A cable tram is a type of tram which is hauled along its tracks by means of an underground cable.
Below the tracks of a cable tram line is a tunnel, open to the surface midway between the rails via a narrow slot. Inside the tunnel runs a cable, carried on a series of pulleys. The cable is leaves the tracks at a "winding house", where engines continually pull the continuous cable through the tunnels. Trams have a "grip" mechanism that extends through the slot in the ground and into the tunnel. On the end of this grip mechanism is the grip itself, operated from within the tram, which grabs and releases the cable as necessary. When the cable is gripped, it pulls the tram along at a steady speed. When the cable is released and brakes applied, the tram slows and stops. By this means, the tram stops where required for passengers to board and alight, but is otherwise moved along the tracks to make its journey.
The cable also has to be released when travelling around some curves and when crossing some other cable tram lines. Initially, cable trams would coast around curves, while the cable would pass around a large horizontal pulley. This led to problems when the trams had to brake unexpectedly, and sometimes the passengers would have to get out and push. However, the first Dunedin line (see below) had a case where the tram was climbing a hill while going around a curve, and coasting was not practicable, so George Duncan, the engineer in charge of the Dunedin cable tram, devised a method involving multiple horizontal pulleys following the line of the curve.
Where cable lines crossed, one cable had to pass below the other, and trams on this route had to release the cable and coast across, grabbing the cable again on the other side of the crossing.
The first cable tram line was opened in San Francisco in 1873 by engineer Andrew Smith Hallidie. Eight years later engineer George Smith Duncan opened a line in Dunedin, New Zealand, based on Hallidie's line in San Francisco, and the first to be built outside America and the last to be closed apart from San Francisco's. Like San Francisco, the Dunedin line was built to operate on the steep hills of that city.
Duncan moved to Melbourne in 1883 at the invitation of Francis Boardman Clapp, who planned to introduce cable trams to Melbourne. Duncan then became responsible for constructing the Melbourne cable tram network, one of the largest in the world, and the largest under a single operator.
Cities with cable trams
The following table has a partial list of cities with cable trams.
|City||First opened||Last closed||Number of routes|
- Cable Car Home Page by Joe Thompson.