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Allen-Bradley MPL-B320P-HJ74AA Servo Motor

1. Product Introduction

The Allen-Bradley MPL-B320P-HJ74AA is a high-speed, low-inertia brushless AC rotary servo motor from the MP-Series MPL servo motor family. It is designed for industrial motion-control systems where accurate positioning, rapid acceleration and deceleration, repeatable movement, and closed-loop feedback are required.

The motor uses a 460 V armature voltage, a 100 mm frame size, a 50.8 mm magnet stack, and a 5000 rpm rated speed. It is equipped with a 2000-line incremental encoder, a keyed shaft extension, a SpeedTEC DIN right-angle connector, and a 24 V DC holding brake.

The HJ74AA configuration is especially useful when an application requires the characteristics of a low-inertia servo motor together with incremental encoder feedback and a motor-mounted holding brake. The brake can be useful for applications where the motor shaft needs to be held when servo power is removed, particularly on vertical or gravity-loaded axes.

The motor has a 3.05 Nm rated torque and a 5000 rpm rated speed, making it suitable for a broad range of high-speed automation applications. The combination of a 50.8 mm magnet stack and low-inertia construction provides a practical balance between torque capability and dynamic response.

The exact model configuration is important because the HJ74AA suffix identifies a specific combination of incremental feedback, keyed shaft, connector arrangement, and 24 V DC brake. A motor from the same general family may look mechanically similar but can have a different feedback system, shaft configuration, or brake arrangement.

2. Basic Product Parameters

Parameter	Specification
Model	MPL-B320P-HJ74AA
Brand	Allen-Bradley
Series	MP-Series MPL
Product Family	MPL Low-Inertia Brushless Servo Motors
Product Type	AC Rotary Servo Motor
Motor Construction	Brushless Permanent-Magnet Servo Motor
Voltage Class	400 V AC class
Armature Voltage	460 V
Current / System Class	400/460 V servo system
Frame Size	3 / 100 mm
Magnet Stack Length	20 / 50.8 mm
Rated Speed	5000 rpm
Maximum Speed	5000 rpm class
Rated Torque	Approximately 3.05 Nm
Peak Torque	Application-dependent; verify exact drive/motor duty data
Continuous Power	Approximately 1.5 kW class
Feedback	Incremental Encoder
Encoder Resolution	2000 lines/revolution
Shaft	Keyed Shaft Extension
Brake	24 V DC Holding Brake
Connector	SpeedTEC DIN Connector
Connector Type	Right-Angle
Connector Rotation	180° Rotatable
Mounting	IEC Metric Flange
Mounting Holes	Free Mounting Holes, Type FF
Shaft Seal	No Shaft Seal
Standard Environmental Configuration	Standard servo-motor enclosure configuration
Rotor Inertia	Approximately 7.8 × 10⁻⁵ kg·m² class
Frame Dimension	100 mm
Magnet Stack Dimension	50.8 mm
Approximate Weight	5.44 kg
Product Status	Discontinued
Brake Voltage	24 V DC

The 100 mm frame, 50.8 mm stack, 5000 rpm speed, 2000-line incremental encoder, keyed shaft, SpeedTEC DIN connector, and 24 V DC holding brake are the defining characteristics of this exact HJ74AA configuration. The listed reference weight is approximately 12 lb, or 5.44 kg.

3. Brand

Brand: Allen-Bradley

Allen-Bradley servo motors are widely used in industrial automation, machine building, packaging equipment, material handling systems, positioning systems, and other motion-control applications.

The MPL-B320P-HJ74AA is intended to operate as part of a complete servo system consisting of a servo motor, compatible servo drive, feedback connection, motor power cable, feedback cable, mechanical transmission, and machine controller.

When identifying the product for purchasing, replacement, maintenance, or inventory management, the complete catalog number MPL-B320P-HJ74AA should be retained because each section of the model number corresponds to a particular motor configuration.

4. Product Series

Series: MP-Series MPL Low-Inertia Brushless Servo Motors

The MPL series is a family of permanent-magnet brushless servo motors designed around a low-inertia construction.

The low-inertia design is particularly useful in applications that require rapid changes in speed or position. Instead of being optimized only for continuous rotation, the motor is intended to respond to changing servo commands with controlled acceleration and deceleration.

The MPL family contains numerous configurations. Depending on the exact catalog number, the motor can have different frame sizes, magnet stack lengths, feedback technologies, shaft arrangements, brake options, and connector configurations.

The MPL-B320P-HJ74AA represents a specific combination of these features:

• 100 mm frame.
• 50.8 mm magnet stack.
• 5000 rpm speed class.
• Incremental encoder.
• Keyed shaft.
• 24 V DC holding brake.
• SpeedTEC DIN connector.

This configuration makes it particularly suitable for servo axes where both fast motion response and motor-mounted holding capability are required.

5. Product Type

The MPL-B320P-HJ74AA is a:

Brushless AC Rotary Servo Motor

Unlike a standard induction motor, the servo motor is designed to work within a closed-loop motion-control system.

The motor’s encoder supplies rotational feedback to the servo drive. The drive processes the feedback and continuously adjusts motor current and torque according to the commanded motion.

This closed-loop arrangement makes the motor suitable for:

• Position control.
• Speed control.
• Torque control.
• Electronic gearing.
• Electronic camming.
• Indexing.
• Coordinated motion.
• High-speed positioning.
• Repetitive machine cycles.
• Automated production processes.

6. Model Number Explanation

The MPL-B320P-HJ74AA catalog number contains several useful configuration identifiers.

Model Section	Configuration Meaning
MPL	MPL low-inertia brushless servo motor family
B	400/460 V-class motor configuration
3	Frame size 3 / approximately 100 mm
20	50.8 mm magnet stack
P	5000 rpm speed class
H	Incremental encoder feedback
J	Keyed shaft
7	SpeedTEC DIN connector configuration
4	24 V DC holding brake
AA	Catalog configuration designation

This model structure is useful when comparing similar motors.

For example, a change from H to another feedback code can indicate a different encoder technology. A change from J to K can indicate a different shaft configuration, while a change from 4 to 2 can indicate whether an integral brake is installed.

For this reason, replacing the motor based only on frame size or rated torque is not recommended.

7. Detailed Technical Specification

Technical Parameter	MPL-B320P-HJ74AA
Model	MPL-B320P-HJ74AA
Motor Technology	Brushless permanent-magnet servo
Application	Closed-loop industrial motion control
Armature Voltage	460 V
Voltage Class	400 V AC
Rated Speed	5000 rpm
Frame Size	100 mm
Magnet Stack	50.8 mm
Rated Torque	3.05 Nm
Continuous Power	Approximately 1.5 kW class
Feedback Type	Incremental Encoder
Feedback Resolution	2000 lines/revolution
Shaft Type	Keyed
Brake	24 V DC holding brake
Connector	SpeedTEC DIN
Connector Style	Right-angle
Connector Rotation	180°
Mounting	IEC Metric
Mounting Hole Type	Free Mounting Holes / Type FF
Shaft Seal	No shaft seal
Rotor Inertia	Approximately 7.8 × 10⁻⁵ kg·m² class
Frame Dimension	100 mm
Stack Dimension	50.8 mm
Weight	Approximately 5.44 kg
Servo Application	High-speed positioning and motion control

The product description identifies the HJ74AA as a 460 V, 100 mm-frame, 50.8 mm-stack, 5000 rpm servo motor with a 2000-line incremental encoder, keyed shaft, SpeedTEC DIN connector, and 24 V DC brake.

8. Dimensions and Weight

Dimensions are particularly important when installing this motor into an existing machine.

The 100 mm frame size describes the principal frame classification, while the 50.8 mm magnet stack identifies the active motor stack length.

These dimensions should not be confused with the complete motor envelope. The total motor length includes the housing, bearing section, shaft extension, encoder/connector area, and brake assembly.

Dimension / Mechanical Parameter	Specification
Model	MPL-B320P-HJ74AA
Frame Size	100 mm
Magnet Stack Length	50.8 mm
Frame Classification	Size 3
Mounting	IEC Metric
Mounting Hole Type	Free Mounting Holes / Type FF
Shaft	Keyed
Shaft Seal	None
Brake	24 V DC
Connector	Right-angle SpeedTEC DIN
Connector Rotation	180°
Approximate Weight	5.44 kg
Overall Motor Envelope	Verify against exact mechanical drawing
Mounting Clearance	Verify according to machine installation requirements
Shaft Projection	Verify against exact mechanical drawing

The reference weight is approximately 12 lb, equivalent to approximately 5.44 kg.

For machine redesign or replacement work, the exact mechanical drawing should be used for the total housing length, shaft projection, mounting-hole geometry, connector clearance, and brake clearance rather than calculating these dimensions from the frame and stack values alone.

9. 100 mm Frame Size

The B320P designation places the motor within the 100 mm frame class.

A 100 mm frame provides a relatively compact mounting envelope while allowing the motor to accommodate the 50.8 mm magnet stack.

This makes the configuration useful for machines where the motor needs to provide meaningful torque without using a substantially larger motor frame.

The metric mounting arrangement also makes the motor suitable for many European-style and international industrial machine designs.

10. 50.8 mm Magnet Stack

The motor uses a 50.8 mm magnet stack, equivalent to approximately 2.0 inches.

The magnet stack is one of the important factors separating different motors within the same general frame.

A longer stack normally provides additional electromagnetic active length and can therefore support a higher torque capability than a shorter motor using the same basic frame architecture.

The 50.8 mm stack is one reason the B320P configuration is useful for applications requiring more torque than shorter-stack MPL motors.

11. 5000 RPM Speed

The MPL-B320P-HJ74AA is rated for 5000 rpm operation.

A 5000 rpm servo motor can be useful in high-cycle production machinery because the motor can complete rotary movements quickly when the load and drive are appropriately matched.

Typical high-speed applications include:

• Packaging.
• Indexing.
• Pick-and-place equipment.
• Printing.
• Converting.
• Material handling.
• Rotary tables.
• Automated assembly.
• Cutting and feeding mechanisms.
• High-speed machine axes.

The actual operating speed should always be determined from the complete load profile rather than from the motor speed rating alone.

12. Rated Torque

The published rated torque for the MPL-B320P-HJ74AA is approximately 3.05 Nm.

Rated torque represents the continuous operating capability under the specified conditions.

In practical machine applications, the motor may experience higher torque for short periods during acceleration, deceleration, positioning, or load disturbances.

The servo drive and motor combination must be selected according to the complete motion profile rather than simply matching the continuous torque number.

13. Peak Torque Considerations

Peak torque is important for servo applications because machine loads are often dynamic.

An indexing axis may require relatively low torque during steady movement but considerably more torque while accelerating a load.

Likewise, a positioning mechanism may require additional torque when reversing direction.

For this reason, servo motor sizing should consider:

• Continuous torque.
• Peak torque.
• Acceleration time.
• Deceleration time.
• Load inertia.
• Reflected inertia.
• Mechanical friction.
• Gear ratio.
• Duty cycle.
• Maximum speed.
• Positioning accuracy.

The exact peak torque available from the motor depends on the drive, operating conditions, temperature, duty cycle, and motion profile, so the complete motor-drive combination should be evaluated when designing the application.

14. Incremental Encoder

The HJ74AA configuration uses a 2000-line incremental encoder.

The incremental encoder provides the servo drive with information about motor shaft movement.

This feedback is used for closed-loop speed and position regulation.

An incremental encoder is different from an absolute encoder because the control architecture normally establishes the machine reference through an appropriate homing or initialization process.

This feedback configuration is well suited to machines where:

• The servo drive is designed for incremental feedback.
• Homing is part of the machine startup procedure.
• Repeatable movement is required.
• High-speed feedback is required.
• The machine control architecture already supports incremental encoder operation.

15. 24 V DC Holding Brake

One of the most important differences between the HJ74AA and a no-brake configuration is the integral 24 V DC holding brake.

The brake is intended primarily as a holding device rather than as the primary method of stopping a rapidly moving machine axis.

The brake can be particularly useful for:

• Vertical axes.
• Z-axis positioning systems.
• Gravity-loaded mechanisms.
• Lifting equipment.
• Vertical linear stages.
• Machines that need shaft holding after servo power is removed.

The brake must be controlled correctly according to the servo system design. It should not automatically be treated as a substitute for a machine safety brake or other safety-rated stopping system.

16. Keyed Shaft

The motor uses a keyed shaft extension.

The keyed shaft is designed for mechanical connection to suitable couplings, pulleys, gearboxes, or other driven components.

A keyed shaft can simplify mechanical integration when the machine’s existing transmission system already uses keyed connections.

When replacing the motor, the shaft diameter, key dimensions, shaft projection, coupling type, and allowable shaft loads should all be checked.

A keyless motor should not automatically be considered a mechanical substitute for this model simply because it has the same frame size.

17. SpeedTEC DIN Connector

The HJ74AA uses a SpeedTEC DIN connector in a right-angle configuration.

The connector is specified as 180° rotatable, which provides flexibility when routing motor cables.

This is particularly useful in compact machinery where a straight cable exit could interfere with guards, frames, linear guides, or other components.

Proper connector installation is important because servo cables should not be subjected to excessive bending, pulling, twisting, or mechanical strain.

18. Electrical Parameters

Electrical Parameter	Specification
Model	MPL-B320P-HJ74AA
Armature Voltage	460 V
Voltage Class	400 V AC
Rated Speed	5000 rpm
Rated Torque	Approximately 3.05 Nm
Continuous Power	Approximately 1.5 kW class
Feedback	Incremental encoder
Encoder Resolution	2000 lines/revolution
Brake	24 V DC
Brake Type	Holding brake
Motor Technology	Brushless AC servo
Connector	SpeedTEC DIN
Connector Style	Right-angle
Connector Rotation	180°
Shaft	Keyed
Rotor Inertia	Approximately 7.8 × 10⁻⁵ kg·m²
Frame	100 mm
Magnet Stack	50.8 mm
Weight	Approximately 5.44 kg

The exact motor-drive combination should be verified before installation because the motor’s feedback and electrical characteristics must match the servo drive and control architecture.

19. Mechanical Parameters

Mechanical Parameter	Specification
Model	MPL-B320P-HJ74AA
Frame Size	100 mm
Magnet Stack	50.8 mm
Mounting Type	IEC Metric flange
Mounting Holes	Free mounting holes / Type FF
Shaft	Keyed shaft extension
Brake	24 V DC holding brake
Shaft Seal	No shaft seal
Connector	SpeedTEC DIN
Connector Orientation	Right-angle
Connector Rotation	180°
Approx. Weight	5.44 kg
Frame Dimension	100 mm
Stack Dimension	50.8 mm
Complete Envelope	Confirm from mechanical drawing
Shaft Projection	Confirm from mechanical drawing
Mounting Geometry	Confirm from mechanical drawing

The HJ74AA is listed with a shaft key and no shaft seal.

20. Environmental and Enclosure Considerations

Environmental protection must be considered separately from the motor’s electrical performance.

The product descriptions identify the motor with a shaft key and no shaft seal.

This means the installation environment should be evaluated carefully if the motor is exposed to coolant, oil, water, dust, washdown conditions, or other contaminants.

The actual protection level of a particular motor installation can depend on the exact motor version, seals, connector arrangement, cables, mounting orientation, and installation practices.

The motor should therefore not be treated as automatically suitable for a harsh washdown environment simply because related versions of the MPL family may have enhanced sealing options.

21. Typical Applications

Packaging Equipment

The MPL-B320P-HJ74AA is well suited to packaging equipment requiring fast and repeatable motion.

Possible applications include film feeding, indexing, cutting, sealing, product positioning, and synchronized rotary mechanisms.

The 5000 rpm speed rating provides useful headroom for high-cycle machine operation, while the incremental encoder supplies the feedback required for closed-loop control.

Vertical Positioning Axes

The 24 V DC holding brake makes this configuration particularly useful for selected vertical positioning applications.

A vertical axis may need to maintain its position when the servo motor is no longer producing torque.

The motor-mounted brake can provide a holding function when properly integrated into the machine’s control and safety design.

Pick-and-Place Machines

Pick-and-place systems frequently require rapid acceleration and deceleration.

The low-inertia motor construction is useful for this type of application because the motor is designed for responsive servo operation.

Indexing Machines

Indexing machinery requires the motor to repeatedly move between defined positions.

The HJ74AA can be used for rotary indexing mechanisms, transfer systems, feeders, and other repetitive positioning axes.

Material Handling

The motor can be used in automated material-handling systems where controlled speed and repeatable positioning are required.

Examples include:

• Conveyor indexing.
• Transfer mechanisms.
• Rotary handling systems.
• Automated positioning systems.
• Packaging transfer axes.

Printing and Converting

Printing and converting machinery can require controlled rotary movement and synchronization.

Servo motors can be used for feed rollers, tension-control mechanisms, indexing systems, cutting mechanisms, and other controlled rotary axes.

Automated Assembly

The motor can also be used in automated assembly equipment.

Typical functions include:

• Component positioning.
• Rotary indexing.
• Tool positioning.
• Feeding.
• Inspection positioning.
• Assembly-axis movement.

22. Main Product Advantages

22.1 Low-Inertia Servo Design

The low-inertia construction is one of the key characteristics of the MPL family.

It allows the motor to respond rapidly to changes in commanded speed and position.

This is useful for applications involving frequent acceleration, deceleration, and direction changes.

22.2 5000 rpm Operation

The 5000 rpm speed rating supports high-cycle machine operation.

A high-speed motor can help reduce cycle time when the mechanical system is designed for the required rotational speed.

22.3 3.05 Nm Rated Torque

The approximately 3.05 Nm rated torque provides a useful output level for medium-duty servo axes.

The 50.8 mm stack provides a higher torque capability than shorter configurations within the same general frame family.

22.4 2000-Line Incremental Encoder

The incremental encoder provides feedback for closed-loop servo control.

It is suitable for applications where the drive and machine controller are designed around incremental feedback.

22.5 24 V DC Holding Brake

The integral holding brake expands the range of applications compared with a no-brake version.

It is especially useful for selected vertical and gravity-loaded axes.

22.6 Keyed Shaft

The keyed shaft is convenient for conventional industrial couplings and mechanical transmission systems.

It can simplify replacement when the existing machine already uses a keyed motor shaft.

22.7 Flexible Connector Orientation

The 180° rotatable right-angle connector can make cable routing easier in compact machines.

This can be useful where the available installation space around the motor is limited.

22.8 Compact 100 mm Frame

The 100 mm frame provides a relatively compact package for a motor capable of 5000 rpm operation and approximately 3.05 Nm rated torque.

23. Five Related MPL-Series Models

The following models are closely related configurations within the MPL family. They should be treated as comparison candidates rather than automatic replacements.

Related Model	Frame / Stack	Speed	Feedback	Shaft	Brake	Main Difference	Dimensions / Weight
MPL-B320P-HJ72AA	100 mm / 50.8 mm	5000 rpm	Incremental encoder	Keyed	No brake	Similar incremental configuration without holding brake	100 mm frame; 50.8 mm stack; exact weight to be verified
MPL-B320P-HK72AA	100 mm / 50.8 mm	5000 rpm	Incremental encoder	Keyless	No brake	Keyless shaft and no brake	100 mm frame; 50.8 mm stack; exact weight to be verified
MPL-B320P-HK74AA	100 mm / 50.8 mm	5000 rpm	Incremental encoder	Keyless	24 V DC	Keyless-shaft brake configuration	100 mm frame; 50.8 mm stack; exact weight to be verified
MPL-B320P-SJ74AA	100 mm / 50.8 mm	5000 rpm	Single-turn high-resolution	Keyed	24 V DC	Different feedback architecture	100 mm frame; 50.8 mm stack; exact weight to be verified
MPL-B320P-SJ72AA	100 mm / 50.8 mm	5000 rpm	Single-turn high-resolution	Keyed	No brake	Similar mechanical configuration without brake	100 mm frame; 50.8 mm stack; exact weight to be verified

These models illustrate the main configuration differences found around the B320P family: feedback technology, shaft type, and brake option.

24. Five Same-Brand Commonly Encountered MPL Models

Model	Series	Voltage Class	Frame / Stack	Speed	Feedback	Shaft	Brake	Dimensions / Weight
MPL-B210V-VJ72AA	MPL Low-Inertia Servo	400/460 V class	Smaller MPL frame	High-speed class	High-resolution feedback	Keyed	No brake	Smaller frame; exact dimensions and weight depend on configuration
MPL-B220T-VJ72AA	MPL Low-Inertia Servo	400/460 V class	Mid-size MPL configuration	High-speed class	High-resolution feedback	Keyed	No brake	Exact frame, stack and weight to be verified
MPL-B230P-VJ74AA	MPL Low-Inertia Servo	400/460 V class	100 mm-class configuration	5000 rpm	High-resolution feedback	Keyed	24 V DC	100 mm-class frame; exact envelope and weight to be verified
MPL-B320P-SJ72AA	MPL Low-Inertia Servo	400/460 V class	100 mm / 50.8 mm	5000 rpm	Single-turn high-resolution	Keyed	No brake	100 mm frame; 50.8 mm stack; exact weight to be verified
MPL-B330P-MJ72AA	MPL Low-Inertia Servo	400/460 V class	Larger MPL configuration	5000 rpm class	Multi-turn high-resolution	Keyed	No brake	Larger MPL frame; exact dimensions and weight to be verified

These models cover several common MPL configurations and are useful when comparing different motor sizes, feedback systems, and brake arrangements.

25. HJ74AA Compared With HJ72AA

The MPL-B320P-HJ74AA and MPL-B320P-HJ72AA are very closely related.

The principal difference is the brake.

Parameter	MPL-B320P-HJ74AA	MPL-B320P-HJ72AA
Frame	100 mm	100 mm
Magnet Stack	50.8 mm	50.8 mm
Speed	5000 rpm	5000 rpm
Feedback	Incremental encoder	Incremental encoder
Encoder	2000 lines/rev	2000 lines/rev
Shaft	Keyed	Keyed
Brake	24 V DC	No brake
Connector	SpeedTEC DIN	SpeedTEC DIN
Connector	Right-angle, rotatable	Right-angle, rotatable
Weight	Approx. 5.44 kg	Approx. 3.6–3.7 kg class; verify exact configuration
Main Difference	Brake-equipped	No integral brake

The HJ74AA is therefore especially relevant when the machine requires a motor-mounted holding function.

26. HJ74AA Compared With SJ74AA

The HJ74AA and SJ74AA are also closely related mechanically.

The principal difference is the feedback technology.

Parameter	MPL-B320P-HJ74AA	MPL-B320P-SJ74AA
Frame	100 mm	100 mm
Stack	50.8 mm	50.8 mm
Speed	5000 rpm	5000 rpm
Shaft	Keyed	Keyed
Brake	24 V DC	24 V DC
Feedback	Incremental encoder	Single-turn high-resolution
Encoder Type	2000-line incremental	High-resolution single-turn
Connector	SpeedTEC DIN	SpeedTEC DIN
Weight	Approx. 5.44 kg	Verify exact configuration
Primary Difference	Incremental feedback	Single-turn high-resolution feedback

The two motors may have similar mechanical characteristics but should not be treated as electrically interchangeable without confirming the servo-drive and feedback architecture.

27. HJ74AA Compared With HK74AA

The HJ74AA and HK74AA represent another useful comparison.

Both are associated with incremental encoder feedback and a 24 V DC brake, while the principal mechanical difference is the shaft configuration.

Parameter	MPL-B320P-HJ74AA	MPL-B320P-HK74AA
Frame	100 mm	100 mm
Stack	50.8 mm	50.8 mm
Speed	5000 rpm	5000 rpm
Feedback	Incremental encoder	Incremental encoder
Shaft	Keyed	Keyless
Brake	24 V DC	24 V DC
Connector	SpeedTEC DIN	SpeedTEC DIN
Main Mechanical Difference	Keyed shaft	Keyless shaft
Weight	Approx. 5.44 kg	Verify exact configuration
Application	Keyed mechanical transmission	Keyless coupling arrangement

This difference can be important when the motor is installed in an existing machine because the shaft interface must match the coupling or transmission component.

28. Advantages in Automated Machinery

The MPL-B320P-HJ74AA combines several characteristics that are useful in demanding servo applications.

The 100 mm frame provides a compact mounting package, while the 50.8 mm magnet stack provides a useful torque capability.

The 5000 rpm speed makes the motor suitable for fast machine cycles.

The incremental encoder provides feedback for closed-loop servo control.

The keyed shaft provides a conventional mechanical interface.

The 24 V DC holding brake allows the motor to be used in applications where shaft holding is required after the motor is disabled.

The low-inertia construction also makes the motor suitable for machines that repeatedly accelerate and decelerate.

29. Installation Considerations

Before installing the motor, the mounting surface should be cleaned and checked for burrs, contamination, or mechanical damage.

The motor should be properly aligned with the driven mechanism.

Excessive shaft misalignment can place unnecessary radial or axial loads on the motor bearings and coupling.

The keyed shaft should be connected using an appropriate coupling or transmission component.

The brake cable and motor power/feedback wiring should be routed carefully so that they are not exposed to excessive bending, pulling, vibration, or mechanical abrasion.

30. Servo Drive Compatibility

The motor should be used with a compatible servo drive capable of supporting its voltage class, motor characteristics, and incremental feedback system.

Important compatibility checks include:

• Motor voltage.
• Motor current.
• Rated speed.
• Rated torque.
• Encoder feedback.
• Encoder resolution.
• Brake control.
• Motor cable.
• Feedback cable.
• Drive firmware or motor database.
• Motion-controller architecture.
• Safety functions.

A mechanically compatible motor can still be unsuitable if its feedback system is not supported by the selected servo drive.

31. Servo Tuning

The low-inertia design can provide fast response, but correct servo tuning remains important.

The following factors should be considered:

Tuning Factor	Importance
Motor Inertia	Determines the basic dynamic response of the motor
Load Inertia	Determines the overall inertia ratio
Gear Ratio	Changes reflected load inertia
Acceleration	Determines peak torque requirement
Deceleration	Determines regenerative and peak torque requirements
Mechanical Stiffness	Influences servo stability
Coupling	Influences mechanical response
Backlash	Can affect positioning accuracy
Friction	Affects low-speed behavior
Resonance	May limit servo gain
Brake Timing	Important for vertical-axis operation

A properly sized motor can still perform poorly if the load inertia, coupling stiffness, or servo gains are not properly matched.

32. Maintenance

Routine maintenance should include visual inspection of the motor and associated wiring.

The following items should be checked periodically:

• Motor mounting bolts.
• Coupling condition.
• Shaft and key condition.
• Motor cable.
• Feedback cable.
• Brake wiring.
• Connector condition.
• Grounding.
• Shielding.
• Excessive vibration.
• Unusual bearing noise.
• Motor temperature.
• Contamination.
• Oil or coolant exposure.

Particular attention should be paid to the brake on applications where the brake is frequently engaged or where it is responsible for holding a vertical load.

33. Replacement Checklist

Replacement Item	MPL-B320P-HJ74AA Requirement
Model	MPL-B320P-HJ74AA
Voltage	460 V
Voltage Class	400 V AC
Frame	100 mm
Magnet Stack	50.8 mm
Speed	5000 rpm
Rated Torque	Approximately 3.05 Nm
Feedback	2000-line incremental encoder
Shaft	Keyed
Brake	24 V DC holding brake
Connector	SpeedTEC DIN
Connector Type	Right-angle
Connector Rotation	180°
Mounting	IEC Metric
Weight	Approximately 5.44 kg
Dimensions	100 mm frame / 50.8 mm stack; verify complete envelope
Shaft Seal	No shaft seal
Drive Compatibility	Must be verified
Cable Compatibility	Must be verified
Brake Control	Must be verified
Mechanical Coupling	Must match keyed shaft

The complete catalog number should be checked before purchasing a replacement. A model with the same frame and stack but a different feedback or brake configuration may not be a direct replacement.

34. Product Advantages Summary

Feature	Practical Advantage
100 mm Frame	Compact industrial servo package
50.8 mm Stack	Provides useful torque capability within the B320P family
5000 rpm	Supports fast machine cycles
3.05 Nm Rated Torque	Suitable for many medium-duty motion axes
Incremental Encoder	Provides closed-loop motion feedback
2000 Lines/Revolution	Suitable for precision servo feedback applications
Keyed Shaft	Easy integration with keyed mechanical components
24 V DC Brake	Provides motor-mounted holding capability
Low Inertia	Supports rapid acceleration and deceleration
SpeedTEC DIN Connector	Compact industrial motor connection
180° Rotatable Connector	Flexible cable routing
Metric Mounting	Convenient integration into metric machine structures
Approximately 5.44 kg Weight	Manageable motor mass for machine installation

35. Recommended Application Areas

The MPL-B320P-HJ74AA can be considered for:

1. Packaging machines.
2. Automated assembly machines.
3. Pick-and-place systems.
4. Rotary indexing equipment.
5. Material-handling machinery.
6. Conveyor positioning systems.
7. Printing machinery.
8. Converting machinery.
9. Automated inspection equipment.
10. Vertical positioning systems.
11. Machine-tool auxiliary axes.
12. Automated production lines.
13. Feeding and cutting mechanisms.
14. Servo-controlled rotary tables.
15. High-cycle industrial machinery.

36. Important Selection Notes

The HJ74AA is not simply a generic 1.5 kW servo motor.

Its complete configuration consists of:

• 460 V electrical class.
• 100 mm frame.
• 50.8 mm magnet stack.
• 5000 rpm speed class.
• Incremental encoder.
• 2000-line feedback.
• Keyed shaft.
• 24 V DC brake.
• SpeedTEC DIN connector.
• Right-angle connector arrangement.

These characteristics must be considered together when selecting a replacement or designing a new servo axis.

37. Overall Technical Summary

The Allen-Bradley MPL-B320P-HJ74AA is a 100 mm-frame, 50.8 mm-stack, 5000 rpm low-inertia brushless AC servo motor intended for closed-loop industrial motion control.

Its major specifications include approximately 3.05 Nm rated torque, approximately 1.5 kW class continuous power, 2000-line incremental encoder feedback, keyed shaft construction, 24 V DC holding brake, and a SpeedTEC DIN right-angle connector.

The reference product weight is approximately 5.44 kg, based on a listed 12 lb motor weight.

The 24 V DC brake is an important feature because it gives this configuration a holding function that is not available on the corresponding no-brake version.

The 5000 rpm speed rating and low-inertia design make the motor suitable for high-speed positioning and repetitive motion, while the 50.8 mm stack provides the torque capability required by many medium-duty industrial servo axes.

The incremental encoder makes the motor suitable for servo systems designed around incremental feedback. Before replacement, the feedback interface and drive compatibility should therefore be confirmed carefully.

38. Final Product Description

The Allen-Bradley MPL-B320P-HJ74AA is a compact, high-speed, low-inertia brushless servo motor designed for demanding industrial motion-control applications.

With a 100 mm frame, 50.8 mm magnet stack, 5000 rpm speed rating, approximately 3.05 Nm rated torque, 2000-line incremental encoder, keyed shaft, and 24 V DC holding brake, it provides a practical combination of dynamic response, positioning feedback, mechanical compatibility, and holding capability.

Its low-inertia design is particularly useful for machines that perform repeated acceleration and deceleration, while the 5000 rpm speed rating supports high-cycle production equipment.

The keyed shaft makes it suitable for conventional mechanical couplings, and the rotatable right-angle SpeedTEC DIN connector helps with cable routing in compact machine layouts.

The integral 24 V DC holding brake is particularly useful for selected vertical axes, gravity-loaded mechanisms, and other applications where shaft holding is required after the servo motor is disabled.

For replacement work, the complete MPL-B320P-HJ74AA catalog number should be matched carefully. Frame size alone is not enough to establish interchangeability because feedback, shaft, brake, connector, electrical characteristics, and mechanical dimensions all affect the suitability of a replacement.

As a result, the MPL-B320P-HJ74AA is best regarded as a complete servo-axis component rather than simply a motor rated at a particular power level. Proper drive compatibility, feedback compatibility, mechanical coupling, inertia matching, brake control, cable selection, and servo tuning are all important to achieving reliable machine performance.