soon as a half revolution is completed, however, the part of the coil which was on top is now at the bottom, and the current which was from front to back in that part of the loop is now from back to front. For every half reduction of a coil in a two-pole field there will be a change in the direction of the current. It is seen, therefore, that an alternating current is generated, and some means must be devised to change the same if direct current is desired. That is the function of the commutator,it commutates or rectifies the current. Fortunately, there is a point called the neutral point or diameter of commutation, where the E. M. F. is reduced to a zero value and changes sign from plus to minus or vice versa, as the case may be. Plus and minus mean positive and negative, same as we learned when discussing primary batteries. At this point of zero value, the brushes should be placed so that when current changes direction in the loop, and hence in the commutator segments, these segments have traded places under the brushes, and while the direction of current has changed in the coil, it still travels in the same direction through the brushes. This can be easily seen by tracing the flow of current as you imagine the loop to rotate. The same results could be obtained if the loop were kept stationary and the magnets revolved, but it would not be as simple a method mechanically. The strength of the E. M. F. developed always depends upon the number of lines of force which the coil or coils cut. Such strength can further be varied by changing the effective length of the conductors, changing the number of revolutions or the strength of the magnetic field. All other conditions being the same, the faster a dynamo is run, the higher voltage will be which it will generate. If we plot a curve to show graphically the nature of the E. M. F. which a single coil dynamo will generate, we will find a curve or set of them like Fig. 6. In this 360° FIG. 6, curve it is seen that the E. M. F. varies from zero through a maximum to zero every 180°. If instead of one coil we make it two, which coils are placed at right angles to one another, and the number of commutator segments increased to four, we would then obtain curves as shown in Fig. 7. From this we gather 360° FIG. 7. that the greater the number of coils, and hence commutator segments, the more nearly we approach an absolute straight line of E. M. F. Constant potential dynamos in practice possess this feature. If such were not the case, incandescent lamps would show unpleasant changes in the intensity of the light, and motors running from such dynamos would show wide and annoying variations in speed. For incandescent lighting and for power purposes, it is absolutely necessary that an even pressure be maintained for any condition of service. Breakdowns. BROOKLYN, N. Y., Feb. 13, 1905. EDITOR JOURNAL: Coming home from the late convention at Los Angeles over one of the trunk lines, while running along at a good speed, I felt the emergency go on and as soon as we stopped, I, of course, went up to the head end to "rubber," and found that the cap had come off the front end of right side rod and the rod bent so as to strike guide yoke; so I stood on the bank with other passengers while the engineer was disconnecting. She was a Rhode Island, three-wheel connected, with the main connections and the eccentrics on the middle pair of wheels, so you see all that was necessary to do was to take down the forward side rods on both sides and run as an ordinary four-wheel connected, but he began to strip everything from the disabled side, and I could not help thinking of what that poor fireman must have thought of the ability of his engineer when compelled to take down that heavy main rod and put it up on the front end of the engine, and after the engineer had taken a tumble to himself, to take it down again and put it up in place, and I could see that he knew they were working wrong, but he did not dare to say a word, as the engineer was very overbearing and bossy. I was talking to a passenger about it and said to him, "I can't see for the life of me what he took down that main rod for, but you wait and you will see him put it up again," and he did. Well, he was three hours doing the job, when it could have been done in twenty minutes, and he had about six Mexican greasers to help him handle the rods, too. This circumstance was brought to my mind lately, when reading of the friction that exists between engineers and firemen, and I thought, "Could you blame that fireman for being mad when he realized the incompetency of that runner?" How much better it would have been if they had been on better terms and the fireman could have given his views. I suppose if that engineer had got discharged for too long a delay or got suspended thirty days or so, the B. of L. E. would have made a kick to get him back in his place. This was an old runner, too, off from one of the largest trunk lines east. Brothers, let's get out of our rut and down off of our high horse and take the fireman into our confidence. CON. TROLLER. Stop Leaky Pistons. WHEELING, W. VA., Jan. 28, 1905. EDITOR JOURNAL: Seeing the many kicks registered in the JOURNAL regarding various matters, I feel encouraged to make a few myself. The Interstate Commerce Commission is looking after the safety device question and getting matters pretty well along. Of what use are all the block signals if you have an overflow pipe in cab, and injector slobbering steam and water, steaming windows so it is impossible to see out? Injectors with uncoupled overflow pipes, and those with such pipes run out of sight into ashpan, should be abolished. Do any of the Brothers ever think of this, or have they had an accident or burnt an engine on account of one or the other? Again, we have leaky packing to contend with, and "can't see ahead" is a common complaint, which is but little regarded by the powers that be, so long as the engine will run and haul cars. Do you think it right some Brothers should condemn a good glass water gauge and, through their influence, deprive the majority from the use of this convenient and essential means af noting the rise and fall of the water in boiler? I think an engineer can do a much better job of pumping with a good glass especially when using alkali water, as some roads delight to do. It seems that some railway companies want alkali water, putting sodaash into good water in order to make trouble. This sort of water will jump at an open gauge cock or any opening made in boiler; whereas, a gauge glass being open at both ends shows the action of water as taking place in boiler. Many Brothers can confirm this, having used saline water during the past dry season. Don't you think the B. of L. E. should use its influence with the I. C. C. to bring about better conditions? Think about these things, Brethren, and remember that block and interlocking signals, automatic air brakes and coupling devices are not the only safety appliances we need. Fraternally yours, JAS. E. MAGONAL. Equalizing Valve Stuck-Can Brakes be Set? GLENN'S FERRY, IDAHO, Feb. 10, 1905. EDITOR JOURNAL: For the past five days here on the Oregon Short Line, the engineers have had an argument in regard to an air question. It is this: Is it possible to set the brakes on a train with the engineer's equalizing piston in a Westinghouse brake valve stuck solid to its seat, by putting the engineer's brake valve in emergency position? Some here on the O. S. L. Ry. claim it can be done. I claim it cannot be done, for the best air books I can get tell me the train line position must be reduced to set the brakes, and increased to release the brakes; so, if the engineer's equalizing discharged piston is stuck solid to its seat, I cannot figure any way to decrease the train-line position by putting the brake valve to emergency position. So, if we get no response from the train line exhaust, how are the brakes to be set by the use of the engineer's brake valve? Suppose we are carrying 70 pounds of air train line pressure and 90 main drum. Drum pressure we draw off 25 pounds with the surplus application. Please say what part of the train line, with its connections, still remains 70 pounds not molested, from which, as stated, 25 pounds has been reduced. Fraternally yours, A MEMBER OF DIV. 366. What Was Wrong With the Gauge? TEXARKANA, TEX., Feb. 10, 1905. EDITOR JOURNAL: I had a brake valve on my engine. When I made a service reduction train line the gauge hand would drop 10 pounds, and seem to stop or almost stop and then go on down slow or at a regular rate. When I stopped drawing off air, train line hand would raise 5 pounds. At first there would be a heavy blow from train line. This is with light engine, pipes were open to little drum, and there were no leaks. Where was the trouble? Fraternally yours, MEMBER, Div. 496. Handling Trains on Heavy Grades. TACOMA, WASH., Jan. 22, 1905. EDITOR JOURNAL: Seeing an article in the October JOURNAL, 1904, “What the Railroads are Doing in Handling Trains on Heavy Grades," I will endeavor as best I can, to describe a trip over the mountain end of the Pacific Division of the Northern Pacific Railway. That is, I will try to describe that part of the work which differs from railroading on the level or over a merely undulating country. The fundamental principle of railroading, of course, is the same here as elsewhere, namely: That a man must constantly keep uppermost in his mind the fact that "two objects cannot occupy the same space at the same time." What I will say in this letter I do not intend as an instruction, by any means, but simply to give the many enginemen in different parts of the country, whose experience has been limited to the prairies, but who are interested in their vocation, an idea of just how trains are handled on long, heavy grades. I was employed for ten years in engine service by a prominent railroad in Illinois, but I will confess that on going to work here I found my knowledge very limited indeed; and right here I must not neglect to say that I received many a good suggestion from the engineers on the Pacific Division and always found them ready to give needed counsel and advice. There are no doubt many members of Div. 238 much better able to cope with the subject than myself, but probably do not care to write, and having both the leisure and inclination, I came to the conclusion to write the matter up myself. Our mountain division extends east from Tacoma to Ellensburg, a distance of 125 miles. We cross the Cascade Mountains through what is known as Stampede Pass, "tipping" over the summit while going through Stampede tunnel, a tunnel of almost two miles in length. The heaviest grade is between Stampede and Weston on the west side of the mountains. The distance between the two points is nine miles, with a descent of 1,000 feet. There are several grades in the United States that are steeper, but none that needs the exercise of more care in handling trains, on account of there being long stretches of straight track approaching the foot. The chain gang engines are tandem compounds of the consolidation type, equipped with two 91⁄2 inch air pumps, one on each side, also the duplex pump regulation. They pull from 850 to 900 tons from Tacoma to the foot of the mountain grade, wending their way up through Green river's picturesque canyon until we come to Lester. Lester and Easton are the terminals for the helper engines. Lester lies at the foot of the cascades on the west side and Easton on the east. Upon arriving at Lester a heavy helper engine is added to the train, being attached to the rear end. They help the train to the summit and then either "drop" back to Lester or continue down the other side to Easton, always being directed where needed most by the dispatcher. If it is necessary to cut off the helper while the train is moving and before "tipping " over the summit, the helper engineer shuts off steam as gradually as possible, to prevent breaking the train in two. When trains of any class by train order or trains of the same class by time table meet on mountain grade, the ascending train must take the siding. If it becomes necessary in ascending to take the siding and wait for another train it is the duty of the helper engineer to work steam until the train is stopped, and when stopped, the lead engineer must not release until the rear brakeman has set sufficient brakes to hold the train. Then again, before starting, the engineer should set the air while the brakeman is releasing the hand brakes. On getting them all released the helper engineer gives his engine steam and whistles off. The lead engineer then releases, whistles off and the train is ready to start. These precautions are taken for safety and to prevent breaking the train in two. In descending, when it becomes necessary to stop and wait any length of time, it is the duty of the front brakeman to set sufficient brakes to hold the train, after which the engineer releases. This keeps the auxiliaries charged so that a start can be made at any time by simply releasing the hand brakes. After arriving at Easton we follow the Yakima River to Ellensburg. On the return trip, on account of the grade not being nearly so heavy approaching the mountains as on the west side, the same engines pull from 1,200 to 1,400 tons to Easton, necessitating on arrival there the adding of two helper engines to the train, one about eight cars back and the other on the rear's end. The passenger trains are simply double-headed up the mountain, but on the freight trains the engines are distributed, as I have mentioned, for train safety and to prevent an undue strain on the draft rigging. After getting the helper engines in position and testing the air to see if it is working through to the rear end, the conductor brings over an air-brake test card which gives number of train, number of engine, gross tonnage, number of cars, number of brakes O. K., condition of air appliances on engine, and after consulting together with regard to braking power, conditions, etc., the engineer must sign the card, also stating if he needs the assistance of hand brakes and how many. The card is then forwarded to the Division Superintendent. The train then proceeds to the summit, providing there are no trains to meet; but after "tipping" over the summit and coming out of the west end of the tunnel the train must be stopped. This is necessary in order to see what condition the brakes are in and to give the brakemen an opportunity to turn up all of the retainers. If the engineer stated on the airbrake test card that he needed the assistance of hand brakes to make the descent, brakemen must set the number stated on the card before leaving the summit. If hand brakes are used, they must be set of the head-end of the train, care being exercised to set them harder on the more heavily loaded cars, to avoid wheel sliding. It is the duty of the brakemen to ride out on top while making the descent. The conductor remains on the rear end, where he can watch the air-gauge with which every caboose is equipped and be ready to act in case of emergency. The helper engines have additional pipes leading to the air-gauge from the train line so that the helper engineers can see the condition of the air pressure at all times, although their brake valve is cut out. Now, we will say that we are ready to commence the descent. We know that the brakes are all working, that the maximum air pressure is pumped up, and, in addition, that the retainers are all turned up. Retainers should all be turned up to prevent an undue amount of braking on a few cars, also give the engineer a better opportunity for recharging and maintaining maximum air pressure. The engineer makes the first application and recharge as soon as possible after leaving the summit. He should do this for two reasons: first, to see how the brakes are holding while the speed is still low and the train still within the limit of safety; second, on account of the retainers being turned up an additional air pressure is kept in the brake cylinders, and, consequently, with a given train pipe reduction, a greater brake cylinder pressure is obtained after the first application and release than with the first application. Also, on account of the brake cylinders being empty, the first application after leaving the summit should be the heaviest, and should consist, as a rule, of one reduction, say fifteen pounds. It is best never to make less than eight to ten pounds reduction at a time. An application should consist of one and seldom more than two reductions. If the engineer sees that with a ten-pound reduction the speed of the train slows down too gradually, he makes a further reduction of ten pounds and slows the train down more quickly and then releases, because the longer the pressure is left applied the weaker the pressure in the auxiliaries becomes and the more air is lost by brake cylinder leakage. It is best to apply and recharge as often as consistent with the work to be done, because in this way the auxiliaries can be kept charged as near the maximum as possible. Besides this, economy is practiced in the expenditure of air by sometimes being able to reapply before the air has ceased escaping from the small port in the retainers. It is impossible to maintain an exact uniform speed. Like everything else, an engineer has to learn by experience just when to release. He must not release too soon, for if he does the speed will increase too much before the auxiliaries will have time to be recharged. Then, again, he must release before the speed is reduced too much, especially on the heavy curves or let-ups in the hill, for if he waits too long before releasing the retainers are apt to stop the train. This can be much more easily avoided with a train that can be handled with the air brake alone, for then, as a rule, it is not necessary to reduce to very slow speed before releasing. But with a heavy train of coal, for instance (as there is no more braking power on a load than on an empty) weighing 1,200 tons, and contained in not more than eighteen cars, where it is necessary to have one-third of the hand brakes set in addition to the retainers in order to control the train while recharging, it is more difficult. If the engineer sees that he has waited a little too long before releasing, he should immediately commence working steam, and continue until the speed of the train has increased enough to prevent stopping. In recharging, it is necessary to leave the brake valve handle around to full release position so as to permit the full flow of air from the main reservoir to enter into the train line through the large ports, in order to recharge as quickly as possible. For once no harm is done if the train line should become overcharged a little, unless the train consists of empty cars. On a level all of the braking power can be used for stopping, but in descending heavy grades a certain amount is needed for holding power. If with a seventypound train-line pressure a fifteen-pound reduction is necessary to keep the speed from increasing there are only five pounds left with which to stop the train. Furthermore, on a level the instant steam is shut off the speed of the train begins to decrease. Consequently, to obtain the same results, an application must be made much sooner on a train descending a long, heavy grade. For instance, we will say that the maximum speed limit is twenty miles per hour descending such a grade. In such case it will be necessary to make the application while the speed is about fifteen miles per hour or less, and by the time the brakes take hold the speed will have increased to twenty miles per hour. In descending a mountain grade, should the engineer see that with a full application he can only keep the speed of the train from increasing, or very gradually slow it down, he should immediately call for hand brakes. (The one short blast of the whistle will never become obsolete in mountain railroading.) He should also get the sand to running, and after the train has slowed down to within the limit of safety, release in time to prevent stopping. That is, if the air supply is not exhausted too much, in which case the train should be stopped until recharged. It is easily seen that it is of as much importance to watch the air gauge as it is the water glass. If the train is extremely difficult to hold the water brake should be applied, and if necessary, kept working continuously until the foot of the grade is reached. It should be applied when the speed is not too great. Before apply ing it, however, the driver brake must be cut out and bled. For this purpose there is a bleed cock connected to the cab within easy reach of the engineer. Now, for the benefit of those who do not fully understand the water brake, I will explain it. It is a simple device with a globe valve on the boiler head below the water line and within convenient reach of the engineer, and with pipes leading from it to the exhaust passages in the cylinder saddles. (Often there are two valves, one for each cylinder.) In using the water brake the throttle should be left closed and the cylinder cocks open. The water valve sbould then be opened about half a turn and the reverse lever then placed several notches back of the center. The color of the discharge from the cylinder cocks should then be noticed. If it is a dense white the water valve is open far enough, but if it is a bluish color the valve should be opened until the discharge becomes white. At night the proper amount can be told by the sound, the same as water or steam in the gauge cocks when running without a water glass. The nearer the reverse lever is pulled back to full stroke, or toward the "corner," the more the braking power is increased. The water admitted to the cylinders has nothing to do with the braking power, but simply acts as a lubricant to the valves and cylinders while the engine is reversed. It is necessary, though, to feed oil to the cylinders the same as when working steam. It is generally known that it is a dangerous practice to release at slow speed with a long train, because on account of the brakes being applied from the engine they set first on the head end, the cars, of course, bunching together. Then again, on account of the train line receiving its supply of air from the engine, the brakes nearest the engine release first. Consequently, if the brakes are released at too slow a speed, the head end will keep moving while the rear end is still stopping, and as the slack runs out quicker than the brakes release, it is not necessary that one be a philosopher in order to see what the result will be. In mountain grade work this is overcome on account of all the retainers being turned up, as they retard the release until the liability of a shock is overcome. It is a good idea, though, to turn up the driver brake retainer just before releasing. However, it often happens that it is necessary to cut out the driver brakes entirely on account of the danger of overheating and loosening the tires, but they must be kept in use as much as possible. The combined automatic and straightair brake with which the engines are now equipped is a much better holding device than the driver brake retainer, as it can |