Today in History - August 2, 1873 - the world’s first cable-powered railroad in San Francisco is tested. The inventor of the cable car was Andrew S. Hallidie (center image above) and contracted by the Clay Street Hill Railroad Company in San Francisco. Hallidie’s system used a continuous looped wire rope that was placed in a tube below the surface of the ground. A motor kept the rope in continuous motion (first image below) and the rope was grasped and released by a griping device on the passenger car and controlled by the “driver”. Bells were used to warn other cars and pedestrians that a cable car was on its way. A code was developed so that the bell could be used to communicate between cable car drivers as well.

Legend has it that Hallidie’s inspiration for the cable car came in 1869 after witnessing horses being whipped while they struggled on the wet cobblestones to pull a horsecar up Jackson Street. When a horse slipped, it was sometimes dragged to its death.

Hallidie’s design was described in the Scientific American Supplement, September 17, 1881 with the title: The Wire Rope Street Railways of San Francisco, California. Hallidie describes how his cable car system operates and the various San Francisco companies (at that time) that had successfully adapted the cable car for their street railway company.

Andrew Smith Hallidie tested the first cable car at 4 o’clock in the morning, August 2nd, 1873, on Clay Street, in San Francisco. For more information, see the San Francisco Cable Car Museum and find out more about how cable cars work, their history and where they operate today. Or check out the Engineering Pathway’s educational resources on cable cars and mass transportation systems.

Cable cars are a great example of the application of simple machines and mechanical advantage. For more information see the Engineering Pathway’s curricular resources and the Mechanical Engineering Education disciplinary community.