The Austrian class U steam locomotives were narrow gauge steam locomotives built in the largest numbers in Europe. 54 units of this 24 metric ton and 7.2 meter / 23 foot 5 inch long locomotive were built from 1894 to 1922 for various narrow gauge railroads in the Austro-Hungary of that time. With a performance of 225 horsepower and its maximum speed of 35 km/h / 29 mph, it fulfilled all of the requirements placed on it. Even today, several of them are used on various museum railroads including road number U2 built in 1900 for the Ziller Valley Railroad, which runs between Jenbach and Mayrhofen in the Tyrol.