Product Description:

The PMB31B-20200-02 is a brushless servomotor manufactured by Pacific Scientific within the PMB Brushless Servomotors series. It serves as a rotary power element in industrial automation. It supplies commanded torque and speed for axes that demand repeatable positioning and quick reversals. The brushless design reduces wear associated with commutators and helps keep routine maintenance low.

The motor is built on a NEMA Size 34 frame, giving it a standard 3.38-inch square face for direct use with common gearheads and mounting brackets. A nominal stall current of 2.7 ARMS at 240 VAC limits drive sizing and indicates the continuous current that can be applied without exceeding thermal limits. Power and feedback cabling leave the housing through flying leads with MS connectors, which simplifies field wiring because the leads are already terminated with military-style circular plugs. Rotor position is reported by a resolver, so the drive can close the servo loop in electrically noisy environments where optical encoders may be less suitable. Torque is transferred through a square key machined into the output shaft, allowing positive engagement with pulleys or couplings while preventing slip under load.

Thermal protection is provided by an internal PTC thermistor, giving the drive a temperature-dependent signal so it can reduce current before insulation limits are reached. The lamination stack uses stack length multiple 1, which is the shortest magnetic core offered in this family and helps keep rotor inertia low for high-cycle indexing. The motor uses standard PMB mounting patterns and connector pinouts, so it fits related PMB mechanical layouts and cabling schemes without changes to brackets, shrouds, or harnesses. It remains compatible with digital drives and legacy cabling conventions used in this product line. This layout supports compact axis assemblies where consistent cable routing and predictable mounting geometry are important.