Product Description:

The PMB31B-20201-01 is a brushless servomotor built by Pacific Scientific within the PMB Brushless Servomotors series. Designed for closed-loop axis control, the unit converts drive current into torque for indexing tables, pick-and-place arms, and other motion modules used in industrial automation. Its magnetic rotor and electronic commutation allow high positioning repeatability while minimizing maintenance compared with brushed designs. The motor is arranged for use with matched digital drives, so it can be integrated into existing motion systems without external commutation hardware. That layout helps the drive respond quickly to speed and position changes during short, repetitive cycles.

The motor is furnished with flying leads with MS connectors, so power, feedback, and ground wires exit the housing ready for coupling to mating circular plugs in a control cabinet. Its frame is classified as NEMA Size 34, which gives it a 3.4-inch square mounting face and supports compatibility with standardized gearheads and flanges. Under 240 VAC operation, the winding can hold a continuous stall load at 2.7 ARMS, which indicates the current level required for sustained torque output. Rotor position is derived from Hall sensors, enabling six-step commutation without an external encoder. Mechanical torque is transmitted through a square key on the output shaft, which helps prevent slip between the motor and the connected load.

The lamination stack uses a 1 stack length multiple. This helps keep rotor inertia low for rapid starts and stops while maintaining the rated torque curve. A factory-installed shaft seal closes the front bearing bore, limiting lubricant loss and helping block airborne contaminants in automated cells. The sealed front end also helps protect the bearing area when nearby tooling or conveyors stir fine dust during routine operation.