Product Description:

The PMB31D-20201-03 is a brushless servo motor manufactured by Pacific Scientific and offered in the PMB Brushless Servomotors series. It is intended for industrial automation axes that require repeatable torque delivery, quick acceleration, and precise velocity adjustment under electronic drive control. This makes it suitable for equipment that starts and stops often while still needing steady motion between positioning moves. Using brushless construction with electronic commutation, the unit supports closed-loop motion in material-handling stations, indexing tables, and light machine-tool feeds.

The motor housing conforms to NEMA Size 34, so its face-mounting pattern matches standardized gearboxes and adapter plates. This frame size also helps the motor fit common brackets used on compact servo assemblies. A nominal stall requirement of 5.4 ARMS at 240 VAC indicates the continuous phase current the companion amplifier must supply when the shaft is locked and fully energized. Power and feedback conductors exit as flying leads with MS connectors, allowing quick field termination without rewiring the stator. Rotor position for six-step commutation is detected by internal Hall sensors, which remove the need for an external encoder in coarse-resolution applications. Mechanical coupling is handled by a square key cut into the shaft to help prevent slip when the motor drives keyed hubs or pulleys.

For environments where dust or coolant could reach the bearings, the motor includes a shaft seal and PTC thermistor. The seal helps block contamination at the shaft, while the thermistor provides temperature monitoring for the winding circuit. A stack length multiple of 1 indicates the shortest magnetic stack in this motor line, which helps reduce inertia and supports faster speed changes. The short stack can also improve response where the driven load has moderate inertia. The permanent-magnet rotor works with electronic commutation to provide responsive motion control, and the temperature input can be used to monitor motor heating during operation.