Map of the planned route: up & down High Street, from Princes St. to Mornington. Click on the image to enlarge it in a new page. Map

Plan from the 1880s of an original grip car (Hocken collection).
Click image to open a larger version in a new window
Original Grip Car

Plan from the 1880s of the track and cable conduit installation (Hocken collection).
Click image to open a larger version in a new window Contract No 9

3D drawing of road bed, showing the cable conduit, as it was in San Francisco
1800s; in 21st century Dunedin an all-concrete format is the likely plan. Illustration from: The Cable Railways Company's System of Traction Railways for Cities and Towns. San Francisco, California, 1881.

CAD drawings of Mornington car 103
(courtesy Lawrie Cooper, Tramway Historical Society, Ferrymead):

From above
From below
Side on oblique
From above
Wheels, braking, and grip from below
Wheels, braking, and grip from above
From above oblique
From above oblique  
Grip mechanism close up. Two vertical plates, one fixed (the shank) and the other sliding up and down, have lengths of "mild-grade" iron (the rhomboids in light grey) attached at their bases. The cable runs between the two lengths of mild-grade iron. Pulling the grip handle brings the movable plate down, and the two lengths of  mild-grade iron grip the cable, and the car now moves forward.   
Scale model of the grip mechanism. On display at Toitu Early Settlers Museum, Dunedin.  

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, to be housed in the permanent Cable Car Building. 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 alternative possibility would be a single large sheave (of diameter of the distance between the middle of the two tracks), similar to the arrangements in the gondolas and ski lifts of Central Otago.
Sheave set