Editing 4-2-0 (section)

{{Short description|Locomotive wheel arrangement}}
{{About||the Kottonmouth Kings song|Rollin' Stoned|other uses|420 (disambiguation)}}
{{Infobox steam wheel arrangement
| name             = 4-2-0 (Jervis)
| image            = WheelArrangement 4-2-0.svg
| alt              = Diagram of two small leading wheels and a single large driving wheel
| caption          = Front of locomotive at left
| image2           = Railway and locomotive engineering - a practical journal of railway motive power and rolling stock (1904) (14760246992).jpg
| alt2             = 
| caption2         = [[Hackensack and New York Railroad]] 4-2-0
<!--Equivalent classifications-->
| hatnote          = 
| UIC/Germany/Italy= 2A, 2'A
| French/Spanish   = 210
| Turkish          = 13
| Swiss            = 1/3
| Russian          = 2-1-0
<!--First tank engine version-->
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<!--First tender engine version-->
| date2            = 1832
| country2         = United States
| locomotive2      = ''Experiment'', renamed ''Brother Jonathan''
| railway2         = [[Albany and Schenectady Railroad|Mohawk and Hudson Railroad]]
| designer2        = [[John B. Jervis]]
| builder2         = [[West Point Foundry]]
| evolvedfrom2     = [[0-4-0]] (US) & [[2-2-2]] (UK)
| evolvedto2       = [[4-4-0]]
| mainbenefit2     = Improved stability
| maindrawback2    = Reduced adhesive weight
<!--First "True type" version-->
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}}

Under the [[Whyte notation]] for the classification of [[steam locomotive]]s, '''{{nowrap|4-2-0}}''' represents the [[wheel arrangement]] of four [[leading wheel]]s on two axles, two powered [[driving wheel]]s on one axle and no [[trailing wheel]]s. This type of locomotive is often called a '''Jervis''' type, the name of the original designer.
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