Referring to Plate XIX, Figs. 1 and 2 each shows the Automatic Control Valve from two points of view the lefthand views showing in section (vertical) the triple valve and control valve, while the right-hand views in part section (vertical), show the safety valve and the flange on the body of the valve section by which it is bolted to the double-chamber reservoir.

The air pressures as represented by colors are as would be taken after an application and release, just as the operative parts have been moved to the RELEASE POSITION, before the pressures have been entirely exhausted from the brake cylinders and control reservoir, and before they can contain only atmospheric

air. The chart is, therefore, self explanatory as to the connections with the different chambers in the Automatic Control Valve.

The names and piece numbers of parts, as shown by Figs. 1 and 2, in Plate XIX, are as follows:

PT 45, Control-piston Pin; PT 57, Graduating Spring; PT 151, Body; PT 152, Triple Valve Piston; PT 153, Control Piston; PT 154, Piston Follower; PT 155, Slide Valve; PT 156, Piston Nut; PT 157, Triple-cylinder Cap; PT 158, Control-cylinder Cap; PT 159, Control-cylinder Gasket; PT 160, Triplecylinder Gasket; PT 161, Exhaust-valve spring; PT 162, Exhaust Valve; PT 163, Auxiliary-reservoir Cap; PT 164, Graduating-stem Nut; PT 165, Main-reservoirchamber Cap; PT 167, Control-valve Check Valve; PT 169, Check-valve Spring; PT 170, Graduating Stem; PT 175, Divided Reservoir; PT 176, Dividedreservoir Gasket; PT 184, Check-valve Guide; PT 186, Graduating Valve; PT 188, Check-valve Seat; PT 217, Inner Check Valve; PT 381, Control-valve Stem; 1 DP 52 C, Tap Bolt; 5 DP 143, Control-stem Cotter; EV 107, Packing Leather; EV 108 A, Expander; QT 3, Piston Ring (31′′); QT 37, Slide-valve Pin; QT 53, Pipe Plug (3′′); QT 49, Spring; QT 504, Slide-valve Spring; 37 RVH, Safety Valve, complete.

Referring to Fig. 2, Plate XIX, the names of the parts comprised in the Quick Action Cylinder Cap are:

PT 57, Graduating Spring; PT 177, Emergency Head; PT 179, Emergency Graduating Stem; PT 180, Emergency Slide-valve; PT 182, Cap Nut; PT 183,

gency Slide-valve Pin; QT 20, Rubber Seat; QT 49, Spring; QT 118 A, Checkvalve Spring; QT 138, Quick-action Valve; QT 139, Guide; QT 141, Cap.

The black line cuts herewith illustrate the port arrangements in the main valves of the Automatic Control Valve. Fig. 3 shows the plan of graduating valve, face of slide valve, plan of slide valve, and plan of slide-valve seat. Fig. 4 shows the plan of exhaust valve and plan of exhaust-valve seat.

Rings, Shells and Ring Dies.

The Standard Steel Works Company, catalogue on Rings, Shells and Ring Philadelphia, Pa., has just issued a new Dies. This very interesting publication contains illustrations of the various types of this class of material such as are used in the Chilean, Huntington, Griffin or Bradley, Kent, and Bryan Mills, as well as cuts of rolled steel rings which are used for various other purposes. The catalogue also contains cuts showing gear rims and blanks for built-up gears for heavy electric service, built-up wheels for Bascule bridges, and wheels for mining service. On the last few pages it contains tables of dimensions of peened, screw, welding, and plain pipe flanges as

well as facsimile of dimension blanks used in the ordering of wheels. They are to be congratulated on this very creditable addition to their catalogue list.

Superheated Steam on Mallet Engines.*

The title of this article expresses briefly the most recent combination resulting from many years of endeavor on the part of locomotive designers to produce a locomotive engine combining a maximum of power and efficiency.

In looking back over the history of the development of the locomotive, covering a period of about 80 years, we find that the first successful engines had a weight of about eight tons, and were capable of drawing a load of about ninety tons at a speed of from twelve to fifteen miles per hour. The efficiencies and economies of these engines were, of course, a sec

*Specially written for the Locomotive Firemen and Enginemen's Magazine.

ondary matter, and it is within only a comparatively few years that consideration of economy in fuel and water has absolutely demanded the most. careful study of locomotive design and the use of devices which would accomplish these results.

From the 16,000-pound engines of bygone times to the 461,000-pound Mallet type of the present time is a gigantic stride. In all of this progress until the past few years the tendency has been to produce heavier and more powerful engines, while their efficiencies (that is, the ratio of .tractive power to coal consumed) have changed but very little.

the present time a total weight of 461,000 pounds has been reached. This is in a Mallet engine having 16 driving wheels, and it is capable of developing a maximum tractive power of 126,000 pounds, when working "simple."

In combination with this type of engine it has been found that the fire-tube superheater, properly designed to give superheat of from 200° to 250° Fahrenheit, has still further increased the efficiency and power.

The list given below shows several Mallet engines, recently constructed, all of which were equipped with the fire tube superheater of the Schmidt design:

The Mallet type of engine has accomplished, of itself, wonderful reductions in the operating cost by increasing the load which a single engine can haul, and at the same time effecting a great reduction in the coal and water consumption per ton-mile. The increase in use of this type of engine, in this country, has been very rapid; and at the present time it is very nearly, if not quite, the most popular of any type of locomotive in

use.

This type of engine was first introduced in this country in 1904, when the Baltimore and Ohio Railroad ordered, as an experiment, one engine of this type. It weighed 334,500 pounds, all of which was carried on the drivers. The tractive power was 70,000 pounds. Since that time the weight of the Mallet type of engine has steadily increased until at

The Schmidt superheater, also known as the Type "A" or "Top Header" superheater, and which is described below, covers the design which has been, at the present time, applied to considerably in excess of 9,000 locomotives and which are in successful operation all over the world.

The general arrangement of this type of apparatus is shown by Fig. 1 and is a drawing of superheater, designed for the Mallet type of engine. It will be noted that the whole of the superheater apparatus is located in the upper portion of the boiler, and the superheater tubes and header are therefore in a favorable location for permitting inspection and performance of the usual front end work. The large flues in the boiler (within which the superheater tubes are placed) are 5" O. D. and made of seamless

steel tubing.

The superheater tubes are also of the same material.

The steam passes from the throttle in the dome through the dry pipe in the usual way. It then enters one part of the superheater header. This header is shown in detail in Fig. 2. The cores of this header are so arranged that the steam is obliged to pass through the superheater tubes before it reaches the steam pipes. This means that the header has, in reality, partition walls which prevent the steam from being "short circuited" through the header, and there

the header, it flows to the steam pipes and then to the steam chests in the usual way.

While passing through these tubes, heat is taken into the steam from the gases flowing through the large flues in which the superheater tubes lie. This insures the evaporating of any water which may have been carried over from the boiler. Then, as it passes along through the superheater tubes, the steam receives a further addition of heat, and its temperature is increased. It is then that it reaches what is called the super

Each superheater tube, some of which are shown in Fig. 3, is made up of four pieces of seamless steel tubing, joined by cast steel return bends, and thus forms one continuous passage for the steam. The steam upon entering the superheater tubes from the header flows back towards the firebox, then forward towards the smokebox, where it passes through the front return bend, back again towards the firebox through the third return bend, and then forward. On leaving the superheater tube it passes into the header, but on the opposite side of the partition wall from where it left in passing into the superheater tube. From the superheated steam compartment, in

during further passage through the superheat tubes, is increased, and it re

enters

he superheater header at a final temperature of about 600° to 650° Fahrenheit.

By referring again to Fig. 1 it will be observed that a damper is located in the smokebox, just below the superheater tubes, and this damper, together with a vertical deflecting plate, forms a means of preventing the flow of hot gases through the large flues when the throttle is closed. This prevents any deterioration in the superheater tubes and return bends which would otherwise take place. if gases at a high temperature were passing along the superheater tubes when no steam is flowing inside. It will be noted

that the damper is connected to a eylinder which takes steam from the steam pipes. When the throttle is closed, the counterweight keeps the damper closed, and prevents the flow of gases, as described above. When the throttle is opened, the steam pressure, which then exists in the steam pipe, acts through the short connecting pipe, on the piston in the damper cylinder, and moves the damper on its axis to the open position. The action of the exhaust then draws the gases from the firebox through the large flues,

be avoided just as carefully as with a saturated steam engine. This is because if high water is carried and foaming takes place, the efficiency of the superheater is decreased and the temperature of the steam reaching the high-pressure steam chest is lower than it should be. Of course, when this takes place, the benefits of superheating are partially lost. A word of caution may not be out of place in discussing Mallet engines, whether they are equipped with the superheater or not. It is, that these enor

as well as through the small boiler tubes, and the steam becomes superheated, as explained.

The above rather brief description covers all the essential points in the construction and operation of the superheater. It is in every respect automatic, and does not require any attention, in operation, from the engineer or fireman. In running a superheater Mallet engine, no different methods are required than with an engine which is not so equipped. It should be noted, however, that, although a superheater is installed, and therefore water can not reach the steam chest of the high-pressure cylinders with damaging results, "high water" should

mous machines should be operated at speeds not in excess of those for which they were designed, and should not (simply because they are capable of running fast) be operated at too high speeds.

In regard to the joint between the superheater tubes and header. It will be noted in Fig. 3 that these joints are made by a spherically formed end on the superheater tube which fits a conically formed seat in the header. With this style of joint all soft metal rings or gaskets are eliminated, and it is, in principle, the same as the ordinary steam pipe ring joint connection. It is easily maintained, and requires little or no attention in the roundhouse or shops. It will be