piston is reduced so as to permit the steam valve to open, when the regulating spring closes valve No. 47? Student.-No, sir. Instructor.-Port "c" is provided for this purpose; it is a very small opening leading from the chamber above the piston to the atmosphere, and should always be open. of the brake apparatus from which the supply is obtained. Student. I understand that when valve 47 is opened, air will begin to escape from port "c" and will escape as long as the valve is open, and until all the pressure is exhausted from the chamber after it is closed. Instructor. That is right. To what Student. I do not understand how any air pressure is the governor connected? Instructor. It is to prevent there being any pressure, of either steam or air, under the piston, No. 28. Steam will leak into this chamber under the piston by the stem connecting the piston with the steam valve, and air by the piston packing ring, and if it is not permitted to escape there will be a pressure under the piston. Instructor. It is to enable using two different air pressures. When they are used with the old style brake valve, one head is adjusted for 70 pounds pressure and attached to train line pressure; the other is adjusted for 100 pounds pressure and is attached to main reservoir pressure. When they are used with the improved brake valve, one head is generally Student. What is the object of the adjusted for 80 pounds pressure, and conspring under the piston, No. 31? Instructor. It is to hold the valve normally open, and assists the steam pressure to open it. Student. Instructor. It is to prevent any air pressure from accumulating on top of the diaphragm. Before starting the pump on an engine without air pressure, what position should the different parts of the governor be in? nection is made to the main reservoir' port, between the rotary and feed-valve attachment, in, the brake-valve. The other is adjusted for 110 pounds and attached What is the small hole for directly to the main reservoir pressure. in the side of the spring box? When used in connection with the "High Speed Brake" or "High Pressure Control" apparatus, one head is generally adjusted for 100 pounds and the other for 130 pounds, both being connected directly to main reservoir pressure. A stop-cock is placed in the pipe connecting the head adjusted for 100 pounds pressure and, when closed, cuts this head out. The head adjusted for the higher pressure has nothing to do with the operation of the governor so long as pressure is admitted to the other head, for the low pressure head will operate and cause steam to be shut off from the pump before the air pressure is high enough to operate the high pressure head. Student. The valve 47 should be on its seat, and the steam valve should be wide open. Instructor.-Assuming that the governor is attached to train line pressure, and set at 70 pounds, what should take place when that pressure is obtained in the train line? Student. The air pressure acting on the under side of the diaphragm forces it up against the tension of the regulating spring, thereby causing the valve 47 to be opened, admitting air to the top of the piston, and the air pressure acting on the top of the piston moves it down, thereby causing the steam valve to be closed, and the pump will stop. Instructor. That is right, but with the pump running moderately and the governor in good condition, there may be only sufficient air admitted to the piston to move it down so that the steam valve will not be entirely closed and the pump will run slowly. Should a reduction of the train line pressure be made, what should take place? Student.-Valve 47 would be closed by the tension of the regulating spring, and when the air pressure above the piston has escaped through port "c" the steam pressure, with the help of the spring 31, should open the steam valve and permit the pump to go to work again. Instructor.-I think you now understand the operation of the governor thor⚫oughly. The duplex pump governor, shown here in Fig. 2, consists of one body and two heads which are constructed like the one I have just explained, and which is shown in Fig. 1. Student.-What is the object of having two heads? Student. I do not understand the benefit of using the duplex governor as you have described it, and I wish that you would please explain. Instructor.-When used with the old style valve it permits the pump to start up when a reduction is made, as the head set for 70 pounds operates just the same as if there were but one, and the pump will now run until the pressure in the main reservoir is 100 pounds, when the head attached to that pressure, and set for 100 pounds, will operate, thereby causing the pump to stop, preventing too high main reservoir pressure being obtained, when handle of brake valve is on lap. When used with the improved valve the pump works against only 80 pounds pressure in maintaining the air pressure. When an application is made it will start up on account of the supply of air to the head set for 80 pounds being cut off by the rotary valve, and the pressure in the main reservoir will be increased to 110 pounds. The use of the duplex governor with the "High Speed Brake" and "High Pressure Control" I will explain when we talk about those devices. How do you think it would affect the governor should port "c" become stopped up? Student.-As I understand the operation it would prevent the air pressure from escaping from the top of the piston, and the steam valve would be held closed. Instructor. The volume of air above the piston is very small, and there is always some leakage by the ring in the piston, so, even with port "c" closed, it will escape very quickly. Student. I do not understand, then, why it is necessary to have port "c." Instructor. I will ask you another question before answering. What do you think the result would be should valve 47 fail to seat tightly, due to dirt lodging on its seat-port "c" at this time being free? Student. I should say if air leaked by valve 47 faster than it could escape from the chamber above the piston, the steam valve would remain closed, and if it did not leak by quite as fast as it was escaping from the top of the piston to the atmosphere, then, the pressure would be reduced above the piston and the steam pressure would open the steam valve. Instructor. That is right. Now suppose that port "c" is stopped up, and the ring in the piston is fairly tight, with valve 47 leaking on its seat, what would the result be? Student. Under these conditions I should say that valve 47 must seat so that there will be no leakage by it or the steam valve will remain closed. Instructor. That is right, and the benefit then of port "c" is to permit air to escape that may leak by valve 47. Of course, should the ring in the piston be perfectly tight, which is not at all probable, the air pressure above the piston could not escape with port "c" closed. What do you think the result would be should the waste pipe become frozen, or stopped up in some other way? Student. With the waste pipe closed, pressure would accumulate under the piston, and the air pressure on top of it could not move it down so as to close the steam valve, and the pump would not be shut off when it should be. Instructor.-I do not think of anything more that I can talk with you about relating to the pump governor, and I feel that you must now understand it thoroughly. Student.-I find that there is a good deal more to it than I had any idea of, but, with your very explicit explanation, I believe I now thoroughly understand it. $ Movement of Trains By H. A. Dalby Latest Revision of the Standard Code. As it is almost two years since extracts from the Standard Code were published, and as frequent references are made to it, herewith are given such rules as have a direct bearing upon the movement of trains. The Code has been revised since that time, though there has been no material change. The rules for double track have been adopted, however, the principle being to incorporate such of the single track rules and forms as are applicable to double track, to revise those which are capable of revision, to omit those which do not apply and to insert new ones if necessary. When a rule is the same for both single and double track, or where only a variation is necessary, the same number is used. All double track rules are prefixed by the letter D. Definitions. Train. An engine, or more than one engine coupled, with or without cars, displaying Markers. Regular Train.-A train represented on the time-table. It may consist of Sections. Section. One of two or more trains running on the same schedule displaying signals or for which signals are displayed. Extra Train.-A train not represented on the time-table. It may be designated as Extra-for any extra train, except work extra; Work extra-for work train extra. Superior Train.-A train having precedence over other trains. A train may be made superior to another train by RIGHT, CLASS or DIRECTION. RIGHT is conferred by train order; CLASS and DIRECTION by time-table. RIGHT is superior to CLASS or DIRECTION. DIRECTION is superior as between trains of the same class. NOTE.-Superiority by direction is limited to single track. Train of Superior Right.-A train given precedence by train order. Train of Superior Class.-A train given precedence by time-table. Train of Superior Direction.-A train given precedence in the direction specified in the time-table as between trains of the same class. NOTE.-Superiority by direction is limited to single track. Time-table.-The authority for the movement of regular trains subject to the rules. It contains the classified schedules of trains with special instructions relating thereto. Schedule. That part of a time-table which prescribes the class, direction, number and movement of a regular train. Main Track.-A principal track upon which trains are operated by time-table, train orders or by block signals. Single Track.-A main track upon which trains are operated in both directions. Double Track.-Two main tracks, upon one of which the current of traffic is in a specified direction, and upon the other in the opposite direction. No train of the new Time-table shall run on any division until it is due to start from its initial station, on that division, after the Time-table takes effect. 4 (B). Each Time-table, from the moment it takes effect, supersedes the preceding Time-table. A train of the preceding Time-table shall retain its train orders and take the schedule of the train of the same number on the new Timetable. A train of the new Time-table which has not the same number on the preceding Time-table shall not run on any division until it is due to start from its initial station, on that division, after the Timetable takes effect. NOTE TO RULES 4 (A) AND 4 (B).-The Committee has recommended two forms of Rule 4, leav Current of Traffic.-The direction in which trains will move on a main track, ing it discretionary with each road to adopt either, as best suits its own requirements. under the rules. covers such signals as slow boards, stop boards, yard limits, switch, train order, block, interlocking, semaphore, disc, ball or other means for indicating stop, caution or proceed. Yard. A system of tracks within defined limits provided for the making up of trains, storing of cars and other purposes, over which movements not authorized by time-table, or by train order, may be made, subject to prescribed signals and regulations. Yard Engine.-An engine assigned to yard service and working within yard limits. Pilot. A person assigned to a train when the engineman or conductor, or both, are not fully acquainted with the physical characteristics, or running rules of the road, or portion of the road, over which the train is to be moved. Time-Tables. 4 (A). Each Time-table, from the moment it takes effect, supersedes the preceding Time-table. A train of the preceding Time-table thereupon loses both right and class, and can thereafter proceed only by train order. 5. Not more than two times are given for a train at any station; where one is given, it is, unless otherwise indicated, the leaving time; where two, they are the arriving and the leaving time. Unless otherwise indicated, the time applies to the switch where an inferior train enters the siding; where there is no siding it applies to the place from which fixed signals are operated; where there is neither siding nor fixed signal, it applies to the place where traffic is received or discharged. Schedule meeting or passing points are indicated by figures in full-faced type. Both the arriving and leaving time of a train are in full-faced type when both are meeting or passing times, or when one or more trains are to meet or pass it between those times. When a train takes a siding, extending between two adjoining telegraph stations, to be passed by one or more trains, the time at each end of the siding will be shown in full-faced type. Where there are one or more trains to meet or pass a train between two times, or more than one train to meet a train at any station, attention is called to it by NOTE TO RULE 5.-The Committee recommends that each company adopt such method as it may prefer in filling the blank. 6. The following signs when placed before the figures of the schedule indicate: Train Signals. 17. The head-light will be displayed to the front of every train by night, but must be concealed when a train turns out to meet another and has stopped clear of main track, or is standing to meet trains at the end of double track or at junctions. 18. Yard engines will display the head-light to the front and rear by night. When not provided with a head-light at the rear, two white lights must be displayed. Yard engines will not display markers. 19. The following signals will be displayed, one on each side of the rear of every train, as markers, to indicate the rear of the train: By day, a green flag. By night a green light to the front and side and a red light to the rear, except when the train turns out to be passed by another and is clear of main track, when a green light must be displayed to the front, side and to rear. 20. All sections of a train, except the last, will display two green flags, and, in addition, two green lights by night, in the places provided for that purpose on the front of the engine. 21. Extra trains will display two white flags and, in addition, two white lights by night, in the places provided for that purpose on the front of the engine. 22. When two or more engines are coupled to a train, the leading engine only shall display the signals as scribed by Rules 20 and 21. pre 23. One flag or light displayed where in Rules 19, 20 and 21 two are prescribed will indicate the same as two; but the proper display of all train signals is required. 24. When cars are pushed by an engine (except when shifting or making up trains in yards) a white light must be displayed on the front of the leading car by night. Movement of Trains. 83. A train must not leave its initial station on any division, or a junction, or pass from double to single track, until it has been ascertained whether all trains due, which are superior, or of the same class, have arrived or left. 84. A train leaving its initial station on each division, or leaving a junction, when a train of the same class in the same direction is overdue, will proceed on its schedule, and the overdue train will run as prescribed by Rule 91. 85. A train must not start until the proper signal is given. 86. An inferior train must keep out of the way of a superior train. 87. A train failing to clear the main track by the time required by rule, must be protected as prescribed by Rule 99. 88. At meeting points between trains of the same class the inferior train must clear the main track before the leaving time of the superior train, and must pull If necesinto siding when practicable. sary to back in, the train must first be protected, as prescribed by Rule 99, unless otherwise provided. 89. At meeting points between trains of different classes the inferior train must take the siding and clear the superior train at least five minutes, and must pull into the siding when practicable. If necessary to back in, the train must first be protected as prescribed by Rule 99, unless otherwise provided. An inferior train must keep at least five minutes off the time of a superior train in the same direction. NOTE TO RULES NOS. 88 AND 89.-The Committee recommends that where greater clearance is necessary, Rule No. 88 should require a clear ance of FIVE minutes, and Rule No. 89 of TEN minutes. 90. Trains must stop at schedule meeting or passing stations, if the train to be met or passed is of the same class, unless the switches are right and the track clear. Trains should stop clear of the switch used by the train to be met or passed in going on the siding. When the expected train of the same class is not found at the schedule meeting or passing station, the superior train must approach all sidings prepared to stop, until the expected train is met or passed. 91. Unless some form of block signals is used, trains in the same direction must keep at least five minutes apart, except in closing up at stations. mends that where greater clearance is necessary, Rule No. 91 should allow a clearance of NOTE TO RULE 91.-The Committee recom TEN minutes or more. |