A 4-4-2+2-4-4, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a Garratt articulated locomotive. The wheel arrangement is effectively two 4-4-2 locomotives operating back to back, with each power unit having four leading wheels on two axles in a leading truck, four powered and coupled driving wheels on two axles, and two trailing wheels on one axle in a trailing truck. Since the 4-4-2 type is usually known as an Atlantic, the corresponding Garratt type is often referred to as a Double Atlantic.
Other equivalent classifications are:
This was not a common Garratt wheel arrangement. Only ten were built by Beyer, Peacock and Company, owner of the Garratt patent, and none by any other builder.
Most of them were built for Argentina to run on 4 ft 8 1⁄2 in (1,435 mm) standard gauge. Five of these were for the Entre Ríos Railway (Ferrocarril Entre Ríos, FCER) in 1927 and three more for the Argentine North Eastern Railway (Ferrocarril Nordeste Argentino, FCNAR) in 1930. After nationalization in 1948 all of them eventually ended up on the Ferrocarril General Urquiza.
The first to be built to this wheel arrangement were a pair for the Tasmanian Government Railways in Australia. These were to 3 ft 6 in (1,067 mm) gauge.