All About Engines

246 All About Engines fraction of the number of men required to manage steam machinery proved an enormous attraction. Thus a writer in the Special Oil Power Number of Gassier’s Magazine in 1911 examined the result of producing the 70,000 horse-power required by the Mauretania in Diesel engines. The space occupied would be only one-third of that now occupied by the steam engines and boilers. And since there would be no need for stokers and coal trimmers, 192 stokers and 120 trimmers might be discharged, with a saving in wages of £40,000 a year ! Only a quarter of the weight of fuel would enable the vessel to travel the same distance without renewal. This, however, is the vision of an enthusiast. It may be possible in the future, but it is not practicable at present. In the first place, it would require engines giving 1,500 horse-power per cylinder. Cylinders giving this power have been constructed, and cylinders giving 1,000 horse-power each are working quite satisfactorily; but they must be double acting and are difficult to make and keep cool. The main obstacles, however, are two in number : the Diesel engine is adapted for running always in the same direction, and it is not very good for slow speeds. Let us amplify these points. Firstly, the engine will run in either direction, but complicated apparatus is necessary for re-timing the valves, and reversal is more usually accomplished through toothed wheels. These have been so greatly improved in recent years, as we shall note in the