SAR class GMA / GMAM
| SAR class GMA / GMAM | |
|---|---|
 GMAM No. 4117 in Vryburg station, South Africa
|
|
| Numbering: | 4051-4170 |
| Number: | 120 |
| Manufacturer: | Henschel , Beyer-Peacock , North British |
| Year of construction (s): | 1952-1958 |
| Retirement: | 1980s – 1990s |
| Type : | (2'D1 ') (1'D2') h4 (Garratt) |
| Gauge : | 1067 mm ( cape track ) |
| Length over coupling: | 28,750 mm |
| Service mass: | 190.4 / 194.8 t |
| Friction mass: | 120 / 122.7 t |
| Wheel set mass : | 15.2 / 15.6 t |
| Driving wheel diameter: | 1,371 mm |
| Impeller diameter: | 762 mm |
| Cylinder diameter: | 520 mm |
| Piston stroke: | 660 mm |
| Boiler overpressure: | 138 N / cm² |
| Grate area: | 5.9 m² |
| Radiant heating surface: | 22.39 m² |
| Tubular heating surface: | 276.3 m² |
| Superheater area : | 69.4 m² |
| Train brake: | Suction air brake |
The vehicles of the class GMA / GMAM of the South African Railways (SAR) are articulated locomotives of the Garratt design . With a built number of 120, it is by far the most numerous Garratt type in the world. Together with the predecessor class GM with the same performance , the GMA / GMAM are among the five most powerful steam locomotive designs that have been used in the southern hemisphere. The GMAM class can take more supplies with it than the GMA class, but is otherwise structurally identical to this one.
history
55 of the locomotives came from Henschel , 33 from Beyer-Peacock and 32 from North British Locomotive Works (NBL), the latter being a subcontract from Beyer-Peacock to NBL.
The locomotives of the GMA / GMAM class were distributed all over South Africa and on many routes were the last state of steam traction before the introduction of diesel and electric locomotives.
They came as general purpose locomotives before coal trains - often schedule in preload operation - used as well as passenger trains. GMA / GMAM had the largest inventory of 74 pieces at the depot in Pietermaritzburg , from where the machines were needed for operation on the heavily trafficked branch lines to Franklin and Greytown , both of which had gradients of up to 33.3 ‰. Here, too, pre-tensioning operations were necessary before long trains, whereby the GMA / GMAM were also used together with Garratts of the GCA and GF classes . Some even steeper gradients had to be mastered on the Lootsberg Pass between Rosmead and Graaff-Reinet and on the Montague Pass between Oudtshoorn and George, typical areas of application for the GMAMs.
In 1979, 21 locomotives were leased to the National Railways of Zimbabwe (NRZ) and at the end of 1980 another eight to the Caminhos de Ferro de Moçambique (CFM).
In 1983 Randfontein Estates Gold Mines (REGM), which operated an approximately 25 km long railway network, bought a total of nine GMAM Garratts in two groups (No. 4084, 4107, 4123, 4128, 4136 as well as 4059, 4060, 4073 and 4079), after comparative studies on diesel or electric operation showed that steam traction was an economical solution. The locomotives were given the numbers R9 to R12 and R14 to R18 and were initially painted in blue and later in chestnut brown, which clearly set them apart from the SAR machines, which were kept in gray and black. The REGM locomotives were in use until the end of the 1990s.
At SAR, the planned use of the GMA / GMAM class ended in 1984. In addition to the REGM machines, two more (No. 4125 and 4168) were sold to industrial railways. Seven GMA / GMAM had previously been scrapped after accidents; one of the locomotives rented to the CFM (No. 4131) was the victim of a bomb attack.
Preserved locomotives
Two locomotives were received from the SAR for use in front of tourist trains and stationed in Mossel Bay .
Locomotive No. 4079, called Lyndie Lou , one of the REGM machines, has been part of the Sandstone Heritage Trust since 1997, along with two other GMAMs . Between 2005 and 2007 the machine was leased to the company Rovos Rail and pulled heavy tourist trains over long distances. Because the locomotive was too stressed in the eyes of its owners, it came into the care of the Reefsteamers Association in Germiston , where it was used in front of lighter excursion trains. The locomotive had to be parked in 2013 with worn wheels. The locomotive should be ready for operation again by March 2017.
NBL built locomotive No. 4112 was brought back to Europe and is in the Summerlee Industrial Heritage Museum in Coatbridge (Scotland).
The GMAM 4135 was purchased by Orange Tree Development in November 2019. She will join the newly resurgent NCCR New Cape Central Company and will be used for tourist services Mossel Bay - George and occasionally for extra trains over the Montague Pass to Oudtshoorn.
technology
The locomotives correspond to class GM in terms of power, dimensions and weight, but are more modern constructions with cast steel frames , roller bearings , welded steel fire rifle and optimized engine mass balancing . Like the GM class, they were equipped with a stoker . Visually, the GMA / GMAM differ from the GM mainly in the rounded shapes of the water and coal containers.
The classes GMA and GMAM only differ in the size of their stocks. The GMAM - the second M stands for Mainline - can carry 2.1 t more coal and 2.4 m³ more water, with both variants, like the GM class, carrying most of the water supply in a water tender (tank wagon). The conversion of a GMA into a GMAM and vice versa is easily possible and has also been carried out so that it is not possible to infer the class based on the locomotive number or delivery series.
literature
- AE Durrant: Garratt locomotives of the world. Birkhäuser, Basel et al. 1984, ISBN 3-7643-1481-8 .
Individual evidence
- ↑ A tale of two Garratts. (No longer available online.) In: Stars of Sandstone Newsletter No. 11. Archived from the original on December 22, 2016 ; accessed on December 26, 2016 (English). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
Web links
- Garratt Locomotive Class GMAM Photos. Transport in South Africa, accessed December 26, 2016 . (Page 2andpage 3)
- A Garratt called 'Lyndie Lou'. Reefsteamers, accessed December 26, 2016 .