Editing 0-4-4-0 (section)

{{Short description|Locomotive wheel arrangement}}
[[File:An 0-4-4-0 of the metre gauge C. de F. de Madagascar.jpg|thumb|An 0-4-4-0 Mallet of the [[metre gauge]] C. de F. de Madagascar. [[Baldwin Locomotive Works]] #44609, built 1916.]]

In the [[Whyte notation]] for the classification of [[steam locomotive]] [[wheel arrangement]], an '''0-4-4-0''' is a locomotive with no [[leading wheel]]s, two sets of four [[driving wheel]]s, and no [[trailing wheel]]s. The arrangement is chosen to give the [[articulated locomotive|articulation]] of a locomotive with only the short rigid wheelbase of an {{whyte|0-4-0}}, but with its weight spread across eight wheels, and with all the weight carried on the driving wheels; effectively a flexible {{whyte|0-8-0}}. Articulated examples were constructed as [[Mallet locomotive|Mallet]], [[Meyer locomotive|Meyer]], [[Berliner Maschinenbau|BMAG]] and [[Double Fairlie]] locomotives and also as [[geared locomotive]]s such as [[Shay locomotive|Shay]], [[Heisler locomotive|Heisler]], and [[Climax locomotive|Climax]] types.{{sfnp|Joy|2012|pages=68–74}} A similar configuration was used on some [[Garratt locomotive]]s, but it is referred to as {{whyte|0-4-0+0-4-0}}. In the electric and diesel eras, the [[Bo-Bo]] is comparable and closest to the Meyer arrangement of two swivelling bogies.{{citation needed|date=April 2024}}

Although rigid [[duplex locomotive]]s were also constructed with pairs of driving axles and the 0-4-4-0 driven arrangement, these were intended for express passenger service and so were given {{whyte|4-4-4-4}} overall arrangements with leading and trailing bogies for stability.{{citation needed|date=April 2024}}

A few Mallet locomotives were built as 0-4-4-0 tender locomotives, mostly by Baldwin for narrow gauge lines, but all others were 0-4-4-0T [[tank locomotive]]s. As one of the main goals of this arrangement was to place the most [[adhesion weight]] on the drivers, it was sensible to include the weight of coal and water with this.