RAILWAYS AND WAR before 1918. VARIATIONS ON A THEME — (60-cm. gauge) 'MAIN LINE' STEAM

RAILWAYS AND WAR before 1918. VARIATIONS ON A THEME— (60-cm. gauge) 'MAIN LINE' STEAM

All the combatants in World War One needed fairly powerful locomotives for 'main-line' haulage on their light railway systems; typical requirement was for haulage of 50 tons up to a 1 in 50 gradient or six loaded bogie wagons (about 70 tons in all) along the level. The French and Germans already had such machines at the outbreak of war, the others had to evolve their own.

Pechot 0-4-4-OT (France)

Oldest design was that evolved by Messrs. Pechot and Bourdon for French artillery railways in 1882. The requirements of hauling heavy artillery pieces (Plate 37) and the very sharp curves found in early fortress railways led to an articulated locomotive that was really a variant of the Fairlie design. It had a rigid frame carrying the cab, side tanks and boilers, mounted on two flexibly connected power bogies. Unlike the Fairlies it had only one firebox, operated from one side of the central cab and with a single massive steam dome mounted directly above it; the huge spark arresters were intended to prevent 'firework displays' giving away its position at night and to allow working in close proximity to artillery explosive stores. The Pechot, built mainly by Franco-Beige at Raismes, was the standard major locomotive well before World War One and was so highly thought of that a further 280 were built during it, 100 by the North British Locomotive Company and 180 by Baldwin's in America. The locomotives were very strong but rather delicate and were used mainly in rear areas on fairly good track.

Feldbahn 0-8-0T (Germany)

Like the French, the Germans developed their military light railway locomotives during the last two decades of the 19th century but in their case mainly for military field railways and colonial lines. They eventually standardised on a neat 0-8-0T which was built in very large quantities by at least eleven makers, over 2500 being produced up to 1919. These locomotives varied in detail but were essentially very similar, and well adapted for light railway working with excellent adhesion and a comparatively roomy cab having a dropped floor to enable enginemen to stand upright. The long wheelbase necessitated by 8-coupled wheels was made flexible by use of Klien-Lindner axles front and rear (Plate 9). These, strongly reminiscent of Sir Arthur Heywood's contemporary design for 15 in. gauge, allowed a degree of lateral and swivel play while retaining fairly rigid coupling rods. Like the Pechots, some machines were fitted with big spark-arresting chimneys of the continental flat-topped pattern. A typical locomotive had 2 cylinders 240-mm. diameter and 240-mm. stroke, a boiler pressure of 215 lb/sq in. and weight in working order of nearly 12\ tons. Coupled wheel diameter was 590 mm. and total wheelbase 2260 mm., though the rigid wheelbase was 790 mm. only.

Hunslet 4-6-0T (U.K.)

The British, who had to start from scratch in 1915, took a different line of development. They envisaged simply enlarging their current 6-coupled designs and carrying the extra weight on idler wheels as was common on British light railways of the period. The choice of a 4-6-0T was to some extent fortuitous, caused by (i) the current practice of turning tank locomotives at each end of their journey, so that a leading bogie which gave the best weight distribution was acceptable, and (ii) the fact that Hunslet's had an existing 0-6-0T design of suitable power readily adaptable to a 4-6-0 configuration.

The result was the very neat and typically British locomotive pictured here, of which about 100 in all saw service. It was strong, well-balanced and much coveted by the light railway troops whose only complaint was that Hunslet could not produce enough. It had features common to all later Allied light railway locomotives, these including 'bumper bars' fore and aft to ensure engines did not derail too thoroughly; massive rerailing jacks with built-in jacking points; and a water-lifter to enable water to be taken from shell-holes and other unusual sources in an emergency. Leading dimensions included cylinders 9\ in. by iof in., boiler pressure of 160 lb/sq in., a coupled wheel-base of $ ft 6 in. and driving wheels 2 ft in diameter. Weight in working order was just over 14 tons.

Baldwin 4-6-0T (U.S.A. for U.K.)

Quite the most common allied locomotive was the 4-6-0T design produced in quantity by Baldwin Locomotive Co. for the War Department when it was found that Hunslet production capacity was insufficient. By coincidence Baldwins, when approached in 1916, already had a 4-6-0T design closely approximating to the British specification and, with slight modifications, turned out no less than 495 between March, 1916 and April, 1917.

These machines were the mainstay of the British light railway effort although they were never as popular as the Hunslets. Rather ungainly with a high centre of gravity, and mass-produced for a short life to lower tolerances than the hand-built British machines, they were rough riders and had a tendency to derail. In particular they proved that the 4-6-0T layout was far from ideal particularly where much bunker-first running was inevitable. None the less they were rugged and had the advantage that parts were easily interchangeable between members of the class; they were used extensively on all fronts except East Africa.

Leading dimensions were: cylinders (2) 9 in. by 12 in.; boiler pressure 178 lb/sq in.; coupled wheelbase 5 ft 8 in.; coupled wheel diameter 1 ft 11J in. Weight in working order was 14\ tons.

ALCO 2-6-2T (U.S.A. for U.K.)

By late 1916, the shortcomings of the 4-6-0T design were becoming apparent and when tenders were invented for further machines, the American Locomotive Company suggested a 2-6-2T design. One hundred were promptly ordered, materialising as handsome, typically American side-tank locomotives fairly similar in appearance to the Baldwins. Although the biggest light railway engines produced for the British, they were nevertheless so well balanced that axle-loading was still well within the specified limits, and they appear to have been strong and well liked by their crews. The trailing truck certainly cut down derailments and their main fault was the still high centre of gravity, which made them somewhat unstable on rough track. Leading dimensions were: cylinders 9 in. by 14 in.; boiler pressure 175 lb/sq in.; coupled wheelbase 5 ft 6 in.; coupled wheel diameter 2 ft 3 in. Weight in working order was a little over 17 tons.

Baldwin 2-6-2T (U.S.A.)

The Americans, coming into the war late, were the last combatants to acquire light railways but they did have the advantage of being able to standardise from the start, building on other people's experience. Thus their standard steam locomotive was an all-purpose machine, designed by Baldwins as a double-ended version of their earlier 4-6-0T. Apart from the more sensible wheel arrangement and a lowered centre of gravity, it was very similar to its predecessor and some hundreds were produced for the U.S. Army. A good many of these went overseas in support of the American Expeditionary Force but numbers also served at bases within the United States.

VARIATIONS ON VARIATIONS (60-cm. gauge)

Baldwin 4-6-0T under repair

Many of the light railway locomotives used by both sides received modifications in the field at various times in their careers—and often borrowed parts from sister locomotives of the same class. The reason was often the primitiveness of repair facilities available in the field, which led to cannibalisation of damaged machines when replacements were urgently needed. This Baldwin 4-6-0T is on a typical open-air servicing track, simply a section of track raised a little above the ground for convenience of working. The blank space on her side-tank indicates that she has either acquired a neighbour's tank or that she is in the throes of a renumbering scheme that occurred during 1917.

Hunslet 4-6-0T with condensing gear

When light railways came into serious use the problem immediately arose of how to conceal movement of trains; steam locomotives in forward areas often gave themselves away through the smoke and steam. The British War Department decided to experiment with condensing gear as fitted to underground trains and the last of an order for 75 Hunslet 4-6-0T (see Plate 78) was so fitted. Unfortunately conversion was rather slow and by the time when it appeared, in mid-1917, satisfactory petrol-engined tractors had been developed which could do the job even more inconspicuously. Therefore, although the condensing gear worked satisfactorily, it was not proceeded with and 375 remained a solitary example.