chamber has no duty to perform further Meanwhile, the application piston and than that of providing for the continua- its attached application valve and exhaust tion of pressure-chamber air expansion. valve are in their lapped positions-situThen, there also comes a time when even ated the same as they were in Service Lap the reduction-limiting-chamber pressure Position; the application chamber and has been built up to an equalization with chamber C being cut off and isolated from that remaining in the pressure chamber any pressure increase after having atand the content of the pressure chamber tained their 86 pounds, as soon as the can reduce no further, and if the brakepipe reduction is continued beyond this point the pressure-chamber air in chamber E by now remaining constant will at once become enough greater than brakepipe pressure in chamber B to drive the release piston to the finish of its application stroke and throw the emergency brake cylinder into action-but the latter event comes properly within the phase of "emergency application."

With the above explanation in general of one of the most important series of functions of the P-C control valve, we will now refer directly to the chart, Plate 85.

service brake-cylinder pressure reached about the same figure-in chamber Mthe application-piston spring moved the piston slightly to the left, closing the application-valve port as shown in the present chart. Any leakage loss of service brake-cylinder air will, of course, be automatically replenished from the service reservoir as heretofore explained.

follow.

The entire mechanism of the Control Valve is "marking time" while the brake pipe over-reduction is continuing-until the emergency brake applies; or the brake-pipe reduction may be stopped before the pressure chamber and reductionlimiting chamber have equalized (which The brake-pipe reduction having been would be at a pressure something over 55 carried below the figure at which the pounds); the latter proposition reprepressure chamber and application cham- sented in the position of "over-reduction ber equalize (86 pounds, if 110 pounds lap," the subject of the next chart to brake-pipe pressure is carried), sufficient differential pressure is established on the In the present position the three chamequalizing piston to cause it to compress bers of the small service-reservoir chargits graduating spring and complete its ing valve are brought into pressure confull application traverse; and momen- nection; air from the application chamtarily there is the same difference in pres- ber and chamber C flows through a port sure between the air in chambers B and in the equalizing slide-valve to chamber G E, against the opposite sides of the re- where it bears against the small end of lease piston, but this piston remains un- the service-reservoir charging valve; moved in the same position as shown in pressure-chamber air from chamber D the preceding chart, for the reason that flows through ports in the equalizing the resistance of its graduating spring is considerably greater than that of the equalizing graduating spring, and that immediately upon the completion of the equalizing piston's stroke the impelling force of pressure-chamber air against the release piston will again begin to lessen.

The finishing stroke of the equalizing piston carried with it its slide valve and graduating valve to the position shown in the present plate, and chamber-D airstill being re-enforced from the pressure chamber-flows through the graduating port in the equalizing slide-valve, past the end of the small graduating valve just the same as it did in Service Position, except that now the graduating port connects with the port in slide-valve seat leading to the reduction-limiting chamber; this chamber having been empty of pressure to begin with, in now receiving the air from the pressure chamber and chambers D and E it takes up the duty of graduating that air down to a still lower pressure-but doing nothing with the pressure taken beyond holding it in store.

graduating- and slide-valves to chamber K where its pressure is against the larger end of the valve; and air from the service reservoir is supplied to chamber H between the two piston ends of the charging valve; but as the pressure-chamber air is being reduced, while the pressure in the application chamber remains fixed at about 86 pounds and the service reservoir is at practically the same pressure, the service-reservoir charging valve is not caused to function nor to change its position at this time.

It will be noted that in the Over Reduction Position air from the service reservoir and from the application chamber are separated only by the packing ring in the smaller end (or piston) of the service-reservoir charging valve; and with reference to this the manufacturers state that "if there is any slight leakage which tends to cause a drop in application-chamber pressure (which is relatively small compared with the service reservoir volume), the air in the service reservoir will gradually find its way around the ring in the small

end of the service-reservoir charging valve lahoma, has invented and patented a and prevent any material drop in appli- means for raising and locking in a horication-chamber pressure, thus practically zontal position the apron between the eneliminating the possibility of the brakes gine and tender in case they should begradually leaking off due to application- come accidentally uncoupled, thereby chamber leakage."

Support for Apron Between Engine and Tender in Case of Accidental Separation.

eliminating the danger of one longitudinal edge of the apron falling down and permitting a man who might be standing on der. It is said to be equally applicable same to fall between the engine and ten

when used between two cars, and that it Mr. James H. Kearns, of Francis, Ok- may be readily and cheaply applied in

Examination Questions and Answers This is the title of a little booklet confor Third Year Enginemen and Firemen. taining the questions and answers as used in the third year examination of locomotive enginemen and firemen on the air brake. The answers to the questions are given in short and direct replies, such as would be used in answering the examiner, and without going into unnecessary or exhaustive detail. It contains 36 pages, size 3§ x 5 inches, bound in stiff paper cover. Price 35 cents. A reduced price will be made when ordered in quantities. Published by Columbia Air Book Co., 1532 5th Street, Harrisburgg, Pa.

Our Special Study Course

TRAIN STEAM AND HOT-WATER HEATING

(PART 8.)

Copyright, 1914, by Brotherhood of Locomotive Firemen and Enginemen.

Instructions for Heating a Train by Direct Steam.-General Operation,
and Troubles that May Occur.

1. The Locomotive.-Before the engine is due to leave the roundhouse it should be known that the steam-heat equipment is in proper working order— no leaks in the piping, the hose between engine and tender and at rear of tender in good condition, and no leakage from couplings, and the reducing valve operating correctly. As there are usually no train-pipe valves on engine nor tender, it will be necessary for the roundhouse inspector to attach a dummy coupling to the steam-hose coupling at rear of tender, and, if steam is piped to the front end, another one to the pilot steam-hose coupling; these dummys are made by closing the steam passage through a steam coupling, except for leaving a 1⁄4-inch hole, and attaching a chain with hook at end. It is but a moment's work to connect a dummy to the regular hose coupling; then turn steam full on at the boiler valve, and see that the pressure will be reduced and steadily maintained by the reducing valve, as indicated on the steam-heat gauge, and which can be raised and lowered by readjustments of the reducing valve. When the Mason reducing valve rattles and chatters it is caused by worn dasher and dashpot which should be renewed; in the use of the Mason style, overcharging of train pipe may be caused by a scale under the main valve, or a very slight particle of matter under the small, auxiliary valve or the latter valve can be stuck from corrosion and cause the overcharging, or closure of the steam supply altogether; when the latter trouble exists it is frequently caused, also, by deposits of lime or soda ash in the dashpot or the lower part of port N.

Just before, or immediately after taking the engine from the roundhouse, the engineman should turn on just enough steam to the train pipe to "show the white feather" from hose coupling at rear of tender. A majority of boiler valves leak just the least bit, not permitting enough steam to enter the train pipe to heat it, but sufficient to condense and collect as cold water in the pocket formed by the hose connection between engine and tender where it freezes; and, as has often happened where engines are changed on through trains, the train gets away from the station before it is discovered that no steam heat is being supplied. Turning on enough steam before leaving the shelter of the roundhouse to heat the locomotive piping will prevent this trouble occurring.

When an engine is required to supply steam heat to a train and the reducing valve fails-will not permit steam to pass through it-if using a Mason reducing valve, first shut off the steam by the boiler valve, then screw off the dashpot at the bottom of valve body and place a couple of coins, washers or something else of equal thickness under the dasher, and replace

the dashpot; this will force and hold the main valve open permanently; then turn on steam by the boiler valve and adjust it to the pressure required. But the steam-heat gauge must be closely watched in such cases, and the boiler valve will have to be constantly adjusted, or the steam-heat pressure will become too low for the comfort of the passengers, or so high as to blow off a hose and a heavy increase of pressure will take place within a very few moments after the system becomes heated to a certain temperature and the traps automatically close.

2. Steam Pressure Required.-Tests indicate that in very cold weather, on trains of from seven cars upward and steam being used with fully opened inlet valves in all radiator coils, the pressure in the train pipe declines from the first car to the rear one at the rate of about five pounds per car; and that a maintained pressure of 20 pounds in the train pipe is sufficient to heat any car in the severest winter weather. Accordingly, the following rule is in effect on many railroads:

"Enginemen will supply whatever steam-heat pressure may be demanded by the conductor, except that they shall not exceed the following by the steam-heat gauge on engine, as the maximum pressure:

"Five pounds for each car in the train, plus 20 pounds. Thus, 35 pounds maximum pressure for a three-car train."

3. The Train.—(At terminals.) One imperative requirement should always be observed, viz., before turning steam from the locomotive into the train pipe of a car or number of cars, see that all train-pipe valves (angle valves) are fully open, as well as that the hose are all coupled properly; the followingwhich is no rare occurrence-will illustrate the reason. A switching engine coupled to three passenger cars on the storage tracks to take them to the station for coupling to a regular train a half-hour later, and steam was at once turned on, to have them comfortably warmed before the passengers would go aboard. All steam hose were coupled on these cars, and pressure turned on, but the angle valve was not opened on the first car at the end farthest from the engine. It was a severely cold day, and the first inrush of steam at once condensed to water in the train pipe of the first car from engine-cold water, which slowly streamed through the leakage groove in the seat of the closed angle valve, filling the pocket formed by the coupled hose between first and second cars where it was frozen at once by the extreme coldness of the iron couplings; this stopped the advance of pressure in the train pipe, the steam continued to flow into the pipes and condense, and the freezing rapidly extended back toward the engine until, when the cars had reached the station (they had started as soon as the steam was turned into the cars, without waiting to inspect the action), every pipe in the steamheating system of the first car was frozen solid, and a portion of the train pipe of the second car.

No matter whether train-pipe valves are of the wheel-handle or leverhandle style, it is impossible to tell at a glance whether they are fully open, partly open, or closed; try them and see that all are open at first. Having notified the engineman to turn on the steam, the attendant should proceed at once to rear of train, and when the condensation has blown out and steam appears, the angle valve at rear of the rear car should be closed-completely, if of the common kind which have leakage grooves in the seats; but if the valve is of the kind which close tightly without leakage, it should be left slightly "broken"-open just enough to permit a very little steam to escape.