Reading 2-6-4 No. 306.
(Unknown, W. Lenheim Collection)
2-6-4 ADRIATIC WHEEL ARRANGEMENT
Under the Whyte notation for the classification of steam locomotives, a 2-6-4 locomotive has two leading wheels, six coupled driving wheels and four trailing wheels.
Schematic of the 2-6-4. Front of locomotive on left.
(Gwernol, Public domain, via Wikimedia Commons)
Overview
With only a few known exceptions, the Adriatic wheel arrangement was usually used on tank locomotives, for which various suffixes to indicate the type of tank would be added to the wheel arrangement, for example 2-6-4T for an engine with side-tanks.
Tender locomotives
The earliest known example was the South African Class 6Z, designed by Cape Government Railways (CGR) Chief Locomotive Superintendent Hazlitt Beatty in 1901. The first engines of the class were modified 2-6-2 Prairie locomotives which were equipped with two-axle trailing bogies. In 1902, more were placed in service, but built with the 2-6-4 wheel arrangement. The latter were the first known tender locomotives in the world to be built with this wheel arrangement.
Philadelphia and Reading 2-6-4T No. 381, side view.
(Unknown, via W. Lenheim Collection)
Tank locomotives
Tank engines with the 2-6-4T wheel arrangement were produced for many different railway systems worldwide and were mainly used for freight and suburban passenger working. They have been less successful on express passenger trains. The earliest known example also originated in South Africa, the Pretoria-Pietersburg Railway's 55 Tonner of 1898.
Equivalent classifications
UIC class: 1C2, 1'C2'
French class: 132
Turkish class: 36
Swiss class: 3/6
Russian class: 1-3-2
First known tank engine version
First use: 1898
Country: South Africa
Locomotive: PPR 55 Tonner
Railway: Pretoria-Pietersburg Railway
Designer: Beyer, Peacock & Company
Builder: Beyer, Peacock & Company
First known tender engine version
First use: 1901
Country: Cape of Good Hope
Locomotive: CGR 6th Class 2-6-4
Railway: Cape Government Railways
Designer: Hazlitt Beatty
Builder: Neilson, Reid & Company
Evolved from: 2-6-2
