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A dreadnaught wheel is a wheel with articulated rails attached at the rim to provide a firm footing for the wheel to roll over, they have also been known as endless railway wheels when fitted to road locomotives,〔〔 and were commonly fitted to steam traction engines .〔 Prior to wide adoption of continuous track on vehicles, traction engines were cumbersome and not suited to crossing soft ground or the rough roads and farm tracks of the time. The "endless rails" were flat boards or steel plates loosely attached around the outer circumference of the wheel which spread the weight of the vehicle over a larger surface and hence were less likely to get bogged by sinking into soft ground or skidding on slippery tracks.〔 Some references〔 also use the term pedrail, but the pedrail wheel of 1903 is a more complex arrangement that incorporates internal springing. Bottrill referred to the rails as "ped-rail shoes".〔 An early version was patented by James Boydell in August 1846 and February 1854. Boydell worked with the British steam traction engine manufacturer Charles Burrell & Sons to produce road haulage engines from 1856 that used his continuous track design.〔 Burrell later patented refinements of Boydell's design.〔 Boydell's design saw service with the British Army in the Crimean War where it was known as "The Megatherium war horse".〔〔A number of horse-drawn wagons, carts and gun carriages were successfully deployed in the Crimean War, waged between October 1853 and February 1856, the Royal Arsenal at Woolwich manufacturing dreadnaught wheels. A letter of recommendation was signed by Sir William Codrington, the General commanding the troops at Sebastapol.〔(【引用サイトリンク】title=Boydell Artillery Wheel )〕 An Australian blacksmith and engineer, Frank Bottrill (1871-1953),〔 after a failed endeavour using wheeled traction engines in outback Australia, and becoming aware of the Boydell wheel, decided to improve the design.〔〔 In 1907 he patented an "improved road wheel for travelling, useful for traction engines". Bottrill's design used two rows of overlapping rails fastened to the rim with cables to smooth the transition from rail to rail. Eventually Bottrill, in association with A. H. MacDonald & Co. of Richmond Melbourne, began producing steam and oil-based tractors fitted with his wheels.〔 The most famous was known as "Big Lizzie" built in 1915〔 with a wheel diameter of 7' 2" (2.2m).〔 At 34 feet (10.4m) long and 45 tons (46 tonnes); with two dreadnought wheeled trailers, it was capable of carrying a total of 80 tons (81 Tonnes) and effectively making its own roads.〔〔 == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dreadnaught wheel」の詳細全文を読む スポンサード リンク
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