The strength of these engines lies in the fact that all wheels, including, in some engines, those under the tender, are driven so that all the weight develops tractive effort. A high ratio of piston strokes to wheel revolutions allowed them to run at partial slip, where a conventional rod engine would spin its drive wheels and burn rails, losing all traction. Shay locomotives were often known as sidewinders or stemwinders for their side-mounted drive shafts. Most were built for use in the United States, but many were exported, to about 30 countries, either by Lima, or after they had reached the end of their usefulness in the US. Classes Approximately 2,770 Shay locomotives were built by Lima in four classes, from , between 1878 and 1945. Class A: two cylinders, two trucks. Weight between . Class B: three cylinders, two trucks. Weight between tons. Class C: three cylinders, three trucks. Weight between . Class D: three cylinders, four trucks. Weight of . These were no more powerful than Class C, but had greater fuel and water capacity, resulting in improved adhesion. Two Shays were built with two cylinders and three trucks. Four Shays, gauge, were built left-handed, all special ordered by the Sr. Octaviano B. Cabrera Co., San Luis de la Paz, Mexico. Survivors 115 Shays survive today, some a combination of parts of two Shays. Herewith a partial list: The Yosemite Lumber Company's #4 Shay is partially restored and is on continuous display at the Sierra Nevada Logging Museum in Arnold, California. It worked at the top of the El Portal Incline, bringing sugar pine logs to the top of the incline, where the loaded rail cars were lowered about 3000 feet in a mile and a half, picked up by a different railroad and taken to the mill. The Arizona State Railroad Museum foundation owns former Anaconda Copper Mining Shay No. 5, which was previously stored in Montana. Although it never operated in the state of Arizona, it was acquired by the ASRM to represent the Shays used by various logging and short line railroads in Northern Arizona, such as the Saginaw and Manistee Lumber Company. It has been displayed by the Grand Canyon Hotel in Williams since 2014. Mount Emily Lumber Company 1 is has been operated by the Oregon Historical Society for several years. Since 2022, Mount Emily Lumber 1 has been owned by the