Pug

'Pug' locomotives are small steam locomotives which were produced for light shunting work, usually at dockyards, factory sites, steelworks, collieries, and other similar locations. The name is derived from a common term in Scotland for a small industrial shunting engine, typically an 0-4-0 tank. Whilst most commonly used for small shunting engines, on some railways the term 'Pug' was used for all tank engines. For example, the very large Glasgow and South Western Railway 540 Class 4-6-4T express passenger locomotives were known to their enginemen as the 'Big Pugs'. Etymology ‘Pug’ was a Scottish dialect word meaning ‘monkey’, and so inferring an ugly appearance. It is suggested that this led to the term being applied to the short and squat shunting engines. An alternative suggestion is that the name is derived from the small sturdy Pug dog, an ancient and well known breed with a snub nose, wrinkled face, and squarish body. Most pug locomotives were saddle tanks, with an overall appearance that was flat-fronted, and squat or square.