LOCOMOTIVE OPERATION Running. The actual handling of a locomotive on the road can only be learned by practice with the engine itself. There are, however, certain fundamental principles which must be borne in mind and applied.
FIRING. Before taking charge of a locomotive, a considerable period must be spent as a fireman. The first things to be learned are the principles governing the composition of fuels.
The difference between the work of a locomotive boiler furnace and one under a stationary boiler is that in the former the rate of fuel consumption is very much greater than in the latter. In locomotive boilers it often occurs that 150 pounds of bituminous coal is burned per square foot of grate area per hour while a consumption of 200 pounds per square foot per hour is not unusual.
Different fuels require different treatment in the fire-box.
Bituminous coal is the most common fuel used on American railroads. It varies so much in chemical composition and heat value that no fixed rule for burning it can be laid down. The work of the fireman varies more or less with each grade of coal used. Ordinarily, the fuel bed should be comparatively thin. It may vary in thickness from 6 to 10 inches or even more, depending on the work the locomotive is called upon to perform. The fuel bed should be of sufficient thickness to prevent its being lifted from the grate under the influence of the draft created by the exhaust.
In order to obtain the best results, the stoking must be very nearly constant. Three shovelfuls at a time have been found to give very good results. The fire door should be closed between each shovelful so as to be only open on the latch. This delivers air to complete the combustion of the hydrocarbon gases which are distilled the moment the fresh coal strikes the incandescent fuel. In placing the fuel in the fire-box, it is well to heap it up slightly in the corners and allow the thinnest portion of the bed to be in the center of the grate. The frequency of the firing depends upon the work the engine is called upon to do.
The fire should always be cleaned at terminals and when the grade is favorable the slice bar may be used and the clinker removed through the furnace door while running.
Anthracite coal. In using anthracite coal, it is best, whenever possible, to do the stoking on favorable grades and at stations. The thickness of the fuel bed varies in size with the kind of coal used. It may vary from three inches with fine pea and buckwheat coal to 10 inches with large lumps. The fuel should be evenly distributed over the entire grate. The upper surface of an anthracite coal fire must never be disturbed by the slice bar while the engine is working. When it is necessary to use the slice bar, it should be done only when there is ample time after its completion to enable the fire to come up again and be burning vigorously before the engine resumes work.
FEEDING THE BOILER. Feeding the boiler is a matter requiring skill and judgment, especially where the locomotive is being worked to its full capacity. The injector is now the univeisal means employed for feeding the locomotive boiler. Where it is possible, the most satisfactory way is to use a constant feed which will be average for the entire trip. In this way the water level will rise and fall but will always be sufficient to cover the crown sheet. Under no circumstances should the water level be allowed to fall below the lower gauge cock.
Where a constant feed cannot be used, the injector may be worked to its full capacity on favoring grades and at station stops. This will give a storage of water to be drawn upon when the engine is working to its full capacity on adverse grades. Under such circumstances, the stopping of the feed may enable the fire to maintain the requisite steam pressure, whereas the latter might fall if the injector were to be kept at work. Further, the use of the injector on down grades and at stations keeps down the steam pressure and prevents the loss of heat by the escape of steam through the safety valves when the fire is burning briskly and the engine is not working.
THE USE OF STEAM. The manner in which an engineer uses the steam in the cylinders is one of the controlling elements in the economical use of coal. In starting, the reverse lever must be thrown forward so that steam is admitted to the cylinders for as great a portion of the stroke of the piston as the design of the valve motion will permit. As the speed increases, the lever should be drawn back, thus shortening the cut-off. It will usually be found that when the engine is not overloaded, a higher speed will be attained and maintained with a short than with a long cut-off. The reason is that with a late cut-off, so much steam is admitted to the cylinder that it cannot be exhausted in the time allowed, resulting in an excessive back pressure which retards the speed.
Experiments have proven, however, that it is not economical to use a cut-off which occurs earlier than one-fourth stroke, for when the cut-off occurs earlier than this, the cylinder condensation will more than offset the saving effected by the increased expansion so obtained. For this reason when the engine is running under such conditions that a cut-off earlier than one-fourth stroke can be used with the throttle wide open, it may be better to keep the point of cut-off at one-fourth stroke and partially close the throttle, thus wiredrawing the steam. The wiredrawing of the steam serves to superheat it to a lmited extent and thus to diminish the cylinder condensation which would occur were saturated steam at the same pressure being nised.
When running with the throttle valve closed, the reverse lever should be set to give the maximum travel to the valve in order to prevent the wearing of the shoulders on the valve seats.
LEARNING THE ROAD. Learning the road is one of the most important things for the engineer to accomplish. He must know every grade, curve, crossing, station approach, bridge, signal and whistle or bell post on the division over which he runs. He must know them on dark and stormy nights as well as in the daytime. He must always know where he is and never be at the slightest loss as to his surroundings. He must not only know where every water tank is located but should also make himself familiar with the qualities of the various waters they contain. Then when he has a choice of places at which to take water he may choose that containing the mallest amount of scale-forming matter.
Grades. In the learning of a road an intimate knowledge of the. grades is of the first importance to the engineer. He must know what his engine can handle over them, how it must be handled when on them, and how they must be approached. An engine will frequently be able to take a train over a grade if it has a high speed at the foot, whereas it a stop or slackening of the speed were to be made at the foot of the grade it would be impossible to surmount it with the entire train.
Handling Trains. Handling trains over different profiles of track requires different methods. On adverse grades, the work is probably the simplest. In such conditions the train is stretched out to its fullest extent. Every car is pulling back and the checking of the movement of the front of the train meets with an immediate response throughout the whole train. The grade also prevents sudden acceleration at the front. It is, therefore, necessary merely to keep the engine at work.
On favoring grades, the whole train when drifting is crowding down upon the locomotive and is likely to be bunched or closed together. Under these conditions, it is necessary to apply the air brakes which are at the front end and keep them applied so as to hold the speed under control and prevent the train from running away. Care should be taken in the application of the driving wheel brakes on long down grades lest the shoes heat the tires and cause them to become loose,
The greatest danger of injury to a train arises in passing over ridges and through sags. First, in leaving an adverse grade in passing over a ridge to a favoring grade, the engineer must be careful not to accelerate the front end of the train too rapidly lest it break in two before the rear end has crossed the summit. There is greater danger, however, in running through a dip where the grade changes from a favoring, to an adverse one. Where brakes have been applied at the rear of the train and the slack prevented the train from becoming bunched, there is not the same danger as when the brakes have been applied at the front of the train. In the latter case, if the engineer is not careful in pulling out the slack, the train may be parted. Accidents of this class will be minimized if in every case the slack is taken up slowly. A steady pull will not break the draft rigging of the car, whereas a sudden jerk may pull it out.
In case a train does break in two, the engine and front portion should be kept in motion until the rear portion has been stopped. In so doing a collision may be avoided. Where air brakes are applied to the entire train, the rear portion will stop first owing to the proportional increase of weight and momentum of the locomotive.
Freight trains require on the whole more careful handling than passenger trains. There is more slack in the couplings of the former than in the latter and the trains are much longer, consequently the shocks at the rear of a freight train, due to variation in speed, are much more severe than on passenger trains. The system of handling, while practically the same for both classes, requires more care in order to avoid accidents with a freight train than with a passenger train.
THE END OF THE RUN. When the run has been finished, the engineer should make a careful inspection of all parts of the engine so as to be able to report any repairs which may be needed in order to fit the locomotive for the next run. The roundhouse hostler should then take the engine and have the tender loaded with coal, the tank filled with water, and the fire cleaned. The engine should then be put over the pit in the roundhouse, carefully wiped, and again inspected for defects.
Table of Contents; Page 156; Page 163; Index
Back to the FAQ Page
