The Thomson Electrack 150 Acme-screw actuator from Danaher Motion, in Marengo, Ill. (www.danaherlinear.com), is maintenance-free and built to withstand outdoor use and harsh environments. For example, a breather tube in the wire harness lets the actuator operate without pulling in water through the seals. And the recyclable plastic cover carries no load, but protects the interior from the environment and contributes to the unit's IP56 rating. To prevent corrosion, the cover tube is made of anodized aluminum, the extension tube is stainless steel, and front and rear adapters are zinc die castings.

The actuator exerts between 110 and 450 lb of dynamic force, 350 to 900 lb of static force, and stroke lengths vary from 1 to 16 in. It is bidirectional, powered by 12 or 24 Vdc, and has an estimated life at rated load of 40,000 cycles.