A Luttermöller axle is an unusual steam locomotives component. Steam locomotives with several axles or wheelsets connected to one another by coupling rods are not able to negotiate tight curves well. In order to assist such locomotives, the manager of the Orenstein & Koppel factory in Berlin, Dr. Luttermöller, built the axle system named after him.
With this system, the outermost of several sets of successive driving wheel sets are not connected by coupling rods to crankshaft journals on the outside of the wheels, but by cogwheels located in the centre of the axles. The axles are housed in the locomotive frame such that they are able to move at right angles to the axis of the rails to a certain degree, likewise the cogwheels are able to slide relative to one another. In this way curves can be negotiated with less friction being generated.
For the Hamburg Harbour railway with its tight curves, the ten-coupled steam locomotives of Class 87 were built with Luttermöller axles, front and rear. The 16 locomotives of this class were however retired as early as 1954, because they tended to overheat at higher speeds and could therefore only be used for shunting duties.
A five-axled, metre gauge, steam engine with the Luttermöller system was procured by the private South Harz Railway (Südharz-Eisenbahn; Braunlage - Walkenried - Tanne) in 1928 from Orenstein & Koppel with operating number 61. It proved itself so well on the winding route, that in 1930 two Mallet locomotives, built in 1925, were converted to the Luttermöller system by Henschel (operating numbers 56 and 57). Henschel had to obtain a licence from Orenstein & Koppel to use Luttermöller axles.