ing of the American Institute of Electrical Engineers, Baltimore, Md., March 27, 1912.

Copyright, 1912. By A.I.E.E.

ECONOMIES IN RAILWAY OPERATION

BY F. E. WYNNE

Never before in the history of modern industrialism has there been such a stupendous effort made by every one for high efficiency as at the present time. It is the keynote of every convention; the proceedings of the Institute and other engineering societies are full of it; magazines and daily papers are devoting a great deal of space to the subject.

Under such conditions it is natural that the pendulum in railway operation, which has until recently been swinging far upon the side of safety and reliability at any cost, started to swing towards the side of reduction in cost, at the price, as some engineers think, of both safety and reliability. When this happens, an extreme is likely to be reached that may show a reduction in cost of some items that have been in the limelight, but will show an increase in other items affected thereby that will far outweigh the reduction. The way to avoid such an undesirable condition of affairs is to analyze carefully every point and study it from all sides before making a change from practise that is giving good results. In other words, the old maxim, "be sure you are right, then go ahead," applies here with special force.

Probably nowhere has this search for efficiency been more active than in the electric railway field. In the first place every part of the equipment has been studied with the greatest care to increase its life and reliability and decrease the cost of maintenance. This has resulted in the present magnificent equipments that are found on all up-to-date roads. Car bodies, trucks, wheels, control and motors have all been improved to an extent undreamed-of a few years ago. Not only has there been

a great increase in reliability-which is always one of the greatest assets a road can have-but the cost of inspection and maintenance has been reduced to a degree that makes it cheaper to scrap old equipments than to operate them.

Since the life of wearing parts has been increased to such an extent that but little return may be expected from further endeavors along that line, the busy minds of engineers all over the country have been turned towards other means of reducing cost of operation and have naturally rested on the cost of power. This is usually one of the larger items in the cost of operation and offers a fruitful field for investigation. A great many engineers have figured out the amount it costs to carry around the dead weight of a car and have given figures varying from 3 to 10 cents per pound per year. These figures must of course depend on the mileage, the cost of power per kw-hr. at the car, and the kind of service. For instance, the mileage of cars may vary from 15,000 to 90,000 miles per annum. Power may cost in one place 0.4 cent per kw-hr. at the switchboard, and in another place may run twice that amount. Then the cost of getting a kilowatthour from the power house to the car varies widely. Finally, the conditions of service may vary so much as to take anywhere from 40 to 150 watt-hours per ton-mile at the car. A road which averages 50,000 miles per car per annum, consuming 100 watthours per ton-mile at the car, and whose power costs 1.5 cents per kw-hr. at the car, will pay 33 cents per pound per annum for power.

But whatever the actual cost may be, it has put the matter before the operating people in such an attractive way that many of them have been bending every energy to reducing weight, thinking that every pound reduced, no matter how reduced, will result in an immediate saving of 5 cents per pound per annum. Some even go so far as to say that every pound removed from the dead weight of a car is worth 75 cents to them-off the car. This is the kind of talk that must be accepted with a good deal of reservation. It is no doubt true that if the cost of operation per ton-mile remains the same with the lighter weight cars and equipments, the saving will be made. The danger is that in reducing the weight, conditions may be altered so much as to make the cost of operation more than before. The cost of

inspection and maintenance may be increased on account of the necessity for more frequent renewals of wearing parts. It is intended to discuss in this paper some of the proposed means for saving power on electric railroads and to clear up, if possible, some of the misunderstandings that exist at the present time.

I. REDUCTION of Weight

In the development of the electric railways, the evolution of cars and equipments from the old horse cars to the modern double truck city cars and the high-speed interurban cars has been attended by much grief and loss. The development was so rapid that the only method possible to pursue was to build the car and equip it, using the best judgment available in proportioning the parts. Where parts broke in service, they were usually strengthened by increasing weight and section, regardless of the actual cause of the break, which might have been in something entirely different. This of course resulted in designs which were unnecessarily heavy. It is the part of good designers and conservative engineers to re-design them, distributing material where necessary for strength and cutting out as much unnecessary material as possible. It is astonishing what results have already been attained in this line, and the end is not yet. The use of high-grade materials and pressed steel shapes with new types especially fitted for them will still further reduce weights of car bodies and trucks, and now the question has been put squarely up to the electrical manufacturers to reduce the weight of the motors and control apparatus. Motors. The weight of motors may be reduced as follows: 1. By cutting out all useless weight; in other words, by very careful designing.

2. By the use of high grades of metal to give the necessary mechanical strength with smaller sections.

3. By the use of higher grades of insulation which will allow operation at higher temperatures and thus permit the use of smaller motors.

4. By the use of forced ventilation, thus enabling the motor to carry larger continuous loads with safe rise in temperature. 5. By increasing the armature speeds, which thus gives a greater output to a given size of motor.

1. Improved Design. The first method of cutting the weight, that is, by eliminating all useless weight, is a quite obvious one, and has been followed to a greater or less extent for years. It

is now being worked to the limit, and it is safe to say that all motors which are designed hereafter will have a minimum of useless weight in them.

2. High-Grade Metals. Higher grades of material have also been used more or less, and there are now very few motors that have cast iron in them where weight would be saved by the use of malleable iron or of steel. Heat-treated steel is also used in some cases for shafts, and will probably be used increasingly hereafter. At present, however, its use on standard apparatus is attended with danger and expense, since the methods of heattreating steel are not generally well-known, and, where special materials are used, it always results in more or less dissatisfaction in making repairs. In any case, the reduction of weight in shafts that is possible by this method is very limited, since the reduction in diameter reduces the stiffness in the shaft very rapidly, and even if the shaft is of the high-grade material, it is not safe to permit the deflection.

Great improvements have been made in steel castings in late years. This permits the use of thinner sections than it has been possible to cast heretofore. This will reduce the useless material.

3. High-Grade Insulation. A certain amount of increase in capacity from a given size of motor may be obtained by the use of heat-resisting insulation, and it has been common practise for years to make use of such insulation in the larger sizes of motors and in field coils for smaller motors, it being common practise to use mica insulation for armatures and asbestos-insulated copper strap for field coils. It is very difficult to increase the output of machines so insulated above that which has been obtained for years. Small wire-wound armatures have been wound in many cases with the wire insulated by preparations of asbestos which have increased the safe temperature limit very materially in such machines. Such insulation, however, must be handled with much greater care than ordinary coils insulated with cotton or similar fabrics, as the asbestos is very weak mechanically, and armatures are more liable to short-circuit. The net gain in capacity by using high-grade insulation is somewhat reduced because better insulating materials are poorer heat conductors and a given load produces higher motor temperature than with poorer insulation. The limit to the temperature in motors at present is the melting point of tin solder, and we believe that very little increase in temperature above the present limits will be possible until a soldering material with higher melting point is produced.

This seems

Tin melts at a temperature of about 225 deg. cent. like a good margin to give a motor which is supposed to operate around 75 to 100 deg. cent.; as a matter of fact, the sudden heavy loads on motors which do not last long enough to heat up the entire armatures will last long enough to melt the solder out or at least soften it to a point where it is thrown out by centrifugal action. This probably will be much more frequent when the motors are normally operated at higher temperatures than at present. Therefore, we feel that this offers no great increase in capacity. At least, any increase in capacity thus produced will be obtained simultaneously with the lower efficiency of motor, since in most cases a small motor operated at heavy overloads and high temperatures will have a lower efficiency than the size larger motor operated in the same service. Thus part of the saving which is effected by the use of a little lighter weight motor is lost in the decreased efficiency of the motor.

4. Forced Ventilation. The fourth method of increasing the output, namely by forced ventilation, has been in use for some years, and is quite effective. It is surprising what an effect a small amount of air circulating through the motor will have on the temperature, and capacity. It has the effect of increasing the continuous capacity of motors, which ordinarily is not more than 45 to 50 per cent of the one-hour current rating, to 65 to 80 per cent of the hour rating. In locomotives, air is forced through the motors by motor-driven blowers in the cab. These blowers take their air chiefly from the outside of the cab through louvres in the side wall of the cab. The air is taken at a sufficient distance above the road-bed so that very little dust is blown into the motors, consequently, they remain quite clean inside.

The single-phase locomotives for the New York, New Haven and Hartford Railway Company were probably the first machines that employed the use of forced ventilation on a large scale. This system is used on all of the single-phase locomotives and some of the motor cars now in use, not only on the New Haven system, but on the Spokane and Inland Empire Railway, St. Clair Tunnel, Rock Island and Southern Railroad, and others. The later locomotives on the New York, New Haven and Hartford Railroad, the first of which has been in operation for two years, are also supplied with fans on the rear end of the armature, which are so arranged as to draw air through longitudinal holes in the armature core, thus greatly increasing the effectiveness of the air which is forced in from the outside. In cases where these