Gravity railroad
From Wikipedia, the free encyclopedia
A gravity railroad is a railroad on a slope that allow cars carrying minerals or passengers to coast down the slope by the force of gravity alone. The cars are then hauled back up the slope using animal power or a stationary engine and a cable or chain. The speed of the cars is controlled by braking mechanism on one or more cars on the train. The typical amusement park roller coaster is designed from gravity railroad technology.
Some gravity railroads were designed to allow the weight of the descending loaded cars to lift the empty cars back up to the top, using a cable looped around a pulley at the top for a portion of the line. A later revision designed by John B. Jervis, used two separate tracks known as the loaded or heavy track going down hill, and the light track, used to haul the empty cars back to the top. This method allowed cars to travel in one direction without the need for passing sidings. A stationary steam engine and a looping cable were used to raise the empty cars up the lift planes. The cars then coasted down a slight grade to the next lift plane. When cars reversed direction at the ends of the line on a switch or turnout, the railroad was known as a switchback gravity railroad.
A funicular is not a true gravity railroad, as cars never coast freely and are always connected to a cable. A cog railway, rack-and-pinion railway or rack railway is also not a true gravity railroad for similar reasons.
[edit] Examples
The Festiniog Railway in northwest Wales, UK, was built in 1832 to carry slate from quarries high in the hills to the sea at Porthmadog. The line was laid out for the wagons to descend by gravity, while horses were originally used to haul the empty wagons up the hill. Later on, steam haulage was adopted. This narrow gauge railway is still operational.
In the United States, The Delaware and Hudson Canal Company operated extensive gravity railroad system from 1828 until 1898. With 22 separate lift planes, the 55 mile Pennsylvania Coal Company Gravity Railroad, was the longest and operated until 1885. A portion of the railroad was purchase in 1886 by the recently constructed, 1882, Shohola Glen Summer Resort and used until 1907. The Mauch Chunk Gravity Railroad hauled coal and passengers from 1827 until 1933, and might possibly be restored.
