A06B0373B169 Fanuc AC Servo Motor AO6B-O373-B169 A06B-0373-B169

FANUC A06B-0373-B169 | Alpha 1/3000 AC Servo Motor — 2 Nm / 3000 rpm / Tapered Shaft / Spring Brake

Alpha 1/3000 with Spring Brake

The A06B-0373-B169 is FANUC's Alpha 1/3000 servo motor in the tapered shaft, brake-equipped configuration. At 2 Nm and 3,000 rpm, it handles compact CNC machine tool axes — tool turret indexing on turning centres, Z-axis feeds on small machining centres, rotary table drives, and other positions where a mid-speed, controlled-torque motor is the right fit.

The spring-applied brake is the defining specification on this variant. The brake engages by default — a spring holds the brake pads against the disc whenever the 24V DC brake coil is not energised. The coil must be powered to release the brake for normal servo operation. When the servo is switched off, E-stopped, or loses power, the coil de-energises and the spring locks the shaft immediately. This is the correct configuration for vertical axes, inclined feeds, and any mechanism where the load has a gravitational component in the direction of rotation when the servo is not actively commanding motion.

The tapered shaft self-centres in the hub bore. The hub is pulled axially onto the taper and secured with a lock nut — a self-aligning fit that handles both radial and axial load without relying on friction clamping alone. Hub installation: use the shaft-end thread and a nut to pull the hub axially into position. Never press or hammer onto a taper shaft — impact loading travels through the shaft to the encoder disc and rear bearing.

A06B-0373 Variant Overview

Within the A06B-0373 series, the B-suffix encodes the shaft configuration and brake options:

All variants share the same Alpha 1/3000 electrical specification — 2 Nm stall torque, 3,000 rpm, 2.9A. The shaft type and brake presence are the only differences.

Key Specifications

FAQ

Q1: The spring brake does not release when the axis is enabled. The 24V coil supply is confirmed at the connector. Is the brake faulty?

With 24V confirmed at the connector, measure the resistance across the brake coil terminals at the motor (with 24V disconnected). A healthy spring brake coil on this motor class typically reads in the 15–40 Ω range. Open circuit confirms a failed coil. If resistance is within range but the brake still does not release, check for mechanical binding in the brake disc — contamination between the disc and friction surfaces can prevent release even with the coil correctly energised.

Q2: What is the difference between B169 (this motor) and B175?

Both are Alpha 1/3000 motors with identical electrical specifications and a spring-applied brake. The difference is the shaft: B169 has a tapered shaft; B175 has a straight shaft with keyway. The driven component's hub determines which is correct — a hub bored for a taper requires B169; a hub with a keyway bore requires B175.

Q3: Can A06B-0373-B169 be used without the brake on a horizontal axis?

The motor will function on a horizontal axis with the brake always released (24V continuously applied to the coil), but this wastes brake coil power and accelerates brake wear. On horizontal axes where gravity does not load the axis, the no-brake variant (B069 — tapered shaft, no brake) is the correct specification. Sourcing the B069 eliminates the brake circuit entirely rather than bypassing it in software.

Q4: The taper shaft hub is stuck after a crash. How should it be removed?

Use a hub puller designed for tapered shafts. Never strike the shaft end or pry against the motor housing — impact force on a taper shaft damages the encoder disc and rear bearing. If the hub does not release with a standard puller, apply even heat from a heat gun (not a torch) to the hub body to expand the bore before pulling.

Q5: What encoder type does the A06B-0373-B169 use?

The A06B-0373 series Alpha motors use FANUC's A64 absolute pulsecoder (64,000 pulses per revolution). The A64 provides absolute multi-turn position on power-up without a homing cycle — the machine knows its exact position immediately at restart. The absolute position backup is maintained by a battery in the servo amplifier, not in the motor. Replace the battery at the amplifier when the low-battery alarm appears to preserve the absolute position counter.