and the brass is then ready for pressing brass as it comes from the stock room into the end of the rod. As the brass is in two separate halves and unfinished was, it will be remembered, bored out in every respect. The two pieces are 3/64ths of an inch larger than the pin, placed one at a time in the shaper and we will now have it only about 1/32d the two inside faces planed off with a of an inch loose on the pin because the fine cut of the shaper tool, this cut being brass closes, many times, more than deep enough only to clean off the brass 1/64th of an inch as it is forced into the at this place, Fig. 4. After this the two rod. halves are taken to the copper or tinning department where they are carefully sweated firmly together on the faces just cleaned and squared by the tool of the shaper. This affords the shaper hand a solid brass to work with in finishing to size, as he could do but little with the two halves separately. The brass is then laid horizontally in the shaper bed and one of the collar bosses trued up with another cut of the shaper tool. This sur A Fig. 3 mit the tail of the keeper bolt a tight fit down into the hole drilled for it in the brass, Fig. 3. This prevents any lateral movement of the rod end on the brass should it be pounded or become loose. The process of fitting up and machining the back and front end main rod brasses, however, embraces much more work, because of the necessity of having them in two parts. We will first take the manner of shaping a back end brass. The Fig. 4 face is then laid on parallel strips and the collar boss on the other side given the same treatment. We now have two side faces exactly parallel with each other. The brass in an upright position is now caught on these faces with the jaws of the shaper chuck, and the same operation repeated with the narrow top faces of the wings of the brass which hold it in the strap. By carefully dividing the amount of stock or surplus material over the exact sizes of the strap, the entire faces of the inner wings and bottoms are cut out squarely to allow the brass a close snug fit into the strap. The verti cal fit of the brass shown by A in Fig. 5, depends of course on the opening between the forks of the strap, but the distance B depends on the space found between the inside end face of the strap and the face of the key at the lowest point of wedge. The brass is now ready for boring to the size of the pin after it has been laid off The exact length of the main rod is in point D, the crosshead is at exactly the many instances taken before the brasses center of its stroke or travel. A square. are bored to the pins, as it eliminates E, is placed directly over the center of many changes which otherwise often have the main driver and held firmly in place. to be made after the rod has been ap- The pointed end of a long stick is held to plied to the engine. The manner in the crosshead pin, the free end of which which this is accomplished can be readily lies back over the body of the square explained, see Fig. 7. When done by the held against the hub center of the driver. above method, the boring of the brasses The distance from F to G plus one-half is delayed until the wheels are under the the diameter of the crosshead pin will engine, and the guides, crosshead and then be the correct length of the main rod. In some cases where more clearance is given the back cylinder head, to this should also then be added the difference, which is hardly ever more than the distance determined by the stick in Fig. 7, the centers are laid out on centering strips driven into the brasses, Fig. 8. The brasses are then pulled from the rods -ROD LENOTH Fig. 8 one-eighth of an inch. The brasses fin- and bored out. When then taken to the ished in every respect but boring, are put engine on the erecting side of the shop temporarily in the strap and bolted to the they are applied without any necessity main rod, which is laid conveniently over of moving the locomotive to determine two horses. With long trammels set to the clearance distances. NEW YORK AIR BRAKE EQUIPMENT* BY JOHN HAMILTON Fig. 58 shows a face view of the triple shown by Figs. 58 and 59 lead into two slide valve used with the automatic con- cavities in the face of the slide valve. trol valve, while Fig. 59 is a plan view, Passage K, Fig. 58, as indicated by dotor a view of the valve as it would appear ted lines, is a passage in the interior of when looking at its top were it possible to the valve, one end of which leads into see the ports and passages in its interior. cavity U, while the other end connects The full line circles in Fig. 59 indicate to a port that leads up into it from the that ports U, W and J lead entirely face of the valve. The size of the openthrough the slide valve, although they do ing between the off-set ports J and U in not all pass through it directly as the the top of the valve, and the same ports holes in the top and face of this valve are in the face of the slide valve is indicated not in line with each other. This applies by the area enclosed by the intersection particularly to port J, while port U is of the two circles representing these slightly off-set, but port W leads directly ports. through the valve. Fig. 59 shows that port P does not lead entirely through the slide valve. It is bored part way up into the face of the valve and then leads out through its side. This is shown more clearly in Fig. 58. Ports W and U as Continued from July, 1914, Magazine. Fig. 60 is a plan view of the graduatig valve looking at it from the back. It contains a cavity V in its face. The small circular hole is used for a pin to attach it to the triple piston. Fig. 61 is a view of the slide valve seat. The safety valve is connected to port L, while the retain pipe connects to port M. The two ports E lead to the N during an automatic application of the control valve reservoir. If it is desired brakes, thus preventing the escape of to study closely the relation existing be- brake cylinder pressure to the exhaust, tween the ports in the triple slide valve and to open port N when making an inP W -J K Fig. 58. Face of Slide Valve and the ports in its seat for the different dependent or automatic release which positions of the former, it is suggested that the student take two pieces of tracing cloth or thin transparent paper and make tracings of both the slide valve and allows brake cylinder pressure to escape to the atmosphere. The duty of cavity V in the graduating valve is to connect ports W and U in the slide valve when K W Fig. 59. Plan of Slide Valve Fig. 60. Plan of Graduating its seat, using of course Fig. 58, the face this valve is in service position, cavity view of the valve, and not the plan view V at such a time serving to connect the of it. By placing one over the other control reservoir with the safety valve. after lettering the ports as shown in the The graduating valve also blanks ports diagrammatic view of the control valve, U and W in automatic service lap posi M L Fig. 61. Slide Valve Seat the relation between the different ports tion of the control valve, thus cutting off can be easily studied as the slide valve communication between the control resis moved to its different positions. Fig. 62 shows a face view of the exhaust valve, while Fig. 63 shows the application valve seat which contains a port N that leads to the atmosphere. The duty of the exhaust valve is to close port ervoir and the safety valve. This valve is also used to open port J, Fig. 58, during service applications, and to close it in automatic service lap position of the control valve. The duty of port P, Fig. 58, is to connect the control reservoir with the safety valve in emergency posi- also serves to connect the safety valve tion. The small port leading from port with the control reservoir in full release P restricts the flow of pressure to the position, this connection being made by safety valve from the control reservoir means of port E which leads to the conat such times, allowing it to pass through trol reservoir, cavity and port U, cavity at about the same rate as it is entering in the graduating valve and port and the control reservoir through pipe CR cavity W, and port L, which leads to the from the automatic brake valve. Port J, safety valve. Considering the slide valve Fig. 58, is a service port, and all pressure seat shown in Fig. 61, port M connects entering the control valve from the aux- to the release pipe and permits control iliary reservoir during service applica- reservoir pressure to pass to this pipe tions passes through port J. This port with the slide valve in full release posiis opened and closed by the graduating tion, and it is through this port that the valve. The duty of port and passage K, pressure in the control reservoir escapes Fig. 58, is to connect the control reser- to the atmosphere with the handle of the voir to the retain pipe with the triple automatic brake valve in running posislide valve in full release position. The tion, which allows the locomotive brakes cavity in the face of the slide valve into to release automatically. Port M is then which port U leads is used to connect an exhaust port. Port L leads to the the safety valve with the control reser- safety valve and connects the control resvoir from service to the beginning of ervoir to this valve in all positions of Fig. 62. Face of Exhaust Fig. 63. Application Valve Seat emergency position of this valve, this conthe slide valve except automatic service nection being made through port L, cavlap. Ports E lead to the control valve ity and port U and port E. The cavity reservoir. The large port is used to adin the face of the slide valve into which mit auxiliary reservoir pressure to the port U leads is employed to connect the control reservoir in service and emersafety valve with the control reservoir gency positions, and it serves to connect while the slide valve is moving from the control reservoir to the safety valve service to the beginning of emergency po in full release position. The small port This schedule differs from sition. This can only be fully under- E is used to connect the pressure in the stood if transparent models of the triple control reservoir to the safety valve in slide valve and its seat are made as sug service position of the triple slide valve, gested. The extent of the movement of this connection being made by means of the triple slide valve will depend upon port L cavity and port W, cavity V in the length of the train. With short trains the graduating valve, and ports U and with a small brake pipe volume, the small port E. triple piston will carry the slide valve Fig. 64 shows the piping arrangement farther across its seat, compressing the of Schedule LT-6, Automatic Control graduating spring but not moving far Equipment. enough to go to emergency position as this spring is placed there to prevent this. With long trains and a greater brakepipe volume, the triple piston does not carry the slide valve so far. The cavities U and W in the slide valve face are then provided to insure that the control reservoir is left connected to the safety valve regardless of the extent of the movement of the slide valve during service aplications, that is, whether such a movement is great or small. The cavity in the slide valve into which port U leads Schedule LT-2 already considered in the type of pump governor used, which necessitates a different arrangement of piping, and therefore with this exception the arrangement of the remainder of the piping of Schedule LT-6 may be disregarded. The pump governor used with this schedule is duplex and is known as the excess pressure governor type. The governor top to which the two pipe connections are made is called the excess pressure head, while the other one is known as the maximum pressure head. The former |