To some extent, part of this expression is redundant, since the text explains what it is / does; I think the key element here is 'pressure switch' = 'pressostat'

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Note added at 10 heures (2016-08-01 06:59:02 GMT)
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Daryo has quite rightly pointed out that i have translated 'pressure-operated switch', but have left out the 'cut-off' part, which to me is redundant: we know that detection of pressure is being used to operate a switch, and the following explanation details what that then does, so 'cut-off' here is only an additional qualification for what the 'pressure switch' is being used for; I don't believe it is, for example, identifying some special type of 'pressure switch' (since in fact we know from what follows that the 'pressure switch' itself isn't actually doing the cutting-off (if it were, it might need to have more generously rated contacts, for example); here, it is just being used to generate a signal to then actuate something else.