▁series ▁circuit . ▁The ▁elect rical ▁isol ation ▁of ▁one ▁locomot ive ▁side ▁was ▁possible ▁by ▁blocking ▁the ▁respective ▁revers ing ▁switch . ▁ ▁The ▁elect rical ▁bra ke ▁was ▁an ▁AC ▁excited ▁res istor ▁bra ke . ▁T ogether ▁with ▁the ▁revers ing ▁pole ▁sh un ts ▁they ▁were ▁mounted ▁on ▁the ▁roof ▁over ▁the ▁c abs , ▁where ▁they ▁were ▁co o led ▁by ▁the ▁head ▁wind . ▁ ▁The ▁locomot ive ▁was ▁equ ipped ▁with ▁the ▁following ▁auxili ary ▁systems : ▁ ▁two ▁compress ors ▁ ▁a ▁converter ▁group ▁for ▁battery ▁charg ing ▁ ▁one ▁shared ▁fan ▁for ▁the ▁two ▁Tsch anz - drive ▁mot ors ▁ ▁two ▁fans ▁with ▁a ▁shared ▁motor ▁for ▁the ▁BBC - drive ▁mot ors ▁ ▁an ▁oil ▁p ump ▁ ▁cab ▁he ating ▁ ▁Service ▁ ▁At ▁the ▁time ▁of ▁the ▁introduction ▁of ▁electric ▁tra ction ▁the ▁locomot ives ▁looked ▁strange ▁to ▁the ▁railway ▁staff . ▁The ▁air ▁gr illes ▁res emble d ▁wr ink les , ▁therefore ▁the ▁locomot ive ▁was ▁sometimes ▁nick named ▁grand m other . ▁ ▁After ▁its ▁delivery ▁in ▁March ▁ 1 9 2 2 ▁the ▁locomot ive ▁was ▁used ▁first ▁on ▁the ▁Bern ▁( B erne ) ▁– ▁Th un ▁line , ▁because ▁this ▁line ▁was ▁the ▁first ▁one ▁elect r ified ▁with ▁the ▁necessary ▁ 1 5 ▁k V ▁ 1 6 <0xE2> <0x85> <0x94> ▁H z ▁AC . ▁Un like ▁the ▁prototype ▁locomot ives ▁with ▁rod ▁drives , ▁the ▁A e   4 / 8 ▁was