ASME-Landmark:Paddle Streamer Uri

Steam navigation on Switzerland's Lake Lucerne opened in 1837. At that time, the predominant design for steamboats on European lakes and rivers included two side paddle wheels driven by an oscillating-cylinder engine. With no crossheads and piston rods directly attached to the crankshaft, steam pressures on these ships were low, generally less than 4 atmospheres, requiring oscillating-cylinder engines to have large-diameter cylinders, which made them bulky and slow.

A new engine design for inland steamers, known as the diagonal compound engine, was introduced during the late nineteenth century, and the paddle steamer Uri is powered by the oldest surviving example (1901). These engines feature crossheads—joints between the piston rods and the main rods to the crankshaft—and non-oscillating cylinders. By eliminating the leak-prone trunion bearings and steals, steam pressure could be raised—to 9 atmospheres on the Uri—increasing the efficiency of the power plant considerably. The diagonal engine can also be compounded. The Uri's engine has cylinder diameters of 720 mm and 1050 mm, with a stroke of 1300 mm and a production of 650 HP. This basic design was repeated for engines up to 1450 HP on numerous lake and river steamers in central Europe.

Uri has remained in service since 1901, with only brief absences due to upgrades and maintenance. In September 207, at 106 years old, Uri surpassed the 2 million kilometer mark to much fanfare in Switzerland. See ASME website for more information