South African Class NG G16A 2-6-2+2-6-2

Red Dragon no. 141 at Port Shepstone, May 1990

Type and origin
♥ No. NG141 - ♠ No. NG155
Power type	Steam
Designer	Alfred County Railway (Phil Girdlestone)
Builder	Alfred County Railway
Serial number	BP 7866, Hunslet-Taylor 3900
Model	Class NG G16A
Build date	1989-1990
Total produced	2

Specifications
Configuration	2-6-2+2-6-2 (Double Prairie)
Driver	3rd & 4th coupled axles
Gauge	2 ft (610 mm) narrow
Leading dia.	21 in (533 mm)
Coupled dia.	33 in (838 mm)
Trailing dia.	21 in (533 mm)
Minimum curve	160 ft (49 m)
Wheelbase	43 ft 3 in (13,183 mm)
• Engine	13 ft 10 ¹⁄₂ in (4,229 mm) each
• Coupled	6 ft 3 in (1,905 mm) each
Pivot centres	23 ft 9 in (7,239 mm)
Length:
• Over couplers	48 ft 5 ¹⁄₄ in (14,764 mm)
Width	7 ft (2,134 mm)
Height	10 ft 4 in (3,150 mm)
Frame type	Bar
Axle load	♥ 6 LT 17 cwt 3 qtr (6,998 kg) ♠ 6 LT 18 cwt (7,011 kg)
• Leading	♥ 6 LT 7 cwt 2 qtr (6,477 kg) front 6 LT 7 cwt 1 qtr (6,465 kg) rear ♠ 6 LT 10 cwt (6,604 kg) front 5 LT 14 cwt (5,791 kg) rear
• 1st coupled	♥ 6 LT 14 cwt 3 qtr (6,846 kg) ♠ 6 LT 18 cwt (7,011 kg)
• 2nd coupled	♥ 6 LT 17 cwt 3 qtr (6,998 kg) ♠ 6 LT 6 cwt (6,401 kg)
• 3rd coupled	♥ 6 LT 15 cwt (6,858 kg) ♠ 6 LT 4 cwt (6,299 kg)
• 4th coupled	♥ 6 LT 14 cwt 2 qtr (6,833 kg) ♠ 6 LT 15 cwt (6,858 kg)
• 5th coupled	♥ 6 LT 14 cwt (6,808 kg) ♠ 6 LT 17 cwt (6,960 kg)
• 6th coupled	♥ 6 LT 14 cwt 3 qtr (6,846 kg) ♠ 6 LT 1 cwt (6,147 kg)
• Trailing	♥ 4 LT 1 cwt 1 qtr (4,128 kg) front 3 LT 10 cwt (3,556 kg) rear ♠ 3 LT 14 cwt (3,759 kg) front 3 LT 19 cwt (4,013 kg) rear
Adhesive weight	♥ 40 LT 10 cwt 3 qtr (41,190 kg) ♠ 39 LT 1 cwt (39,680 kg)
Loco weight	♥ 61 LT 5 cwt 2 qtr (62,260 kg) ♠ 59 LT 2 cwt (60,050 kg)
Fuel type	Coal
Fuel capacity	♥ 6 LT 4 cwt (6.3 t) ♠ 4 LT (4.1 t)
Water cap	♥ 1,325 imp gal (6,020 l) front ♠ 1,325 imp gal (6,020 l) front 540 imp gal (2,450 l) rear
Firebox type	Round-top
• Firegrate area	19.5 sq ft (1.81 m²)
Boiler:
• Pitch	5 ft 5 in (1,651 mm)
• Diameter	4 ft 7 ³⁄₄ in (1,416 mm)
• Tube plates	9 ft 3 ⁵⁄₈ in (2,835 mm)
• Small tubes	152: 1 ³⁄₄ in (44 mm)
• Large tubes	15: 5 ¹⁄₂ in (140 mm)
Boiler pressure	180 psi (1,241 kPa)
Safety valve	Pop
Heating surface	85.91 m² (924.7 sq ft)
• Tubes	60.24 m² (648.4 sq ft)
• Flues	18.7 m² (201 sq ft)
• Firebox	6.97 m² (75.0 sq ft)
Superheater:
• Type	15 elements
• Heating area	14.9 m² (160 sq ft)
Cylinders	Four
Cylinder size	12 in (305 mm) bore 16 in (406 mm) stroke
Valve gear	Walschaerts
Valve type	140 mm (5.5 in) Piston
Valve travel	90 mm (3.5 in)
Valve lap	22.22 mm (0.9 in) steam lap 1 mm (0.0 in) exhaust lap
Valve lead	3.5 mm (0.1 in)
Couplers	Bell link-and-pin

Performance figures
Tractive effort	95 kN (21,000 lbf) @ 75%

Career
Operators	Alfred County Railway
Class	Class NG G16A
Number in class	2
Numbers	141, 155
Nicknames	Red Dragon
Delivered	1989-1990
First run	1989

The Alfred County Railway Class NG G16A 2-6-2+2-6-2 of 1989 was a steam locomotive from the South African Railways era.

Between 1937 and 1968, the South African Railways placed 34 Class NG G16 2-6-2+2-6-2 Garratt articulated steam locomotives in service. In 1989 and 1990, two of these locomotives were rebuilt to Class NG G16A by the Alfred County Railway.^[1]^[2]

Manufacturers

Altogether 34 Class NG G16 2-6-2+2-6-2 locomotives were built for the South African Railways (SAR) between 1937 and 1968. Four were delivered by Société Anonyme John Cockerill of Seraing in Belgium in 1937, twenty-two by Beyer, Peacock and Company between 1939 and 1958, and the last eight by Hunslet-Taylor in Germiston, Transvaal in 1967 and 1968.^[2]^[3]^[4]^[5]

The locomotives were superheated, with a superheater area of 14.9 square metres (160 square feet) and fifteen elements of 38 millimetres (1.5 inches) outside diameter and a 31 millimetres (1.2 inches) bore.^[1]

Alfred County Railway

When the four narrow gauge branchline systems in Natal were closed down by the SAR, the Weenen and Mid-Illovo lines were torn up, but the Harding line was privatised in 1988 as the Alfred County Railway (ACR), operating out of Port Shepstone. The ACR was also known as the Banana Express from the tourism part of its operation.^[6]^[7]

Class NG G16A rebuilding

As part of the ACR's strategy to keep the narrow gauge railway competitive, two of its Class NG G16 Garratt locomotives were rebuilt, using technology similar to that used by mechanical engineer David Wardale in the creation of the Class 26 Red Devil in 1980, based on developments pioneered by Argentinian engineer L.D. Porta. The Class NG G16 rebuilding incorporated a gas producing combustion system (GPCS), Lempor exhausts, an improved spark arrester, lightweight multi-ring articulated piston valves, improved valve events and improved mechanical lubrication.^[1]^[8]

The rebuilding was done by mechanical engineer Phil Girdlestone, who was employed as Chief Mechanical Engineer of the ACR primarily for this purpose. The work was carried out at Port Shepstone, and the first locomotive to undergo the treatment was the Beyer, Peacock-built no. 141 in 1989.^[1]

The modifications were similar in scope to that of the Red Devil, although not as extensive. Like the Class 26, no. 141 was also painted red and was consequently soon nicknamed the Red Dragon. Dragon emblems were later mounted on the cab sides and bunker ends.^[1]

The second locomotive, the Hunslet-Taylor-built no. 155, was rebuilt in 1990, but it retained its traditional ex-SAR black livery. Both modified locomotives were reclassified to Class NG G16A.^[1]

Gas producing combustion system

The GPCS is a single-stage gas producer which achieves an improved combustion and steaming rate, reduces the emission of wasteful black smoke and overcomes the problem of clinkering. The most serious waste of fuel in a conventional steam locomotive is the loss of unburned coal particles from the fuel bed through the exhaust because of the rapid flow of air through the grate.^[9]^[10]

Secondary air inlets with swirl inducers and a spark arresting plate

The GPCS relies on the gasification of coal on a low temperature firebed so that the gases are then fully burnt above the firebed. To achieve this, the amount of air being drawn up through the firebed is minimised, while the main sources of air required for combustion is through secondary air inlets located in the firebox sides and through the vertically sliding firedoor. The air inlets contain swirl inducers to spread the incoming air inside the firebox.^[1]^[2]^[8]^[9]

With the GPCS, the coal is therefore heated to drive off the volatile components which are then burned in the secondary air admitted above the grate. The result is improved combustion, thereby minimising black smoke, which is evidence of incomplete combustion and unburnt coal particles being ejected through the exhaust. Note the clear exhausts in the picture below of numbers 141 and 155 double-heading on the climb from Bongwana to Nqabeni.^[1]^[9]

Lempor exhaust

One of the most obvious externally visible differences between the original and the rebuilt locomotives is the megaphone-shaped Lempor chimney, which contains a cylindrical mixing chamber and a wide angled diffuser. The object of the latter is to convert the kinetic energy of the combustion gas and exhaust steam mixture to a pressure as close to atmospheric as possible. This requires that the outlet area should be as large as possible since that would allow the largest possible blast nozzle area and therefore the lowest back pressure.^[1]

Steamchest pressure gauges and cylinder steam flow gauge in no. 141

Ejector pump efficiency depends on the length-to-diameter ratio of the exhaust chimney. Although less obvious, both Wardale GPCS locomotives, Class 19D no. 2644 and Class 26 no. 3450, have exactly this shape of chimney, but because of height constraints in large locomotives, their chimneys had to be doubled or even tripled to achieve the correct proportions, hence the double exhausts of the two Wardale locomotives. Narrow gauge locomotives like the Class NG G16, on the other hand, have plenty of height available for the exhaust, so a single long chimney was achievable.^[1]

Other visible differences are larger mechanical lubricators and external drive from the valve spindle, a vacuum ejector exhaust muffler just in front of the safety valves, pipes conveying exhaust and ejector steam to the ashpan for mixing with the primary air, the secondary air inlets in the firebox sides with spark arresting plates outside them, and the snifting and bypass valves which were removed and blanked off since the modified locomotive drifted in mid gear with steam supplied from the drifting valve.^[1]

Performance

In comparative testing, no. 141 achieved a fuel saving of 25% compared to a standard Class NG G16 Garratt, a performance which was easily maintained in regular service. Power outputs of over 700 indicated horsepower was achieved and the locomotive was probably capable of achieving a maximum of 800 indicated horsepower, some 25% more than the Class 91-000 narrow gauge diesel-electric locomotive. The improvement in performance and economy of the locomotive was brought about by the higher grate limit by means of the GPCS and better flow past the improved valves, valve motion and exhaust. Other basic elements of the locomotive remained more or less the same.^[1]

The cost of the work paid off financially within twelve months and led to a proposal to develop a Class NG G17 Garratt. That proposal, however, never became reality since the line's farming produce traffic was gradually lost to road transport on the improving road network, a decline which eventually led to the ACR's demise.^[8]^[11]^[12]

Illustration

No. 155 shunting at Nqabeni, c. 1991
No's 141 & 155 climbing from Bongwana to Nqabeni, c. 1992

References

1 2 3 4 5 6 7 8 9 10 11 12 Information supplied by Phil Girdlestone
1 2 3 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10–11, 78–79, 107, 109–110. ISBN 0869772112.
↑ 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
↑ South African Railways and Harbours Locomotive Diagram Book, 2'0" & 3'6" Gauge Steam Locomotives, 15 August 1941, as amended
↑ Durrant, A E (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. pp. 126–127. ISBN 0715386387.
↑ Ash, Paul (2005). Living Steam (Lambert, Anthony – editor) (1st ed.) London, Cape Town, Sydney, Auckland: New Holland Publishers. pp. 120-123. ISBN 1-84330-872-X
1 2 3 "Alfred County Railway 2-6-2+2-6-2 NG G16A Garratts 141 & 155". martynbane.co.uk. Retrieved 2009-07-10.
1 2 3 Gas Producer Combustion System (GPCS)
↑ South Africa's 'Red Devil' (Accessed on 28 July 2016)
↑ "The Ultimate Steam Page – P. Girdlestone". trainweb.org. Retrieved 2009-07-10.
↑ Middleton, John N. (2002). Railways of Southern Africa Locomotive Guide - 2002 (as amended by Combined Amendment List 4, January 2009) (2nd, Dec 2002 ed.). Herts, England: Beyer-Garratt Publications. pp. 32–33.

External links

External video
Alfred County Railway NGG16A Garratt November 1996 Follow the Banana Express from the coast at Port Shepstone up the hill to Paddock, hauled by NG G16A 155. On the return trip, 155 picks up 300t of timber in addition to the passenger cars. (12 minutes 22)

Wikimedia Commons has media related to South African Class NG G16A (2-6-2+2-6-2).

Locomotives of South Africa

Steam

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4' 8½" gauge	Cape 0-4-0T Blackie Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid Natal 0-4-0ST Durban Natal 0-4-0WT Natal Natal 4-4-0T Perseverance

3' 6" gauge Tank engines	CGR 0-4-0ST 1873 CGR 0-4-0ST 1874 CGR 0-4-0ST 1881 CGR 0-4-0ST 1881 Coffee Pot CGR 0-6-0ST CGR 0-6-0T CGR 2-6-0ST 1900 CGR 2-6-0ST 1902 CGR 1st Class 0-4-0ST 1875 CGR 1st Class 0-4-0ST 1876 CGR 1st Class 2-6-0ST CGR 1st Class 4-4-0T CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack 4-6-4RT CSAR Railmotor Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth 0-4-0ST Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NGR 2-6-0T Durban & Pietermaritzburg NGR Class I 2-6-2T NGR Class K 0-4-0ST NGR Class K 0-6-0ST NGR Class K 2-6-0T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner PPR 26 Tonner PPR 35 Tonner Portuguese SAR Class A SAR Class B SAR Class C SAR Class C1 SAR Class C2 SAR Class D SAR Class E SAR Class F SAR Class G SAR Class H SAR Class H1 SAR Class H2 SAR Class J SAR Class K SAR Railmotor SAR Dock 0-4-0ST SAR Dock 0-4-0T SWA 2-8-0T

3' 6" gauge Tender engines	CGR 1st Class 2-6-0 1876 BP CGR 1st Class 2-6-0 1876 Kitson CGR 1st Class 2-6-0 1879 CGR 1st Class 2-6-0 1891 CGR 1st Class 4-4-0 CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 3rd Class 4-4-0 1883 CGR 3rd Class 4-4-0 1884 CGR 3rd Class 4-4-0 1889 CGR 3rd Class 4-4-0 1898 CGR 3rd Class 4-4-0 1901 CGR 3rd Class 4-4-0 1903 CGR 4th Class 4-4-2 CGR 4th Class 4-6-0TT 1880 CGR 4th Class 4-6-0TT 1882 CGR 4th Class 4-6-0TT 1882 Joy CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 NGR Havelock NGR Class I SAR Class Exp 1 SAR Class Exp 2 SAR Class Exp 3 SAR Class Exp 4 SAR Class Exp 5 SAR Class Exp 6 SAR Class S SAR Class S1 SAR Class S2 SAR Class 1 SAR Class 1A SAR Class 1B SAR Class 2 SAR Class 2C SAR Class 3 SAR Class 3A SAR Class 3B SAR Class 4 SAR Class 4A SAR Class 5 SAR Class 5A SAR Class 5B SAR Class 6 SAR Class 6A SAR Class 6B SAR Class 6C SAR Class 6D SAR Class 6E SAR Class 6F SAR Class 6G SAR Class 6H SAR Class 6J SAR Class 6K SAR Class 6L SAR Class 6Y SAR Class 6Z SAR Class 7 SAR Class 7A SAR Class 7B SAR Class 7C SAR Class 7D SAR Class 7E SAR Class 7F SAR Class 8 SAR Class 8A SAR Class 8B SAR Class 8C SAR Class 8D SAR Class 8E SAR Class 8F SAR Class 8R SAR Class 8X SAR Class 8Y SAR Class 8Z SAR Class 9 SAR Class 10 SAR Class 10A SAR Class 10B SAR Class 10C SAR Class 10D SAR Class 11 SAR Class 12 SAR Class 12A SAR Class 12B SAR Class 13 SAR Class 14 SAR Class 14A SAR Class 14B SAR Class 14C 1st SAR Class 14C 2nd SAR Class 14C 3rd SAR Class 14C 4th SAR Class 15 SAR Class 15A SAR Class 15B SAR Class 15C SAR Class 15CA SAR Class 15E SAR Class 15F SAR Class 16 SAR Class 16A SAR Class 16B SAR Class 16C SAR Class 16D SAR Class 16DA 1928 SAR Class 16DA 1930 SAR Class 16E SAR Class 17 SAR Class 18 SAR Class 19 SAR Class 19A SAR Class 19B SAR Class 19C SAR Class 19D SAR Class 20 SAR Class 21 SAR Class 23 SAR Class 24 SAR Class 25 SAR Class 25NC SAR Class 26 SAR Katanga SWA 2-8-0

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2' & 600mm gauges	ACR Class NG-G16A CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T SAR Class NG1 SAR Class NG2 SAR Class NG3 SAR Class NG4 SAR Class NG5 SAR Class NG6 SAR Class NG7 SAR Class NG8 SAR Class NG9 SAR Class NG10 SAR Class NG-G11 SAR Class NG-G12 SAR Class NG-G13 SAR Class NG-G14 SAR Class NG15 SAR Class NG-G16 SWA Class Ha SWA Class Hb SWA Class Hc SWA Class Hd SWA Jung SWA Zwillinge

Electric

Amcoal Class E38

Gas-electric

SAR Gas-electric

Diesel

3' 6" gauge Diesel-electric	PRASA Class Afro 4000 SAR Class DS SAR Class DS1 SAR Class 31-000 SAR Class 32-000 SAR Class 32-200 SAR Class 33-000 SAR Class 33-200 SAR Class 33-400 SAR Class 34-000 SAR Class 34-200 SAR Class 34-400 SAR Class 34-500 SAR Class 34-600 SAR Class 34-800 SAR Class 34-900 SAR Class 35-000 SAR Class 35-200 SAR Class 35-400 SAR Class 35-600 TFR Class 35-800 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 39-200 TFR Class 43-000 TFR Class 44-000

2' gauge Diesel-electric	SAR Class 91-000

3' 6" gauge Diesel-hydraulic	SAR Class 61-000

3' 6" gauge Electro-diesel	Spoornet Class 38-000

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