Fanuc A06B-0147-B075 — High-Torque α22/2000 AC Servo Motor, Straight Shaft, A64 Pulse Coder, 22 Nm

Product Overview

Part Number: A06B-0147-B075

Also Searched As: A06B0147B075, Fanuc A06B-0147-B075, FANUC A06B0147B075

Motor Model: α22/2000

Classification: Fanuc Alpha Series AC Brushless Servo Motor — 22 Nm Stall Torque, 2,000 rpm, Straight Smooth Shaft, No Brake, A64 Incremental Pulse Coder, IP65

The Motor in Context

The Fanuc A06B-0147-B075 belongs to the original Fanuc alpha series — not the later αi or αiS families, but the first-generation alpha platform that powered a large population of Fanuc-controlled machine tools through the 1990s and into the 2000s. Many of those machines are still running in production today, and when the A06B-0147-B075 eventually fails, sourcing a correct replacement is not always straightforward. Understanding exactly what this motor is — and what distinguishes it from closely related variants — is the starting point for getting the right part.

At 22 Nm stall torque and 2,000 rpm, the α22/2000 is a high-torque, moderate-speed motor designed for the heavier feed axis applications of large-format machine tools: heavy table drives on gantry machining centres, primary carriage feeds on large turning centres, and main axis drives on heavy-duty machining equipment where the axis load demands more than the smaller alpha series motors can sustain.

The A06B-0147-B075 baseline is: straight smooth shaft (no keyway), no brake, A64 incremental pulse coder. Every element matters for replacement ordering — a motor with a keyway (#7008 suffix), a brake (B175 series), or a different encoder is a different part.

Technical Specifications

22 Nm Stall Torque: What It Means on a Heavy Machine Axis

Twenty-two Newton-metres of continuous stall torque places the α22/2000 at the higher end of the original Fanuc alpha servo motor family. This is not a motor for light positioning axes or compact machining centres. It belongs on machines where the axis mass, cutting forces, and sustained load demands exceed what smaller alpha series motors — the α6, α12, α15 — can cover.

On a 10mm pitch ball screw with 90% efficiency, 22 Nm sustains approximately 12.4 kN of axial force. That kind of sustained axial force covers the heavy table drives on large horizontal machining centres, the carriage axes of substantial turning centres handling large diameter workpieces, and the primary feed axes of gantry-type machines where the saddle mass alone runs to hundreds of kilograms.

The 2,000 rpm rated speed reflects the axis type this motor serves. Large, heavy axes with substantial ball-screw pitches do not need 4,000 or 5,000 rpm shaft speeds — they need torque. At 2,000 rpm with a 20mm pitch ball screw, the α22/2000 drives the axis at 40 m/min in direct coupling. That is practical rapid traverse for a large machining centre without requiring intermediate gearing that would add backlash and mechanical complexity.

At 3.7 kW rated output, the motor draws 15A from the 157V motor supply at rated conditions — figures that match the αSVU1-80 amplifier's rated output for this motor class.

Straight Smooth Shaft: The Base Configuration

The A06B-0147-B075 carries a straight, smooth shaft with no keyway — the SLK (slick) designation in Fanuc's motor description. This is the standard coupling interface for machines that use friction-clamp coupling hubs or flexible disc couplings on the motor shaft.

At 22 Nm stall torque, the coupling selection for this motor demands real attention. A coupling hub sized for the stall torque alone may be marginal against the peak torque the axis experiences during aggressive acceleration. The coupling must be sized to the full peak torque demand, not just the sustained stall figure, to prevent slipping under hard acceleration cycles. Split-hub coupling designs at this torque level are standard industrial products — the shaft diameter of the α22/2000 accepts these hubs directly.

For machines where the driven component requires a keyed bore — a gear coupling, a rigid flange mount, or any hub where a key is required by the coupling design — the A06B-0147-B075#7008 variant carries a keyway in the shaft. The keyway variant and the base SLK variant are otherwise identical in performance. The correct shaft specification must match the coupling hub in the machine.

No Brake: Servo Lock on Horizontal Heavy-Axis Applications

The B075 base part number carries no electromagnetic brake. Position at rest is held by the Fanuc α series servo amplifier's servo lock — the position loop active, the A64 encoder feeding back position continuously, and the amplifier supplying corrective current to maintain the commanded shaft angle.

For the horizontal table drives, carriage feeds, and saddle drives that the α22/2000 typically serves, servo lock is entirely adequate. These axes have no net gravitational force acting along the shaft rotation direction, and servo lock holds a heavy axis at rest reliably without drift.

The brake variant for this motor is the A06B-0147-B175 series (not B075). The B175 adds a spring-applied holding brake for vertical axes or inclined feeds where mechanical holding is required at servo-off. If the machine's failed motor was a B175, the B075 is not an appropriate replacement — the brake provides a safety function that servo lock cannot replicate.

A64 Pulse Coder: Incremental Encoder on the Original Alpha Platform

The encoder fitted to the A06B-0147-B075 is the A64 — the 64,000-count-per-revolution incremental pulse coder used throughout the original Fanuc alpha motor series. This is not the serial absolute encoder of the αi generation. It is a parallel-signal incremental encoder that communicates via the standard differential pulse interface of the original alpha amplifier platform.

Incremental means homing is required. Every time the CNC powers up — after a planned shutdown, after a power interruption, after an alarm recovery — the axis must execute a reference-return cycle to establish its machine coordinate. The CNC does not know the axis position until the reference marker is found. For large-format machines where the homing movement traverses a substantial portion of the axis travel range, this homing cycle is a real operational step that must be managed correctly in the machine's startup sequence.

64,000 ppr. At 64,000 counts per revolution on a 20mm pitch ball screw, each encoder count corresponds to 312 nanometres of linear displacement. For the heavy-duty machining applications this motor serves, this resolution is adequate for the positioning accuracy required. Sub-micron repeatability is not the design target for a large gantry machining axis driving a 500 kg table — reliable, accurate, repeatable positioning within the tolerances the machining operation requires is.

A64 vs serial encoders. When sourcing a replacement A06B-0147-B075, confirm the CNC and amplifier are the original alpha generation that expects A64 parallel encoder signals. The αi-generation amplifiers expect serial encoder protocol — a motor from the α (not αi) series cannot be used with αi amplifiers without an adapter, and vice versa. This generation matching is the most common sourcing error on machines running original alpha series hardware.

Compatible Amplifiers and CNC Systems

The A06B-0147-B075 is designed for the Fanuc α (original alpha) series servo amplifiers — specifically the αSVU1-80 (80-amp unit) specified for the α22/2000 motor. This is the original alpha SVU amplifier, not the αiSV of the later αi generation. The motor is not compatible with αi or αiS series amplifiers.

Compatible CNC platforms include Fanuc Series 15, 16, and 18 on the original alpha generation — the CNC systems that were current when the α series servo platform was introduced. Later CNCs running the αi servo amplifier platform are not compatible with this motor without appropriate interface hardware.

When the A06B-0147-B075 fails and the machine is down, the priority is like-for-like replacement: same motor model, same shaft configuration, same encoder type. Fitting a motor from a different generation — even with identical nameplate torque and speed — will not work with the existing amplifier if the encoder protocol differs.

A06B-0147 Series: Key Variants

The B075 base number is the straight smooth shaft, no brake, standard IP65 configuration. The #7008 suffix adds a keyway; the #7076 suffix upgrades sealing to IP67. Always confirm the exact suffix configuration matches the machine before ordering.

Typical Applications

Primary table drive on large horizontal machining centres. X and Y saddle and table drives on large horizontal machining centres where heavy workpiece and fixture masses demand the 22 Nm stall torque that smaller alpha motors cannot deliver. The α22/2000 was a common specification for these axes on Fanuc 16 and 18 controlled equipment.

Heavy carriage and cross-slide drives on large CNC turning centres. Z-axis carriage drives on large diameter CNC turning centres where the carriage mass and sustained feed force during heavy turning operations require high sustained torque at moderate speed.

Gantry machining centre feed axes. X, Y, and Z axis drives on gantry-type machining centres where the bridge or saddle mass runs to several hundred kilograms and the axis load budget demands 22 Nm continuous torque at the motor shaft.

Main axis drives on heavy-duty transfer and special-purpose machines. Primary positioning axes on transfer line machines, special-purpose machining stations, and heavy-duty automation equipment controlled by original Fanuc 15 or 16 CNC systems where the motor has remained in service since original installation.

Field replacement on machines with original Fanuc alpha amplifiers. Any machine equipped with αSVU1-80 amplifiers and α22/2000 motors where the motor has reached the end of its service life or has failed and requires a like-for-like replacement to restore production.

FAQ

Q1: What is the difference between the A06B-0147-B075 and the A06B-0147-B075#7008?

The base part A06B-0147-B075 has a straight smooth shaft with no keyway — the coupling hub clamps to the smooth shaft OD using a split-hub friction interface. The #7008 suffix variant has the same straight shaft but includes a machined keyway, allowing a keyed coupling hub to transmit torque through the key rather than friction alone. All other specifications — torque, speed, encoder, brake configuration, and amplifier compatibility — are identical. The correct shaft specification must match the coupling hub design in the machine.

Q2: Does the A06B-0147-B075 use an absolute or incremental encoder?

The A64 pulse coder on this motor is incremental, not absolute. Position is not retained through power-off events. Every time the Fanuc CNC powers up, the axis must execute a reference-return (homing) cycle to establish its machine coordinate before production can resume. This is standard behaviour for original alpha series motors — the absolute encoder was introduced on the later αi generation. Machines built around this motor have their homing sequences already programmed; the sequence must be followed on every CNC power-up.

Q3: Is the A06B-0147-B075 compatible with newer Fanuc αi series amplifiers?

No. The A06B-0147-B075 uses the A64 parallel incremental encoder, which communicates via the original alpha series encoder interface. Fanuc αi series amplifiers expect the serial encoder protocol used by αiS and αiF motors — these two encoder systems are incompatible without an interface adapter. The A06B-0147-B075 requires an original Fanuc α series amplifier (αSVU1-80). Fitting this motor to an αi amplifier without the appropriate adapter hardware will result in encoder communication faults.

Q4: Can the A06B-0147-B075 replace the A06B-0147-B175 (brake variant)?

Not without assessing the axis safety requirements first. The B175 variant carries a spring-applied electromagnetic brake, which means it was specified for an axis that requires mechanical holding at servo-off — typically a vertical axis or an inclined feed where gravity would cause movement without the brake. The B075 has no brake and holds position only through servo lock. Fitting a B075 on an axis designed for a B175 eliminates that mechanical safety function. If the axis is confirmed horizontal with no gravitational load component, the B075 may be acceptable — but this determination must be made by the machine builder or a qualified engineer, not assumed.

Q5: This is an older alpha series motor — is it still serviceable?

Yes. The A06B-0147-B075 remains in service on a significant installed base of Fanuc-controlled machine tools worldwide, and the motor is rebuildable. Qualified servo motor repair facilities can replace bearings, seals, and the A64 pulse coder to return a worn or damaged unit to specification. Refurbished and exchange units are also available from servo motor specialists. For sites where the machine cannot be economically upgraded to a current-generation CNC and amplifier platform, maintaining the existing alpha series hardware through repaired or refurbished motors is the practical and cost-effective route to keeping the machine in production.