Product Description:

The PMB31D-20114-02 is a brushless servomotor produced by Pacific Scientific and supplied within the PMB Brushless Servomotors series. It is designed to deliver closed-loop rotary motion for positioning tables, pick-and-place axes, and other automation tasks that require fast acceleration, repeatable speed regulation, and accurate response to changing command signals. By combining permanent-magnet construction with electronic commutation, the motor provides high torque density while minimizing maintenance associated with brush wear.

The frame conforms to NEMA Size 34, so the mounting pilot, bolt circle, and shaft height match standard 3.4-inch flange hardware used on gearboxes and linear stages. Under a 240 VAC supply, the winding can tolerate a nominal stall current of 5.4 ARMS, a value that helps size drive amplifiers and thermal protection. Rotor position is reported by an optical encoder that delivers 2048 ppr of incremental feedback, enabling ±1 pulse velocity smoothing when paired with a high-resolution controller. Power, feedback, and thermal leads exit the housing as flying leads with AMP connectors, allowing direct crimp-style termination to cabinet wiring harnesses. Torque is transferred through a shaft that carries a square key, preventing slippage between the motor and the driven component during start-stop cycles.

A digital encoder with commutation track is integrated, so sinusoidal or trapezoidal phase currents can be aligned automatically at startup without separate Hall devices. For overtemperature protection, a PTC thermistor embedded in the stator changes resistance sharply near the insulation limit, permitting the drive to fold back current if excessive heating is detected. The stack length multiple is 1, indicating a single lamination section that keeps inertia low for rapid speed changes. The integrated feedback and thermal device reduce the need for separate external sensing components.