£^NOVEMBER 20, 1914. THE COLLIERY GUARDIAN. 1081 INDUSTRIAL LOCOMOTIVES.* By J. W. Hobson. (Concluded from page 1018.J Wheels, Axles, and Tyres. For engines with cylinders up to 14 in. diameter cast iron wheel centres are all that is required, but for engines above this size it is better to adopt cast steel centres. The wheels should not be too small in dia- meter, otherwise parts of the engine are brought too close to the rails. This point is especially important in the case of an engine having to travel over a portion of the main line where it is not permissible for any part to be within 6 in. of the rail. The parts likely to be within this distance are the connecting and coupling rod ends, brake gear, and springs when of the under- hung type. The axle bearings should be of ample pro- portions to prevent heating. The load per sq. in. on the basis of length by diameter of the journal with the weight of the wheels and axles deducted should not exceed 2501b., though there are numerous examples of this being as high as 2801b. per sq. in. Axle Boxes and Guides. Some builders make these parts of cast iron, but cast steel is the better practice. Cast iron to cast iron is an ideal bearing surface, and there is some likelihood of a cast steel axle box cutting into a cast iron wheel boss; but the number of broken cast iron boxes, especially with underhung springs, gives the cast steel boxes a great advantage; and if it is found that the latter is detrimental to the wheel centre, gunmetal or steel plate liners can easily be fitted to the bosses. This objection does not, of course, apply to cast steel centres. Again, cast steel axle box guides add materially to the strength of the engine frames, supporting the same effectively at the weakest parts. The axle boxes are fitted with hard gunmetal bearings and cast iron keeps, and these should all be finished flush in order to offer a large bearing surface to the boss of the wheels. For this class of engine opinion is divided as to whether white metal in the bearings is an advantage or otherwise, because if heating does take place, there is a danger of the metal running, necessitating a long delay while the engine is lifted, the boxes and journals cleaned, and the metal renewed in the brasses. Of course, heating is generally due to insufficient lubrica- tion, or foreign matter getting into the bearing, and great care should be taken to keep the oil boxes, oil channels, trimmings, etc., as clean as ever possible. With regard to lubrication, admitting oil to a groove in the crown of the brass gives better results than side grooves; In addition, oil is gathered by the journal passing over the pad or waste in the axle box keep. Valve Gear. The valve gear employed for this class of locomotive is the Stephenson type, excepting for service abroad, when the Walschaert gear is often adopted, especially for narrow gauge engines. Practically all the valve gear work of the present day is of mild steel, with the eyes, pins, and wearing surfaces carefully and thoroughly case-hardened. Oil holes and grooves should be generously provided, and moreover they should be as large as possible. An important item to watch is the security of the eccentric sheaves on the axle, as if any slack exists this will inevitably result in the slackness becoming increased, owing to the heavy demand made upon the sheaves in operating the valve gear. The adoption of piston valves or balance slide valves would relieve the duties of the sheaves and the valve gear generally; but other and more serious troubles would be introduced. . Bearing Springs. As broken springs are a somewhat common occur- rence, especially with badly laid rails, too much atten- tion cannot be bestowed on the design and manufacture of them. A suitable spring is one which will give uniform deflections for similar additions of weight, and should possess strength and ductility combined, the former enabling it to withstand severe shocks conse- quent on uneven rails, and the latter permitting it to depart from, and return to, its normal camber easily, as the load upon it increases or decreases. The leaves should be made from the best spring steel in the form of bars cut to length, with nibs and slots to prevent side- slipping, heated, and the correct curvature given them. They are then tempered by heating and cooling down in oil or water depending on the class of steel. The buckles should be of mild steel made from the solid, as there are fewer failures than with Yorkshire iron welded buckles. Tank. By far the greater number of industrial locomotives are constructed with the saddle type of tank, which gives easy access to the gear between the frames. This form is cheaper to manufacture than two side tanks of equal capacity, and is convenient when extensive repairs are to be carried out. For the larger engines, side tanks are preferred by many engineers, on account of their smarter appearance, and in many cases the improved outlook from the cab in a forward direction. The adoption of side tanks is also an advantage, and in some instances a necessity when an engine has to be constructed to a limited height, qr when the Belpaire firebox is desired. Cab and Bunkers. As these engines have generally to work in very exposed places, it is advisable to afford the driver every protection against the weather—at the same time, there * From a paper read before the North-East Coast Insti- tution of Engineers and Shipbuilders. is a danger of stuffiness if too much enclosed. A good plan to adopt in the case of 4 w.c. locomotives is to have a removable back plate, which may be dispensed with during the summer months, and hinged or swivelling windows give all the ventilation required. With regard to 6 w.c. engines, it is, of course, possible to obtain a more roomy cab, which if found to be stuffy can be remedied by having a ventilator fitted in the roof, which, in addition to the opening windows, should afford comfort. The fuel bunkers are placed at the sides of the fire- box in the case of the 4 w.c. class, in order to reduce the overhang of the engine as much as possible; but the hind platform is more convenient and assists the better distribution of weight in the case of 6 w.c. engines. In any case the bunkers should not require filling from the inside of the cab, which is a serious disadvantage. Sand Boxes. These engines having to work on sharp curves and severe grades, and the rails about works and collieries being generally in a very greasy condition, a good supply of dry sand should always be available, for which pur- pose there should be four sand boxes provided. These boxes should be watertight, and placed in accessible positions, where they can be quickly and easily filled without sand falling on to the motion, valve gear, or axle boxes. They should also be arranged to deliver the sand on the rail as far under the wheels as it is possible to take the pipes. It has been found advisable to have the front and hind boxes controlled separately by two handle^ in the cab, and not all boxes operated by one handle. In fact, some engineers go so far as to have a separate handle and gear for each box. Copper Pipes. The best practice is to have all steam and water pipes of solid drawn copper, though some builders adopt cast iron steam pipes in the smokebox, and wrought iron pipes for the internal and feed pipes, in order to cheapen production. There is, however, too great a variation in temperature and consequent expansion for such to be suitable for locomotive work. The smokebox steam pipes give the most trouble. These are acted upon by the waste gases at a temperature of 500 to 700degs. Fahr., and severely stressed by engine vibration especi- ally in the case of outside cylinder engines. Fracture in almost every instance occurs in the locality of the brazed end at the T or L piece unless lens joints are fitted (the lens joint being on the principle of a ball and socket joint permits the pipe to adjust itself). A further safeguard is to have these pipes re-annealed about every 12 months. Another source of trouble is caused by ash being allowed to remain in the smokebox bottom, which incites rapid deterioration, and for which there is no remedy. Therefore it is imperative for the smokebox to be frequently cleaned out. External pipes if of copper and properly treated by re-annealing every few years will last the life of the engine; wrought iron pipes, of course, will not. Lubrication. This question is a most important one, and has con- sequently received considerable attention. For lubri- cating the slide valves the old form of Roscoe lubricator fixed on the smokebox sides, and delivering the oil into the steam pipes is still the most favoured method. In place of these some engineers prefer a sight feed lubri- cator fixed in the engine cab; but cases have been brought to the author’s notice where this method has been so unsatisfactory, owing to the pipes and small holes of the lubricator becoming readily choked up, as to necessitate reversion to the old method. Another system, of which favourable reports have been received, is a single feed mechanical lubricator placed in the cab, operated by gear from one of the eccentrics, delivering the oil into the regulator ports, and after lubricating the slides, carrying it to the steam chests. In spite of the good reports, the author cannot feel in agreement with this method, first because a regu- lator in a dome should not require lubricating, and secondly there is a danger of the oil getting into the boiler and causing priming. Mechanical lubrication, being certain in its action, is attractive to the engineer, and having become established in other branches of engineering, will no doubt be more extensively adopted for, at any rate, the slide valveo and cylinders of locomotives. Vegetable oils, such as rape oil, are very suitable for the working parts of a loco- motive, but are unsuitable for use in the steam chests and cylinders where mineral oils which possess the pro- perty of withstanding the temperatures met with are generally used. All working parts of the engine should be effectively lubricated, otherwise heating troubles will cause delay and annoyance, and excessive wear is sure to result. Instead of oil for such parts as slide bars, coupling and connecting rod bearings, and eccentric straps, grease has been tried with remarkable success. In one instance locally a clear saving of 25 per cent, is effected—a matter of some importance when it is remem- bered that 15 locomotives are employed. In their case the grease cups are so designed as to require one turn per day, which permits a spring behind a piston gradu- ally to force the small, measured quantity of grease into the bearing, and the cups contain sufficient grease for a fortnight. The lubricant employed for the axle boxes should possess the property of supporting consider- able weight without being squeezed out. Oil has been found to be more satisfactory than grease unless the tendency to heating is very great, in which case grease should be used temporarily. A small quantity of engine oil is all that is required for the axle box guides. Brake Gear. It is customary to fit the smaller engines with hand brake only, but on locomotives of over 20 tons weight a steam brake should be fitted in addition. The brake power should not be excessive, otherwise the wheels may become locked and flats worn on the: ty?0S,; which will shorten the life of the same considerably, to say nothing of the annoyance of a noisy running engine;' 'The brake power should be about 60 to 70 per cent, of the weighs fully loaded, and should not exceed 80 per cent, of the weight with tanks and bunkers empty. The ratio of brake power to tractive effort is generally about 3 to 1. The steam having to be carried a distance to the brake cylinder, and the latter being usually in a cold condition, it is found that the pressure available for. brake power is 18 to 20 per cent, less than the working pressure, when the brake is first applied. All wheels should be braked, and in the same direction,' otherwise severe strains are thrown upon the coupling rods. All brake pull rods should be arranged to be in tension when the brake is applied, and adjusting screws and nuts should be provided on the main pull rods to enable the wear of the brake' blocks to be taken up. Otherwise the latter wear very unevenly, and their life is unduly short. When an engine is required to control trucks on varying grades of considerable length, a steam brake reducing valve is of immense assistance, to the driver, enabling him to regulate the brake power to suit the circumstances. If, on the other hand, the brake is only required for ordinary shunting operations, a simple steam brake valve is more suitable. Some engineers prefer wearing parts of brake gear to be case-hardened; but a surface hardening, such as potash, is all that is necessary, and deep case-hardening is liable to set up fractures owing to the sudden and severe shocks received. Combined Shunting and Crane Locomotives. This type of industrial engine is a most useful one, as evidenced by the number in service. The varieties in use may be roughly divided into two classes, viz. :— (1) Those with jibs fixed as regards height; (2) Those with movable jibs. The former class may have the jib revolving on the chimney, supported from the bunker, or carried on castings over the boiler. The principal disadvantage of this type is, however, apparent,’ viz., that to ensure a reasonable lift, the height of jib exceeds the usual main line loading gauges and height restrictions in works, etc. The movable jib type is represented by a speciality of Messrs. R. and W. Hawthorn, Leslie and Company. The crane, which is mounted over an ordinary loco- , motive boiler, and rests on the frames in or about the centre of the engine, thus giving a good weight distri- bution, is controlled by the difference in pressure on the top and under sides of a piston attached to the end of the jib; and the load is slewed to any part of a circle in either direction by a small two-cylinder turning engine. The handles for lifting, lowering, and slewing being duplicated on each side of the engine, are always within easy reach of the driver. These engines conform to the main line loading gauges; the cranes are capable of lifting bulky packages over the sides of trucks, and the entire machine effects a considerable saving in time, and labour in any establishment where large quantities of goods and material have to be handled—such as in shipbuilding yards, iron and steel works, docks, quays, - railway goods depots, etc. • Conclusion. , Before concluding, the author wishes to state that foi obvious reasons the question of initial cost has not been touched upon. This, however, is a very fluctuating quantity, depending upon a variety of circumstances. With regard to running costs, very few users take the . trouble to keep analysed accounts. Is this because the steam locomotive is so efficient? In any. case, figures which apply to one establishment are not likely to apper- tain to another, as a shunting engine may be working at full power continuously in the former, and only inter- mittently in the latter. Electric locomotives for industrial purposes are few in ' number as compared with steam; but huge electrifica- tion schemes, being in development, it is. difficult to prophesy whether the former will prove a formidable competitor. Locomotives having oil engines as their source of power, using such fuels as petrol, paraffin, kerosene, alcohol, etc., are in the early experimental stage. As yet their initial cost is much against them, the price of a reliable internal combustion engine alone being much above that of a steam locomotive of equal power. To balance this extra initial outlay, the cost of running and upkeep would have to be very much in favour of the former, even if required for only intermittent working. This paper is necessarily in a certain measure descrip- tive, but in extenuation it may be stated that only such . questions have been dealt with as are repeatedly raised by those responsible for the purchase and running of industrial locomotives. A report of the General Purposes Committee brought before the Metropolitan Water Board on Friday stated that-