Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 4-6-0+0-6-4 is a Garratt articulated locomotive. The wheel arrangement is effectively two 4-6-0 ten-wheeler locomotives operating back to back, with the boiler and cab suspended between the two swivelling power units. Each power unit has two pairs of leading wheels in a leading bogie, followed by three coupled pairs of driving wheels and no trailing wheels.
A similar wheel arrangement exists for Mallet type locomotives, but is referred to as 4-6-6-4. On a Mallet locomotive, only the front engine unit swivels while the rear unit is rigid in relation to the main frame.
This was a rare wheel arrangement for Garratt locomotives, with only seven locomotives built for two South American customers.
- The first was for the metre-gauge Mogyana Railway of Brazil, with five examples built by Beyer, Peacock and Company in 1912 and 1914.
- The other was two locomotives built for the 3-foot gauge Ferrocarril Pacifico de Colombia by Armstrong Whitworth in 1924.
|3 ft||Ferrocarril Pacifico de Colombia||565-566||2||1924||Armstrong Whitworth|
|1,000 mm||Mogyana Railway, Brazil||5529-5530||2||1912||Beyer, Peacock|
|1,000 mm||Mogyana Railway, Brazil||5787-5789||3||1914||Beyer, Peacock|
- Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives produced by Beyer, Peacock, retrieved 10 November 2012
- Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives from Other Builders, retrieved 10 November 2012