Product Description:

The PMB31B-10101-03 is an AC servo motor delivered by Pacific Scientific within the PMB Brushless Servomotors series. Designed for industrial positioning axes, the unit converts controlled current from a matching drive into torque for medium-inertia loads used in packaging, assembly, and material-handling systems. Its compact frame and permanent-magnet rotor support rapid acceleration, while the embedded commutation devices enable closed-loop speed and position regulation. The motor can be mounted in any orientation with a suitable coupling and fits systems built around 3.4-inch face-mount equipment.

Mechanical geometry is based on the NEMA Size 34 frame, giving the motor the 3.4-inch square flange common to many stepper and servo stages. At a maximum 240 VAC bus voltage, the phase windings support a nominal stall current of 2.7 ARMS, so the drive must be sized to supply that continuous current without thermal overload. Power exits through flying leads with AMP connectors, which reduces the need for bulkier side-mounted receptacles. Rotor position is reported by a three-channel Hall sensor, permitting trapezoidal commutation at startup or low speed. The output shaft has a round profile, which simplifies direct coupling to pulleys or flexible couplings that do not require keyways.

For thermal protection and sealing, the motor includes a shaft seal that helps limit lubricant migration and an embedded PTC thermistor that changes resistance sharply if internal temperature rises too high, allowing the drive to inhibit current. The motor has a stack length multiple of 1, which keeps the magnetic circuit short and helps maintain low inertia for fast indexing duty. Its permanent-magnet, brushless construction minimizes maintenance because there are no commutator surfaces to wear. This design also supports smoother torque delivery across the speed range.