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Plan from the 1880s of an original grip car (Hocken collection).
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Inner workings of a cable car. This is a Roslyn car (such as Car 95), which had an additional brake mechanism, a "Fell brake", which clamped onto a third rail on the Roslyn line (none such on High Street, and so the Fell brake on Car 95 is now locked in position). Drawing from Don McAra's book Hold Very Tight Please! The Cable Cars of New Zealand (Grantham House, 2007). Reproduced with the kind permission of Don McAra, without whose dedication over many years we would not now have the cable cars in the Mornington Interim Cable Car Building.
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Plan from the 1880s of the track and cable conduit installation (Hocken collection).
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3D drawing of road bed, showing the cable conduit, as it was originally in San Francisco, and had been similarly in Dunedin (above). Illustration from: The Cable Railways Company's System of Traction Railways for Cities and Towns. San Francisco, California, 1881.
When San Francisco renewed their system in 1982-84, the tracks were completely replaced, and set in concrete. It is likely a similar format will apply in Dunedin, when our service is reinstated. Photo of July 1983 from Steve Morgan, Wikimedia.
The "Pull Curve" was Dunedin's important contribution to Cable Car technology, invented in 1881 by George Duncan, and which enabled cars to take a curve. A pull curve will be (re)installed on the Mornington line, where High Street turns into Eglinton Road. Drawing from Don McAra's book Hold Very Tight Please! The Cable Cars of New Zealand.
Video: A worm's eye view of the grip mechanism and the cable
A camera placed below street level, actually in the cable conduit, with the cable continuously running, on one of the San Francisco lines. Every now and then, a cable car arrives, with its grip mechanism sitting on either side of the cable. When the grip lever is pulled, the jaws of the grip come together, and clamp upon the sides of the cable. The sparks are due to the friction of the soft iron of the jaws as they grasp the steel of the cable; once the contact is complete and the car is running at cable-speed (15.3 km/hr), there is no more friction. Unsurprisingly, the soft iron needs frequent replacement. The style of the Mornington grip will probably be a little different, with the clamping imposed vertically on the cable; see the CAD picture further down.
Click photo for YouTube video of a view from within the conduit, as the cars release and grip the cable.
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CAD drawings of Mornington car 103
(courtesy Lawrie Cooper, Tramway Historical Society, Ferrymead):
Scale working model of the Dunedin cable car grip mechanism, which is on display at Toitū Early Settlers Museum, Dunedin. The larger lever controls the central sliding plate, which, when in the raised position (as it is in this view, the handle at full stretch), grips the cable. The horizontal bar is the point of attachment to the car chassis. 
The central chassis of Car 103 under reconstruction with the Tramway Historical Society at Ferrymead. Note the ironwork in the middle, which will house the grip and brake mechanisms, and the axle attachments (no springs on these cars!) on the next beam.
Format of the cable winding apparatus which powers the San Francisco cable cars (from Watermusic in the Track. A History of San Francisco Cable Cars, Mike Phipps & Don Holmgren, publ. Friends of the Cable Car Museum, San Francisco, 2012). An analogous format, using large-diameter sheaves, applied during the first Mornington period (1883-1957), and the photo (kindly provided by Graham Stewart) shows the Roslyn system in operation. The format for the second Mornington period (2020s-forever) will be determined following expert advice..jpg)
