ANY VEHICLE FITTED WITH A SERVICE BRAKE ACTUATED BY AN ENERGY RESERVOIR MUST , WHERE THE PRESCRIBED SECONDARY BRAKING PERFORMANCE CANNOT BE OBTAINED BY MEANS OF THIS BRAKE WITHOUT THE USE OF STORED ENERGY , BE PROVIDED WITH A WARNING DEVICE - IN ADDITION TO A PRESSURE GAUGE , WHERE FITTED - GIVING AN OPTICAL OR ACOUSTIC SIGNAL WHEN THE STORED ENERGY IN ANY PART OF THE SYSTEM FALLS TO A VALUE AT WHICH , WITHOUT RECHARGING OF THE RESERVOIR AND IRRESPECTIVE OF THE LOAD CONDITIONS OF THE VEHICLE , IT IS POSSIBLE TO APPLY THE SERVICE BRAKE CONTROL A FIFTH TIME AFTER FOUR FULL-STROKE ACTUATIONS AND OBTAIN THE PRESCRIBED SECONDARY BRAKING PERFORMANCE (WITHOUT FAULTS IN THE SERVICE-BRAKE TRANSMISSION DEVICE AND WITH THE BRAKES ADJUSTED AS CLOSELY AS POSSIBLE).
"2.2.1.13 Vsako vozilo, opremljeno z delovno zavoro, ki jo aktivira hranilnik energije, mora biti, ko predpisani učinek pomožnega zaviranja ni mogoč brez uporabe shranjene energije, opremljeno z opozorilno napravo - poleg manometra, če je nameščen - ki s svetlobnim ali zvočnim znakom opozori, kadar se shranjena energija v kateremkoli delu sistema zniža na vrednost, pri kateri je mogoče, brez ponovnega napajanja hranilnika in ne glede na obremenjenost vozila, uporabiti napravo za upravljanje delovne zavore tudi petič, potem ko je bila štirikrat polno aktivirana, in pri tem doseči predpisani učinek pomožnega zaviranja (brez okvar v napravi za prenos delovne zavore in s čim tesneje nastavljenimi zavorami).