Just WHY do they supply those with a joiner on the back-end?????????????
They remind me of a Roneo Vickers system that we had to prepare the installation of (weren't allowed to install it) in the records department of a certain government department - cue Miss Moneypenny.
The rails were totally tubular in section, and the little trucks (which were battery powered and self-directing) had wheels like pulleys mounted in pairs above and below the rail. The rail could be laid in any axis, so the truck could climb vertically, could run on its side, or hang below the track. This allowed it to twist and turn through the narrow confines of a 1920s building, fortified in the late 1930s and being converted for use in the 1970s (and apparently still in use as confirmed by a spook about 5 years ago).