tain communication between the brake valve 3. Should a second application be pipe and chamber 0-1 until the brake is made there will be no local reduction of released. From this it is evident that brake-pipe pressure by the triple valve, the triple valve assists the brake valve as chamber 0-1 is now charged to a in reducing the brake pipe pressure up- pressure equal to that of the brake pipe, on the initial application only, due to which will reduce with the brake-pipe chamber 0-1 being empty at the begin- pressure as succeeding applications are ning of this application. After the ini- made. These applications may be contial application, chamber 0-1 being equal- tinued until the auxiliary reservoir and ized with the brake pipe, no further re- brake-cylinder pressures equalize, and duction in brake-pipe pressure can be when this occurs piston 2 will not be made through the quick service ports. returned to service lap position. Fig. 84 shows the triple valve in serv

Fig. 85 shows the triple valve in re

Fig. 84. GN-2 Triple Valve. Service Lap Position

ice lap position. When the desired brake-pipe reduction has been made, air from the auxiliary reservoir continues to flow through ports Y and O to the brake cylinder until the auxiliary reservoir pressure is slightly less than that of the brake pipe, when piston 2 will be moved to the right until its shoulder comes in contact with slide valve 3. As piston 2 moves to the right, it carries graduating valve 4 and the latter closes port Y in slide valve 3, preventing further flow of air from the auxiliary to the brake cylinder, as shown in Fig. 84. Chamber 0-1 is in communication with the brake pipe through ports Y and K-1 of the slide valve seat and cavity T of slide

stricted release position. The triples on about the first 30 cars on the head end of the train will assume this position following a release, and behind them the brakepipe pressure cannot be raised enough above auxiliary pressure to force the triple pistons to compress the retard springs, as shown in Fig. 85. The triples therefore behind the first 30 cars will move to normal release position, as shown in Fig. 82, with the exception that the retard spring will be compressed enough for the feed port F to be fully opened. In restricted release position then, the brakecylinder pressure on the first 30 cars will escape slowly through port O, restricted port H, and passage G in the slide valve

to the exhaust port, while the brake-cylin- these triples are in normal release posider pressure on a car in the rear will es- tion. When the recharging of the auxilicape freely through port O in the slide aries is uniform there is no danger of the valve seat, cavity R in the slide valve and re-application of the front end brakes due port S to the exhaust, as shown in Fig. to the head end auxiliaries charging 82. The pressure in chamber O-1 is also higher than the rear end ones, followed free to pass to the exhaust port through by an equalization of brake-pipe pressure port K-1 in the slide valve seat, cavity T between the front and rear of the train in the slide valve and port R-1 in the after the brake valve has been moved to slide-valve seat. The front brakes will running position. The movement of the then be releasing slowly while the rear triples that are in restricted release posibrakes will be releasing at their normal tion from this position to normal release rate, but as the front cars have begun to position will now be considered, and the release first, as they felt the increase in first movement will be to normal release brake-pipe pressure first, the final release after restricted release position due to the

Restricted Release Position

retard spring acting to move the triple piston as the pressures on each side of it raise until the difference is about equal to the power of the compressed retard spring.

Fig. 85. GN-2 Triple Valve. of all brakes will be accomplished at practically the same time, this uniform release being further assisted by the triples that were in restricted release moving as the brake-pipe and auxiliary pressures Fig. 86 shows the GN triple valve in equalize to a position that will increase normal release after restricted release the opening between the brake cylinder position. In this position the triple pisand the exhaust port, or they will move to ton has moved far enough to the left, taknormal release after restricted release ing the slide valve and graduating valve position. The release of brake-cylinder with it, for the brake-cylinder pressure to pressure is occurring simultaneously with exhaust to the atmosphere through port 0, the recharge of the auxiliary pressure to cavity R, restricted passage H, passage G, standard and in restricted release position and port S, also through cavity R, passage it will be noted that the recharging of the X, cavity W in the graduating valve and auxiliaries is also restricted, while the re- port G-1 to passage G. Chamber 0-1 recharging of the auxiliaries on the rear mains in communication with the exhaust cars is occurring at a normal rate as port through port K-1 and R-1 in the

slide-valve seat and cavity T in the slidevalve 3. The auxiliary reservoir is charged through feed port F, chamber I and port J-1, but this latter port is somewhat restricted, and as the greatest feed port opening between the brake pipe and the auxiliary reservoir does not exist until the triple piston is slightly to the right of normal release position, the triple assumes normal release position when the brake pipe and auxiliary pressures have about equalized. It will then be noted that the triples back of about the first 30 cars move when the brake-pipe pressure

through which the brake cylinders are exhausting, first assuming normal release after restricted release position and next moving to normal release position, the movement of the triple being continuous after it has once started. This will result in practically all brakes releasing at about the same time and also all auxiliaries recharging at about the same rate. All triples will finally assume normal release position at about the same time with the packing rings on the triple pistons partly covering ports F, which will cause the triple pistons to promptly close

is increased to normal release position, these ports when a reduction is made in and these auxiliaries will begin to re- brake-pipe pressure.

charge and the brake-cylinder pressure Fig. 87 shows the GN triple valve in will begin to exhaust through maximum emergency position. When an emerport openings. The first 30 triples will gency application of the brake is desired move to restricted release position and a quick, heavy reduction of brake-pipe their auxiliaries and brake cylinders will pressure is made which causes piston 2 receive and reduce pressure through the to move quickly to the left. This movesmallest sized ports used for this purpose. ment is so rapid that the pressure in These triples will remain in this position chamber M, which was equal to that until the difference between the pressure of the brake pipe, cannot escape through in the brake pipe and in the auxiliary is ports L in vent piston 1 so rapidly as about equal to the tension of the retard is necessary to let the pressure in chamspring, and the triples will begin to move ber M reduce at the same rate at which so as to increase the port opening through the brake pipe pressure is reducing. The which the auxiliaries are recharging and air trapped in chamber M momentarily

forms a cushion between vent piston 1 valve and slide valve and opens and and triple piston 2, and under this con- closes the feed ports. The graduating dition triple piston 2 and vent piston 1 valve graduates the amount of pressure move together to the left, and as the entering the brake cylinder from the stem of vent piston 1 passes through its auxiliary reservoir during service appliguide, ports L are blanked, which re- cations. The cavity in its face also stricts the flow of air from chamber M. forms a connection between the brake In moving to the left, the stem of vent cylinder and the exhaust port in normal piston 1 presses against the lever arm release after restricted release position. of vent valve 8, throws the vent valve The slide valve controls the flow of presfrom its seat and permits air from the sure from the auxiliary to the brake cylbrake pipe to flow from chamber E to inder and from the brake cylinder to the chamber Z and the atmosphere. Vent- atmosphere. It also connects the brake ing brake pipe air to the atmosphere in pipe with chamber 0-1 in quick service

this way provides for a full and quick position, and connects this chamber with application of the brakes. Port Y in the exhaust port in all three release posislide valve 3 fully registers with port tions of the triple valve. The vent valve O in the slide valve seat and permits a piston unseats the brake pipe vent valve full equalization of auxiliary reservoir during emergency applications. The repressure with the brake cylinder. The tard spring governs the movement of the pressure that is trapped in chamber M triple piston between restricted release will reduce through ports L in vent piston 1 and allow spring 9 to return vent valve 8 to its seat, thus closing communication between the brake pipe and the atmosphere.

The duties of the moveable parts of this triple valve are as follows: The triple piston operates the graduating

and normal release position. The plug shown in the top of the triple valve permits of the feed ports being cleaned without taking the triple apart.

Fig. 88 shows the graduating valve used with the GN triple valve. It has a cavity W in its face. Figs. 89 and 90 show a plan view and a face view

of the slide valve. Port Y leads indi- X in the slide valve during normal rerectly through the valve. Cavity R, lease after restricted release position, Figs. 89 and 90, has two ports leading these ports and the cavity providing an into it, namely, H and X. The latter additional passage for the escape of

W

Fig. 88. Face of Graduating Valve

port passes entirely through the valve, but port H does not, and merely leads into the passage connecting port G-1 on the top of the valve, Fig. 89, and port G in the face of the valve, Fig. 90. This passage leads over cavity R and is

X G-I

Ө

brake cylinder pressure at such a time. The duty of port Y in the slide valve is to connect the auxiliary to the brake cylinder during service applications. Cavity T connects the brake pipe with chamber 0-1 in the triple during service and emergency applications, and connects this chamber to the exhaust in all other positions except service lap. Cavity R conveys brake cylinder pressure direct to the atmosphere in normal release position, and indirectly thereto in restricted release by way of port H and passage G, and by way of ports H and X in normal release after restricted release position. Passage G is used in both restricted release and normal release after

also leads to the chamber in the triple pressure entering and exhausting from into which brake-pipe pressure is vented the brake cylinder passes through port during a quick service application. 0; in the latter case, the pressure in the Port R-1 is also bored into the exhaust brake cylinder finally reaches the exhaust port. Therefore both ports S and R-1 through port S. The pressure in chamlead to the exhaust port. ber 0-1 passes through port R-1 to the exhaust in the three different release positions of the triple valve, this pressure

The duty of cavity W in the graduating valve is to connect port G-1 and