|SAR NGG 13 Class and SAR NGG 16 Class|
|South African Railways gauge NGG16 class Garratt, preserved in operating condition on the gauge Welsh Highland Railway|
|Built||1927 - 1968|
|Number of pieces|| NGG 13 - 23|
NGG 16 - 34, 2 converted to NGG 16A
|Numbers of engines||NG 40 - NG 156|
|Wheel Arrangement||(2-6-2) + (2-6-2T) Garratt|
|Wheel arrangement||2-6-2 + 2-6-2T|
|Length over couplers||48 ft 5 in|
|Total wheelbase of loco||43 ft 3 in|
|Coupled wheelbase of each power unit||6 ft 3 in|
|Power unit wheelbase inc. trailing axles||13 ft 10½ in|
|Driving wheel diameter||2 ft 9 in|
|Trailing wheel diameter||1 ft 9 in|
|Total heating surface||1,049.1 square feet|
|Heating surface of tubes||859 sq ft|
|Heating surface of firebox||82.1 sq ft|
|Heating surface of superheater||149 sq ft|
|Grate area||19.5 sq ft|
|Boiler pressure||180 psi (1.24 MPa)|
|Cylinders (x 4)||12" diameter, 16" stroke|
|Tractive effort @ 85% pressure||21,553 lbf (95.872 kN)|
|Water capacity||1,823 imperial gallons (8,288 L)|
|Weight in working order||62 tons (approx.)|
The last locomotives of the NGG16 class were built in 1968 - the last Garratts built, and the last steam locomotives purchased by SAR.
Freed in 1927 of the HW Garratt articulation patent, SAR approached Hanomag of Germany to develop a new class of Garratt locomotives, which led to the first three NGG 13 locomotives of 1927. Performance trials of the NGG 13's proved them to be both powerful and free steaming, despite having a smaller grate area than the NGG 11's. This led to an immediate follow on order of two engines, and a further seven the following year.
In 1936 Hanomag's locomotive building business was sold to Henschel & Son's in Kassel, Germany; so SAR returned to Beyer, Peacock and Company. However, BP's workshops were full, so they designed the NGG 16 locomotives and outsourced the construction of the first batch to John Cockerill of Seraing, Belgium. Further batches resulted additional locomotives built in Manchester until 1958.
Beyer Peacock had gone bankrupt in 1966 and their designs and good will was sold to the Hunslet Engine Company. When SAR wanted further batches of NGG16s in 1967 and finally in 1968, Hunslet allocated the construction to their subsidiary Hunslet-Taylor of Johnnesburg, South Africa.
However, the Garratt design has some inbuilt problems. The first problem is tractive effort, whereby locomotive traction reduces with reduced weights of water and coal. Standard gauge Garratt's often overcame this with use of water carrying wagons behind the locomotive, which were used to fill up the locomotives water capacity and hence keep tractive effort high. On long length journeys in central Africa the additional weight and resultant increased distance between refuelling brought speed advantages. The second problem was tilting. The NGG 13 and NGG 16 had inter changeable boilers of nearly 1.5 metre diameter on a frame width of 2.10 metres. This created the risk of the locomotive tilting over on tight radii curves.
All locomotives were controlled via efficient Walschaerts valve gear, with the only substantial difference being the addition of an improved flue system and roller bearings on the NGG 16. All locomotives were built to be coal fired, by some were modified locally to become oil fired.
The success of the design is proven by the forty years of procurement of the design, even into the oncoming diesel locomotive era.
12 locomotives of NGG 13 Class were built 1927 and 1928 by Hanomag (No. NG 49, 50, 58-60, 77-83). In 1937 the first batch of NGG 16 Class were built by Cockerill-Sambre (No. NG 85-88), and eight from Beyer, Peacock (No. NG 109-116). In 1951 a further seven machines followed from Beyer, Peacock (No. NG 125-131).
Beyer, Peacock and Company supplied a further seven locomotives in 1958 for the mines of the Tsumeb corporation in Southwest Africa (today Namibia), but they were transferred to SAR in light of Tsumeb's change to Cape gauge (No. NG 137-143). These locomotives were a modified design, in that they only had coal supplies on the rear chassis, as opposed to the earlier designs which had side water tanks with a central coal bunker. The front chassis had a lesser curvature to increase water capacity, but these locomotives were often attached to a water wagon like the standard gauge Garratt locomotives. These locomotives were painted red on delivery, and started the classes sub division of Red Devils.
SAR ordered a further eight locomotives in 1965, but as Beyer, Peacock were already winding down their locomotive building activity the construction was outsourced to Hunslet Taylor. The locomotives (No. NG 149-156) were delivered in 1967 and 1968 supplied as last steam engines for the SAR, and the last Garratt locomotives at all. The increased front water tank of the Tsumeb supply was maintained, but the design of the rear chassis was returned to those supplied in 1951.
In 1989 and 1990, two locomotives of the Alfred County Railway (No. 141 and 155) were converted in order to improve their economy. Owing to the fuel savings of 20 to 25%, the works paid back financially within 12 months. The converted locomotives are called class NGG 16A.
SAR transferred the NGG13's and NGG 16's to Natal to the 122 kilometre route from Port Shepstone to Paddock via Izotsha. The route had some curves of 45 metres, but with gradients of up to 3 in 100/3%, the Garratt's were ideally suited to hauling both the diverse freight traffic of wood, sugar beet and banana crop to Port Shepstone, as well attracting additional tourist passengers to the trains which became known as the Banana Express. The route was closed by SAR in 1986, but in a new partnership sold on a long term lease to listed company the Port Shepstone and Alfred County Railway in March 1988. The venture lost money heavily initially, but after making profits from year three failed when it lost a key contract supplying wood to a pulping plant that took 48hrs to deliver to the factory due to the requirement to transfer the goods from gauge to either the standard gauge railway or the vastly expanding truck industry. SAR forced the venture into bankruptcy, and although the popular Banana Express was continued the following summer by Patons Country Railway, it is presently not running.
The locomotives of the PS&ACR were sold as a result of the failure to either state owned concerns, or to international railways. The early stages of the Welsh Highland Railway benefited from the purchase of three NGG 16's and excess track and sleepers, while the Sandstone Railway either took locomotives directly or via the Transnet Foundation.
|NGG 13||50||United States||Hempstead and Northern Railroad||Bought in 1976 by the Hempstead and Northern Railroad in Hempstead, Texas; and is the first ever and presently only Garratt locomotive in North America|
|NGG 13||77||England||Exmoor Steam Railway||In Store|
|NGG 13||82||England||Phyllis Rampton Trust||In Store at a private site in Surrey. Previously resided at the Brecon Mountain Railway|
|NGG 16||87||Wales||Welsh Highland Railway||Purchased from the Exmoor Steam Railway. Currently being overhauled at Boston Lodge|
|NGG 16||109||England||Exmoor Steam Railway||In Store|
|NGG 16||115||England||Exmoor Steam Railway||In Store|
|NGG 16||130||England||Exmoor Steam Railway||In Store|
|NGG 16||138||Wales||Welsh Highland Railway||Overhaul (WHR Dinas Workshop)|
|NGG 16||140||Wales||Welsh Highland Railway||Overhaul (WHR Dinas Workshop)|
|NGG 16||143||Wales||Welsh Highland Railway||Working Order. The last Garratt locomotive built by Beyer Peacock.|