Tender Locomotives 4-8-2 “Mountain”

The wheel arrangement 4-8-2 designates a steam locomotive that has a two-axle leading bogie, four coupled axles and a trailing axle. In different countries, this wheel arrangement is referred to as follows:

Mountain

UIC: 2'D1'

Whyte: 4-8-2

Switzerland: 4/7

France: 241

Turkey: 47

The main features of the Mountain were good guidance at speed due to the two-axle leading bogie/truck and a large firebox above the trailing axle that provided a high sustained steam production. While the first 4-8-2T tank locomotives were already built in the late 19^th century, the first 4-8-2 tender locomotives were only created in 1906.

Like the first 4-8-2T, the first 4-8-2 was also introduced in Natal, South Africa. This was the NGR class B, originally built as 4-8-0. After it was found out that these locomotives had a bad running stability due to the big overhang at the rear, D.A. Hendrie fitted a trailing Bissel axle to six locomotives. The first new built 4-8-2 was the NZR class X of 1908 that still had its firebox above the rear driving axle. 

A new NGR class B was introduced in 1909 that had its firebox behind the last driving axle. This allowed to fit a larger ash pan and grate, what led to a considerable increase in power. Soon the 4-8-2 became the most successful wheel arrangement in South Africa. Several classes were introduced over the years which grew heavier and heavier and soon were more powerful than earlier Garratts. This ultimately led to 255 locomotives of the class 15F and 235 of the class 19D, both introduced in the late thirties. They were mainly used as freight locomotives, but also had to haul heavy passenger trains.

In the USA, the wide firebox 4-8-2 was used where Pacifics were not powerful anymore for heavy passenger trains. The Chesapeake & Ohio was the first railroad in this country to introduce this wheel arrangement in 1911. Since their class J-1 was used to traverse the Allegheny Mountains, they chose the name “Mountain” for this wheel arrangement. Over the next decades, US railroads received around 2,200 Mountains. Their largest operator was the New York Central which called them “Mohawks” and ordered a total of 600. Others used them mainly in fast freight service, like the Pennsylvania Railroad with their 301 class M1 and M1a locomotives.

Another country where many 4-8-2 locomotives were used in fast freight service was Australia. In Europe, the 4-8-2 was a heavy express locomotive. French railways used a total of 275 of these types, there called 241. Many of these were four-cylinder compounds. Also Spain called this type 241 and more than 200 were ordered by several Spanish railways. Other European countries which successfully used 4-8-2 express locomotives were Bulgaria and Czechoslovakia. In Britain, where eight-coupled locomotives were usually used for heavy goods trains, the only two 4-8-2 locomotives were narrow gauge. 

The most important successor of the 4-8-2 was the 4-8-4 “Northern” that had a larger firebox thanks to the two-axle trailing truck. For use in heavy and fast freight service, some railroads ordered the 4-10-2 that was like a 4-8-2 with an additional driving axle. But the 2-10-4 was more successful and had been derived from the 2-8-4 “Berkshire”.