Help Needed: A lifting device for a linear rail

If you could use a spreader bar and a crane of sorts, this would provide the stabillity you want with equal distribution of the weight. Can you attach slings or lifting lugs or eye bolts? Check out the Crosby website.This company specializes in rigging and lifting equipment and hardware.

Look into putting a support cable at each end, with EACH cable running over a pulley vertically above its load. Bring BOTH cables to a single winch drum (for a few hundred pounds, manual is more than adequate). If you know how the harnesses lift individual heddles on a loom, you'll understand immediately. Here's an image of it (Google "Loom +harness" and go to page 9) shows just about enough: the bi-color cords at the ends lift each heddle, and pass over pairs of pulleys to meet at the central "Y", where a single down-cord pulls in response to a treadle below. More typically, both cords go to one side and then down, but winch location is something you'll need to decide.

The above suggestions are great, but( I failed to mention in the first post) we need to lift from the bottom as our max height must be less than 5'. Thanks for your responses.

OK: I must still be missing something. Your only "overhead" [pun] is the diameter of the sheave at each end, since it can be mounted on the side of its support and essentially be flush at the top,where the cable turns 90 degrees and parallels the rail. It can turn downward again to the spool, so the winch is beneath the rail, if desired. Imagine a 4' tall sawhorse straddling the rail end-to-end, or a cut-down kids' swing set, with pulley wheels on the top rail near the leg junctions, and the winch mounted on the leg itself. If you still must lift from below, a pair of nuts can be attached to the rail, and threaded rods going through them can terminate in sprockets resting on thrust bearings (top or bottom). Sprockets permit synchronized rotation, hence give level lift (like the table on a wood planer). You'll need to provide guidance, say by trapping each end of the rail within a vertical channel to prevent sideways buckling, if working from beneath. Acme threaded rod and nuts are readily available (www.jlindustrial.com item GNG-82020D, e.g.) - and you WANT acme for friction, life, and strength reasons. A handwheel on the top of one (or both) rods gives manual input for lifting.