Product Description:

The PMB31D-20214-03 is a brushless servo motor produced by Pacific Scientific and belongs to the PMB Brushless Servomotors series. Designed for closed-loop motion axes, the unit converts electromagnetic torque into precise rotary movement for indexing tables, pick-and-place heads, and similar automation loads. Its rare-earth rotor magnets and stator windings are optimized for direct connection to a compatible digital drive. This makes it suitable for synchronized motion tasks that depend on accurate speed and position control throughout repeated production cycles. Typical applications include gantry axes, carton erectors, and compact tool changers that need repeatable velocity and torque.

With a 240 VAC bus supply, the nominal stall current is 5.4 ARMS, meaning that phase current can be sustained indefinitely without exceeding thermal limits at standstill. The frame uses the NEMA Size 34 outline, so its 3.4-inch square face fits equipment built around that standard. Position feedback comes from a 2048 ppr incremental encoder, which provides 8192 counts after quadrature to the controller. A digital encoder with commutation also supplies electrical angle signals for sinusoidal current loops. Output torque is transmitted through a shaft with a square key for pulleys or rigid couplings.

System wiring is simplified by flying leads with MS connectors, so power, encoder, and thermistor conductors exit on preterminated cables that mate with panel receptacles. The optional package includes a shaft seal and a PTC thermistor, which help keep contaminants out and report winding temperature so the drive can limit current before overload. A stack length code of 1 marks the shortest magnetic core in the family, which helps reduce inertia for rapid indexing. This short stack is suited to axes that benefit from quick starts and stops without adding unnecessary rotor inertia.