The class 1200 locomotives can be characterized by their side vents, which were used in three different versions. The purpose of these vents was on the one hand air to cool the traction motors and to allow drive train resistance, and the other to prevent too much dirt and dust getting into these motors. The six and two part air conditioning vents, which had replaced the original three, two, and single piece side vents starting in 1955, worked in one respect too well! They filtered the air so efficiently that the cleaning intervals became very short. In an extensive test procedure, the single piece vents "Krap and Lex" prevailed.
Prototype: Dutch State Railways (NS) class 1200 electric locomotive. Road number 1220. The locomotive looks as it did in the mid-Seventies.