Transfer Tank

I’d never heard of a transfer tank until today – or at least, if I have, it’s never registered with me. It appears to be something that you hold gallons of petrol in, if you’re a truckie, and like all such things, they come in various shapes and sizes. Of course you could no doubt hold any kind of liquid in it, but I suspect petrol is the norm.
Of course, it isn’t the sort of thing you cart about with you, even without the 74 gallons some of them hold. I suspect it might be just on the heavy side, even for the average truckdriver. I’m working my way towards this, you realise, but I suspect I’ve seen these things on the sides of those enormous trucks that bear down on us while we’re driving on the English motorways. Of course I haven’t noticed anything while we driving; keeping my eyes firmly fixed on the road has been about all I can do at the time. But when we stop in one of those parking spaces on the side of the road, and an enormous truck pulls in beside us and threatens to crush us in the process, that’s when I’ve seen a transfer tank.