An Etymological Dictionary of the German Language/Annotated/schränken
schränken, verb, ‘to cross, entwine, enclose with a railing, limit,’ from Middle High German schręnken, ‘to lay aslant, fence in, plait,’ Old High German skręnchen, ‘to lay aslant, deceive,’ Middle English schręnchen, ‘to cheat.’ The root implied is Teutonic skrank, Aryan skrang (see Schrank), which is identical with the Aryan root skrak appearing in schräg.