過熱蒸氣機關車の最大引張力算定に用ふべき新線圖に就て

抄録

The empirical formulae proposed by various authors for estimating the amount of tractive force of railway steam locomotives afford very often the results remarkably different from each other. Dr.K.Asakura, C.M.E of the rolling stock section of the J.G.R., pointed out that the diversity arises principally from the too simple and liberal idea that the resistance of railway locomotives may be assumed directly proportional to their weights. He recommended a new method of calculation based on his original principle which holds fairly good for the most of various test-results and has been adopted since by the majority of engineers of the J.G.R. However, as the method requires a series of complicated calculations he also recommended the use of a set of charts prepared from the data which he had at hand at that time. The object of this paper is to recommend another set of new charts which are believed to be simpler in use and closer in result inaccordance with the characteristics of the modern locomotives fitted with superheaters as well as feedwater-heaters and working at higher steam pressure. 1. By assuming the rate of combustion (B) and computing the principal dimensions of the locomotive we find Q_<max>/NJP, ratio of the maximum evaporative power of the boiler to the product of the total piston displacement into the boiler pressure.(Fig. 8). 2. The ratio of the mean effective pressure to the boiler pressure multiplied by the mechanical efficiency of the steam engine (yη) is to be found corresponding to Q_<max>/NJP and n, the r.p.m. of the driving wheels (Fig. 9.) 3. The tractive force at the driving wheel tread (Z) is to be found by calculating graphically (Fig. 9) the following formula, where D is the diameter of the driving wheel. Z=y.η. 20 NJP/πD 4. The tractive force at the drawbar will be got by subtracting the running resistance corresponding to the speed from the value of Z.