2ft gauge Little Titans for the Welsh Highland - The 'NGG16s'

Phil Girdlestone & Shaun McMahon introduce the Garratts ordered for the WHR

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Hot on the heels of the news that the Ffestiniog had been awarded the Light Railway Transfer Order to take over and rebuild the derelict Welsh Highland Railway, came the announcement that the FR's provisional order for 2ft gauge Garratts from South Africa to work the line had been confirmed.

'NGG11' No 51, the first SAR 2ft Garratt and arguably the first Garratt in the country. A true Beyer-Garratt and showing some strong similarities to its Tasmanian forebear, it is seen here well-worn after years of service.© Ian Allan Library

The locos concerned are Narrow Gauge Garratts 16th Class ('NGG16s'), owned by the independent Alfred County Railway but surplus to its needs. The contract is for five to come to North Wales, two in time for 1996, the others arriving over the next few years. They will be 'demothballed' and fully overhauled at the ACR before shipment, a sensible choice as the skills and spares for this are still available there.

So, what are these locos which will form the front-line fleet of Britain's longest preserved railway?

Origins

More than anywhere else, Southern Africa is Garratt country. The type developed with the growth of the region's railways. Most were 'Cape Gauge' 3ft 6in, though the generous loading gauge allows rolling stock larger than found on many European systems. But there were also numerous narrow gauge (2ft) lines, mainly in Natal, the Cape Midlands and South West Africa (now Namibia).

The most extensive SAR 2ft lines were Port Shepstone-Harding (120km/75 miles), Umzinto-Donnybrook (150km/93 miles) and Port Elizabeth-Avontour (280km/174 miles). Not surprisingly the motive power requirements were exacting and locos developed accordingly, to a size exceeded nowhere in the world.

'NGG16s' under construction at Hunslet Taylor in 1968. At least three locos are visible, at least in part. © A.A. Jorgensen

Herbert Garratt managed to interest locomotive builders Beyer Peacock in his idea for a new type of articulated loco early in the century. The very first ones built were two 0-4-0+0-4-0 compounds, in 1909 for the Dundas Tramway in Tasmania, followed by a similar but simple version for the Darjeeling Himalayan Railway in 1910. The Tasmanian locos had cylinders at the inward ends of the power units but this was clearly not ideal for on the Darjeeling loco they were moved to the outer ends, which has remained standard ever since.

The Garratt offered many advantages to railways being constructed worldwide at the time. It enabled powerful locos to operate over the typical light track, sharp curves and harsh gradients of lines built to a tight budget. Evidently the potential was soon realised, for South African Railways ordered its first ones from Beyer Peacock in 1914. Due to World War 1, they were not delivered until 1921: three 2ft gauge and two other designs for the Cape Gauge. The 2ft ones were erected and tested first.

The first of a long line of SAR Garratts, they were 2-6-0+0-6-2s, unsuperheated, with Belpaire fireboxes and slide valves, perhaps in line with the view of the time that any degree of sophistication was unnecessary on the narrow gauge. Numbered NGG51-53, they were successful enough for two more to be ordered. Arriving in 1925, NGG54-55 were improved by superheating and piston valves.

Designated 'NGG11s' they became popular with the crews after some initial resistance and in fact survived in regular service into the late 1960s. Three are preserved.

In 1927 Hanomag of Germany delivered the first 'NGG13s', which set the standard for SAR narrow gauge locos for the next 40 years. American influence showed itself in the outside bar frames of the power units. They were 2-6-2+2-6-2s, superheated with roundtop boilers, Walschaerts valve gear and piston valves. Designed for lines laid with 45lb/yd rail, maximum axleload was 7 tons. The outer carrying wheels were conventional pony trucks but the inner ones were arranged on the Golsdorf system to allow some lateral movement. The initial order for three (NGG58-60) was increased by two (NGG49 & 50) with another seven (NGG77-83) ordered before the first ones had been delivered. They worked until the arrival of diesels in the early 1970s and nearly all have survived.

The next order introduced another manufacturer, John Cockerill, who supplied four, NGG85-88, in 1937. Almost identical to the 'NGG13s' (and at first included in that class), they had improved carrying-wheel designs to eliminate problems. Carrying wheelsets had Timken roller bearings and were all arranged as conventional pony trucks. The 'NGG16s' had arrived.

Building history

Beyer Peacock returned as suppliers with the next orders and remained so until steam loco construction ended at Gorton. It supplied another eight '16s' in 1939 (NGG109-116) and seven, NGG125-131, in 1951.

The next seven, the last steam locos built by Beyer Peacock, NGG137-143, were ordered by the Tsumeb Copper Corp of South West Africa in 1958 but when its line was altered to Cape Gauge, SAR took over the order. The locos still bear evidence of this switch, many components being stamped with TC6-12 numbers. (So by coincidence, the first and last Garratts built at Gorton were 2ft gauge.)

One of the last 'NGG16s' built, No 149, is seen complete but as yet bereft of numberplates at Hunslet Taylor, Germiston, in December 1967, newly-built and being steamed for the first time. © A.A. Jorgensen

Finally, in 1965, more 2ft power was needed by a still-steam-minded SAR. Beyer Peacock was in the throes of closure, so the order went to Hunslet and its Johannesburg subsidiary, Hunslet Taylor. NGG149 & 150 were delivered in 1967, and NGG151-156 in 1968. No 156 has the twin distinctions of being the very last steam loco built for SAR and the last Garratt built in the world. It is still in service on the Alfred County Railway, largely restored to original SAR condition.

There were two other classes, the two Franco-Belge 'NGG12' 2-6-2+2-6-2s of 1927, NGG56 & 57, and the solitary 'NGG14', NGG84, built by Hanomag in 1931. Small and light locos, with maximum axleloads of tinder 4 tons, they were built for lightly-constructed branch lines. All were scrapped in 1952.

By contrast, the 'NGG16' class has survived intact. They were shared between Natal and the Port Elizabeth-Avontour line until the latter was dieselised in 1973, when they were concentrated in Natal. With the gradual closure of the Natal 2ft lines, ending with the 1986 closure of Port Shepstone-Harding, the story could well have ended for the class too.

Luckily that section was taken over by the Alfred County Railway Co and the use of Garratts continues to this day.

With the ACR being committed to steam, a sub-class was created in 1989, when No 141 was rebuilt with Gas Producer Combustion and other improvements. With No 155, rebuilt in 1990, it forms Class NGG16A.

'NGG16a' No 141, seen in its striking red livery on the Alfred County Railway. At the head of the 'Banana Express', the Garratt is waiting to pass a double-heading pair of Class 91 diesels with the ACR's life-blood - a timber train from Harding. © A.A. Jorgensen

The ACR operation and museum and tourist operations at Port Elizabeth should ensure that South Africa will have `NGG16s' at work well into the 21st century.

Class details

South African railway operations tend to be on the grand scale, on both gauges. The 'NGG16s' fit this bill, tipping the scales at almost 62 tons in full working order, carrying over 1,800gal of water and 4 1/2 tons of coal. The largest 2ft gauges locos ever built, their power is comparable with a BR Standard Class 2 Mogul (tractive effort is 21,3601b at 85% pressure, compared with the Class 2's 18,5151b) and the grate area, at 19.2 sq ft, is larger.

Boilers are typically Garratt, short and fat (almost 5ft diameter), and carry 15-element superheaters. The locos feature many features normally found only on standard gauge classes, such as power-operated shaker grates, self-cleaning smokeboxes, sealed beam electric headlights, cab lighting and Gresham & Craven SSJ vacuum ejectors, Stones Turbogenerators, Ross Pop safety valves and multifeed Wakefield mechanical lubricators, 15gal reservoir tanks are fitted to later examples.

Obviously with a class built in batches over some 40 years, variations and improvements occurred. Early examples copied current SAR practice of steam brakes on locos with vacuum brakes on tenders, by having the front power unit vacuum-braked, with an 18in cylinder, and steam brakes on the rear unit. This also applied to the 'NGG13s'. From 1958 onwards, both units were vacuum braked, from two 21in cylinders slung under the boiler. Beyer Peacock's in-house refinements showed with plain pivots being replaced by adjustable ones from 1951, the same year in which Wakefield lubricators replaced the hydrostatic type. The first ones were five-feed models, replaced for the last two batches by eight-feed ones, which delivered through dividers to 17 points per unit including (apart from pistons and valves) the pivot, slidebars, valve spindles and piston rods, steam and exhaust ball joints and steam pipe expansion glands. (On the two 'NGG16As' this is again extended to 21 points.)

A remarkable meeting of Garratts shows that the 'NGG16s', big as they are for 2ft gauge locos, are positively dwarfed by SAR standard (3ft 6in) gauge specimens. In 1980, two 'GMAM' locos with auxiliary water tank wagons, hauling the commemorative special marking the 100th anniversary of the Durban-Pietermaritzburg main line, pass an 'NGG13' at Umlaas Road. © A.A. Jorgensen

Water tanks and bunkers were originally rivetted; welded construction took over gradually. The most visible difference was on the Tsumeb locos, built to carry coal only in the rear bunkers due to the long distances involved. This raised coal capacity to 6 1/4tons, with water capacity down to the front tank only at 1,340gal, a slight increase on the standard 1,325gal by giving the tank a flat top rather than the earlier broad curve. Extra water would have been carried in auxiliary tanks pulled tender-like, a common Garratt feature on SAR. The last batch reverted to water tanks under the coal bunkers but retained the flat-top front tank.

The ACR's conversion to `NGG16A' was carried out by Phil Girdlestone at Port Shepstone. As well as the Gas Producer firebox, a single Lempor exhaust with de Laval blower, improved low draught loss, advanced spark arrestor and improved lubrication, light low-wear smoothed multiring piston valves, modified valve gear and roller bearings on the return crank rods were fitted.

The work was part of the ACR's then total commitment to steam and the need to raise efficiency and power while lowering exhaust pollution risks - in short, making steam the most cost-effective form of motive power. Official tests showed a coal saving of 25% compared with standard members of the class. Availability and utilisation levels of 90% were achieved and the costs of the modification recovered in 12 months.

Performance

South Africa's topography features a high plateau reached by steep climbs from the coastal areas, where most of the 2ft gauge lines were found. Plenty of power was therefore essential to keep the traffic moving at acceptable speeds.

The Alfred County line is typical, climbing at a ruling grade of 1 in 37 for 20 miles after leaving the coast. (The Donnybrook line was worse, featuring a ruling grade of 1 in 33 uncompensated for curvature.) However, even up these grades the 'NGG16s' can haul loads up to 160 tons, and 275 tons on 1 in 45 grades. They easily negotiate 2½ chain radius curves and where curves are less severe can run at speeds of 25mph. From heavy freight to pick-up goods the hard work of many years rests lightly on them, an integral and well-remembered part of rural life to generations of South Africans.

Few classes of loco have been built over such a long period with virtually no significant changes. It is equally remarkable that so many survive today, with just one 'NGG13' scrapped due to accident damage. The prospect of a batch being rejuvenated and shipped to Wales for a new career is an unexpected twist in the tale.

Prospects

The largest and most powerful steam locos available on the 2ft gauge will certainly be a turn-round for the WHR, whose previous existence was marked by underpowered locos trundling or struggling, depending on the grade, with short trains. The plan for the new WHR, though, demands power and speed. Ten-coach trains equipped to standards yet unknown on British 2ft gauge lines, running at speeds of 25mph where possible to complete the Caernarfon-Porthmadog journey in 90min, need adequate power.

Especially when you consider the nature of the Welsh Highland: it does have its long, easily curved and graded sections. Equally it has lengths with punishing reverse curves or with lengthy 1 in 40 grades in both directions, most notably the unbroken climb from Aberglaslyn Pass to Pitts Head, four miles at around 1 in 40, including the principal intermediate station at Beddgelert, and with long sweeping reverse curves looping through the woods to ease the grade. A harsh line to work and in typically Snowdonia weather (wet with damp intervals), needing rather special locos.

Brand new 'NGG16' No 156 positively gleams as it forges uphill on its first public trip, a goods train from Umzinto to Ixopo, Natal, in October 1968. © A.A. Jorgensen

Here is where the Garratts score, with their flexibility allowing them to cope with curves that would drag a rigid loco of less or similar power to a crawl and proven ability to cope better with wet rails. On a rigid loco, if the coupled wheels slip, that is it, you've lost everything and can only cut back then try again, by when you have lost speed to a dangerous extent. A Garratt's front unit might loose its feet from time to time but it is preparing the rails for the back unit, which plods steadily on.

Also, these engines' ability to run, given the road, will turn the easier stretches into narrow gauge racetracks. Caernarfon-Dinas and the crossing of the flatlands at the Porthmadog end, plus sections on the high moorland around Quellyn Lake, will see long, Garratt-hauled trains hurrying along at respectable speeds, before roaring up the next tough climb.

With an interesting array of conventional locos lined up in the wings, plus occasional sorties by the FR's Fairlies, Monarch and possibly the historic Garratt K1, to give variety to the motive power, the Welsh Highland promises to be a real mecca to connoisseurs of narrow gauge steam. But in power and sheer presence, the Garratts will be the stars; further proof that the new Welsh Highland is a very serious railway indeed.

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Webmaster's notes (July 2004):

• NGG16s 138 and 143 are now in operation on the Welsh Highland Railway.
• NGG16 140 is stored in the open, but covered by a tarpaulin, at the Ffestiniog Railway's Glan-y-Pwll depot, Blaenau Ffestiniog.
• More information on the WHR Garratts can be found here.