Introduction

The Allen-Bradley MPL-A420P-MK72AA Servo Motor is a low-inertia MP-Series brushless AC servo motor designed for precision industrial motion control. Its combination of a 115 mm frame, 50.8 mm magnet stack, 4.74 N·m continuous torque, and 5000 RPM speed capability makes it a versatile choice for compact automated machinery.

A major characteristic of this model is its absolute multi-turn feedback. In a closed-loop servo system, feedback allows the controller and drive to determine the actual position and movement of the motor. Multi-turn feedback extends this position information across multiple revolutions, which can be valuable for applications involving extended rotary travel or precise positioning sequences.

The low-inertia design also gives the motor an advantage in dynamic applications. When a machine has to move rapidly from one position to another, the motor needs to accelerate and decelerate efficiently. Excessive rotor inertia can make these changes slower and increase the amount of effort required from the servo system.

For packaging machinery, this can translate into more responsive indexing. In automated assembly equipment, it can help coordinate multiple movements within a short cycle. Similar benefits can be obtained in printing, converting, material handling, and machine-tool applications.

The motor's 5000 RPM capability provides additional flexibility for applications where high rotational speed is required. However, speed should always be considered together with torque, load inertia, acceleration profile, and the mechanical transmission between the motor and machine.

Mechanical compatibility is another important consideration. The MPL-A420P-MK72AA uses a keyless shaft and a right-angle SpeedTEC DIN connector. The connector can be rotated to accommodate different cable-routing arrangements, which can be particularly useful in compact machine designs.

The motor is supplied without a brake. This distinction is important when selecting a replacement for machinery with vertical axes or loads that must remain mechanically held after servo power is removed.

For maintenance departments, matching the exact catalog number is strongly recommended. MP-Series motors can look similar while differing in feedback, shaft, connector, brake, winding, or other configuration details. Selecting the correct version helps avoid unnecessary commissioning problems.

Technical Specifications

Parameter	Specification
Manufacturer	Allen-Bradley / Rockwell Automation
Product Family	MP-Series
Series	MPL Low-Inertia
Model	MPL-A420P-MK72AA
Product Type	Rotary Servo Motor
Motor Technology	Brushless AC Servo Motor
Voltage Class	200 V AC
Rated Voltage	230 V AC
Frame Size	115 mm
Frame Designation	Frame 4
Magnet Stack Length	50.8 mm
Continuous Output Torque	4.74 N·m
Peak Output Torque	10.20 N·m
Continuous Power	2 kW
Rated Speed	5000 RPM
Maximum Speed	5000 RPM
Rotor Inertia	0.00026 kg·m²
Feedback Type	Multi-turn Absolute
Feedback Resolution	Sin/Cos, 1024 cycles/rev
Feedback Protocol	Hiperface
Shaft	Keyless Shaft Extension
Shaft Seal	No Shaft Seal
Brake	No Brake
Connector	SpeedTEC DIN, Right Angle
Connector Adjustment	180° Rotatable
Mounting	IEC Metric, Free Mounting Holes
Cooling	Natural Convection
Enclosure	IP66
Maximum Operating Temperature	40 °C
Dimensions	Frame Size: 115 mm
Weight	4.30 kg (9.48 lb)

Recommended Related Models

Model	Product Type	Main Configuration
MPL-A420P-MJ72AA	MP-Series Servo Motor	115 mm, Multi-turn Feedback
MPL-A420P-MJ74AA	MP-Series Servo Motor	115 mm, Multi-turn Feedback
MPL-A420P-MK72AA	MP-Series Servo Motor	115 mm, Multi-turn Absolute Feedback
MPL-A420P-MK74AA	MP-Series Servo Motor	115 mm, Multi-turn Absolute Feedback
MPL-A420P-SJ72AA	MP-Series Servo Motor	115 mm, Absolute Single-turn Feedback
MPL-A420P-SK72AA	MP-Series Servo Motor	115 mm, Absolute Feedback

These related models belong to the same general MP-Series servo motor range and can be useful when evaluating alternative configurations. The feedback type, shaft design, connector arrangement, brake option, and electrical characteristics should be checked carefully before selecting a substitute.

Popular Related Models

Model	Product Type
MPL-A310P-HK74AA	MP-Series Servo Motor
MPL-A420P-HK72AA	MP-Series Servo Motor
MPL-A420P-HK74AA	MP-Series Servo Motor
MPL-A420P-MJ72AA	MP-Series Servo Motor
MPL-A420P-MJ74AA	MP-Series Servo Motor
MPL-A420P-MK72AA	MP-Series Servo Motor
MPL-A420P-MK74AA	MP-Series Servo Motor
MPL-A430P-MK72AA	MP-Series Servo Motor

The Allen-Bradley MPL-A420P-MK72AA Servo Motor combines low-inertia construction, 5000 RPM speed capability, 4.74 N·m continuous torque, and high-resolution multi-turn absolute feedback in a compact 115 mm frame. It is a strong fit for automated machinery requiring responsive positioning and repeatable motion, while its keyless shaft and rotatable right-angle connector provide useful flexibility during machine integration.

Applications

The Allen-Bradley MPL-A420P-MK72AA Servo Motor is an MP-Series low-inertia brushless AC servo motor developed for industrial automation systems requiring fast and repeatable rotary motion. With a 115 mm frame, 50.8 mm magnet stack, 5000 RPM operating speed, and absolute multi-turn feedback, it is well suited to machinery where dynamic response and accurate motion control are important.

This servo motor can be applied to packaging equipment, automated assembly machines, indexing systems, printing and converting machinery, material-handling equipment, machine tools, and other high-cycle production systems.

Its low-inertia design is especially useful when the driven mechanism must accelerate and decelerate repeatedly. A servo system with appropriately matched motor and load inertia can respond quickly to motion commands while maintaining stable operation during rapid changes in speed.

The multi-turn absolute feedback configuration is valuable for applications requiring detailed position information over multiple motor revolutions. This makes the motor suitable for motion systems where repeatability and controlled positioning are central to machine performance.

The MPL-A420P-MK72AA can also be considered for replacement projects involving existing Allen-Bradley MP-Series equipment. When the original motor has reached the end of its service life, selecting the correct configuration can help minimize mechanical modifications and simplify system recommissioning.

Advantages

Low-inertia construction for dynamic motion

The motor's low-inertia rotor characteristics make it suitable for applications involving rapid acceleration, deceleration, indexing, and reversing. This can help improve overall machine response when the motor is correctly matched to the mechanical load.

High-resolution absolute feedback

The MPL-A420P-MK72AA uses multi-turn high-resolution absolute feedback. Accurate feedback allows the motion-control system to monitor motor position and make precise corrections during operation.

5000 RPM speed capability

With a maximum speed of 5000 RPM, the motor provides useful headroom for high-cycle automated equipment requiring rapid rotary movement.

4.74 N·m continuous torque

The motor provides 4.74 N·m of continuous output torque, with a peak torque capability of 10.2 N·m. This gives the motor useful dynamic capability for appropriately sized motion applications.

Compact 115 mm frame

The 115 mm frame helps integrate the motor into machinery where installation space is limited. Its compact format is well suited to OEM machine designs and replacement applications.

Keyless shaft design

The keyless shaft extension provides a clean mechanical interface for compatible couplings and can simplify certain machine designs where a keyed shaft is not required.

Flexible connector orientation

The right-angle SpeedTEC DIN connector can be rotated, providing greater flexibility when routing motor cables inside compact machine structures.

No-brake configuration

This version is supplied without a motor brake, making it appropriate for applications where an external mechanical holding function is not required. Applications involving vertical axes should be evaluated carefully before selecting a non-brake configuration.

MP-Series platform

The MPL-A420P-MK72AA belongs to the established MP-Series low-inertia servo family, making it a practical option for compatible Allen-Bradley motion-control systems.

Technical FAQs

1. What type of servo motor is the MPL-A420P-MK72AA?

It is an Allen-Bradley MP-Series low-inertia brushless AC rotary servo motor designed for closed-loop industrial motion control.

2. What is the continuous output torque of the motor?

The MPL-A420P-MK72AA has a continuous output torque of 4.74 N·m and a peak torque rating of 10.2 N·m.

3. What is the maximum motor speed?

The motor is rated for a maximum speed of 5000 RPM, making it suitable for relatively high-speed motion applications.

4. What type of feedback does this model use?

This configuration uses a multi-turn high-resolution absolute encoder with Sin/Cos feedback and Hiperface protocol.

5. Does the motor have a keyed shaft?

No. The MPL-A420P-MK72AA uses a keyless shaft extension. The machine coupling should therefore be compatible with the specified shaft arrangement.

6. Does this model include a holding brake?

No. This catalog configuration is supplied without a brake. A separate braking or holding solution may be necessary for vertical or gravity-loaded axes.

7. What servo drives can be used with this motor?

The motor should be paired with a compatible Allen-Bradley servo drive that supports its voltage class, feedback technology, motor characteristics, and communication requirements. Drive selection should be confirmed before installation.

8. What could cause a following error during operation?

Following errors can result from excessive acceleration, insufficient torque, incorrect servo tuning, excessive load inertia, mechanical backlash, coupling problems, or feedback faults. Both the mechanical and control systems should be checked.

9. Why can servo motors become unstable after replacement?

A replacement motor may have different electrical or feedback characteristics even when its frame size is similar. Incorrect motor identification, feedback configuration, or tuning parameters can cause oscillation, overshoot, or unstable positioning.

10. What should be checked before installing this motor into an existing machine?

Verify the complete catalog number, motor voltage class, continuous and peak torque requirements, feedback type, shaft configuration, mounting arrangement, connector orientation, brake requirement, and servo-drive compatibility.

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