▁the ▁r he ost at ▁which ▁has ▁to ▁be ▁ex cluded ▁again , ▁for ▁the ▁following ▁combinations ▁until ▁the ▁end ▁of ▁the ▁parallel ▁combination ▁is ▁reached . ▁ ▁The ▁sh un ts ▁increase ▁the ▁current ▁into ▁the ▁mot ors ▁by ▁sh un ting ▁some ▁motor ▁sp ires ▁( through ▁a ▁contact or ▁in ▁parallel ); ▁this ▁reduces ▁the ▁magnetic ▁flux ▁and , ▁as ▁said , ▁increases ▁the ▁current ▁( since ▁the ▁two ▁are ▁in vers ely ▁proportional ). ▁There ▁are ▁various ▁" sh unt ▁levels ", ▁depending ▁on ▁the ▁locomot ive , ▁as ▁is ▁further ▁explained ; ▁usually , ▁there ▁is ▁one ▁per ▁combination . ▁ ▁It ▁is ▁also ▁important ▁to ▁remove ▁the ▁sh un ts ▁before ▁making ▁a ▁transition , ▁in ▁order ▁to ▁avoid ▁flash es ▁due ▁to ▁ab norm ally ▁high ▁curr ents . ▁ ▁Like ▁some ▁E . 6 2 6 s , ▁E . 6 3 6 ▁locomot ives ▁are ▁not ▁provided ▁with ▁the ▁" CE M " ▁motor ▁combin er ▁( CE M ▁stands ▁for ▁Com bin atore ▁Es clud itore ▁Mot ori ), ▁a ▁device ▁that , ▁during ▁trans itions , ▁rot ates , ▁combining ▁the ▁mot ors ▁accordingly ▁through ▁various ▁contact ors . ▁ ▁On ▁E . 6 3 6 , ▁this ▁is ▁achieved ▁through ▁the ▁uses ▁of ▁more ▁del icate ▁sp ires , ▁so ▁trans itions ▁( es pecially ▁back ward ▁ones ) ▁need ▁to ▁be ▁very ▁slow ▁and ▁grad ual . ▁The ▁optimal ▁moment ▁to ▁pass ▁to ▁the ▁following / pre ced ing ▁combination