▁the ▁de pression . ▁The ▁maximum ▁pressure ▁that ▁can ▁be ▁reached ▁into ▁the ▁bra ke ▁cyl ind ers ▁on ▁E 6 3 6 ▁is ▁, ▁which ▁corresponds ▁to ▁a ▁pressure ▁inside ▁the ▁general ▁pipe ▁of ▁about ▁. ▁ ▁In ▁case ▁of ▁emer gency ▁bra king , ▁the ▁bra ke ▁pipe ▁is ▁put ▁to ▁direct ▁communication ▁with ▁outside ▁atmosphere , ▁rapidly ▁dro pping ▁pressure , ▁and ▁consequ ently ▁making ▁the ▁train ▁bra ke ▁very ▁fast ly ▁( though ▁there ▁isn ' t ▁a ▁variation ▁of ▁bra king ▁power : ▁only ▁the ▁bra king ▁speed ▁is ▁affected ). ▁ ▁To ▁release ▁bra kes , ▁the ▁driver ▁makes ▁the ▁pressure ▁rise ▁in ▁the ▁, ▁via ▁the ▁bra ke ▁controller ; ▁the ▁pressure ▁in ▁the ▁bra ke ▁pipe ▁is ▁restored ▁( air ▁is ▁taken ▁from ▁the ▁main ▁res er voir ▁t anks , ▁and ▁from ▁the ▁main ▁pipe ▁if ▁present ) ▁to ▁the ▁value ▁present ▁in ▁the ▁. ▁Inside ▁the ▁ ▁the ▁bra ke ▁pipe ▁pressure ▁wins ▁over ▁the ▁command ▁res er voir ▁pressure ▁and ▁so ▁the ▁connection ▁between ▁the ▁bra ke ▁cyl ind ers ▁and ▁the ▁auxili ary ▁t anks ▁is ▁modified ▁( or ▁cut , ▁depending ▁on ▁the ▁pipe ▁pressure ); ▁the ▁bra ke ▁cyl ind ers ▁un load ▁themselves ▁sending ▁their ▁air ▁outside ▁until ▁their ▁pressure ▁reaches ▁a ▁value ▁proportional ▁to ▁the ▁entity ▁of ▁the ▁de pression . ▁When ▁pipe ▁pressure ▁is ▁, ▁the ▁cyl ind ers ▁will ▁un load ▁until ▁they ▁are ▁empty . ▁ ▁For ▁a ▁faster ▁bra kes ' ▁release ,