automatic equipment, that preceding the der, or cylinders with the driver brake. ET equipment, a reducing valve (feed The only moving part of the double check valve) supplied from the main reservoir valve is a spool-shaped valve with a and set at 45 pounds; a straight-air brake leather seat on each end so as to make valve to admit any pressure, up to this a joint at one or the other of the two maximum, to the engine and tender brake openings at the ends of its travel. Ascylinders; a gauge to show the pressure suming the automatic application had in these cylinders (for the driver brake been released and the straight-air brake it shows this pressure in automatic appli- valve handle moved to application posications also); a safety valve each for the tion, the air thus admitted to the straight-air brake pipe would shift each double check valve to straight-air position, opening the passage to the brake cylinder and closing that to the triple valve. engine and tender brakes and set at 53 pounds so as to guard against excessive cylinder pressure; and for each of these brakes a double check valve. Its duty is to shift the connection from the straightair brake valve or the triple valve to the The two pipes ending at cocks C and brake cylinder, depending on whether D are for use down steep grades where straight-air or automatic is being used. it is desired to prevent automatic appliFig. 1 shows the complete equipment and with an automatic application, each double check valve making a connection from the triple valve to the brake cylin cations of the driver and tender brakes so that they may be applied while recharging the train brakes, thus aiding to better control the train without overbeating the driving and tender wheels. Cock D is lo- swabs, and piston rod packing is not cated near the engineer's seat and, by tight in either steam or air ends."-R. opening, permits of releasing an autoJ. M. matic application of the driver brakes at any time. A much better and improved arrangement is by adding a small attachment to the straight-air brake valve, making it the S-3-A type, and instead of cock D connecting its end of this pipe to the attachment just mentioned. The straightair brake valve can then be used to reduce or release the driver brake cylinder pressure after an automatic application, a valuable feature when either wheel sliding or overheating is probable. Fig. 2 shows the S-3 straight-air brake valve in lengthwise section and with the cap nuts and most of the springs removed from below the two poppet valves. The handle 4 rotates shaft 2, the collar of which is held against leather washer 6 by spring 7. The shaft 2 is slotted on opposite sides and steel tappet pieces are riveted into the slots. The illustration shows the handle drawn toward the reader, to straight-air application position. The ridge or flange at the near edge of the slot shown has forced the application valve 8 from its seat, thus allowing the reduced main reservoir pressure to flow past it, through passage b, and into the straight-air brake pipe at DCV, leading to the double check valve. Moving the handle in the opposite direction first allows the application valve 8 to be seated by the spring below it, thus stopping any further admission of air to the locomotive brake cylinders. This is lap position. Moving it farther causes the tappet piece directly oposite from its two rivets, shown just below 2 on the shaft, to unseat release valve 9 and permit the air to flow from the driver and tender brake cylinders past it and out through the exhaust passage at the bottom to the atmosphere, thus releasing these brakes. This exhaust opening is not shown in Fig. 2, being in the part removed to show the operating details. This is a very simple and satisfactory brake valve, easy to operate and to maintain. A feature liked by engineers is the additional resistance to handle movement on commencing to open either the application or the release valve, this permitting the man to "feel" how much the valve being operated is opened. Answer. The term "chatters" is too indefinite to permit of an understanding of the action referred to. If short, rapid strokes are meant state whether with one or both sides, there being two air and two steam pistons; if one side state whether it is with the high-pressure steam piston (right side facing the compressor) or the low-pressure steam piston; and say what the positions of the pistons are at the time, near top or bottom of strokes. If the unusual action is not as just suggested then describe it accurately. Possibly a much quicker stroke with one side than the other is meant. The cross-compound compressor, with its two steam cylinders, valve motion for controlling them, its two air cylinders and eight air valves, is necessarily more complex than the simple type. Consequently there are a few more possibilities of defects. One defect which might cause shortstroking with the high-pressure steam piston at the top and the low-pressure at the bottom of their strokes is worn-valve motion when well lubricated and with steam closely throttled by the steam valve or the governor and the compressor working against full pressure. The instant that completion of the up-stroke of the high-pressure steam piston lifted the reversing rod and valve and thereby reversed the stroke the air in the clearance space above the low-pressure air piston would start it and the high-pressure steam piston down suddenly. The weight of these parts would aid. With little steam being admitted this would suddenly expand the small volume from, say, the almost closed governor and its pressure would drop too low to hold the reversing valve firmly against its seat. Consequently, with good lubrication the weight of this valve and its rod would cause them to drop and thereby reverse the stroke at its beginning. The repetition of this might be termed "dancing" or "chattering." The low-pressure air piston should never work against more than about 40 pounds, due to the fact that compressing its full cylinder of atmospheric air into the high-pressure air cylinder will give no more than 40 pounds. However, if 1059. Cross-Compound Air Compres either an intermediate discharge valve or sor "Chatters."-"What causes a West- a final discharge valve leaked the lowinghouse cross-compound pump to chat- pressure air piston would work against ter either when pressure is pumped up more than 40 pounds when completing its with a long train or with the lone engine? Air and steam cylinders are prop- stroke toward the end with the leaky erly lubricated, as are also piston rod valve. This would at least cause an irreg ular stroke, slower toward the end with tion cylinder of the distributing valve to the leaky valve. A bent reversing valve rod always tends to cause too early reversal and is more liable to cause short-stroking when steam is closely throttled as the reversing valve is then easier to move, the reason having been explained previously. This rod will almost certainly be bent if in place when the top head is being removed or replaced. Hence, it should be out at such times. the atmosphere, thus allowing applicationcylinder pressure to escape. As this pressure governs that in the engine and tender brake cylinders it follows that these brakes will then release. Holding position merely closes the passage through the rotary valve. Hence the function of holding position is to hold the locomotive brakes applied while the train brakes are being released and recharged. In this it is assisted by release position as while the automatic brake valve is in release position its rotary valve has the opening closed from phere, thereby keeping the locomotive brakes applied with the same force as exerted by them just before going to release position. Clogged air passages are quite probable with this compressor if the air portion is not given a thorough cleaning with strong, hot lye water at times, but this fault will not cause short-stroking. How often the the application cylinder to the atmosair end should be cleaned with lye water depends mainly on the severity of the service the compresor has to perform. In general it should be so cleaned every three months. For this purpose there should be a suitable reservoir for the lye water, with means for heating the solution by a steam coil through the solution, but not discharging into it, and suitable connections to join the compressor suction and discharge openings to the reservoir so that by working the compressor slowly the lye water may be circulated through the air portion for 30 minutes or more. Washing with clear water and oiling completes the job. If making the reversing rod straight and putting the rest of the valve motion in good order does not remedy the trouble, then explain the compressor action in more detail, advising also whether the same action occurs at any other time than when the governor is controlling the compressor, if so stating when. Excessive lubrication of the steam end tends to magnify the trouble. 1060. Functions and Uses of Holding Position. "Please explain the functions and advantages of holding position of the No. 6 ET locomotive brake equipment." -T. H. B. The uses or advantages of holding position are (a) to hold the locomotive brakes applied while completing release and recharge of the train brakes (too long use of release position would over-charge at least the head brakes and possibly all), and (b) to then release the locomotive brakes gradually. The object is to aid in preventing the slack from running out harshly when releasing the train brakes and then, by the gradual release of the locomotive brakes, to let any slack run out gradually that has been held in. To get these results requires moving from release direct to holding position and then, at the proper time, making short movements to running position and back, so spacing them as to guard against a rapid release and running out of slack. With a heavy locomotive and train do not assume that this holding feature will alone permit of releasing a long train safely at low speed. It helps to control the slack but alone will often be inadequate. This is one reason why the K type of triple valve, with its retarded release feature, is necessary. The two work in harmony. 1061. Over-Charged Brakes and What To Do.-"Supposing the train pipe and the auxiliaries are excessively charged through allowing the automatic brake valve to remain at release position too long, would this set the brakes? If so, what is the best way to release them?" Answer.-Holding position is between running and lap positions. In so far as the train brakes are concerned it is the same as running position as in either the feed into the brake pipe is controlled by the feed valve. But with the locomotive brakes it is different as, once they have been applied, holding position keeps them applied, but running position releases T. H. B. them, assuming that the independent brake valve is in running position and the equalizing portion of the distributing valve is in release position, as they then should be. With these other parts as just stated running position of the automatic brake valve makes an opening from the applica Answer.-There are two kinds of overcharging. The more common is where too long use of release position charges the head brakes above the adjustment of the feed valve, but not the brakes farther back. This is more liable where an attempt is made to release the brakes on a long train after a light reduction from full Answer. The H-6 automatic brake valve is the one used with the No. 6 ET locomotive brake equipment. pressure. In such a case return from stop application to 20 pounds does not release to running position is followed by accomplish this, lower the feed valve ada prompt reapplication of the over- justment, make the final release and then charged brakes due to the lower pressure readjust the feed valve to standard presin brake pipe and auxiliary reservoirs sure. toward the rear aiding brake pipe leakage to make a comparatively fast reduction in 1062. "Tracing" Air Through Autothe brake-pipe pressure near the engine. matic Brake Valve. "Please trace the If the pressure toward the rear was up flow of the air through the six different 'to standard at this time the feed valve positions of the H-6 automatic brake will be slow in opening and will then valve; also, give the names of the ports." merely prevent a farther fall, thus allow-G. S. W. ing the head brakes that applied to stay So. To a certain extent head brakes are always liable to reapply after releasing a long train, even where they are not charged above the pressure carried in running position. The first essential is to have an ample main reservoir pressure. The next is not to endeavor to release after a light application until it has been made heavier. The third is not to stay in release too long, about 15 seconds being the maximum under ordinary conditions. The fourth is to make the "kick-off," to release for a second and back, within 7 to 10 seconds after moving from release to running position. This last is to release any head brakes that may have reapplied, yet without again overcharging them. The other kind of overcharging is where the brake pipe and auxiliary reservoir pressure on the entire train has been raised above the adjustment of the feed valve, as in case the engineer carelessly leans against the brake valve handle, as when adjusting lubricator feeds, moves it into release position and fails to observe the noise of the warning port. If the handle is returned to running position no air will be supplied to the brake pipe by the feed valve until the pressure has reduced to the feed valve adjustment. This is almost sure to cause some brakes to apply and may even produce undesired quick action as a siow fall in brake-pipe pressure, as from unsupplied leakage only, renders this more probable. The proper way to handle this matter as soon as the error is noticed is to maintain the brake-pipe pressure had then until the next opportunity for reducing it by an application, as on approaching the next stopping point. If the pressure is as high as it will go then merely leave the brake valve handle in release, but if it is, say, 8 or 10 pounds above standard pressure temporarily raise the feed valve adjust ment to maintain it, with the brake valve in running position. After the next stop see that the pressure has been reduced about 15 pounds below the standard, releasing and reapplying if increasing the Release Position allows the main reservoir pressure to flow freely, through large ports, into the brake pipe and, through smaller ports, into the equalizing reservoir. If used long enough the pressures in these parts will become equal. In this position the feed valve pipe is opened to the atmosphere through the very small warning port. Main reservoir pressure is admitted to the under side of the diaphragm of the excess pressure governor head. The opening from the application cylinder of the distributing valve is now closed. Running Position cuts off the direct connection from the main reservoir to the brake pipe and connects the latter with the feed valve pipe. As this pipe is supplied from the main reservoir through the feed valve this reduced pressure is then allowed to feed irto the brake pipe, but at a slower rate than with release position. The equalizing reservoir is supplied with the same pressure at this time, and main reservoir pressure is still admitted under the diaphragm of the excess pressure governor head. The application cylinder of the distributing valve is now open to the atmosphere, assuming the independent brake valve is in running position, and the equalizing parts of the distributing valve are in release position. Hence, while release position of the automatic brake valve would hold the locomotive brakes applied, running position allows them to release. Holding Position makes but one change from running position; it closes the opening from the application cylinder to the atmosphere and thereby prevents the locomotive brakes from releasing if they were previously applied. Lap Position blanks all ports except as noted later. While this does not apply the brakes the then unsupplied brake-pipe leakage will if it reduces the brake-pipe pressure fast enough. Main reservoir pressure is cut off from the under side of the diaphragm of the excess pressure gov -J. H. R. Answer. The accompanying illustration, Fig. 3, shows the emergency magnet valve with the R-2-C triple valve similar to that now in use on the Inter ernor head and is admitted to the feed 1064. The Air Brake Electro-Magnet valve pipe, thus increasing the pressure Valve.-"Please explain through the colon the upper side of this governor dia- umns of the Magazine, and by means of phragm, thus preventing this governor an illustration if possible, how an elechead from acting and allowing the air tro-pneumatic valve works, showing what compressor to raise the main reservoir sayle of valve is generally used and how pressure to the adjustment of the high- the electro-magnet opens and closes it." pressure governor head. The application cylinder of the distributing valve is now closed, thereby retaining any pressure admitted to it. The brake pipe and the equalizing reservoir are now separated. Service Position makes but one change borough Railroad of New York City. from lap position. It opens the equaliz- As the fundamental idea of the magnet ing reservoir to the atmosphere through valve is to use electricity to control the the small preliminary exhaust port. This flow of air, irrespective of where from reduces the pressure above the equalizing or to, this illustration will serve as well In this piston. The then higher brake-pipe pres- as others that might be used. sure raises the equalizing piston, thereby instance the brake pipe passage to the opening the valve formed by the lower main piston of the triple valve is reend of its stem, and escapes to the at- duced at e so that the opening of the mosphere until reduced a trifle below the valve 530 will cause a sudden reduction pressure remaining in the equalizing res- of brake-pipe pressure in chamber h, ervoir, when the brake valve handle was through g, f, b, d and EX to the atmosreturned to lap, then gradually closes. phere, thus causing quick action. This applies the brakes gradually. As is generally known, a magnet attracts steel and iron. A permanent magnet is one which exerts this force at all times and without the aid of elecA familiar form is the horsetricity. An electro-magnet shoe shaped magnet. is one that exerts this attraction alone when an electric current is flowing This is explained more in around it. detail as follows: When iron Emergency Position makes a large and direct opening from the brake pipe to the atmosphere. This causes the quick and heavy reduction of brake-pipe pressure needed to apply car brakes in quick action. The automatic brake valve also connects the main reservoir through a small port, with the application cylinder of the distributing valve. This quickens The passing of an electric current the application and raises the pressure in the application cylinder to the limit through a wire creates a field of magallowed by the safety valve, set to open netic force around the wire. at 68 pounds, and maintains the pres- is placed in a magnetic field it becomes An electro-magnet such as sure even though there may be some magnetized. leakage from the application cylinder. is used in connection with the electro It thereby insures maximum efficiency of pneumatic brake consists essentially of the locomotive brakes in an emergency. a coil of insulated wire, wire covered To give the names of the ports would with a substance that electricity cannot be useless as they are merely designated pass through, surrounding a soft iron Therefore, when electric current by letters so as to permit the student to core. find on illustrations the ports referred is passed through the wire forming the to by the reading matter of instruction coil of the electro-magnet a magnetic books. If this is part of an examination field will be set up all around the coil, question it can be advantageously and particularly in the iron core, thus omitted as it requires tiresome study to causing the iron core to become magmemorize the letters and is thereafter netic. of no practical value. In fact, the term "trace the flow of air" is not definite as it means as much or as little as an examiner chooses to require of the student. 1063. H-6 Brake Valve Lap Position. -"Are all ports blanked in lap_position of the H-6 brake valve?"-H. H. H. Answer. The answer to the previous question replies to this one. In the form of electro-magnet with which we are concerned the core is made in two parts, one of which is stationary with respect to the coil, and the other of which, called the armature, fits loosely in a bushing in the center of the coil, permitting of easy movement up and down in this bushing. If the two portions of the core are separated by a slight distance, the tendency, when magnetized by current being passed through the coil, is to pull the separated portion together, resulting |