Benguela Railway Beyer-Garratt Locomotives in Angola

Class 10aI (Locobase 519)

Data is from Wiener (1930) and from Gavin Hamilton's compilation of Garratt data posted at []

(6 September 2005). Hamilton shows a slightly lower evaporative and superheat heating surface; "Benguela Railway-Design 1155", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [], p. 51 et seq, BP works numbers were 6333-6338.

Fitted with plate frame, copper Belpaire firebox and arch tubes. The Double Mountain Garratt wheel arrangement premiered with this octet. They burned eucalyptus wood and carried 540 cu ft (and four firemen) at a time--by all accounts, the engine smoke exuded a distinctive fragrance. (See Locobase 2860 for Peter Ball's discussion of eucalyptys as a fuel."

BP's 1931 brochure quoted the rationale underlying purchasing the first six Garratts presented in "A Brief History of the Benguela Railway". Water supply, the climate, the spacing of the "halts", and gradients all needed consideration. Because the Benguela also wanted to increase their typical trailing loads to 500 tons, their choice narrowed to Double Mountain Garratts. And indeed, the class 10s traveled over the light rail without issue and easily scaled the 2 1/2% ruling grade between Lengue and Cubal. Max speed was 45 mph (72.5 kph); flangeless outer drivers and four-wheel bogies on the leading and trailing trucks permitted these engines to take 300-ft radius curves.

After the first two years in "'gruelling' service over 60 lb/yard (30 kg/metre) rail on the most severe section between San Pedro and Huambo--which measured 372 km (231 miles), the Benguela more than doubled down on its 1929 order; see Locobase 520.

NB: Tube length is an estimate based on the calculation of tube surface area by subtracting reported firebox heating surface from reported total evaporative heating surface

Class 10aII (Locobase 520)

Data from Gavin Hamilton's excellent compilation of Garratt data posted at [] (6 September 2005). .uk/hamilton/dimensions.html

(6 September 2005); and "Benguela Railway-Design 1155", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [], p. 51 et seq, BP works numbers were 6602-6615.

Obviously pleased with the earlier batch of 10As (Locobase 519), the Benguela ordered these 10aII Double Mountain Garratts three years later. Like the earlier engines, this larger order used copper Belpaire fireboxes burning eucalyptus wood, but adopted a bar frame in place of the earlier plate frame. (See Locobase 2860 for Peter Ball's discussion of eucalyptys as a fuel.)

Class 10aIII (Locobase 521)

Data from Gavin Hamilton's excellent compilation of Garratt data posted at [] (6 September 2005); and A[rthur] E[dward] Durrant, Garratt Locomotives of the World (revised edition) (Newton Abbott, UK: David & Charles, 1981), p.167.

Postwar repeats of the successful Double Mountain Garratt design of the late 1920s.Durrant wrote that BP updated the original design with streamlined water tanks, cylinders offering straight ports and long-lap valves, and bogie axles turning in SKF roller bearings. Their bunkers held 540 cu ft (15.3 cu m) of eucalyptus wood. (See Locobase 2860 for Peter Ball's discussion of eucalyptys as a fuel.)

After Beyer Peacock delivered a later batch with self-adjusting pivots,positve results persuaded the CFB to manufacture its own such pivots in Nova Lisboa (renamed from Huambo and later reverting to that earlier name). 343 later traded its Kylchap exhaust setup for Giesel ejectors and , Du rrant reported, showed a 12.4% reduction in fuel consumption.

Durrant also explained the meaining of "dupla" working. It used two locomotives (either both Garratts or one Garratt and one rigid-wheelbase engine) in what would later be termed "distributed" working in the diesel age. One Garratt pulled from the front and one added its effort while spliced into the middle of the train.

Class 10aIV (Locobase 522)

Data from Gavin Hamilton's excellent compilation of Garratt data posted at [], first accessed 6 September 2005. See also A[rthur] E[dward] Durrant, Garratt Locomotives of the World (revised edition) (Newton Abbott, UK: David & Charles, 1981), p. 172, 176.- Works numbers were 7667-7676 in 1955.

Part of a continuing series of postwar additions to the Angolan Double Mountain Garratt stud. These arrived in 1955 with only slight changes. They were equally successful as the earlier 10-class engines and served into the 1970s before the 1974 War shut down the railway.