8′ 0″ diam., 18 rectangular spokes, very low inner rim. The tyre does not overlap the wheel center.
Hub 17″ face dia., 6″ out from the tyre.
Sources: drawings by E.W. Twining and by M. Sharman (M. Sharman, The Crampton Locomotive, 1983.)
Casting: 108 mm tread dia., 100.3 mm i/d., hub 7.5 mm allowance above the tyre for skimming to match the thickness of your cam disc. The central boss is cast with a machining allowance on the sides as well as on the top.
Note: the inner faces of the tyres were level with the outer surface of the wheel centres - without any overlap on the front, and so without any step down to the internal diameter of the wheel.
Suitable for the Gauge 3 Society 2010 minimum tyre width of 6.8 mm, or the earlier standard of 8.0 mm.
9 Apr 2013