On the subject of Foden gear changing .. I drove (civvy) artic road tankers in the 'eighties, with 9 speed Fuller 'boxes & Lippe-Rollway (spelling?) clutches with what's known as a clutch-stop. To change up the pedal was depressed half way when coming out of gear, then fully depressed to slow the engine slightly before selecting the higher ratio, thus enabling a faster change. Down changes were made by just depressing half way & matching road speed/engine revs. as in any 'crash' box. If you really knew what you were doing, changes both up & down could be achieved without using the clutch at all.
Models from the 'seventies had a wonderful (not) system of a 4 speed main 'box & separate control on the side of the instrument panel for low/direct/overdrive selection, giving a total of 12 speeds, but I don't recall these versions having a clutch-stop.
Happy days ! (most of the time anyway)