Garratt
The design Garratt is a special type of steam locomotives with two separate engine units, which carries through a bridge frame, the boiler and cab are connected.
The name Garratt goes back to engineer Herbert William Garratt, who developed this type of locomotives together with the Beyer, Peacock & Co. in Manchester. The first Garratt, the TGR- class K of the Tasmanian Government Railways, was delivered in 1909 for the North - East Dundas Tramway in Tasmania.
Technical Features
The Garratt steam locomotive was developed under the requirement applied to tracks with a light superstructure and tight bends enough traction for heavy trains. These Garratts were built with two separate chassis, each with its own steam engine. The front suspension was fitted under a preceding vehicle frame with water tank, rear suspension under the rear tender with another water tank and the fuel tank. The boiler including the cab leaning on a bridge-like frame with the ends of which pivot from the two suspensions. Because of this construction, and due to the deep basin- thereby benefiting the boiler can be optimized freely and without disabilities by driving wheels and frame components with respect to thermal and maintenance technical characteristics:
- Large diameter, numerous and close the heating tubes in the superheater
- Depth firebox free and open ashtray
- Allseits just firebox walls, thereby advantages in production and maintenance
The types Mallet and Meyer are with respect to these characteristics comparatively at a disadvantage. The problem with Garratt - equipment because of the water tank on the front drive access to the smoke chamber and the boiler tubes, therefore the water tank is either provided with a niche for swinging the smoke box door or a sufficiently large distance between the boiler and the front water tank available. The distance view of the staff is by design limited.
Due to the particularly favorable and thermally effective boiler construction of the Garratt design that is also possible especially in tight clearance profiles, as well as by the favorable distribution of the mass of the vehicle on many axes and a great length and, not least, compared to other joint structures excellent running properties, the construction of high-performance machines with low axle load possible. In particular, they proved themselves to built with little effort routes in the former African colonies. Disadvantages are the necessary mobile steam lines and the fluctuating operating friction load, which does not occur in this form in a Tender locomotives generally design.
The success of the Garratts made at Beyer- Peacock for planning of super Garratts each with a mallet thruster pair under each tender. The patent was granted, the machine but never got beyond the planning phase out.
Areas of application
Garratt locomotives were widespread, especially in Africa, Asia, Australia and Brazil.
In Europe, it was only in Spain a greater use of different inventory Garratt designs. After all, 33 Garratt locomotives were used by the London, Midland and Scottish Railway under the name LMS Garratt in heavy freight traffic.
The main producer was Beyer, Peacock & Co., followed by the name Beyer- Garratt explains commonly used. Sublicense or after expiration of the patent, they were built by other manufacturers, including at Henschel & Sohn in Kassel, Cockerill -Sambre in Liège, Euskalduna and Babcock & Wilcox in Spain.
Today Garratts are mainly on museum railways in use. In Europe, in particular the Welsh Highland Railway is known for their commitment inventory of three to four Garratts, and in Switzerland the Schinznacher Baumschulbahn ( Their Garratt locomotive gave it as LGB model). The National Railways of Zimbabwe, however, put a few copies in shunting a commercial. The Ferrocarril Austral Fueguino in Tierra del Fuego has two 1994 and 2006 newly built 500 mm narrow gauge Garratt type FCAF class KM in operation.