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Cable railways are steeply graded railways that use a cable or rope to haul trains. The gradient of these lines is typically so steep that a conventional adhesion train could not climb the track. Most commonly the cable is operated by a stationary engine, although other methods such a gravity or water balance are also used.
Many cable railways connect to conventional adhesion lines at their top and bottom, allowing trains to be lifted from a lower line to a higher one. A specific type of cable railway is the funicular which is a self-contained railway, unconnected to another line. This requires the loading and unloading of passengers and goods at both ends.
In the United Kingdom cable railways are sometimes known as "inclined planes" or simply "inclines".
Operation
Normally graded tracks are arranged above and below the gradient to allow wagons to be moved onto the incline either singularly or in short rakes of two or more. On the incline itself the tracks may be interlaced to reduce the width of land needed. This may mean that a single track of two rails or a three-rail track where trains share a common rail. At the centre of the incline there will be a passing loop to allow where ascending and descending trains pass each other (a gantlet track).
Railway workers attach the cable to the upper wagon, and detatch it when it arrives at the other end of the incline. Generally special-purpose safety couplings are used rather than the ordinary wagon couplings. The cables may be guided between the rails on the incline by a series of rollers so that they do not fall across the rail where they would be damaged by the wheels on the wagons.
A few inclines hauled up locomotives using the cable, but these were comparatively rare as it was normally cheaper to provide a separate fleet of locomotives on either side of the incline, or else to work the level sections with horses.
On early railways, cable-worked inclines were also used on some passeneger lines, for example at Cowlairs in Glasgow.
Types
Stationary engine
A stationary engine drives the winding drum that hauls the railroad cars to the top of the inclined plane and may provide braking for descending loads. Only a single track and cable is required for this type. The stationary engine may be a steam or internal combustion engine, or may be a water wheel.
Gravity balance
In a gravity balance system two parallel tracks are employed with ascending tains on one and descending trains on the adjacent track. A single cable is attached to both trains, wound round a winding drum at the top of the incline to provide braking. The weight of the loaded descending cars is used to lift the ascending empties.
This form of cable railway can only be used to move loads downhill and requires a wider space than a stationary engine driven incline, but has the advantage of not requiring external power.
Water balance
This is a variant of the gravity balance incline that can be used to move loads uphill. The weight of the unloaded descending train is increased using water until it is greater than the train travelling uphill. At this point gravity allows the uphill train to ascend. The water is either carried in an additional water wagon attached to the descending train, or is carried in a platform on which the train descends.
This form of incline has the advantages of a gravity balance system with the added ability to haul loads uphill. It is only practical where a large supply of water is available at the top of the incline.
Locomotive hauled
An uncommon form of cable railway uses locomotives to power the cable. The cable is attached to a locomotive, usually at the upper end of the incline. The locomotive is driven away from the head of the incline, hauling wagons up the inclined plane. The locomotive itself does not travel on the steeply graded section.This is most commonly used for a temporary incline where setting up the infrastructure of a winding drum and stationary engine is not appropriate.
Examples
- Cromford and High Peak Railway opened in 1831 with grades up to 1 in 8.
- Liverpool and Manchester Railway
- Opened with cable haulage down 1 in 48 grade to dockside.
- Designed with for cable haulage up and down 1 in 100 grades at Rainhill just in case locomotive haulage was impracticable. Rainhill Trials showed that locomotive could handle 1 in 100 gradients.
- The Welsh slate industry made heavy use of gravity balance and water balance inclines to move slates from quarries down to transhipment points. Examples of substantial inclines were found in the quarries feeding the Ffestiniog Railway, the Talyllyn Railway and the Corris Railway amongst others.
See also
"Cable railway"