inder as to move the piston of the reducing valve down far enough to have port a open. It has always been a great Z CYLINDER TO BRAKE 6 auxiliary reservoir air will also be wasted, which is of very much more importance. With the ordinary quick-action brake, 10-inch brake cylinder and 8-inch piston travel, 16 pounds reduction will cause the auxiliary pressure of 70 pounds to equalize into the brake cylinder at 54 pounds pressure. With the High Speed Brake, train line and auxiliary reservoir pressure 110 pounds, a 16-pound reduction will develop in a 10-inch brake cylin der with 8-inch piston travel 54 pounds pressure. Student. I can not understand how that can be. I should think that with the same reduction, 110 pounds pressure in the auxiliary reservoir would give very much more pressure in the brake cylinder than when the auxiliary reservoir is charged to only 70 pounds pressure. Instructor.-As 10 pounds reduction will be a more convenient one to consider in this explanation, I will say the 10 pounds reduction will develop 27 pounds pressure in a 10-inch brake cylinder with 8-inch piston travel, whether it is all exhausted. It would require 11 reductions. Instructor. That is right. Now suppose that the auxiliary was only charged to 70 pounds pressure; how many reductions would be required? Student. It would require only seven 10-pound reductions in this case. If Instructor.-I now want you to imagine that the auxiliary reservoir contains 110 pounds pressure, divided into eleven separate cells, so arranged that they can be removed and still contain 110 pounds pressure of air, and that the auxiliary reservoir containing 70 pounds pressure is divided into seven separate cells arranged so that any one of them can be removed, and still contain 70 pounds pressure of air. The two reservoirs, you understand, are of the same size, so the cells in the one containing eleven cells must be somewhat smaller than those in the one containing only seven cells. we should take out one of those cells from the auxiliary containing 70 pounds pressure and in some way squeeze it together so that it is no larger than one of the cells in the auxiliary reservoir containing 110 pounds pressure we would have 110 pounds pressure in this cell also. Again, if we should measure the number of cubic inches of free air in a cell taken from each reservoir we would find that they contain exactly the same number. So it is really the same amount of air that we admit into the brake cylinder, whether it is 10 pounds from 110 pounds or 10 pounds from 70 pounds. Instructor.-As I said before, 20 pounds reduction will develop about 60 pounds in the brake cylinder, and if a further reduction is made, not only the train line air will be wasted but the auxiliary pressure will also be wasted, and very little if any more pressure will be developed in the cylinder, but if no more reduction is made than what is necessary to develop 60 pounds in the cylinder the brake may be released, and without recharging again applied and 60 pounds again developed. now be released, and without recharging applied in the emergency, and as much pressure developed in the cylinder as can be with the ordinary quick-action brake. The brake can Student. I should think this would be a great benefit on fast passenger trains. Instructor.-It certainly is, but can not be had unless the brake is handled as it should be. Student.-Why are two tops to the governor required, and two slide-valve feed-valves? Instructor-One top to the governor is adjusted for 100 and the other for 140 pounds pressure, both being connected to the main reservoir pressure. In the pipe from the low pressure top is a stop-cock. When it is open the high pressure top does not affect the operation of the governor, but when it is closed then the pressure is permitted to accumulate in the main reservoir until the pressure at which this top is adjusted for is reached. One slide-valve feed-valve is adjusted for 70 pounds train line pressure, and the other 110 pounds. They are so arranged that either one may be cut into use. The object of having a low and high main reservoir and train line adjustment, which may be cut into use by simply changing the position of a stop-cock, is to facilitate the changing from the ordinary Student. You have certainly made quick-action brake to the High Speed that very clear to me. Brake. The same pressure will be developed in the brake cylinder so long as no more pressure is admitted from the high pressure auxiliary reservoir than what is required from the low pressure auxiliary reservoir to equalize the pressure into the brake cylinder. tablishes the limit, which is usually from 6 a. m. to 7 p. m., and work orders are in effect only between those hours, unless the order specifies others. In giving an order under a rule of this kind it is necessary to give the date on which it is to be used, and is in the following form: "Engine 292 will work extra Saturday, May 2d, between Berne and Turin." it is desired to work at a time other than that specified by rule the order reads: "Engine 292 will work extra until 9 p. m. Saturday, May 2d, between Berne and Turin." If Another provision, which we think is of considerable value, is found in some rules and requires the conductor of a work train, when he is done using his working orders, to send a message to the effect that he is "tied up," and this "tie-up" annuls his working order. This very often facilitates the work of the dispatcher. There are a number of methods for handling a work train with respect to its relationship to freight trains passing over the road. Of course the desired end is to give the work train the use of the track until the expected train is to pass over the portion so occupied, the work train to immediately clear the main track, but this is extremely difficult to perfectly accomplish unless the freight train is on a schedule and on time. For extra trains and for regular trains which are late we know of no way whereby, generally speaking, this can be accomplished without some delay to either train, for the reason that there is no dispatcher who can correctly guess, an hour or two in advance, what time a train will be at any particular point. The nearest approach to its accomplishment is by the use of examples (b) and (e) under Form H, whereby the work train is permitted to work under protection of a flagman until the expected train arrives, but even then there is often delay to the freight train, especially if the work extra must run toward the approaching train in order to get in on the siding. On the other hand, where the work train must clear the main track at a certain time, whether the expected train is there or not, a serious delay often results to the former. There are various practices. If the freight train is very important and it is desired that it run over the working limits without any delay whatever, it is given (in the case of a regular train) either a "run late" order or a "wait" at a certain station until a certain time for the work extra. In the case of an extra this can be accomplished by the use of example 1 (b), using the words "keep clear of." This almost invariably incurs delay to the work train and should not be used unless the freight train is of great importance. As a rule the loss of time to the work train is more expensive than a corresponding loss to a passing freight train, and for that reason the Standard Code provides for a work train to work under protection of a flagman until the expected train approaches. The prescribed forms are found under example 1, (b), (d) and (e). We know of at least one road where the rules permit a work extra to protect against second and third class trains, and we think it is a good rule. It relieves the dispatches from sending a great many long train orders, and in our experience we have seen but very few freight trains of so great importance that this rule could not be used to advantage. Of course it must be understood that the work train must get out of the way immediately on the approach of the other train, and if necessary it can be instructed by message about when to expect an important train and practically no delay will result. many roads where this rule is not in effect it is the custom to insert in the order a provision to protect against second and third class trains, which accomplishes the same result, but with considerably more work for the dispatcher. On In reviewing the rules of another large system we find the following under this form: "When an order has been issued to 'work' between designated points, no other extra shall be authorized to run over that part of the track without a definite meeting order with the work extra. "When it is anticipated that a work extra may be where it can not be reached for orders it may be directed to report for orders at a given time and place, and a meeting issued with other extra. "To enable a work extra to work upon the time of a regular train, the following form may be used: "No. 55 will wait at Berne until 6 p. m. for work extra 292.'" There is no provision in the rules of this road for a work train to protect against another train. The work train must have a "meet" order with other e tras, and the only means whereby je can work on the time of a regular train is by the use of the "wait" or "mect" order. Another method, which can be used where the limit is very short or the work |