A NEW DEPARTURE.

Hawera Star, Volume XLVII, 18 January 1928, Page 9

A NEW DEPARTURE.

BLG LOpOAIIOTIVKS ORDERED UiSE ON MAIN TRUNK LINE. As a further step in the improvement of the New Zealand railways, the Department has accepted a tender for the supply of three big Garratt articulated locomotives which will be the most up-to-date and one of the most powerful types used on any 3ft (iin gauge in the world. They are intended primarily for use on the central section of the North Island .main trunk line where heavy grades and sharp curve's make haulage difficult for the locomotives at present in use, says the “ Wellington Evening Post.” Negotiations for the supply of engines of this improved type have been in train between the Bailway Department and Britain firms for some time past, and the tender of Messrs Beyer, Peacock, and Co., Ltd., Manchester has now been accepted. The first of the three new engines is expected to arrive next Christmas. THE ENGINE DE'SCEUBED. The principle of the Garratt type of locomotive is to obtain the greatest power with the minimum of axle load, tlic total weight of the engine being distributed over a greater length. The new engines on order will therefore lie much longer than engines now in use, the total length over all being 77 feet, The fact that each will develop a tractive effort of 51,5801 b as compared with 20,0001 b developed by the Ab class . of locomotive at present in principal use in New Zealand, and that the weight in working order will be Mb ton s as against 84 tons 15-cwt in the case of the Ab, gives a good idea of the superior power and size ot the more up-to-date engine. The Garratt is in reality a combination of engines, and in those of the design under order is equivalent to two locomotives working with one boiler. Another interesting fact is that the locomotive is m three separate sections, as is well illustrated in the photograph reproduced to-day. The boiler section in the middle has a pivot point at each end, sitting over the respective leading and trailing engines. No turntable is required for reversing at termini, as tn engine will run equally well in cither direction. Water tanks are carried at each end,, one containing 2500 gallons and the other 1500 gallons, a total of 500 gallons ■ more than the Ab. The coal bunker will have a capacity for six tons of coal, as against 44 tons in the Ab. In the new engines there is a radical departure from the usual practice in New Zealand as regards firing, for they are mechanically stoked. The coal is fed from the bottom of the tender to the face-plate of the boiler, and is then lifted to nozzles and sprayed into the tire-box. A further new departure is that they will be of the three-cylinder simple type at each end. Thev will also have super-lieated boilel’s and a working pressure of 2001 b to the square inch. The grate area will be 58 square feet this being the largest grate on any locomotive in New Zealand. .SOME ADVANTAGE. One of the great advantages of the new engine so far as the New Zealand railways are concerned will be in the greater power provided without the necessity for increasing the size of bridges to take the weight of heavier engines of the type a.t present in use. If it were decided to acquire eugines of the same power as the Garrett, but not of the ,articulated type, the axle load would be increased to such an extent that enormous expenditure would b e necessitated in the strengthening of bridges. The new engines will also obviate the necessity of putting two engines, as is the present practice, on heavy trains travelling across the difficult country between Frankton and Taihapc. The purpose of the three new locomotives is heavy haulage rather than speed, but they will be capable of a, speed of 75 miles an hour. On heavy gradients and sharp curves Garratt locomotives are far more efficient than orthodox* types, but as additional advantages it has been proved that they are the means of enabling train loads to be increased, reducing running time, increasing the capacity of the line, and reducing the cost per ton-mile. It is not in the hauling ot heaw freight trains alone that such economies can be effected; experience on manv railwavs has fully demonstrated that Garratt .locomotives are suitable for operating any class ot traffic, from shunting to fast passenger trains.

LTKE THE “FEY INO SCOTSMAN. ’ ’ [n an interview, the Chief Meehaniral Engineer of the Railway Department, Mr G. S. Lynde, 0.8. E., Mech.E., said that lie had decided upon the three-cylinder type after very careful consideration. It was interesting tnat although the Garratt tvite of locomotive had two distinct engines, each locomotive would be very similar to the “Flying Scotsman three-cylinder Pacific class, whose poiforniane.es at Home had given every satisfaction and recently created a world’s record non-stop run between London and Newcastle-on- Tyne. Mi Lynde also pointed out that the rauwav system in South Africa, India, the Argentine. Brazil, and many other countries had adopted the Garratt type.