The Pamphlet Collection of Sir Robert Stout: Volume 8
|1st.||Tramways worked by compressed air engines.|
|2nd.||The centre-rail system to allow of friction wheels.|
|3rd.||The endless wire rope system, worked with stationary engines.|
The first method has not yet been sufficiently worked to allow of an estimate being formed of its suitability for street traffic, or of the expenditure involved in its construction and expense of working.
The Centre-rail System was adopted in the Mont Cenis Railway, but owing to the complications involved in the construction of the locomotive, and its liability to be thrown out of gear, it is questionable whether it could be adopted profitably as a permanent mode of transit. Another objection to this system would be the position of the centre rail, which would require to be elevated above the level of the street, and this would interfere with the ordinary traffic.
The third method is now in use in San Francisco, California, where three lines are laid down in different parts of the city. It has worked admirably, and financially is a great success.
It appears to us that this last system is the most practicable, and will be most suitable for working the steep incline. Such being the case a brief description of the modus operandi will be sufficient in the meantime to convey a fair idea of the general working arrangements.
An endless wire rope, lin. in diameter is laid down on the incline between any two fixed points, and is weighted at page 5 one end so as to keep it always in the proper tension. The rope is supported on sheaves fixed in iron or timber tubes, laid below the ground. These tubes are made with a continuous slot which runs the whole length, to admit of the connection with the car. The wire rope is made to revolve continuously during the hours the line is open for traffic, by means of a stationary engine fixed at either end of the incline. The tramway has a double line of rails, and the tubes are fixed in the centre of each line. The whole of the permanent way is laid below the surface of the ground so that ordinary dray traffic will not be interfered with.
The working of the cars may be described as follows:—A traction car or dummy is constructed which takes the place of a locomotive and to this the passenger car is coupled. The dummy is connected to the wire rope by an arm projecting downwards through the slot in the tube and carrying at its lower end a gripping cast iron jaw; this jaw can be made by the car conductor to grip the wire rope, which then draws the dummy with the car attached to it. On releasing the grip the dummy is free of the rope and can be brought to a standstill by the brake, so that cars can be stopped and started at any portion of the incline, for the purpose of taking up and letting down passengers. The dummy and car are provided with brakes, which can be applied instantaneously, doing away with almost any liability to accident.
The working of the cars is so arranged that an equal number are travelling up and down on the incline at the same time, thus reducing the amount of power that would otherwise be required from the stationary engine.