New York and Westinghouse air brakes

Front matter

and

WestingliQiisc^

AIR BR^kis

Table Of Contents

Automatic Quick Action Compressed Air

Brakes Essential Parts of Air Brakes Names of Different Pressures .

Arrangement of Apparatus Air Pumps

II

f

means of suitably constructed reversing valve gear to provide for the up and the dov^u strokes of the pistons. The pistons are combined steam and air pisions; that is, there is a steam piston head on one end of the piston rod and an air piston head on the other, so that when the steam piston makes a stroke the air piston also makes a stroke.

In the air cylinders of the pumps are suitably arranged air valves for the admission of air from the atmosphere to the air cylinder, as the air piston moves in one direction, and the discharge of this air intO' the main reservoir, as it is compressed by the air piston when moving in the opposite direction.

In the Westinghouse pump there are four air valves, two receiving and two discharge ; in the New York pump there are six air valves, two receiving, two combined intermediate receiving and discharge, and two final discharge valves.

At each stroke made by the Westinghouse pump, the air received on the previous stroke is discharged direct into the discharge pipe and the main reservoir, while the New York pump discharges all the air, received in the large air cylinder, into the small air cylinder, and the latter then discharges into the main reservoir all the air received from the large air cylinder and from the atmosphere direct.

The reversing valve gear for the Westinghouse 9j^-inch pump consists of a slide valve, held between pistons of unequal diameter ; a reversing slide valve, a tappet rod, working in a hollow piston rod and a reversing tappet rod plate bolted to the steam piston head.

As the steam piston approaches the end of its stroke it alternately pulls and pushes the tappet rod and reversing slide valve up and down, thus alternately admitting steam through suitably arranged ports in the reversing valve seat to and exhausting it from, one side of the large differential piston head, and in this way provides for the movement of the main slide valve, which alternately opens and closes the steam and exhaust ports to the upper and lower ends of the steam cylinder.

The reversing valve gear for the New York pump consists of two ordinary D slide valves, two tappet rods, and two reversing tappet rod plates, bolted to the steam piston heads. Each piston rod is made hollow on its steam end, and the tappet rods work in the hollow portion of each piston rod, and each tappet rod has one D slide valve attached to its lower end which is moved up and down together with the tappet rods and in so moving opens and closes the steam and exhaust ports in their bushings leading to the upper and the lower ends of the steam cylinders.

From the figure of the duplex pump it will be noticed that the steam ports are crossed; that is, that the steam ports in the pump head directly under one steam cylinder lead to the other steam cylinder, and from this it will be learned that the steam piston, tappet rod, etc., of one steam cylinder move the slide valve under it so as to admit steam to and exhaust it from the other steam cylinder, and that when one piston has made a stroke, it must wait until the other makes a stroke before it can make its return stroke. On account of one of the air cylinders being made so as to have twice the cubical capacity of the other, the duplex pump will economize in the use of steam-, as three measures of air are compressed for each two measures of steam used. The main reservoir is intended to hold in storage a large volume of compressed air for releasing the brakes, and recharging the auxiliary reservoirs and the train pipe. It also acts as a catch basin or trap for all moisture and dirt that may be contained in the air as it leaves the pump. Mr. Gesner adds : ''It should always be placed below the pump in the air brake system and the larger it can be made the better it will fulfill its proper functions.''

THE ENGINEER'S BRAKE VALVE.

The Engineer's Brake and Equalizing Discharge valves of the Westinghouse and the New York types differ largely in their construction and appearance, but perform- the same functions in nearly the same manner.

The principal valve in the Westinghouse engineer's brake valve is called the rotary, because of its rotary motion when in operation. There is a secondary valve called the equalizing discharge valve, which has a piston, attached to one end of its stem.

The equalizing discharge piston under normal conditions is balanced between the train-pipe pressure, bearing upwards from beneath, and the equalizing reservoir pressure bearing downward on the top.

The equalizing feature of the brake valves operate in all service- applications, but not in emergency applications.

In the New York engineer's brake valve the principal valve is a slide valve^ as is also the secondary or graduating valve.

The graduating valve is moved by means of an air tight piston, acted upon by pressure in the supplementary reservoir, and a lever connecting the equalizing discharge piston and graduating valve.

The equalizing discharge piston is exposed to train pipe pressure in front of it, and supplementary reservoir pressure behind it.

The difference in operation of the two types of brake valves consists in the way in which the train pipe reduction is made and gradually closed off in the service application. In the Westinghouse the required service reduction in train-pipe pressure is accomplished by moving the handle of the brake valve to the service position, and reducing the equalling reservoir pressure the required amount, and then returning the handle to the lap position.

The pressure in the train pipe (the moment it is greater than in the equalizing reservoir) will raise the equalizing discharge piston and valve, and permit the train pipe-pressure to escape to the atmosphere, gradually moving back to its seat as the pressure in the train pipe falls to an amount equal to that remaining in the equalizing reservoir. The service reduction in train pipe pressure is made with the New York brake valve by placing the handle in one of the service graduating notches and allowing it to remain there until the train pipe exhaust closes.

As the train pipe pressure reduces in front of the equalizing discharge piston, the pressure in the supplementary reservoir pushes the equalizing piston forward until the graduating valve covers the service port in the main sHde valve.

By referring to the cuts, a view of the external appearance and of the interior constructio-n of the respective brake valves may be obtained, and from them it will be seen that the handle of one is moved in a horizontal plane, and the handle of the other in a vertical plane, to apply and to release the brakes.

PLAIN TRIPLE VALVES.

The plain triple valves are shown in Figs. I, 2 and 3. They consist of a triple piston;

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a slide (or exhaust) valve; and a graduating valve, enclosed in suitable cylinders and bushings that are securely pressed into the cast iron body.

The Westinghouse triple piston has a varying stroke, depending on whether it is a slow and graduating application of the brake that is required, as in making ordinary station stops, or quick application, such as is required in emergencies ; while the New York triple piston valve Fig. 2, has the same stroke in both the service and the emergency applications.

The essential parts of the plain triple valve in either type are, first, a triple piston ; second, a slide valve; and third, a graduating valve.

These parts are enclosed in the body of the triple, that portion in which the triple piston operates being of cylindrical form, with a short groove, called the feed groove, cut in the upper forward extremity ; and that portion in which the slide and graduating valves move being formed so as to provide an air tight seat for those valves.

As the air pressure flows into the train pipe from the engineer's brake valve it presses against one side of the triple piston and moves it along, with the slide and the graduating valve, to the release position, as shown in the cuts, and when in this position the small feed groove, spoken of above, in the triple cylinder is uncovered, and the air flows through it to the auxiliary reservoir,

WESTINGHOUSE PLAIN TRIPLE VALVE.

^TIPE TAP O AUXIUARY RESERVOIR

Triple valve body.

Cylinder cap.

Cap nut.

Piston.

Slide valve. . Graduating valve. 8 Graduating stem.

m

Fig. I.

PLAIN TRIPLE VALVE.

Graduating-stem spring.

Graduating-stem nut.

Cylinder gasket.

Packing ring.

Bolt.

Slide valve spring.

i8

NEW YORK PLAIN TRIPLE VALVE.

Fig. 2.

PLAIN TRIPLE VALVE.

Piston ring.

Slide valve spring.

II

Cap.

Gasket.

M

Drain plug.

4°

Bracket.

i6

N ipple.

Cap bolt.

Triple valve body.

Plug.

Slide valve.

Piston.

Graduating valve.

Graduating valve spring.

charging the latter to the same pressure as is contained in the train pipe.

When, therefore, a reduction, either graduated or quick, is made from any cause in the train pipe pressure, the greater pressure which then remains in the auxihary reservoir will move the triple valve (the triple piston, the triple slide, and the graduating valves combined) in the direction of the weaker (train pipe) pressure, the triple piston first moving a sufficient distance to close the communication, through the feed groove, between the train pipe and the auxiliary reservoir, then moving the slide valve to a position closing the communication, called the exhaust port, between the brake cylinder and the atmosphere, and the graduating valve to a position uncovering the service port in its seat, leading from the auxiliary reservoir to the brake cylinder. Through the service port, when open, the auxiliary reservoir pressure will expand into the brake cylinder, and force the brake cylinder piston out, and thus by means of the connected foundation brake rigging, apply the brakes.

It will be seen from the foregoing and from a careful study of the figures that after once the auxiliary reservoirs are charged up equal to the train pipe, that any ordinary reduction of four or more pounds in train pipe pressure, from any source, will operate the triple valves, and apply the brakes. Mr. Roach adds : "U the reduction be large enough. For this reason the triple valve is considered the most important part of the air brake apparatus, and it is due to its peculiar construction that the air brake is automatic or selfacting. The new style New York triple valve is shown by Fig. 3 The operations of this valve are the same as those previously described. This is a special driver brake triple and is used only with 12-inch, 14-inch and 16-inch driver brake cylinders.

The quick action triple valve differs from the plain triple in that it has a set of additional valves which are so arranged in the body of the triple that they lie inactive during a gradual reduction in train pipe pressure, but wdienever a quick reduction is made in the train pipe pressure they go into action instantly, and in so doing vent the train pipe air locally into the brake cylinder or into the atmosphere — into the brake cylinder if it is a Westinghouse triple and into the atmosphere, if it is a New York triple.

The reason for venting the train pipe air locally either to the brake cylinder or to the atmosphere, is to hasten the reduction in the train pipe pressure throughout the whole lengtli of the train pipe on long trains that all the brakes may be applied almost instantly, and thus in emergencies bring the train to a stop in the shortest time and distance, and also to avoid the shock to the rear end of the train that would be had if any considerable time should elapse between the application of the brakes on the front and on the

NEW STYLE PLAIN TRIPLE.

TO AUXILIARY RESERVOIR rear of the train, owing to the slack in the train allowing the rear cars to run in against the heavily braked cars in front.

The quick action mechanism of the Westinghouse triple valves consists of an emergency piston, an emergency valve, a non-return check valve, and an emergency port in the seat of the triple slide valve.

The quick action feature of the New York triple consists of a vent valve, a vent piston, an emergency piston, an emergency valve, and a brake cylinder check valve.

When the triple valve of the Westinghouse type makes its full stroke the slide valve will uncover the emergency port in its seat and permit the auxiliary reservoir pressure to flow to the top of the emergency piston, forcing the latter downward which in turn by reason of its stem bearing against the emergency valve forces this valve away from its seat, when train pipe pressure, which is always directly underneath the emergency valve, can flow to the brake cylinder. The non-return check valve prevents the air in the brake cylinder from flowing back into the train pipe, should the pressure in the train pipe be reduced below that in the brake cylinder.

The quick action mechanism of the New York triple valve is put into action by a sudden reduction in train pipe pressure. Between the main triple piston and the vent valve piston there is a chamber charged with air to the same pressure as that in the auxiHary and in the train pipe, which, when a gradual reduction is made in the train pipe pressure, can reduce at the same rate along with it and thus allow the triple valve to move without disturbing the vent valve. But when a quick reduction in train pipe pressure is made, causing a quick movement of the triple valves, the triple piston of the latter cushions on the air in the vent-piston chamber and forces the vent piston along in the same direction. The stem- of the vent piston strikes against the lever arm of the vent valve, forcing the latter away from its seat and it thus permits the train pipe pressure, which is behind it to escape to the vent passage, formed in the triple around through the body leading to the emergency piston.

As the air thus vented into the emergency passage, rushes toward the outlet, it is directed against the emergency piston forcing it over against the emergency valve, forcing the latter away from its seat, and then it escapes to the atmosphere through the vent ports at the side of the triple body under the emergency cap.

Behind the emergency valve we have auxiliary reservoir pressure, and as this valve is forced back from, its seat the auxiliary pressure flows into the brake cylinder, through the passage leading thereto through the body of the triple, forcing from its seat, as it does so, the brake cylinder check valve, which seats after the auxiliary reservoir pressure has entered the brake cylinder.

The brake cylinders are constructed in the ordinary way of cast iron, and are bored out so as to have a perfectly cylindrical and smooth interior surface. The brake cylinder piston is made so as to- fit the brake cylinder air tight, the air tight joint being formed by a packing leather which is held securely on the piston rod by a follower plate and four bolts. Mr. Gesner adds : ''and an expanding ring."

All brake cylinders, auxiliary reservoirs, angle cocks, cut-out cocks, conductor's valves, release valves, and pressure retaining valves are so near alike in both types of brakes, and so plainly shown by the illustrations as to need no description.

The pump governors of both types of brakes, while somewhat different in construction, in operation they are similar.

They consist essentially of a regulating spring, a regulating screw and nut, an air valve, a governor piston, a steam valve and stem, and a suitable casing and body to enclose those parts, and to form a seat for the steam valve and a steam, passage through which the steam can pass to the pump.

The function of the governor is to control the pump in such a manner as to prevent it from accumulating in the main reservoir and the train pipes more than the fixed standard air pressure which it is desired to carry. Mr. Dickson says: ''The function of the governor is not to- control the speed of the pump, but to start and stop it. The pump throttle regulates its speed."

The main reservoir pressure operates the pump governor, with the Westinghouse brake valve except when the old style D 8 valve is used. With the D 8 brake valve the train pipe pressure operates the governor. With the New York brake valve the train pipe pressure operates the governor. Therefore, in one the tension of the regulating spring is adjusted to withstand a pressure of ninety pounds which is the main reservoir pressure generally carried; and in the other the tension of the regulating spring is adjusted to withstand a pressure of seventy pounds, the standard train pipe pressure.

With either governor, when the air pressure for which it is adjusted is attained, the regulating spring is compressed, and a diaphragm w^hich forms an air tight separation between the regulating spring casing and the air chamber beneath it, is raised from its seat, or as in the case of the Westinghouse governor, it and the pin valve along with it, is raised, opening a communication with the chamber above the governor piston through which air can flow to the top of the latter and force it together with the steam valve and stem, downward, until the steam valve seats and shuts off the steam to the pump, thus slowing the latter down to a very slow rate of speed.

As soon as the air pressure falls below that for which the governor is adjusted, the diaphragm, if the New York, or the diaphragm and pin valve, if it is in the Westinghouse, will seat and close the passage leading down to the governor piston. Then the air on top of the governor piston will quickly escape to the atmosphere and allow the pressure on the top of the governor piston to fall to zero, after which the steam pressure under the steam valve will raise the latter, together with the governor piston, and thus steam will again be admitted to the pump and the latter will start up promptly.

In the construction of these pump governors, the aim has been to make them* as sensitive to slight variations in the air pressure as it was possible to make them ; this in order that the pumps may be allowed to run slowly but a very short time at each operation of the governor.

In Figs. 23 and 24, pages 84 and 86 the internal construction of the governors are shown and all parts numbered and named for easy reference.

The air gauges for either type of brake are of the duplex pattern ; that is, there are two gauges in one case, one gauge to indicate the train pipe pressure, and one to indicate main-reservoir pressure.

The black hand on the air gauge indicates train pipe pressure, and the red hand, main-reservoir pressure.

WESTINGHOUSE EIGHT-INCH AIR PUMP.

fROM BOILERr-

Fig. 4.

EIGHT INCH AIR PUMP.

2 Top head. 33

3 Steam cylinder. 34

4 Center piece (forms lower 35

steam head and upper

air head). 36

5 Air cylinder.

6 Air cylinder head. 37

7 Main valve.

8 Upper main valve pack- 38

ing ring.

9 Lower main valve pack- 39

ing ring.

10 Steam piston and rod. 40

11 Air piston. 41

12 Steam piston packing ring. 42

13 Air piston packing ring. 43

15 One-inch exhaust pipe 44

union nut. 45

16 Reversing valve. 46

17 Reversing valve stem. 47

18 Reversing valve plate.

19 Reversing valve bush. 48

20 Reversing valve chamber

cap. 49

21 Reversing cylinder cap.

22 Reversing cylinder 50

23 Reversing piston. 51

24 Reversing piston packing

ring. 52

25 Upper main valve bush. 53

26 Lower main valve bush.

27 Packing nut. 54

28 Packing gland. 55

29 Upper valve chamber cap. 56

30 Upper discharge valve. 57 31. Upper receiving vaive. 58 32 Lower discharge valve. 59

Lower receiving valve.

Lower valve chamber cap.

Three-fourths-inch reservoir-union nut.

Upper steam cylinder gasket.

Lower steam cylinder gasket.

Upper air cylinder gasket.

Lower air cylinder gasket.

Air cylinder oil cup.

Drain cock.

Cylinder head bolt.

Valve chamber bush.

Discharge valve stop.

\'^alve stop set screw.

Chamber bush set screw.

Three-fourths inch reservoir union stud.

One-inch exhaust pipe union stud.

Three-fourths inch steam pipe union stud.

Main valve stop.

Reversing valve plate bolt.

Pump head bolt.

Three-fourth inch union swivel.

Governor union nut.

Governor union stud.

Piston stuffing box.

One-inch union swivel.

Piston rod nut.

Cylinder head plug.

EIGHT-INCH PUMP.

O. In which end of the eight-inch pump is the power used to run it ? ^ A. In the upper or steam cyHnder end.

Q. What functions are performed by the lower end?

A. The lower end compresses the air, taken into the air cylinder from the atmosphere, and discharges it into the main reservoir.

Q. Where does the steam first enter the pump?

A. At the steam connection made at the side of the pump, and it fills the steam chamber between the ends of the m-ain steam valve 7.

Q. What duties does the main steam valve perform ?

A. The same duties as a sHde valve in the steam chest of an engine; it alternately admits steam to the upper, and to the lower end of the steam cylinder; and after this steam has done its work in moving the steam piston, it provides for its escape, or exhaust, to the atmosphere.

O. When the steam piston is ready to commence its down stroke how is the upper steam port uncovered?

A. The upper piston head of the main steam valve is much larger than the lower, and for this reason the total steam pressure upon it is greater, and forces it upward until the steam port in the upper end of the valve chamber is opened;

admitting steam to the top of the steam- piston at the same time that the upper steam port is opened to admit steam to the pump, the lower exhaust ports are open to the atmosphere, permitting the steam used on the up-stroke to exhaust to the atmosphere.

Q. When the down-stroke is completed how is the movement of the piston reversed ?

A. xA.s the upper piston of the main valve has a greater area than the lower, and an additional pressure is required to assist the lower piston to move the main valve downward, in order to open the lower steam port, this additional pressure is supplied by piston 23, called the reversing piston, which bears down upon the large piston of the main valve whenever steam is admitted upon top of it. To admit steam to the top of the reversing piston, the reversing slide valve 16 is moved to its lower position by the reversing rod 17, where the small steam port, leading from its chamber to the top of the reversing piston, is uncovered, and steam is admitted to the reversing cylinder. The pressure thus had on the top of the reversing piston acts downward upon the main steam valve, moves the latter down to a position uncovering the steam port to the lower end of the steam- cylinder, and at the same time opens the exhaust port at the upper end, permitting the steam to escape to the atmosphere from the upper side of the steam piston 10.

Q. The steam supplied to the reversing cyUnder is obtained from where?

A. The steam, supplied to the reversing cylinder is admitted to the reversing slide valve chamber through a small port leading from the main valve chamber and located between the ends of the main steam valve. This cylinder is, therefore, filled with steam at the same pressure as the main valve chamber.

• Q. When the piston reaches the end of the up-stroke, how is its motion reversed ?

A. As the steam piston approaches the end of its up-stroke the reversing valve rod plate engages the reversing valve rod, moving the latter, together with the reversing slide valve, upward. When the reversing slide valve is moved to the upper end of its travel it closes the steam port leading to the reversing valve cylinder and opens the exhaust port leading from the same chamber, allowing the steam on top of the reversing piston to escape to the atmosphere. When the pressure is removed from the top of the reversing piston, and from the top of the larger piston of the main steam valve, the upward pressure on the larger area of this piston will overcome the pressure exerted in the opposite direction on the smaller or lower piston of the same valve, and, in consequence the main valve will move upw^ard, uncovering the steam port leading to the upper end of the steam cylinder, and will open the exhaust port in the lower end of the same cylinder, permitting the steam to escape, and thus the movement of the steam piston will be reversed.

Q. When the steam piston is making the up and the down strokes, what action is taking place in the air cylinder of the pump?

A. As the air piston and the steam piston head are attached to the same rod, one at one end and one at the other, it follows that whenever the steam piston makes a stroke the air piston will make a stroke also. As the air piston moves upward, the lower air receiving valve 33 is raised by atmospheric pressure, and air enters the air cylinder behind the upward moving air piston. At the same time the air contained in the air cylinder, above the air piston, is being compressed and driven out through the upper discharge valve to the main reservoir. On the downward stroke the lower receiving valve closes, and the confined air is compressed and driven out through the lower air discharge valve 32 to the main reservoir, while at the same time the upper discharge valve to the main reservoir is closed, and the upper receiving valve is opened by atmospheric pressure, and air enters the upper end of the air cylinder filling all space in the air cylinder behind the downward moving piston.

Q. What are the duties of the nine and one-half inch pump ?

A. They are the same as those of the eight inch pump and are performed in nearly the same manner.

NINE AND ONE-HALF INCH AIR PUMP.

Air valve seat.

Air valve cage.

Air valve chamber cap.

One and one-fourth inch union stud.

One and one-fourth inch union nut.

One and one-fourth inch union swivel.

One inch steam pipe stud.

Governor union nut.

Stuffing box.

Stuffing box nut.

Stuffing box gland.

Air cylinder oil cup.

Short cap screw.

Long cap screw.

Upper steam cylinder gasket.

Lower steam cylinder gasket.

Upper air cylinder gasket.

Lower air cylinder gasket.

Drain cock.

Air strainer.

One-inch steam pipe sleeve.

Left main valve head gasket. •

Right main valve head gasket.

Main valve head bolt.

Cap screw.

Cylinder head plug.

Top head.

Steam cylinder.

Center piece 1 forms lower steam head and upper air head.

Air cylinder.

Lower head.

Steam piston and rod.

Air piston.

Piston packing ring.

Piston rod nut.

Reversing valve plate.

Reversing valve plate bolt.

Reversing valve rod.

Reversing valve.

Reversing valve chamber bush.

Reversing valve chamber cap.

lOI

Main valve bush.

Main piston valve.

Large main valve piston head.

Large main valve piston packing ring.

Small main valve piston head.

Small main valve piston packing ring.

Main valve stem.

Main valve stem nut.

Main slide valve.

Right main valve cylinder head.

Left main valve cylin-

1 10 der head.