TWO POWERFUL CLASSES.
Problems to be Solved.
The Railways Commissioners have de- cided that it is advisable to introduce two very powerful new classes of locomotives to deal with the increasing traffic.
The A2 class, designed before the war by Mr. T. H. Woodroffe, who was then chief mechanical engineer of the Victorian Railways, have given, and are still giving, admirable service; but with the increasing weight of the express trains they are no longer powerful enough for their work; and it will, no doubt, have been noticed during the last three or four years that it is frequently necessary to haul the Ade- laide and Sydney expresses with two en- gines.
For the heaviest class of express traffic the A2's, therefore, will be superseded by a much heavier and more powerful engine, which will be capable of hauling possibly 11-car trains over the ruling gradient on the main lines. Trains made up of eight cars, it may be mentioned, constitute a full load for an A2 locomotive. Another and still more powerful engine of the "mountain" type will be introduced for sections where the grades are exception- ally long and severe.
The chief mechanical engineer (Mr. A. E. Smith) and his staff are confronted by a number of difficult problems in connection with the design of this new motive power. For example, the axle loads of the newer classes of locomotives are already up to the limit allowed by the ways and works branch. This is 18 tons; but the axle load (that is the weight on any particular pair of wheels) cannot be kept below 23 tons for the new engines. Apart from that, the engines will be so high that it will be possible to get them under the bridge structures only by cutting down the funnels to a mere collar, and reducing the domes to a "pimple," as one of the engineering staff described it. Nor is that all. The cylinders of the recently introduced classes come within a few inches of the platforms as it is, and it is questionable whether it will be possible to provide the cylinder dimensions required for the new engines without cutting away a portion of the platforms and other structures which would be in danger of being fouled if still larger cylinders were introduced. This would be a costly and difficult undertaking. The alternative would be to keep the size of the cylinders within the required limits by having three cylinders in place of two. With two cylinders, for instance, the cylin- der diameter in the case of the proposed "Pacific" engines would be 24in.; but by putting a third cylinder between the frames it would be possible to keep the diameter down to 20in. Mr. Smith, however, will not resort to this solution of the problem unless he considers it absolutely imprac- ticable to solve it otherwise, because it would introduce about 33 per cent. more moving parts into the engine, which would result in considerably increased mainten- ance charges.
Electric Units Satisfactory.
The electric locomotive (in two units) recently completed at the Newport work- shops has been under test for some weeks, and it is proving entirely satisfactory. So far, the tests have been confined to shunt- ing and to suburban goods service. Later, it may be tried on the Frankston line for passenger service, but officers in the Rail- ways mechanical department question whether it will prove speedy enough for such work. When the two units are coupled together they have a haulage power equal to that of the C class steam loco- motives, which are the most powerful on the Victorian Railways, for these will haul 500-ton trains up gradients of 1 in 50.