THE ORIGINS OF ORENSTEIN & KOPPEL

I was interested to see the reference on page 161 of RECORD 40 to the Orenstein & Koppel Mallets with the rear cylinders located under the driver's cab, also the illustration of such a machine. I enclose a commercial card from my collection showing MAGNET No.3 at work on the Waratah-Magnet tramway in Tasmania. (The message on the postcard was written on 30th January 1911 and the Mallet is identified as "the engine that takes you to Magnet.") The Magnet tramway was a 2ft gauge line built to transport gossan and sulphide ores from tin mines at Mount Magnet to Magnet Junction, some ten miles distant. Surveyed and built between January 1901 and January 1902, it was laid with 30lb rail and connected about 1½ miles east of Waratah with the Guilford-Waratah branch (closed 1939) of the 3ft 6in gauge Emu Bay Railway, which had begun life as the 45 mile long horse worked Burnie-Waratah line of the Van Diemen's Land Co. The latter operated in this manner between 1877 and 1881, and was then rebuilt as a steam traction line in 1884. Two Mini Mallets and an 0−4−0 tank (all by Orenstein & Koppel) were supplied through Central Mining & Tramway Appliances Proprietary Ltd for use on the Magnet tramway. Arriving in 1901, the 0−4−0 tank became No.2 and was used on construction work initially: later it saw use at the tin mines. Mallet No.1 arrived in October 1901 and was put into service by the beginning of November, following assembly. Its main dimensions were:- front (low pressure) cylinders 12in by 12in; rear (high pressure) cylinders 8in by 12in; wheel diameter 2ft 1in; rigid wheelbase 4ft 3in; total wheelbase 10ft; boiler pressure 170lb per sq in; weight in working order 18 tons. A second similar locomotive, No.3, was purchased some time between 1903 and 1905. After the line closed the two Mallets went to mining tramways in Western Australia, where one of them - probably No.3 or a combination of the two - still exists awaiting future preservation.

The reason for the rear cylinders was presumably because there were no turning facilities on the lines where these locomotives were used and they therefore had to work equally well in either direction. Garratts and double Fairlies have cylinders similarly placed, no doubt for the same reason. Indeed, there seems to be a difference of opinion between Kenya and Tanganyika about the correct direction to work a Garratt! (See "Transactions of the Newcomen Society", Vol XL, 1967−68.) The North East Dundas Tramway, for which the first Garratt was built, was of course another 2ft gauge line much like the Magnet tramway, but I have been able to find out little about it. It may have had an earlier articulated locomotive, for according to C.C. Singleton and David Burke in "Railways of Australia" (Angus & Robertson, Sydney, 1963) the Tasmanian Government - which owned the Dundas line - purchased in 1902 a 2ft gauge J. Hagans Patent 2−6−4−0 tank. So far I have not been able to find out what sort of articulated locomotive this was.

SOUTH CROYDON DEREK A. BAYLISS

(Surely the main point about Orenstein & Koppel's adaptation of Anatole Mallet's idea is that it enabled a much larger grate area to be provided on a small gauge. The general Mallet principle, of course, involved the rear set of wheels and high pressure cylinders being set in the normal manner within the main frame, carrying boiler and superstructure and being an integral part of the locomotive. The front set of wheels and low pressure cylinders were contained in an articulated power bogie under the front end of the engine. (Reference to the photograph at the bottom of page 313 of RECORD 45 will help to illustrate this). However, by placing the high pressure cylinders at the extreme rear, the front wheels can be taken as far forward as the power bogie, thus increasing the rear wheelbase and enabling the fitting of a longer firebox and ashpan. Similarly outside main frames (not normally a Mallet feature) allowed a wider firebox and ashpan. Apart from longer steam pipes both to and from the high pressure cylinders under the cab there would appear to be no disadvantage over the usual Mallet design. In the latter a larger grate area could only be obtained by pitching the boiler higher, allowing the ashpan to sit over the frames; this would probably be quite acceptable on wider gauges. Perhaps Orenstein & Koppel's design was specifically developed to obtain a lower centre of gravity on 2ft gauge? Lionel Wiener, in his book "Articulated Locomotives", does not record this Drewitz variation. A further example still existed in April 1963 on the Pithiviers - Toury line in France; Orenstein & Koppel 1772 of 1905 (TPT 22.7). l am unaware of its previous history but understand it was cut up shortly after our visit. The TPT at that time possessed a veritable feast of articulated locomotives.

In the Hagans system, invented in 1894 and mentioned by Derek Bayliss in his letter, the front set of wheels is fixed rigidly within the main frames of the locomotive; the trailing set consists of a truck. The cylinders are in front of the leading wheels and drive them in the usual manner. The drive is also transmitted to the axles of the trailing bogie by a system of rods and oscillating levers which allow lateral displacement of the trailing bogie. The system has been described as ingenious: bewildering might have been a better word! — REW)