4-2-0

First known tender engine version
First known tender engine version
First use	1832
Country	United States
Locomotive	Experiment, renamed Brother Jonathan
Railway	Mohawk and Hudson Railroad
Designer	John B. Jervis
Builder	West Point Foundry
Evolved from	0-4-0 (US) & 2-2-2 (UK)
Evolved to	4-4-0
Benefits	Improved stability
Drawbacks	Reduced adhesive weight

Equivalent classifications
Equivalent classifications
UIC class	2A, 2'A
French class	210
Turkish class	13
Swiss class	1/3
Russian class	2-1-0

4-2-0 (Jervis)
	Front of locomotive at left
	Hackensack and New York Railroad 4-2-0
UIC class
Equivalent classifications
UIC class	2A, 2'A
French class	210
Turkish class	13
Swiss class	1/3
Russian class	2-1-0
First use
First known tender engine version
First use	1832
Country	United States
Locomotive	Experiment, renamed Brother Jonathan
Railway	Mohawk and Hudson Railroad
Designer	John B. Jervis
Builder	West Point Foundry
Evolved from	0-4-0 (US) & 2-2-2 (UK)
Evolved to	4-4-0
Benefits	Improved stability
Drawbacks	Reduced adhesive weight

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