In August, 1897, arrangements were courteously made at my request by the Hon. Cecil Parker and by Mr. W. A. Forster, to enable me to test the weight of minerals that could be transported in a full day’s work, over the three miles of line from Balderton to Eaton. Care was taken to obviate any delays in loading and unloading, but every truck had to be weighed separately on leaving Balderton, a process occupying about ten minutes with each train. Six trips were run during the day, and 69 tons of coal and road-metal were transported. There were four loaders at Balderton, and two unloaders at Eaton. The trains consisted of 12 wagons and van. The average gross weight, exclusive of engine, was about 17 tons, and the weight of minerals, or paying load, 12 tons. The speed was just under 10 miles per hour for the loaded trains, and 11.5 miles per hour for the empties. The engine left the shed at 8.15 a.m., and returned at 5.45 p.m., with a delay of 55 minutes for dinner. The weather was as bad as possible, slight showers all through the day making the rails so greasy as to necessitate the constant use of sand up the inclines. Time was also wasted in an extra journey for empty wagons, and in other unavoidable delays. About 1 hour 10 minutes was the average time taken over a trip out and back, reckoning to the time of next start. It is thus apparent that, with a little more arrangement, eight trips could have been run in the day. In the earlier trips, the gross loads hauled were only about sixteen tons, increasing later in the day to eighteen and nineteen tons. These larger loads might just as well have been also hauled on the earlier trips and it was apparent that, under less adverse conditions, 100 tons of paying load could have been transported in the day. Only 3 cwt. of coal was burned, including lighting up. The total distance run was 41 miles, and the average consumption of coal per mile, including that burned while standing, was 83 lbs. For Eaton Railway Regulations see Appendix C.
V.
LOCOMOTIVES.
The first locomotive put upon my line was completed in 1875. This engine was constructed, not so much as a model of what a small locomotive should be, as to provide the requisite motive power for the experiments I desired to carry out. No great care was, therefore, observed in the details, and in its construction a good deal of material which happened to be at hand was utilized to save time and expense; this much in excuse of the want of proportion in some of the dimensions, which will be found in detail under the head of No. 1 in the table of locomotive dimensions on page 31.
The boiler was of the launch type, a cylindrical shell with a cylindrical fire-box terminating in tubes. This pattern of boiler, though giving less heating surface for its size than one of ordinary locomotive design, has the great merit of having no fire-box projecting below the barrel, thus enabling the over-hang of the frame beyond the wheel-base to be equalised at each end, a matter of the first importance in small tank engines. Its low first cost and the ease with which it can be kept in order are additional advantages. So well was I satisfied with the working, that in the four boilers since designed for my locomotives I have adhered to the original plan, which was copied from some shunting engines made by Mr. Ramsbottom for the London and North Western Railway. I go so far as to think that, without getting rid of a depending fire-box, no really satisfactory tank engine can be constructed for a small gauge railway unless idle wheels are introduced, a proceeding that cannot too strongly be deprecated. The gradients, which are almost invariably the concomitants of these small lines, make it essential that the whole of the available weight should be utilized for adhesion.
The difficulty of carrying on four wheels a boiler of sufficient length for a more powerful engine, and the unsuitableness of an ordinary six-coupled engine to the sharp curves in which narrow-gauge lines generally abound, led me, in 1877, to work out a design by which the wheel-base of an engine of the latter type could be made to accommodate itself to any required degree of curvature. At this time I was in communication with officers engaged in promoting a scheme for an army field railway, where great power conjoined with perfect flexibility was essential. As the result, I constructed the engine of which the dimensions are given under No. 2 in the table, this being put to work in 1881. While avoiding the complication of the double-bogie system, this engine possesses most, if not all, of its advantages. It is six-coupled in the ordinary way, the axles having outside bearings and cranks. The wheels, of cast steel, are not fixed upon the axles, but each pair is keyed upon a cast iron sleeve, through which the axle passes. The sleeve upon the middle axle is capable of sliding 1 in. in each direction laterally, but cannot revolve upon its axle thus, when the engine reaches a curve, the arc of the rail draws the middle wheels on their sleeve to an amount equal to the versed sine of the arc, without interfering with the rigid position of the axle. The leading and trailing pairs are likewise mounted on sleeves, but here the connection of the sleeve with the axle is by means of a ball joint at the centre, so constructed as to leave the sleeve free to radiate in any direction, but obliging it to revolve with the axle. The middle sleeve is so connected by external hoops and links with the leading and trailing sleeves that, when the former makes a lateral diversion, the two latter are radiated precisely to the required curve, providing it is within the limit of the travel of the middle sleeve, which, in this case, is arranged for a radius of 25 ft. This engine excited considerable interest among visitors to my railway at the time of the Royal Agricultural Show in Derby in 1881, but the opinion was expressed that the arrangement would not stand hard work. A few years later, however, when some officers of the Royal Engineers were trying the engine with a view to adopting the plan on the military railway at Chatham, they subjected it to very severe tests, loading it up steep inclines to its utmost capacity; stopping it with the steam brake almost dead when travelling at various speeds and over the most awkward places; and, finally, giving it a fifty mile run with all the load that could be got together, at an average speed of seven and a half miles an hour, stops being made for water, &c., for twelve minutes in each hour. This was followed, shortly after, by a continuous run with a similar load for an hour and thirty-five minutes, the extreme limit to which the water in the tanks would hold out.
There was no heating of any part during the trials, nor failure of any kind. After eight years’ work, chiefly on gradients of 1 in 10 to 1 in 12, where sand has to be used freely, the engine came into the shops to be overhauled. During this time there had been no mishap or breakage whatever, nor had a wheel ever left the rails, except on one occasion in descending the steep incline, when, owing to the slippery state of the rails, and sand failing, the engine slid away and left the road; less than an hour, however, sufficing to get it running again.
On removing and examining, shortly after this, the working parts of the radiating gear, they were found in perfect order, the tool marks being still visible in the ball joints; and in August, 1895, the engine, which was then sent over to do the ballast work on the Eaton Railway, where it worked for thirteen months, showed still a clean bill of health. The engine is now rebuilding, and it is proof of the excellence of the radiating gear that this part is being put together again without re-adjustment of any kind. There is thus no doubt of the success of this radiating principle.
This engine is fitted, as already noticed, with a steam brake, which can also be applied by hand but the latter alone is far too slow in action for the abrupt stops necessary on a line like mine.
The space between the frames being occupied by the radiating arrangements, the valve gear is necessarily outside, and, to avoid overhung eccentrics, I designed a modification of one of Mr. Charles Brown’s Swiss valve gears, which are also the parents of what is known in this country as Joy’s gear. I venture to think that my plan, in which nothing projects below the connecting-rod, is better suited to small engines where the motion is almost always near the ground than any yet produced. The gear is extremely simple, and has worked without any trouble, the only setting required being the adjustment to length of the valve spindles, and the setting of one fixed centre on each side of the engine.
The springs consist of rubber pads placed between the axle-box and the horn-block. They are simple to fit, take up no room, never get out of order, and last many years. I have no steel-carrying spring on any of my stock.