K1 is an 0-4-0+0-4-0 articulated Garratt locomotve, one of a pair built in 1909 by Beyer Peacock for the North-East Dundas Tramway in Tasmania. This unique and very special locomotive holds a special place in the hearts of WHR supporters. In this section of the website we'll give an insight into the history of this facinating locomotive from when it was built right up to to the present day.
What is a Garratt?
The Garratt is a type of articulated steam locomotive. This means that unlike a conventional locomotive, where the whole machine is carried on a single set of rigid frames, a Garratt has three separate frames. The power units, front and rear, each have running gear much like a smaller conventional locomotive; the boiler frame is pivoted between the power units, and carries the boiler and cab. Water tanks are carried on both power units, with the rear one also carrying the fuel supply. The design allows for a much larger boiler than can be carried on a conventional locomotive of the same gauge, and the articulation means the engine can traverse relatively tight curves. The design found particular favour in Africa, where engines such as the East African Railways 59th Class (metre gauge) and the South African Railways GMAM Class (3' 6" gauge) were among the largest steam locomotives ever built, despite their narrow gauges.
The name "Garratt" derives from the engineer Herbert William Garratt, who devised the type, and developed it in association with the Manchester firm of Beyer Peacock, which built most of the Garratts used around the world - including all but one of those in use on the Welsh Highland. Following the expiry of Garratt's patent in 1928, Beyer Peacock no longer had exclusive rights to build Garratts, or to licence other firms to build them. The firm thus termed all the Garratts it built subsequently as "Beyer-Garratts", to distinguish them from locos built by other firms. Thus K1 should properly be termed a Garratt, and the later South African NGG16 class in use on the Welsh Highland comprises Beyer-Garratts.
K1's Technical Details
| Length over frames | 32 feet 2 inches |
| Wheel arrangement | 0-4-0 + 0-4-0 T |
| Total wheelbase | 26' 9" |
| Wheelbase of each power unit | 4' 0" |
| Wheel diameter | 2' 7.5" |
| Total heating surface | 628 square feet |
| Heating surface of tubes | 568 sq. ft.* |
| Heating surface of firebox | 60 sq. ft.* |
| Grate area | 14.8 sq. ft. |
| Boiler pressure | 195 pounds per sq. inch* |
| High-pressure cylinders (x 2) | 11" diameter, 16" stroke |
| Low-pressure cylinders (x 2) | 17" dia., 16" stroke |
| Valvegear | Walschaert |
| Tractive effort @ 85% pressure | 16,290 lb. |
| Water capacity | 840 gallons |
| Weight in working order | 33.5 tons (approx). |
* Note: This figure is for the original boiler unit
Much more information and further reading on the Garratt type of locomotive can be found on Gavin Hamilton's The Garratt Locomotive site.
More background to Herbert William Garrat can be found in Wikipedia.