Tony M Nov 19, 2016:

@ Asker: 'toggle' In many contexts, 'toggle' has the sense of 'two ways round / options' — as we find in the now slightly dated 'toggle switch', and the idea that pressing the button repeatedly toggles successively between 'on' and 'off'" — in which sort of sense, we see it a lot it computers, where a command is said to 'toggle' if it alternates between two conditions each time you click it etc.

So I would understand this as talking about 'turning the symmetrical wear ledge round to the opposite position' — as described in your text, to prolong the useful life of this component.

In some senses, this might be translated as 'basculement' — but that doesn't seem to me to really fit here. Maybe 'inversion'?