When energized, the motor drives a sliding contact in steps, one turn at a time inside the enclosure. There are limit switches in the motor assembly, but I have not taken the time to diagram the wiring. These units should be great for remote antenna couplers for ham use. Some units have the original power plug attached, some do not, so state if this is important to you. Removed from equipment, and guaranteed.
Photo shows three units in various positions.
I have a small supply of these motor driven variable inductors for sale. These inductors were part of a military antenna coupler, but the type of coupler is unknown. They are almost certainly Collins made. I counted 28 turns on the coil, approx. When energized, the 28 VDC motor drives a fiberglass insulated tube inside the coil, which selects each turn of the coil successively.