South African gas-electric locomotive

The South African Railways gas-electric locomotive of 1923 was an experimental suction gas-electric locomotive.

In 1923, the South African Railways experimented with gas-electric motive power and constructed a single experimental producer gas-electric locomotive. The locomotive remained in service for several years and was followed by another, built by the General Electric Company, which was not successful and never entered line service after undergoing experimental trials. The gas-electric concept was eventually superseded by diesel-electric traction.^[1][2][3]

Branchline non-profitability

The non-profitability of many branchline operations had been a problem for the South African Railways (SAR) from the outset. The question of non-paying branchlines was raised by Sir William Hoy, South African Railways and Harbours General Manager, in a paper read at the Imperial Motor Transport Conference in London in 1913. He drew attention to the fact that, in isolated districts with vast agricultural and mineral capabilities in many parts of the Union of South Africa, development was hampered by the lack of means of transportation.^[1]

In an attempt to reduce the cost of using steam locomotives on infrequently used and non-profitable branchlines, other forms of motive power were considered in the early 1920s. Diesel and diesel-electric locomotives were still in their infancy and were therefore not yet an attractive proposition, while the cost of electrification of such branchlines would be prohibitive. The first alternative form of traction to enter service, was the Dutton road-rail tractor system in 1923.^[1][2]

During October 1922, Hoy encouraged further experiments to determine the practicability of the use of suction gas (also known as producer gas) as fuel for an alternative form of motive power, suitable for use on branchlines. Mr. C. Lawson, Superintendent Mechanical of the SAR, was tasked with the experiment.^[1][3]

Suction gas principle

Combustion gases, rich in carbon monoxide and known variously as water gas, producer gas and mond gas, are generated by passing air and steam through some kind of red-hot burning carbonaceous fuel, usually coal. The gas generator consists of a combustion portion, where the fuel is initially burned to generate the required steam. The steam is then blown through this same burning fuel, taking air with it, and the producer gas is then liberated as a by-product of this combustion. Ordinarily, burning produces carbon dioxide, but by forcing steam through the burn, a certain amount of incomplete combustion is caused which produces carbon monoxide.^[3]

Depending on the vessel used, the gas created may be under a slight pressure, caused by the velocity of the steam, and an expansion chamber is used to reduce this pressure. Experimenting established that the suction created by a petrol engine running on the gas, actually increased the generation of the producer gas by drawing more steam and air through the burn. This could possibly make the expansion chamber superfluous. Producer gas generated by this method became known as suction gas. With a suction gas engine, the amount of gas produced is therefore partially dependent on the speed and throttle setting of the engine using it.^[3]

Development

Lawson's experimental locomotive was based on the same principle as contemporary Swedish diesel-electric locomotives, except that the diesel engine prime mover would be replaced by a petrol engine, running on carbon monoxide producer gas. As with a diesel-electric locomotive, an electric generator and traction motor combination would be used to transfer the engine's power to the wheels.^[3]

The locomotive was constructed on an old 40 feet (12,192 millimetres) bogie truck underframe. The producer gas generator was constructed from the smokebox section of a scrapped 6th Class locomotive's boiler. Smokebox char was used as fuel and the gas was passed from the gas generator through suitable wet scrubbers to remove tar, to two Tilling-Stevens petrol engines, which came from Whippet tanks and were obtained from the Defence Department. A gas expansion chamber was constructed from an old chimney. The two engines drove shunt wound dynamos, obtained from General Electric, to power the traction motors, which were two tramway motors obtained from De Beers in Kimberley. Since the gas was generated by the suction from the two internal combustion engines, the vehicle became known as a suction gas locomotive.^[1][2][3]

It ran in three forms. During the experimental stage, it was run from Germiston to Johannesburg station as a flat truck with all the components assembled on top and occupying about half of the deck space, but uncovered, to be viewed by the members of the Railway Board.^[1][2][3]

During the testing stage, an enclosed body was added. During a 167 miles (269 kilometres) test run to Volksrust, various adjustments were made to the water circulating arrangements, which improved the power output to the extent that the tram traction motors were unable to stand the continuous current which was generated, and they were replaced by two 50 horsepower (37 kilowatts) Siemens traction motors, supplied by General Electric. These, in turn, required more current than the Whippet engines could generate and they were replaced by a 120 horsepower (89 kilowatts) Holt engine from a Caterpillar tractor, supplied by Messrs Fraser and Chalmers of Bulawayo in Southern Rhodesia.^[3]

The gas generator was never altered in principle from the first experiment and the expansion chamber was kept as it was, but the original wet scrubber was replaced with a dry scrubber early during development. Control of electrical current was by two tramway series-parallel controllers and resistors to ensure a range of speeds. The current generated with the engine at its normal working of 750 revolutions per minute was 140 amperes and 500 volts. 600 volts could be obtained by speeding up the engine, but this could place a too heavy load on the generator.^[3]

Service

In its final guise, a small third-class compartment for twenty passengers was added on the unused deck space at the rear. The 28 long tons (28,450 kilograms) locomotive, numbered GE1, was capable of negotiating a 3% curve at 6 miles per hour (10 kilometres per hour) and could attain a top speed of 25 miles per hour (40 kilometres per hour) on level track.^[1][2][3]

The Gas-electric locomotive was finally placed in service on the Winter's Rush branchline from Kimberley, where it often hauled a passenger coach. It remained in service on that line for several years.^[2]

Termination

In June 1923, Colonel F.R. Collins DSO, the SAR Chief Mechanical Engineer, approved plans for a 200 horsepower (150 kilowatts) suction gas locomotive, but it never materialised. In 1925, a new 280 horsepower (210 kilowatts) suction gas locomotive was purchased instead. It was designed to SAR specifications by Mr. Harry Ricardo of Ricardo Brothers of Shoreham and built by General Electric Company in England. At the time, it was claimed to be the largest of its type in the world, but it never emerged from the trial stages. It was found that the variable demand on the gas generator precluded a regular supply of gas of the required quality. The gas-electric locomotive was eventually superseded by the diesel-electric locomotive, which proved to be a far more convenient and much less cumbersome machine to operate over long distances.^[1][2][3]

The locomotive's frame, bogies and traction motors were later used to construct an electric motor coach, which was placed in service between Mason's Mill and Pietermaritzburg. No more suction gas locomotives were acquired.^[1]

Illustration

The main picture shows engine no. GE1 in service on the Winter's Rush branchline, while the following photographs all show it during development and testing, c. 1923.

• 
  No. GE1, right side
• 
  No. GE1, left side
• 
  No. GE1, left side

References

Wikimedia Commons has media related to Gas-electric locomotives of South Africa.

Locomotives of South Africa
Steam	7' ¼" gauge East London 0-4-0VB Table Bay 0-4-0ST Table Bay 0-4-0T Table Bay 0-4-0WT 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 3' 6" gauge Articulated engines CGR Fairlie CGR Kitson-Meyer SAR Class FC SAR Class FD SAR Class GA SAR Class GB SAR Class GC SAR Class GCA SAR Class GD SAR Class GDA SAR Class GE SAR Class GEA SAR Class GF SAR Class GG SAR Class GH SAR Class GK SAR Class GL SAR Class GM SAR Class GMA SAR Class GO SAR Class HF SAR Class KM SAR Class MA SAR Class MB SAR Class MC SAR Class MC1 SAR Class MD SAR Class ME SAR Class MF SAR Class MG SAR Class MH SAR Class MJ SAR Class MJ1 SAR Class U 2' 6" gauge Cape Copper John King & Miner Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay 2-4-2T Hope 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 SAR Class ES SAR Class ES1 SAR Class Exp-AC SAR Class 1E SAR Class 2E SAR Class 3E SAR Class 4E SAR Class 5E s1 SAR Class 5E s2 SAR Class 5E s3 SAR Class 5E1 s1 SAR Class 5E1 s2 SAR Class 5E1 s3 SAR Class 5E1 s4 SAR Class 5E1 s5 SAR Class 6E SAR Class 6E1 s1 SAR Class 6E1 s2 SAR Class 6E1 s3 SAR Class 6E1 s4 SAR Class 6E1 s5 SAR Class 6E1 s6 SAR Class 6E1 s7 SAR Class 6E1 s8 SAR Class 6E1 s9 SAR Class 6E1 s10 SAR Class 6E1 s11 SAR Class 7E SAR Class 7E1 SAR Class 7E2 s1 SAR Class 7E2 s2 SAR Class 7E3 s1 SAR Class 7E3 s2 Spoornet Class 7E4 SAR Class 8E SAR Class 9E s1 SAR Class 9E s2 SAR Class 10E SAR Class 10E1 s1 Spoornet Class 10E1 s2 SAR Class 10E2 SAR Class 11E SAR Class 12E Spoornet Class 14E Spoornet Class 14E1 TFR Class 15E Spoornet Class 16E Spoornet Class 17E Spoornet Class 18E s1 TFR Class 18E s2 TFR Class 19E TFR Class 20E TFR Class 21E TFR Class 22E
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
List of South African locomotive classes South African locomotive numbering and classification