Product Description:

The PMB33F-20201-03 is a brushless servomotor designed by Pacific Scientific as part of the PMB Brushless Servomotors series. Intended for closed-loop motion sections in automated machinery, the unit delivers commanded torque and speed in direct response to a matched drive. Its permanent-magnet design, wound for standard industrial bus voltages, supports positioning axes, pick-and-place heads, and index tables that require repeatable movement. Because it operates with a matched drive, speed and torque can be adjusted closely as load conditions change during a machine cycle.

The power conductors exit as flying leads with MS connectors, allowing quick disconnection while remaining compatible with shielded cable assemblies. The frame follows NEMA size 34, which uses a 3.4-inch square mounting pattern that matches common gearboxes and linear actuators. When the shaft is locked, the winding draws a nominal stall current of 11.0 ARMS at up to 240 VAC, a value that helps set drive amplifier sizing and overload limits. Rotor position information is provided by a Hall sensor, enabling six-step commutation for low-speed startup and direction verification. Overall axial length is set by a stack length multiple of 3, which increases the iron volume so higher continuous torque can be produced without enlarging the footprint.

Mechanical protection and thermal supervision are built into the motor. The unit includes a shaft seal and a PTC thermistor; the seal helps block lubricant wash-back into the stator, and the thermistor provides temperature feedback so the drive can react before winding insulation is overstressed. Torque is transmitted through a square key machined into the shaft, providing positive engagement with couplings and pulleys rather than relying only on clamping force. The keyed shaft suits applications where the transmitted load changes direction during normal operation.