A linear motor is functionally the same as a rotary electric motor with the rotor and stator circular magnetic field components laid out in a straight line. Where a rotary motor would spin around and re-use the same magnetic pole faces again, the magnetic field structures of a linear motor are physically repeated across the length of the actuator.
Since the motor moves in a linear fashion, no lead screw is needed to convert rotary motion to linear. While high capacity is possible, the material and/or motor limitations on most designs are surpassed relatively quickly due to a reliance solely on magnetic attraction and repulsion forces. Most linear motors have a low load capacity compared to other types of linear actuators. Linear motors have an advantage in outdoor or dirty environments in that the two halves do not need to contact each other, and so the electromagnetic drive coils can be waterproofed and sealed against moisture and corrosion, allowing for a very long service life.