Solen Fillatre (asker) Apr 21, 2020:

inverted technical speak Thank you for the brilliant explanation, it's starting to make sense to me when you look at it this way, thank you Tony and Cyril. I can take another run at this now.

Cyril Tollari Apr 21, 2020:

Agree relais de commande du témoin de desserrage total
variations possibles sans les de: relais commande, témoin desserrage, etc
variations possibles voyant pour témoin, etc et tous les autres synonymes, mais je crois aussi que c'est cet ordre des mots qui veut dire quelque chose

http://www.deschamps-web.com/site/eb/frein/partie2/partie2.h...
https://patents.google.com/patent/EP0244543A1/en
https://patents.google.com/patent/EP0235035A1/en

Tony M Apr 21, 2020:

@ Asker OK, this is beginning to give a glimmer of insight into your other expressions: as I suspected, this is 'inverted technical speak', where the order of the words is adjusted to indicate the priority of the terms (and often, for easier alphabetization!)

So I would understand this as 'the relay that controls the indicator lamp that warns of total brake relaease'

This may also shed some light on your other question with 'short release' — perhaps for some reason the brakes may be partially released (= a short travel) or totally released (= maximum travel)??

The fact you have CO (= changeover) and DP (double-pole) certainly seems to confirm we are indeed talking about the RELAY as the main element here.