South African Dutton road-rail tractors

Dutton rail-only tractor no. RR1155, c. 1924

Type and origin
Power type	Internal combustion (Prototype) Steam (Production)
Designer	South African Railways (Frank Dutton)
Builder	William Beardmore and Company
Build date	1923-1924
Total produced	3
Rebuilder	Britannia Engineering Works

Specifications
Gauge	2 ft (610 mm) narrow
Axle load: • Leading	3,000 lb (1,361 kg) (Prototype)
Adhesive weight	5,655 lb (2,565 kg) (Prototype)
Fuel type	Power paraffin (Prototype) Coal (Production)
Cylinders	Six (Prototype)
Couplers	Drawbar and pin

Performance figures
Power output	35 hp (26 kW) (Prototype)

Career
Operators	South African Railways
Number in class	3
Numbers	RR1501, RR1155, RR973
First run	1923-1924
Last run	1927

The South African Railways Dutton road-rail tractors of 1923 were road-rail steam tractors.

In 1923, the South African Railways conducted trials with a prototype petrol-paraffin powered road-rail tractor and, in 1924, placed at least two steam road-rail tractors in service on the new narrow gauge line between Naboomspruit and Singlewood in Transvaal.^[1]^[2]

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 before 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]

Development

In an attempt to assist in solving the branchline problem, Major Frank Dutton, SAR Signal Engineer and the Motor Transport Superintendent, developed and took out several patents on a loco-tractor system. The aim was to replace or eliminate the steam locomotive on non-profitable branchlines, since he considered the locomotive to be the main deciding factor on the questions of grades, curves and weight of rails, which governed the cost of construction.^[1]^[3]^[4]^[5]

Dutton argued that a rubber tyre in contact with a hard road would be better at transferring tractive power than a steel wheel on steel rail. He claimed that the tractive effort to be obtained by using rubber-tyred driving wheels running on roads, was 1,330 pounds (603 kilograms) per long ton of adhesive weight, compared to the 334 pounds (151 kilograms) per long ton which could be obtained by using steel wheels running on rails. His proposed system would use railway trucks on rails, hauled by a rail-and-road-borne tractor which would be guided by a four-wheeled bogie on the rails, but with driving wheels fitted with solid rubber tyres which would run on well-prepared strips of road on each side of the rail track.^[1]^[2]

Canada Junction test track layout

General Manager Hoy authorised a trial of the system and a test circuit was laid on the veld at Canada Junction, 9 miles (14 kilometres) from Johannesburg. The dog-bone test circuit was 742 yards (678 metres) around, laid with light 16 pounds per yard (8 kilograms per metre) rails on 7 pounds (3 kilograms) steel sleepers and hook bolts. The track included tight curves of as low as 37 feet (11 metres) radius, and steep gradients of as much as 1 in 17 (5.88%).^[1]

The prototype loco-tractor was a modified Dennis tractor, powered by a 35 horsepower (26 kilowatts) six-cylinder petrol-paraffin engine, which was fitted with a removable bogie between the front wheels to lift them high enough to prevent ground contact. A ball pin on the bogie fit into a socket in the front axle, and the bogie could easily be removed or replaced by running the tractor up a pair of ramps, placed on both sides of the track. The tractor's weight distribution was 3,000 pounds (1,361 kilograms) on the rail and 5,655 pounds (2,565 kilograms) on the rubber-tyred driving wheels.^[1]^[6]^[7]^[8]

Singlewood Branch

The experiments proved successful and authority was granted in 1923 to construct a 2 ft (610 mm) narrow gauge line from Naboomspruit to Singlewood, built to the Stronach-Dutton system, the low cost of construction being one of the motivating factors. The section to Crecy was completed on 15 April 1924 and the full 20 miles 47 chains (33.1 kilometres) line to Singlewood was opened on 22 September of that same year.^[1]^[2]^[9]

At least two tractors were used on this road-rail line, both steam-powered and both rebuilt by the Britannia Engineering Works of Johannesburg from Beardmore steam tractors with Yorkshire boilers.^[2]^[6]

One, no. RR973, was a modified William Beardmore steam tractor, fitted with jacks at the front, to allow a separate bogie to be manoeuvred into position underneath the front axle to guide it on the rails. Without the bogie, the vehicle could still be driven on ordinary roads and had the advantage of being able to be detached and run around the train, without requiring special loops for that purpose. For reversing on the track, as when shunting, the rear wheels were modified to be steerable.^[2]^[3]
The other, no. RR1155, underwent more drastic modification to turn it into a rail-only vehicle. It had a bogie at either end with the single pair of driving wheels on a differential axle in the centre, and was arranged for forward and reverse movement at all speeds. While it was reversible, it could only be used on the rails. Since, on occasion, the vehicle had to be transported by road, its construction was such that it could be readily disassembled into more easily transportable units, to be moved on road wheels to a workshop or for transfer of any other kind.^[2]^[3]^[5]

British Empire Exhibition

Both tractors were exhibited and demonstrated at the 1924-25 British Empire Exhibition at Wembley, where it was presented as a solution to the transport problems which were experienced in several British Colonies. Similar systems were subsequently introduced in many countries, colonies and territories, which included Australia, England, India, Morocco, Palestine, Scotland, Spain, Uganda and Tasmania.^[6]^[7]^[10]

Termination

In South Africa, however, the system was short-lived. The tractive effort per ton of axle load which was assumed by Dutton for the loco-tractor was found to be unduly optimistic, while that for rail traction was unduly pessimistic. The system of combined road-and-rail turned out to have the limitations of both and advantages of neither.^[1]

While the tractors were on exhibition at the British Empire Exhibition, their place was taken by Class NG6 Lawley no. NG98. By 1927, it was joined by Lawley no. NG103, but by this time the loco-tractor system was already terminated. By 17 October 1927, the Singlewood branch was regauged to 3 ft 6 in (1,067 mm) Cape gauge for regular steam locomotive working and, by 11 June 1928, it was extended to Zebediela.^[9]^[11]^[12]

Illustration

Power-paraffin fueled Dennis tractor, prior to modification to Dutton road-rail tractor no. RR1501
Prototype no. RR1501 being demonstrated to Sir William Hoy, seated next to the driver, Canada Junction, August 1920
Prototype no. RR1501 demonstrating shedding its bogie, Canada Junction, August 1920
Road-Rail tractor no. RR973, a modified William Beardmore steam tractor, c. 1924
Dutton reversible rail-only tractor no. RR1155, rebuilt from a Beardmore steam tractor, in service on the Singlewood branch, c. 1925

References

1 2 3 4 5 6 7 8 Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, October 1945. pp. 782-783.
1 2 3 4 5 6 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 118–119. ISBN 0869772112.
1 2 3 Patent: Dutton Light Railway System and Locomotive Therefor, US 1306051 A, Jun 10, 1919
↑ Patent: Locomotive for light railways, US 1416625 A, May 16, 1922
1 2 Patent: Vehicle for Service on Roads and Rails, US 1561510 A, Nov 17, 1925
1 2 3 Stronach-Dutton Road-Rail - The Roadrail System of Traction
1 2 Transport Problems in South Africa - The Dutton Loco-Tractor Advocated as a Solution. Article in The Commercial Motor, 24 August 1920. p. 14.
↑ Important Development Roadrail Transport. Article in Commercial Motor, 26 September 1922. pp. 168-169.
1 2 Statement Showing, in Chronological Order, the Date of Opening and the Mileage of Each Section of Railway, Statement No. 19, p. 188, ref. no. 200954-13
↑ The Stronach-Dutton Road-Rail Tractor 1925, British Film Institute National Archive
↑ Cash, R.G. (2015). The Stronach-Dutton Roadrail System of Traction. The Narrow Gauge, Autumn 2015. The Narrow Gauge Railway Society. pp. 30-31.
↑ Statement Showing, in Chronological Order, the Date of Opening and the Mileage of Each Section of Railway, Statement No. 19, p. 189, ref. no. 200954-13

Wikimedia Commons has media related to Dutton's Road-Rail tractors.

Locomotives of South Africa

Steam

7' ¼" gauge	East London Harbour 0-4-0 Table Bay Harbour 0-4-0ST Table Bay Harbour 0-4-0T Table Bay Harbour 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 Coffee Pot CGR 0-6-0ST 1902 CGR 0-6-0T 1876 Back-to-Back 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 1876 CGR 1st Class 4-4-0T 1875 CGR 2nd Class 4-4-0T 1882 CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack CSAR Railmotor DSWA Eight-Coupled Tank 2-8-0T Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth Harbour 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 0-4-0ST 1903 SAR 0-4-0T no. 69 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 Clayton

3' 6" gauge Tender engines	CGR 1st Class 2-6-0 1876 Beyer, Peacock 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 1879 CGR 1st Class 4-4-0TT 1881 CGR 2nd Class 2-6-2TT 1875 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 Joy 1882 CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 DSWA Eight-Coupled Tender 2-8-0 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 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

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 0-6-0T 1871 Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer

2' & 600mm gauges	ACR Class NG-G16A CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T DSWA Class Ha DSWA Class Hb DSWA Class Hc DSWA Class Hd DSWA Jung DSWA Zwillinge NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T 1899 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

Electric

Amcoal Class E38

Gas-electric

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 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 35-800 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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