{{short description|Wheel with articulated rails attached}} thumb|240px|Bottrill's "Big Lizzie" with dreadnaught wheels thumb|240px|Illustration from Bottrill's 1912 patent filing in the United Kingdom A '''dreadnaught wheel''' is a wheel with articulated rails attached at the rim to provide a firm footing for the wheel to roll over. These wheels have also been known as "endless railway wheels" when fitted to road locomotives,<ref name=QuickFarmMachnines /><ref name=gracesguide /> and were commonly fitted to steam traction engines.<ref name="JRASoE_20" /> They are very similar to pedrail wheels, differing primarily in that their rails are not connected to the wheel directly, but articulated to each other.
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 wheels, which spread the weight of the vehicle over a larger surface and hence made it less likely to get bogged by sinking into soft ground or skidding on slippery tracks.<ref name="JRASoE_20" />
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.<ref name="Lane 1971 p. 23" /> Burrell later patented refinements of Boydell's design.<ref name=TheEngineer />
A number of horse-drawn wagons, carts and gun carriages using Boydell's design saw service with the British Army in the Crimean War (October 1853 and February 1856).<ref name=QuickFarmMachnines /><ref name=unusualloco /> The Royal Arsenal at Woolwich manufactured the wheels, and a letter of commendation was signed by Sir William Codrington, the General commanding the troops at Sebastapol.<ref>{{cite book |title=The story of the St. Nicholas Works: A History of Charles Burrell and Sons |first=Michael R. |last=Lane |year=1994 |publisher=Unicorn Press |location=London |isbn=978-0906290071}}</ref><ref name="Boydell artillery wheel">{{cite web |url=https://web.archive.org/web/20171005051153/http://www.users.waitrose.com/~brbeamond/Boydell%20Artillery%20Wheel.pdf |title=Boydell Artillery Wheel |accessdate=2013-09-30}}</ref>
An Australian blacksmith and engineer, Frank Bottrill (1871–1953),<ref name=adbANU /> after a failed endeavour using wheeled traction engines in outback Australia, and becoming aware of the Boydell wheel, decided to improve the design.<ref name=QuickFarmMachnines /><ref name=unusualloco /> 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.<ref name=OzTracIndig /> The most famous was known as "Big Lizzie," built in 1915,<ref name=adbANU /> with a wheel diameter of {{convert|7|ft|2|in|m}}.<ref name=unusualloco /> At {{cvt|34|ft|m|1}} long and {{convert|45|LT|t|disp=preunit||metric|abbr=off}}, with two dreadnought wheeled trailers it was capable of carrying a total of {{convert|80|LT|t|disp=preunit||metric|abbr=off}} and effectively making its own roads.<ref name=QuickFarmMachnines /><ref name="aussietractors" />
Some references<ref name=OzInvent /> also use the term pedrail. The issue is further confused by Bottrill referring to his design as "ped-rail shoes".<ref name=pedrail /> The two concepts are similar in that they attempt to improve cross-country performance by spreading out the load on a flat surface. The difference is primarily in how the pads are connected; the dreadnaught wheel connects the pads to each other and ride along the wheel, whereas in the pedrail arrangement, introduced in 1903, each pad is connected to a pivot on the wheel itself, and there are no inter-pad connections. Some pedrail systems also include internal suspensions to improve their performance over rough ground. Bottrill's design spans the definition, as its cable attachments are similar to the pedrail connections, albeit much more simple.
== References == {{Reflist|30em| refs= <ref name="QuickFarmMachnines">{{cite book |last= Quick |first= Graeme R. |title= Remarkable Australian Farm Machines: Ingenuity on the Land |year=2007 |publisher= Everbest Printing |isbn= 9781877058585 |url= https://books.google.com/books?id=eiqZ7KmeLRMC&dq=dreadnaught+wheel&pg=PA5 |edition=1 |pages=5–8}}</ref>
<ref name="gracesguide">{{cite web |title= Charles Burrell and Sons: Road Locomotive |url=http://www.gracesguide.co.uk/Charles_Burrell_and_Sons:_Road_Locomotive |work= Extract from Steam Locomotion on Common Roads by William Fletcher. Published 1891. |author= William Fletcher |year=1891}}</ref>
<ref name="JRASoE_20">{{cite book | title= Account of the Application of Steam Power to the Cultivation of the Land| first=John Algernon | last=Clarke | work=Journal of the Royal Agricultural Society of England | publisher= Royal Agricultural Society| year=1859| volume=20 | pages= 202–203 | url=https://books.google.com/books?id=S03OAAAAMAAJ&pg=PA202| accessdate=2011-01-24}}</ref>
<ref name="Lane 1971 p. 23">Burrell Showmans Road Locomotives, Lane (1971), p. 23</ref><!--I got this ref from another wikipedia page, can't find where now... -->
<ref name="OzInvent">{{cite book|title=Australian inventors|year=1978|publisher=Cassell Australia|url=https://books.google.com/books?id=fLgAAAAAMAAJ&q=pedrail|isbn=9780726967986|pages=205|author=Leo Weiser Port|author2=Brian Carroll|accessdate=10 February 2013|quote=He called it the Pedrail or Dreadnought wheel.}}</ref>
<ref name="pedrail">{{cite web|title=Improvements relating to Ped-rail Shoes for Heavy Road Vehicles.|url=http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=191208844A&KC=A&FT=D&date=19121017&DB=EPODOC&locale=en_EP|accessdate=11 February 2013}}</ref>
<ref name="unusualloco">{{cite web|title=CHANGES AROUND THE TRACK I (OFF-ROAD LOCOMOTION)|url=https://web.archive.org/web/20190326130959/http://www.unusuallocomotion.com/pages/locomotion/changes-around-the-track-i-off-road-locomotion.html|accessdate=10 February 2013}}</ref>
<ref name="adbANU">{{cite Australian Dictionary of Biography |last=Kendall|first=F.J.|title=Bottrill, Frank (1871–1953)|id2=bottrill-frank-5302 |volume=7, (MUP), 1979|accessdate=10 February 2013|year=1979}}</ref>
<ref name="aussietractors">{{cite web|title=Big Lizzie|url=http://members.ozemail.com.au/~bobkav/aussietractorpage/aussietractors.htm#I|accessdate=10 February 2013|archive-date=24 November 2012|archive-url=https://web.archive.org/web/20121124013936/http://members.ozemail.com.au/~bobkav/aussietractorpage/aussietractors.htm#I|url-status=dead}}</ref>
<ref name=OzTracIndig>{{cite book|title=Australian Tractors: Indigenous Tractors and Self-Propelled Machines in Rural Australia|year=2006|publisher=Rosenberg Publishing|isbn=9781877058394|page=82|url=https://books.google.com/books?id=QaYm2BRTokUC&dq=%22dreadnought+wheel%22&pg=PA81|author=Quick, Graeme R. }}</ref>
<ref name=TheEngineer>{{cite web|title=Burrell's Traction Engine and Carriages|url=https://books.google.com/books?id=P8REAQAAIAAJ&pg=PA26|work=The Engineer, Volume 8, July 8, 1859|publisher=Morgan-Grampian|accessdate=11 February 2013|page=26|year=1859}}</ref> }}
== External links == * [https://books.google.com/books?id=eiqZ7KmeLRMC&dq=dreadnaught+wheel&pg=PA5 Early use in Australia] * [http://www.abc.net.au/dimensions/dimensions_in_time/Transcripts/s870182.htm Transcript of interview regarding Big Lizzie] * {{webarchive |url=https://web.archive.org/web/20170923144546/http://www.4wdonline.com/ClassicTrucks/BigLizzie.html |date=September 23, 2017 |title=Big Lizzie with photo next to a Land Rover 4WD}} * [https://web.archive.org/web/20131002130241/http://www.gracesguide.co.uk/images/8/86/Im1862EnV13-p284.jpg Boydell's Endless Railway] * [https://web.archive.org/web/20120529224958/http://s2.e-monsite.com/2010/05/23/07/resize_250_250//9-James-Boydell-System-during-Crimean-War.jpg Crimean gun carriage] * [http://www.picturevictoria.vic.gov.au/site/mildura/images/14492.jpg "Big Lizzie" hauling wheat] * [http://www.picturevictoria.vic.gov.au/site/mildura/images/13777.jpg One of Big Lizzie's trailers]
Category:Tracked vehicles Category:English inventions Category:British inventions