B&R 8MSA4L.R0-31 2.01 kW 3000 RPM Servo Motor

Description

Product Introduction & Engineering Value

The B&R 8MSA4L.R0-31 is a Size 4, long-stack 8MS synchronous servo motor intended for applications where the existing B&R motion architecture already dictates the motor family and feedback arrangement. The published specifications identify a 400 V-class, 3-phase motor without a holding brake, rated at 2.01 kW and 3,000 RPM.

The important replacement detail is the R0 resolver configuration. Do not substitute another 8MS motor simply because its frame appears mechanically compatible. Feedback type, motor data, drive configuration, connector arrangement, brake configuration, and nameplate ratings all need to agree with the existing axis configuration.

Technical Specifications

The 2.01 kW, 6.4 Nm, 4.35 A, 29.4 A and 7.5 Nm figures are reported for this exact model by industrial automation parts references. A separate listing reports additional motor constants, including 3 Ω stator resistance, 19.2 mH stator inductance, 66-minute thermal time constant, and 7.7 kg weight without a brake.

Engineering note: Some secondary-market listings contain contradictory specifications for this part number. For a live replacement project, the motor nameplate and original machine documentation should take precedence over generic reseller databases. This is especially important for voltage, torque, current, connector and feedback details.

Field Application & the “Trench” Experience

A practical failure scenario is a packaging machine whose longitudinal indexing axis suddenly loses its servo motor after years of operation. The maintenance team finds the original 8MSA4L.R0-31, but the manufacturer no longer offers the same motor as a current production item. The temptation is to install a visually similar B&R motor from the same family.

That is where mistakes happen.

The replacement motor needs to reproduce the original axis characteristics, including the R0 resolver feedback and motor data expected by the ACOPOS drive. The commissioning engineer should verify the drive’s motor identification/configuration data before enabling the axis. A mechanically compatible motor that reports the wrong feedback or electrical characteristics can turn a straightforward replacement into a lengthy commissioning problem.

This motor is particularly relevant to applications such as:

1. Packaging-machine indexing axes where repeatable positioning and controlled acceleration are required.
2. CNC or machine-tool auxiliary feed axes using legacy B&R ACOPOS motion hardware.
3. High-duty material-feed mechanisms where an existing 8MS motor must be replaced without redesigning the complete motion system.

The 8MSA4L.R0-31 has also been identified in industrial spare-parts databases as a cancelled/discontinued product, so maintaining a verified spare can be more practical than waiting for a future equivalent after an unexpected motor failure.

8MSA4L.R0-31

8MSA4L.R0-31

Transparency SOP: QA & Testing

For New Surplus stock, the meaningful distinction is not simply whether the box looks new. A sensible receiving inspection should cover:

1. Part-number verification — confirm 8MSA4L.R0-31 directly from the motor nameplate.
2. Physical inspection — check housing, shaft, connectors, mounting flange and cable interfaces for storage or handling damage.
3. Electrical checks — verify winding resistance and insulation condition using procedures appropriate for the motor and its insulation system.
4. Feedback verification — confirm resolver wiring and feedback behavior before installation.
5. Mechanical inspection — rotate the shaft manually and check for abnormal bearing noise, binding or excessive play.
6. Documentation check — compare the motor’s ratings with the machine’s existing servo-drive configuration.

For refurbished stock, functional testing should additionally establish that the motor can operate under controlled drive conditions before being released for shipment.

New surplus does not automatically mean factory warranty. Secondary-market sellers explicitly distinguish unused surplus, original packaging, repackaged unused stock and refurbished stock. Warranty coverage therefore needs to be confirmed with the actual supplier before purchase.

The Veteran’s Tech Trap Guide

⚠️ Trap #1 — Matching only the motor family

“8MS” is not enough. The suffix matters. The R0 resolver configuration is a critical identification point. Do not assume an encoder-equipped or differently configured 8MS motor is a drop-in replacement.

⚠️ Trap #2 — Ignoring the brake configuration

The 8MSA4L.R0-31 is listed as a non-brake version. A motor with an integrated holding brake can have different wiring, control requirements, inertia and mechanical behavior. Confirm the original machine configuration before accepting an alternative.

PRO TIP: Before removing the failed motor, photograph the complete nameplate, connectors, cable routing and drive parameter screen. Those four records can save hours when commissioning a legacy axis.

⚠️ Trap #3 — Trusting inconsistent online specifications

There are secondary-market pages that publish materially different electrical and torque figures for this exact model. That is a procurement warning, not a minor documentation issue. Use the original nameplate and B&R machine documentation as the controlling reference, and ask the supplier to confirm the exact physical unit before issuing a purchase order.

Dynamic FAQ

Is the B&R 8MSA4L.R0-31 still a current-production motor?

Available industrial parts references identify the model as discontinued or cancelled. It is therefore primarily a legacy replacement/spare-parts item rather than a normal current-production selection.

What feedback does the 8MSA4L.R0-31 use?

The model designation is associated with an R0 resolver feedback configuration. This should be verified against the physical nameplate and existing machine documentation before installation.

What are the main performance ratings?

Published data identifies approximately 2.01 kW rated power, 3,000 RPM rated speed, 6.4 Nm rated torque, 4.35 A rated current, and 29.4 A peak current.

Does this motor have a holding brake?

The available model-specific specification identifies the 8MSA4L.R0-31 as a version without a holding brake. Do not assume that every 8MSA4 motor has the same brake configuration.

Is New Surplus the same as factory-new OEM stock?

Not necessarily. “New Surplus” generally means unused secondary-market inventory and does not by itself establish current OEM warranty coverage. One supplier specifically defines its NSNB stock as unused surplus that may have been handled, trial-fitted, or powered for verification.

What should I request before purchasing a replacement?

Request clear photographs of the actual nameplate, connector end, shaft, mounting face, and complete part number, along with the supplier’s stated condition and warranty. For a discontinued B&R motor, that evidence is more useful than a generic catalog description.