The Stockton & Darlington Railway Hackworth Bookmark

Timothy Hackworth designed the plugwheel which went on to be used on the Royal George (1827) and on nearly every other engine on the Stockton & Darlington Railway and other railways for many years. It was cast iron with wrought iron tyres shrunk on; Hackworth was the first to apply the wrought iron tyre to a wheel. The wheels were made up in parts as there were no lathes in the Shildon workshops, where Hackworth worked, large enough to turn up the rims when fixed upon the axle. The centre part or ‘boss’ was machined true, and the outer rim trued by the centre and made tight by wooden plugs and iron wedges. They were dotted with curious plug holes (hence the name plug wheel) to ensure sound castings and reduce unnecessary weight, and in practice were found extremely efficient. (Source: Timothy Hackworth and the Locomotive by Robert Young 1923).