California which operated with a unique Gravity Mule Car. Mules provided the propulsion on the uphill segment, and a pull-out trailer allowed the mules to ride along for the gravity-powered downhill return. Mule cars operated from 1887 to 1895 when the line was electrified. From 1896 through 1929, steam trains carried passengers up Mount Tamalpais in Marin County, California. In 1902, gravity cars began carrying passengers from the mountain's summit down the twisting single-track railway to the city of Mill Valley and starting in 1907, the first tourists into Muir Woods. Gravity service supplemented the steam train service. The powerful Shay and Heisler geared steam engines of the Mount Tamalpais & Muir Woods Railway then towed the gravity cars back to the summit for the next scheduled run. "Gravities" were kept to a strict speed limit of . On May 3, 2009, the Gravity Car Barn museum opened at the east peak of Mount Tamalpais to display this novel form of transportation. There, a recreated gravity car rolls on of track. Italy The Modena-Sassuolo railway, activated on 1 April 1883, was also known as the "trenèin dal còcc": in the Modenese dialect the "còcc" was the initial impetus to the train departing from Sassuolo, taking advantage of the mild and regular gradient down to Modena. The train could operate down hill at 20 to 30 km/h under the influence of gravity, and returned to the top with a steam locomotive. Other inclined railroads A funicular is not a true gravity railroad, as cars never coast freely and are always connected to a cable. A rack-and-pinion railway or rack railway is also not a true gravity railroad for similar reason. See also Cable railway Lynton and Lynmouth Cliff Railway External links The Shohola Glen Switchback Gravity Railroad The Mauch Chunk Switchback Gravity Railroad References Bibliography Railways by type