If the brake vacuum booster makes vacuum on one side and the other is with normal atmospheric pressure, why doesn't it get sucked by itself towards the vacuum side? (mechanics.stackexchange.com)
The compact tandem - type vacuum booster consists of two 9 - inch diameter booster chambers. (hondanews.com)
It has independent dual circuit hydraulic brakes, operated by tandem master cylinder that comes with vacuum booster function. (cardekho.com)