I find this recent article fascinating. A concrete underpass box was fabricated next to a railway embankment in the UK. It was slid into its final position along a "skidway" using a set of "air pads" pressurised with nitrogen.
Although the word "tribology" is not used in this article, it is clearly of interest to this forum. I certainly have a few questions, and I haven't managed to answer them online.
Why is pure nitrogen used? Is the pressure really 30 bar, or is it adjusted according to the requirement? Do the air pads have to comply with the Pressure Equipment Directive? What is the leakage rate, and hence, what is the power required to maintain a constant height/clearance? How much contact is there between the edge of the skirt and the skidways? How much wear takes place? (8 tonnes of shear force distributed over the perimeter must do some damage unless the skidway is clean and smooth)
A very similar task was undertaken about 12 years earlier in Denmark. The basic principle has been around much longer than that.
Credit is due to all these authors for bringing a piece of ingenious tribology into the public domain.
I suspect the modern Air Pad technology may have been developed outside of the UK and could be described online in other languages.
Can you answer any of my questions about this technology?