Krauss-Helmholtz bogie

In this way radial forces during curve running are more or less evened out on both axles, so that riding qualities similar to those of a normal bogie are achieved and wear and tear reduced on wheel flanges and rails.

The bogie is a type of pony truck and was named after the locomotive firm of Krauss and the engineer, Richard von Helmholtz.

Because the advantages of a pony truck come into play particularly on tight curves, the Krauss-Helmholtz bogie initially appeared on branch line, Lokalbahn and narrow gauge locomotives.

Later this pony truck arrangement was also adopted by the DRG standard locomotives (Einheitslokomotive) of the Deutsche Reichsbahn, e.g. on the ten-coupled classes: 44, 45, 50 and 85.

Even the electric locomotives of Reichsbahn classes E 04, E 17, E 18 and E 19 were fitted with comparable pony trucks, known as AEG frames (AEG-Gestell).