessary cable bending.

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15. IP66 Protection

The motor has an IP66 enclosure rating.

This provides a useful level of protection against dust and water exposure in industrial environments.

The IP66 rating makes the motor suitable for many factory-floor applications where dust, dirt, moisture, or incidental water exposure may occur.

Typical applications include:

• Packaging machines
• Production equipment
• Assembly machines
• Material handling
• Industrial conveyors
• Automated processing equipment
• General factory automation

However, the IP66 rating should always be considered together with the actual environment.

Chemical exposure, high-pressure cleaning, temperature, cable connections, and installation conditions can all affect the long-term suitability of the motor.

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16. Product Introduction

The MPL-B420P-SJ74AA is a high-performance industrial servo motor designed for fast and precise motion.

Its low-inertia construction makes it particularly suitable for applications where the motor repeatedly changes speed.

The motor can accelerate quickly, decelerate quickly, stop at a defined position, and repeat the same motion many times.

This type of operation is common in automated production machinery.

The 5000 RPM speed rating allows the motor to support fast machine cycles, while the 4.74 N·m continuous torque provides a useful level of load capacity.

The 13.5 N·m peak torque capability provides additional dynamic capacity during short acceleration and deceleration events.

The single-turn high-resolution encoder provides precise feedback to the servo system.

The keyed shaft provides a conventional mechanical interface.

The integral 24 V DC brake adds another useful feature for applications where the motor must hold a load after power is removed.

Taken together, these characteristics make the MPL-B420P-SJ74AA a versatile servo motor for industrial automation.

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17. Main Product Advantages

17.1 High-Speed Performance

The 5000 RPM rating allows fast rotary movement.

This can help reduce machine cycle time and increase production throughput.

It is especially valuable in machines where the servo axis repeatedly moves between positions.

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17.2 Strong Continuous Torque

The 4.74 N·m continuous torque rating provides a useful balance between motor size and load capacity.

It allows the motor to handle many medium-duty servo applications without moving immediately to a larger motor platform.

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17.3 High Peak Torque

The approximately 13.5 N·m peak torque capability gives the motor additional short-term load capacity.

This is useful for rapid acceleration and other dynamic conditions.

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17.4 Low-Inertia Construction

The low-inertia design supports fast changes in motor speed.

This can improve machine response when the axis repeatedly starts, stops, accelerates, and reverses.

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17.5 High-Resolution Feedback

The single-turn high-resolution encoder provides detailed position feedback.

This is important for accurate servo control and repeatable machine movement.

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17.6 Integrated Holding Brake

The 24 V DC brake is a major advantage for vertical applications.

It can hold the motor shaft when the servo system is not energized, provided that the brake is correctly integrated into the machine design.

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17.7 Keyed Shaft

The keyed shaft provides a familiar mechanical interface for industrial power-transmission components.

This can simplify integration with compatible couplings, pulleys, and gear mechanisms.

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17.8 IP66 Protection

The IP66 housing provides good protection against dust and water exposure.

This improves the motor’s suitability for demanding factory environments.

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17.9 Flexible Connector Position

The right-angle connector with approximately 180-degree rotation provides greater freedom during installation.

This can be particularly useful when machine space is limited.

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17.10 Compact Industrial Package

The 115 mm frame provides a useful balance between physical size and motor output.

The motor delivers approximately 1.9 kW while maintaining a relatively compact frame configuration.

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18. Typical Applications

Packaging Machinery

The MPL-B420P-SJ74AA is well suited to packaging applications where fast and repeatable movement is required.

Typical uses include:

• Film feeding
• Product positioning
• Labeling
• Cutting
• Sealing
• Rotary indexing
• Conveyor synchronization
• Packaging material control

The high-speed operation and low-inertia characteristics can be particularly useful for high-cycle packaging machines.

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19. Automated Assembly Equipment

Automated assembly systems frequently require multiple servo axes operating in coordination.

The motor can be used for:

• Component positioning
• Rotary indexing
• Tool positioning
• Part feeding
• Pick-and-place
• Assembly mechanisms
• Inspection stations

The high-resolution encoder can provide the position information required for precise movement.

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20. Vertical Positioning

The integral brake makes this motor particularly attractive for vertical applications.

Possible applications include:

• Z-axis systems
• Vertical slides
• Lifting mechanisms
• Automated feeders
• Vertical transfer units
• Pick-and-place lifting axes
• Gravity-loaded mechanisms

When the machine is vertical, the brake can provide a holding function when motor torque is removed.

The complete load-holding and safety strategy should still be designed independently of the motor’s brake.

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21. Material Handling

The motor can be used in material-handling systems that require rapid and controlled movement.

Typical applications include:

• Conveyor positioning
• Transfer systems
• Sorting equipment
• Pallet positioning
• Product alignment
• Rotary transfer mechanisms
• Automated loading
• Automated unloading

The high-speed capability can help reduce transfer time.

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22. Pick-and-Place Systems

Pick-and-place machines require fast movement and accurate positioning.

The low-inertia design is useful for repeated acceleration and deceleration.

Possible applications include:

• Electronic component handling
• Product transfer
• Packaging
• Automated inspection
• Small-part assembly
• Product sorting

The integral brake is especially useful when the pick-and-place mechanism includes a vertical axis.

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23. Rotary Indexing Systems

The MPL-B420P-SJ74AA can also be used in rotary indexing applications.

Examples include:

• Rotary tables
• Indexing plates
• Packaging wheels
• Assembly stations
• Inspection stations
• Component positioning systems

The servo controller can command the motor to accelerate, reach the required speed, decelerate, and stop at the required position.

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24. Machine Tools

The motor can also be used for machine-tool auxiliary motion.

Potential applications include:

• Rotary positioning
• Feed mechanisms
• Tool positioning
• Workpiece positioning
• Indexing
• Automated tool handling

The actual suitability depends on load inertia, acceleration, duty cycle, transmission ratio, and required positioning accuracy.

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25. Printing and Converting Machinery

High-speed servo motors are useful in printing and converting equipment.

Possible applications include:

• Roller control
• Material feeding
• Web positioning
• Cutting
• Registration
• Synchronization
• Indexing

The 5000 RPM speed and low-inertia construction can support fast changes in machine speed.

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26. Five Related Models in the Same Series

The following five models are closely related to the MPL-B420P-SJ74AA.

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-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-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-RJ74AA	Resolver	Keyed	24 V DC	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	115 mm
MPL-B420P-MJ74AA	Multi-turn High-resolution Encoder	Keyed	24 V DC	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	115 mm

These models share the same general B420P platform.

The differences are primarily related to feedback technology, shaft configuration, and brake configuration.

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27. Related Model Detailed Comparison

Model	Voltage	Power	Speed	Continuous Torque	Peak Torque	Feedback	Shaft	Brake	Approx. Weight	Frame / Stack
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	5.44 kg	115 mm / 50.8 mm
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	115 mm / 50.8 mm
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	115 mm / 50.8 mm
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	115 mm / 50.8 mm
MPL-B420P-RJ74AA	460 V	1.9 kW	5000 RPM	4.74 N·m	13.5 N·m	Resolver	Keyed	24 V DC	Approx. 5.7 kg	115 mm / 50.8 mm
MPL-B420P-MJ74AA	460 V	1.9 kW	5000 RPM	4.74 N·m	13.5 N·m	Multi-turn Encoder	Keyed	24 V DC	Approx. 5.4 kg	115 mm / 50.8 mm

The exact mass of related models can vary according to the specific configuration.

The most important comparison factors are usually feedback type, shaft type, brake, mounting arrangement, and compatibility with the existing servo drive.

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28. Five Popular Allen-Bradley Models for Comparison

The following models provide a useful comparison across different output levels and configurations within the Allen-Bradley servo motor range.

Model	Series	Voltage	Speed	Continuous Torque	Peak Torque	Power	Feedback	Shaft	Brake
MPL-B310P-SJ74AA	MP-Series MPL	460 V class	5000 RPM	Approx. 1.58 N·m	Approx. 3.61 N·m	Approx. 0.77 kW	Single-turn Encoder	Keyed	24 V DC
MPL-B320P-SJ74AA	MP-Series MPL	460 V class	5000 RPM	Approx. 3.05 N·m	Approx. 7.91 N·m	Approx. 1.5 kW	Single-turn Encoder	Keyed	24 V DC
MPL-B330P-SJ74AA	MP-Series MPL	460 V class	5000 RPM	Approx. 4.18 N·m	Approx. 11.1 N·m	Approx. 1.8 kW	Single-turn Encoder	Keyed	24 V DC
MPL-B420P-SJ74AA	MP-Series MPL	460 V class	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	Single-turn Encoder	Keyed	24 V DC
MPL-B430P-SJ74AA	MP-Series MPL	460 V class	5000 RPM	Approx. 6.55 N·m	Approx. 19.8 N·m	Approx. 2.2 kW	Single-turn Encoder	Keyed	24 V DC

These models show a practical progression in output capability.

The B310P is suitable for lower-torque applications.

The B320P provides additional torque while remaining relatively compact.

The B330P moves into a higher torque range.

The B420P provides approximately 4.74 N·m of continuous torque.

The B430P provides still greater torque for applications requiring more powerful servo performance.

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29. Popular Model Parameter Comparison

Model	Rated Power	Continuous Torque	Peak Torque	Speed	Feedback	Shaft	Brake	Approx. Weight	Frame
MPL-B310P-SJ74AA	Approx. 0.77 kW	1.58 N·m	3.61 N·m	5000 RPM	Single-turn Encoder	Keyed	24 V DC	Approx. 2.7 kg	100 mm class
MPL-B320P-SJ74AA	Approx. 1.5 kW	3.05 N·m	7.91 N·m	5000 RPM	Single-turn Encoder	Keyed	24 V DC	Approx. 4.5 kg	100 mm class
MPL-B330P-SJ74AA	Approx. 1.8 kW	4.18 N·m	11.1 N·m	5000 RPM	Single-turn Encoder	Keyed	24 V DC	Approx. 6.1 kg	100 mm class
MPL-B420P-SJ74AA	1.9 kW	4.74 N·m	13.5 N·m	5000 RPM	Single-turn Encoder	Keyed	24 V DC	5.44 kg	115 mm
MPL-B430P-SJ74AA	Approx. 2.2 kW	6.55 N·m	19.8 N·m	5000 RPM	Single-turn Encoder	Keyed	24 V DC	Approx. 9.2 kg	Larger MPL frame

The weight figures for related models are approximate comparison values.

The actual weight can vary according to the motor configuration, brake option, connector configuration, and mechanical construction.

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30. MPL-B420P-SJ74AA vs. MPL-B420P-SJ72AA

These two models are extremely close in their basic motor characteristics.

Parameter	MPL-B420P-SJ74AA	MPL-B420P-SJ72AA
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
Brake	24 V DC	No Brake
Frame	115 mm	115 mm
Stack	50.8 mm	50.8 mm
Connector	Right-angle DIN	Right-angle DIN
Protection	IP66	IP66
Approx. Weight	5.44 kg	Approx. 5.0 kg

The primary difference is the brake.

The MPL-B420P-SJ74AA includes a 24 V DC holding brake.

The MPL-B420P-SJ72AA does not have an integral brake.

For vertical applications, the SJ74AA configuration can be particularly useful because the brake can provide a holding function when the motor is not energized.

For horizontal applications where no holding brake is required, the SJ72AA may be a simpler configuration.

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31. MPL-B420P-SJ74AA vs. MPL-B420P-SK74AA

These two models have very similar electrical characteristics.

Parameter	MPL-B420P-SJ74AA	MPL-B420P-SK74AA
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 Encoder	Single-turn Encoder
Shaft	Keyed	Keyless
Brake	24 V DC	24 V DC
Frame	115 mm	115 mm
Stack	50.8 mm	50.8 mm
Connector	Right-angle DIN	Right-angle DIN
Protection	IP66	IP66

The main difference is the shaft configuration.

The SJ74AA uses a keyed shaft.

The SK74AA uses a keyless shaft.

This can determine whether the motor can be directly installed as a replacement for an existing motor.

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32. MPL-B420P-SJ74AA vs. MPL-B420P-RJ74AA

The main difference between these models is feedback.

Parameter	MPL-B420P-SJ74AA	MPL-B420P-RJ74AA
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	Resolver
Shaft	Keyed	Keyed
Brake	24 V DC	24 V DC
Frame	115 mm	115 mm
Stack	50.8 mm	50.8 mm
Connector	Right-angle DIN	Right-angle DIN
Protection	IP66	IP66

The SJ74AA is the encoder-feedback version.

The RJ74AA is the resolver-feedback version.

This distinction is important because the servo drive and feedback interface must be compatible with the motor.

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33. Application Selection Guide

Application Requirement	Suitability
High-speed servo motion	Excellent
5000 RPM operation	Excellent
Approximately 4.74 N·m continuous torque	Excellent
High-resolution positioning	Excellent
Packaging machinery	Excellent
Automated assembly	Excellent
Rotary indexing	Excellent
Pick-and-place	Excellent
Horizontal positioning	Excellent
Vertical positioning	Excellent, with brake
Material handling	Very Good
Printing machinery	Very Good
Converting machinery	Very Good
Inspection equipment	Very Good
Machine-tool auxiliary motion	Good to Very Good
Gravity-loaded axis	Good, with proper brake and safety design

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34. Installation Considerations

The motor should be installed on a rigid mounting surface.

The mounting flange should be correctly aligned with the machine structure.

The motor shaft should be properly aligned with the driven component.

Incorrect shaft alignment can result in excessive mechanical loading, vibration, bearing stress, and reduced service life.

The keyed shaft should be matched with a compatible coupling or transmission component.

The coupling should not impose excessive radial or axial loads on the motor shaft.

The right-angle connector also requires sufficient clearance.

Cable routing should be planned before the motor is installed permanently.

The feedback cable should be routed appropriately to reduce electrical interference.

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35. Brake Considerations

The integral 24 V DC brake is useful, but it should be correctly integrated into the machine control system.

The brake is primarily intended as a holding device.

For a vertical axis, the machine designer should consider what happens when:

• Servo power is removed
• Main power is lost
• The controller faults
• The servo drive faults
• The machine enters an emergency stop condition
• The mechanical transmission fails

The motor brake should be evaluated together with the complete machine safety strategy.

The brake should not automatically be considered a substitute for a dedicated safety system.

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36. Maintenance Considerations

Regular inspection can help maintain reliable servo performance.

The following items should be checked periodically:

• Motor mounting bolts
• Shaft coupling
• Motor vibration
• Bearing noise
• Motor temperature
• Power cables
• Feedback cables
• Connector condition
• Brake operation
• Servo alarms
• Encoder feedback
• Mechanical backlash
• Contamination

The IP66 housing provides useful environmental protection, but proper installation remains important.

The motor should not be exposed to operating conditions beyond its specified environmental limits.

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37. Replacement Selection Checklist

When replacing an existing motor with an MPL-B420P-SJ74AA, the following parameters should be checked.

Item	Required Configuration
Brand	Allen-Bradley
Series	MP-Series MPL
Model	MPL-B420P-SJ74AA
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	24 V DC
Frame	115 mm
Stack	50.8 mm
Connector	Right-angle SpeedTEC DIN
Connector Rotation	Approximately 180°
Protection	IP66
Approximate Weight	5.44 kg
Mounting	IEC Metric Flange

Matching only the rated power is not sufficient.

A proper replacement should also match the feedback system, shaft configuration, brake, mounting dimensions, connector arrangement, and drive compatibility.

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38. Overall Product Advantages

The main strengths of the MPL-B420P-SJ74AA can be summarized below.

Advantage	Description
High Speed	5000 RPM
Continuous Torque	4.74 N·m
Peak Torque	13.5 N·m
Rated Power	1.9 kW
Low Inertia	Fast acceleration and deceleration response
Encoder Feedback	Single-turn high-resolution feedback
Shaft	Keyed shaft extension
Brake	Integral 24 V DC holding brake
Protection	IP66
Frame	115 mm
Stack	50.8 mm
Connector	Right-angle SpeedTEC DIN
Connector Flexibility	Approximately 180° rotation
Mounting	IEC metric flange
Industrial Use	Suitable for demanding automation applications

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39. Final Product Summary

The MPL-B420P-SJ74AA is a 1.9 kW, 460 V class, 5000 RPM low-inertia rotary servo motor in 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 package while maintaining useful torque and speed performance.

The motor uses a single-turn high-resolution encoder with Hiperface feedback, providing detailed motor-position information for precise servo control.

The keyed shaft makes it suitable for compatible mechanical transmission systems using keyed couplings, pulleys, gears, or other mechanical components.

One of the most useful features of the MPL-B420P-SJ74AA is its integral 24 V DC holding brake.

This makes the motor particularly attractive for vertical axes and other applications where a load needs to remain stationary when servo power is removed.

The right-angle SpeedTEC DIN connector provides a compact cable connection, while its approximately 180-degree rotational capability gives machine designers additional freedom during installation.

The IP66 housing provides protection against dust and water exposure and makes the motor suitable for a wide range of industrial automation environments.

The motor is particularly well suited to packaging equipment, automated assembly, rotary indexing, pick-and-place machinery, vertical positioning, material handling, inspection equipment, printing and converting machinery, and other high-speed motion-control applications.

The strongest overall feature of this motor is the balance between speed, torque, feedback accuracy, mechanical compatibility, and holding capability.

The 5000 RPM speed supports fast machine cycles.

The 4.74 N·m continuous torque provides useful sustained load capability.

The 13.5 N·m peak torque provides additional capacity during dynamic acceleration and deceleration.

The single-turn high-resolution encoder supports accurate motion control.

The keyed shaft provides a conventional mechanical interface.

The 24 V DC brake adds a valuable holding function.

The 115 mm frame keeps the motor within a relatively compact industrial package.

For machine builders and maintenance engineers, the most important point is to evaluate the complete model configuration rather than selecting a motor based only on power or torque.

Feedback type, shaft type, brake configuration, connector arrangement, mounting dimensions, motor weight, and servo-drive compatibility should all be considered before installation.

Overall, the MPL-B420P-SJ74AA is a strong choice for industrial servo applications that require fast response, accurate positioning, high operating speed, moderate-to-high torque, encoder feedback, and an integrated holding brake.