▁Neg ri - type ▁transmission , ▁except ▁for ▁units ▁▁ 1 9 5 - 1 9 8 ▁and ▁ 1 7 6 - 1 8 3 ▁which ▁had ▁a ▁rub ber ▁t amp ons ▁in ▁place ▁of ▁co il ▁pack s ▁and ▁double ▁h ollow ▁ax le ▁transmission ▁and ▁rub ber ▁t amp ons ▁respectively . ▁ ▁All ▁the ▁following ▁built ▁units ▁had ▁the ▁same ▁transmission ▁type ▁of ▁ 1 7 6 - 1 8 3 ▁but ▁slightly ▁different . ▁ ▁D ifferent ▁locomot ives ▁have ▁received ▁various ▁g ear ▁r ati os ▁( see ▁" Special ▁Units " ▁for ▁more ▁details ): ▁ ▁A ux ili ary ▁and ▁p neum atic ▁services ▁▁ ▁The ▁motor ▁cool ing - f ans ▁were ▁activ ated ▁by ▁two ▁ 4 . 5   k W ▁ 3 , 0 0 0   V ▁dedicated ▁mot ors ▁until ▁unit ▁ 2 0 1 ; ▁later ▁units ▁have ▁ 1   k W ▁mot ors ▁identical ▁to ▁the ▁ones ▁used ▁on ▁F S ▁Class ▁E 6 4 6 ; ▁they ▁are ▁also ▁used ▁as ▁dynam os ▁to ▁re charge ▁the ▁ 2 4   V ▁batter ies ▁( only ▁if ▁line ▁voltage ▁is ▁greater ▁than ▁ 1 , 5 0 0   V ) ▁used ▁to ▁feed ▁low ▁t ension ▁devices ▁( light s , ▁locomot ive ▁he ating ▁systems , ▁contact ors ▁etc .) ▁ ▁Air ▁production ▁on ▁the ▁locomot ive ▁was ▁granted ▁by ▁two ▁C 3 8 ▁type ▁compress ors ; ▁later ▁they ▁were ▁upgrad