Linear servo actuator exerts mighty push/pull

-- EDN, 12/7/2000

Direct-drive linear tubular motors from California Linear Devices provide a peak force of 750 lbs with 30A excitation current over strokes ranging from 2 to 12 in. in 2-in. increments. The 5024-4 linear servo motor uses neodymium-iron-boron permanent-ring magnets in a patented arrangement of alternating polarities to develop a maximum frequency response of 60 Hz over a distance of 0.125 in. (Picture). The linear motor uses three-phase, brushless-dc technology. Its configuration is similar to that of a rotary brushless motor, except that its ring-shaped permanent magnets are arranged in alternating polarity along the length of the shaft. The stator uses cylindrical coils and pole pieces placed around the shaft. This arrangement allows electromagnetic reaction to occur over the entire surface area of the shaft, yielding a high linear force per unit volume. Position and force are fully programmable through the use of a servo controller. An encoder transmits detailed position information to the motion controller. Stroke lengths of 2, 4, 6, 8, and 12 in. are standard. The 5024-4 linear actuator costs $4400.

California Linear Devices Inc, www.calinear.com.

—by Bill Travis