Product Description:

The PMB31D-20100-02 is a brushless servomotor produced by Pacific Scientific and supplied within the PMB Brushless Servomotors series. As a closed-loop rotary actuator, it converts controlled electrical energy into precise shaft torque for indexing tables, conveyors, or packaging axes in automated equipment. Its resolver feedback keeps the drive synchronized with the mechanical load so the controller can hold position or modulate speed under changing process demands. This feedback arrangement also supports stable position holding at standstill and smooth speed regulation during motion.

This model is built on a NEMA Size 34 frame, which provides a standard reference for flange dimensions and mounting hole pattern. Its nominal stall current is 5.4 ARMS when used with 240 VAC drives, so the drive must be able to supply that current without entering current limit first. Motor terminations are provided as flying leads with AMP connectors, which allows cable routing through tight machine frames before final connection. Rotor position is reported by a resolver, a two-phase transformer that tolerates heat and vibration better than optical devices while still allowing fine interpolation in the drive. Torque is transferred through a shaft with a square key, which helps prevent slippage between the motor and the attached load under peak acceleration.

To guard the windings, the stator includes a PTC thermistor that changes resistance sharply near its trip temperature. This allows the amplifier to reduce current before insulation limits are exceeded during repeated duty cycles. The electromagnetic core uses a single magnetic stack with a stack length multiple 1, which helps keep inertia low for fast indexing cycles. Lower rotating inertia can improve response during frequent starts, stops, and short positioning moves.