During 1930, Norton motorcycles, a company far more famous for it's road racing machines, produced a dirt-track model for the new sport of speedway. The sport was enjoying a real boom era and most of the British manufacturers tried to produce a machine that would put them in front of the considerable crowds gathered around the cinder ovals.
Norton used a modified version of their ES2 engine and a simple countershaft fitted in a standard sturmey archer gearbox shell. The front forks were Webb speedway items and it was all attached to a modified diamond frame. It was not a success though. Unfortunately for Norton, J.A.Prestwich of Tottenham had launched their legendary speedway motor at around the same time and by August of that year, the J.A.P had become the engine of choice for most speedway riders.
One speedway model Norton was still in regular use into the 1980s as a Wall of Death machine in the Netherlands. The machine was almost original too only missing the stand and the lower chain stays. The owner had also fitted a set of gears into the gearbox shell.
This illustration is taken from my friend Jeff Wilson's photostream on flikr where you will find many more illustrations of vintage dirt track machines. Information taken from "The Pictorial History of Norton Motorcycles" by Jim Reynolds. Published by Temple Press in 1985. (ISBN 1 85152 905 5)