A jim crow or rail bender is a tool for bending rails, consisting of a U-shaped or V-shaped armature with a hefty screw rod in its axis. Deluxe models are outfitted with rollers for continuous bending. Illustrations of rail benders with rolls
Practice
Railway rails are quite flexible and bend easily to radii of or more. The jim crow is needed to bend rails to tighter radii, especially near the ends.
References
External links http://www.catskillarchive.com/rrextra/tkwk03.Html (with illustration) Photograph Railway Object Name Thesaurus