This website looks very handy! If you're building it for home use fill your boots but if it's for business use don't bother, the red tape and insurance issues will be horrific!
I spotted this website a while ago when I was prowling the internet looking for lifting beam dimensions and capacity without having to do any sums! I put a fixed beam in my workshop.
The design must be fairly solid as it's a commercial product, but I agree the 'A' looks stronger.
have you got or can you install fore and aft beams somewhere in your roof space? If so, you could create a poor man's travelling crane setup. This is the one I have recently completed in my main workshop. I've put this in because I don't have the strength nowadays to mount the 12" chucks on my "big" lathe. Also need to lift the head off the Bridgeport occasionally to fit the riser block.
I have previously built something very similar in my two garages for shifting big stuff around. The runners/rollers for the main beam are made from sawn up girder trolleys, The RSJ is reclaimed. I can push a 1/2 ton load on this with one hand so it does save a lot of effort.
This is a very timely thread, am roughing out plans to do a similar thing in my workshop extension. Popped into the local one man band steel stockist and scared myself with the prices of what I need
@Stueeee was thinking along the same lines as you with the grider trucks, been scouring the internrt looking for cheap used ones but no luck yet
I have an extension goes over the end of my engine crane and a tractor weight to counter balance it. But like the mobile gantry idea. As it could be stored above the lathe and not eat up space.