Paul Synnestvedt.

Diseases of the air brake system; their causes, symptoms and cure online

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Air Brake System





The W. F Hall Pkiktixg Company









Main Drum

Engineer's Brake Valve

Train Pipe

Auxiliary Reservoir 67

Brake Cylinder 69

Triple Valve 71

Pressure Retaining Valve 86

Hose Coupling 89

Foundation Brake 91

Special Cases 99

Appendix 107


Plate Tage

2— Westinghouse S-iuch Pump S

3 and 3a— Westiughouse 9>4-inch Pump ijaud iS

4— New York Duplex Pump 20

5— Westinghouse D. 9 Governor 24

6— Westinghouse Improved Governor 26

7— New York Governor 28

7a— Mason Regulator 32

S, 9 and 10— Westinghouse Equalizing Discharge Valve 3S. 40 and 42

II, 12, 13, and 14— Westinghouse Equalizing Discharge Valve, with Feed

Valve attachment 48, 50 and 52

15 and 16— New York Engineer's Valve 55 and 56

i6a-Method of stopping Coupling Leak with nail 62

16&— Car Drain Cup stopped with dirt 62

i^—Westinghouse Quick-Action Triple Valve 72

i8_Westinghouse Quick- Action Triple Valve (perspective) 74

iSa— Freight Cylinder, Reservoirs, and Triple Valve 66

iS&— Exhibits of Strainers clogged with dirt 76

19— Westinghouse Plain Triple Valve 78

20— Westinghouse Plain Triple Valve (perspective) So

2i_New York Quick-Action Triple Valve 84

22— Pressure Retaining Valve S7

23— Hose Couplings 88

24— Tender Brake Lever Arrangement 92

25— Push-Down Driver Brake ■■ 9^

25a_ilhistrations of right and wrong position for Shoes 96

26— Outside Equalized Brake 98

27_piain Freight Triple 100

28— Equalizing Valve of iSSS '02

29-Old Style Governor ., 104

30, 31, 32 and 33— Exhibits of Defective Apparatus 108

34. 35. 36 and 37— Exhibits of Defective Apparatus no

38, 39 and 40— Exhibits of Defective Apparatus 112


In submitting the following work to the railroad public
it is proper that the author should begin with a few words
of explanation.

He does not wish, like many authors, to apologize for
what he has done, and he does not wish to belittle his own
exertions, for the preparation of the work has cost consid-
erable labor; but he does wish to ask the indulgence of
critical readers, submitting it as a truth, self-evident, that
no man's work is infallible, and acknowledging in all
humility that many air-brake doctors, some of them in
their lines more competent than he, may find fault with
many of the prescriptions that he has written.

In spite of all this, however, he is not without hope
that his work, incomplete and imperfect though it may
be, will, in a measure at least, supply a long felt want.

To those desirous of becoming good air brake "doc-
tors," he would say: Always use your reason first and
your HANDS afterward.

Treat your case just as a doctor does his patient, first
finding out the nature and cause of the disease, and then
prescribing and applj^ng the remedy-.



As long as a man's body is in perfect health, it causes
him little or no trouble. He is not conscious that he has
a brain, heart, lungs or stomach; nor has he any need to
be. They perform their allotted functions without fric-
tion or inconvenience, and all goes well until "disease"
begins to show itself. A pain appears in some particular
part. Then he must needs learn the functions of that
part, that thence he ma}- discover what interference with
those functions has caused it to rebel.

As long as the air brake system is in perfect health it
gives little or no trouble. In such a condition no thought
is given to its inner workings, and, in fact, there is no
need of such concern. As soon, however, as some "dis-
ease" appears the case assumes a different aspect. The
action of the apparatus is no longer satisfactory. The
necessity then arises of locating the seat of the disorder,
removing the cause, and thus curing the ' 'disease." This
requires study of the principle of operation of the whole,
and the particular use of each part in its relation to the
whole. As in the case of a headache from a disordered
stomach, defective action of one part may be only a
symptom of a disease in some other part, far removed as
to space but closely connected in function.

While it has been necessary in arranging the following
work, to treat of the various "diseases" under the heads

52 ^ 52 ,,„,

Pl*te 2. NVestinghousr s Inch Pump.


Diseases of the Air Brake System. 9

of the individual parts of the system, it must not there-
fore be inferred that every part is entirely distinct from
every other part. On the contrary, every part is closelj^
related to every other part in the performance of a com-
mon use, and this fact must be kept clearlj- in mind in
the treatment of all cases.


Eight'Inch Westinghouse Pump — Plate 2.

The disorders that arise in this pump may be classed
under two general heads:

1st. Trouble in the upper or steam cylinder.

2d. Trouble in the lower or air cylinder.

The parts in the upper cjdinder most liable to derange-
ment are the main-valve (7), reversing piston (23 ), revers-
ing valve (16), reversing- valve stem ( 17 ), and the revers-
ing valve plate (18).


Of the main valve (7), the packing rings (8 and 9),
become worn so as to cause quite a blow into the exhaust,
in which case they must be taken out and new ones fitted.
AY hen this is done, the bushings (25 and 26) should be
carefull}' calipered and replaced with new ones if they are
worn out of true (larger diameter in the middle than at
the ends ) .

Quite frequently the small nut on the top of the main
valve works loose and comes off, sometimes causing stop-
page of the pump. This may require renewal of the
valve-rod. The nut should be made to go on hard, and
should be riveted fast when screwed down.

10 Diseases of the Air Brake System.

If the small stop-pin (50) gets broken or worn too short,
the pump will stop because of the main-valve traveling
down so far as to allow the lower small packing ring to
expand below the bushing and catch. Although a little
thing to repair in itself, it requires considerable work and
much care. Some have done it without taking the pump
apart by forcibly pulling out the main valve, drilling out
the stub of the pin (50) and inserting a new one from
above by means of a stick with a socket in the end. This
forcible removal of the main valve will generally break
the small ring or spider, or both, and necessitate their


The reversing piston (23 ) is generally the first thing to
require attention in case the pump stops. This is due
largely to the fact that when a pump is run short of oil,
the reversing piston gets scarcely au}^ on account of its
location, the oil tending downward rather than upward.
The rings (24) when they are loose or worn so as to open
wide at the joint, should be replaced, as also the bushing,
if it is out of true or worn large in the opening through
which the rod works.

Often the rod breaks off just at the point where it joins
the piston head. This will render the pump liable to
frequent stoppage, due to the head being without a guide,
traveling so far upward as to partially close the upper
ports, or tilting over so as to catch.

Rapping the pump lightly on the top of the outer cap
will often start it by jarring the reversing piston head
down into place.

Diseases of the Air Brake System. 11

It may here be noted that a pump that requires frequent
rapping to keep it going is in need of overhauHng.


The reversing valve (16) itself does not give as much
trouble as the spindle or stem (17) which operates it. If
the valve seat becomes badly worn, a new valve should be
substituted and it should be a pretty close fit inside of the
bushing. Any disarrangement of the reversing valve or
spindle generally results in an erratic stroke of the pump,
jumping, or "jiggling," or half stroke, caused b}- its
reversing at the wrong time. The spindle should fit
snugly, both where it passes through the bushing and in
its bearing in the top cap. If badly worn in either
place, the spindle, and often the cap and bushing, also,
should be replaced with new ones. Another place verj'
liable to excessive wear is where the spindle is struck by
the reversing plate (18), and the shoulder and button on
the spindle, and both sides of the plate should be care-
fully examined, especialh' if a pump pounds badly. The
under side of the plate generally wears the most rapidly,
and must not be overlooked in making an examination.
If the reversing rod gets bent slightly it ma}^ rub against
the plate hard enough to cause the pump to reverse at the
wrong time.

Straightening the rod is of course all that is necessary
to remed}^ this. In putting the top head on after repair-
ing, the copper gasket should be examined to see that it
does not cover the small port through which steam goes
to the reversing valve cavity in the top head.

12 Diseases of the Air Brake System.


The parts in the lower or air cylinder most liable to
derangement are the air valves (30, 31, 32 and 33). If they -
become worn so as to lift too far, it will result in the
pump pounding. They must be replaced with new
ones, having the projection on top filed down just enough
to give them the right amount of lift.

Authorities differ slightly as to what this should be.
Some say about 1-16 of an inch. The discharge- valves
(30 and 32) should not have as much lift as the receiving
valves (31 and 33).

Sometimes the valve-chamber bushings (43 and 34)
become worn so badly where the valves seat that they
must be replaced.

Occasionally one of the air-valves gets broken. Any
difficulty with these valves can generally be detected by
careful examination of the suction of the air at the inlet
ports. If the air blows back at the beginning of the
stroke, the receiving- valve does not seat properly. If the
suction is very weak, either the discharge- valve is not
seating properly or else the packing rings (13) in the
main piston head are blowing. The latter difficulty,
which is very common, can be detected by taking off the
lower head and working the pump very slowly, holding a
light under the piston head.

These rings (13), as also those in the steam cylinder
(12), not infrequently require renewal.


Of course, when either the upper or lower cylinder be-
comes badly worn, it must be rebored. Putting new rings

Diseases of ihe Air Brake System. 13

into a cylinder which is unevenly worn does not do ver^y-
much good.

Another trouble that has oeen found in the lower cyl-
inder is the working loose of the nut (58; that holds the
piston-head on the rod. This will either result in stop-
ping the pump (in case the nut strikes the lower head
before the piston has traveled far enough to reverse ) or it
will cause the piston-rod to wear into the head, constantly
aggravating the difficult3^ One case came under the
writer's notice in which the rod had punched its way
entirely through the head.


In general, the various disorders of the pump of most
common occurrence are :

"Stoppage" (complete). Cannot be remedied by rap-
ping or coaxing.

"Stoppage" (temporary' or occasional). Pump can
generally be started by rapping.



"Jiggling" or "Fluttering."

Unequal stroke (fast on one stroke, slow on the other).

Fairly rapid stroke, but low effective capacity (pumps
little air) .

STOPPAGE (complete).

This may be due to the stop-pin (50) being broken
(see page 10) ; the small nut on top of the main valve being
loose (see page 9) ; the small port to the reversing- valve
chamber being obstructed (see page 11); or the nut (58)
working loose.

14 Diseases of the Air Brake System.


This ma}' be due to lack of oil in the steam valves
(especiall}' the reversing-piston 23) ; broken reversing
piston-rod (see page 10); loose nut on top of main steam-
valve (see page 9); badl}' worn packing-rings in main
steam-valve, or reversing piston ; or sometimes excessive
wear of the reversing-valve plate (18) ; (see page 11).


Pounding may be due to any one of a great variety of

It may be a pounding of the steam-valves, air-valves,
or main piston itself. Anything which will allow the
main piston to strike either cylinder-head before the pump
reverses will cause a heavy "pound." This may result
from too tightly fitted steam valves or rings, or rings too
loose, either causing sluggish motion in the reverse move-
ment; dr^-ness in the steam cylinder-valves; badly worn
reversing-valve plate or stem ; or too long a reversing-valve

A pump may also pound if the air-valves have too much
lift. This can generally be detected by a careful exami-
nation of the suction ports, to see whether the air is drawn
in properly at the very beginning of the stroke.


This most frequently results either from dirt or gum in
the discharge passages or too much clearance of the piston
in the air-cylinder. Of course, if a pump is run full speed
for a long time it is sure to heat more or less, one inevitable
consequence of compressing air being the accumulation of

Diseases of the Air Brake System. 15

heat. This is a case where a grain of prevention is worth
a pound of cure. If a pump gets very hot it must be prac-
tically stopped and allowed to cool before much can be
done to it. If notice is taken of it before it reaches what
might be called the "explosive" point, a slight reduction
in speed with a very little good valve oil in the air-cylin-
der may save further trouble.

Many have asked the writer if water should be used to
cool it.

There certainly can be no serious objection to this, pro-
vided the pump be stopped before the water is poured on,
so it will not be sucked into the cylinder. All scientific
air-compressors used in mines or similar service are
"water-jacketed," and some use a jet inside the cylinder.

A pump that has been "dosed" for some time with too
much oil in the lower cylinder is almost sure to heat, sim-
ply because the air-discharge passages become clogged
with gum.


This term is used to designate a kind of jumping or
short, catching stroke, and is almost alwaj^s due to some
trouble in the reversing-valve or stem. (See page 11).


This ma}' be said to indicate lack of oil. yet it has been
noted by man}' men that the pumps that have been get-
ting the largest quantities in the air-c3-linder are most
liable to make this noise.

This fact is hard to explain. The writer will only say
that a "groaning" pump is frequently helped by thorough
cleaning of the air cylinder and careful use of oil there-

16 Diseases of the Air Brake System.


This is generally caused by unequal lift of the air dis-
charge-valves (30 and 82). If the up stroke is slower
then the down stroke, valve (30) has less lift than valve
(32), and vice-versa.

The other causes of this trouble will be found in slug-
gish action of the steam-valves.


This trouble is always found in the air-cylinder. Either
the valves do not seat properly; the piston has too much
clearance; the rings (13) leak, or the cylinder is worn out
of true. (.See page 12).


Nine-and-a-Hxlf-Inch Westinghousk Pump.— Platk 3.


IVTaiimWi-vc &»»i ii»i^


75 !

i=^ J^ -^


^ ft

Diseases of the Air Brake System. 19

Nine=and-a=Half=Inch Westinghouse Pump —
Plates 3 and 3a.

The latest design of pump furnished b}^ the Westing-
house Company is shown in Plate 3. It has not yet been
in service long enough to enable any one to write
a very complete account of the disorders to which it is
subject, and a few remarks concerning it will be sufiicient
at present.

All the valve motion for the steam cylinder is in the top
head, so that in case of any failure to woi k properly a
new head can be substituted until the old one can be
fixed. There are a number of points in which this pump
is similar to the 8-inch pump, and in which it will be
liable to the same troubles.

It has the same arrangement of hollow^ piston-rod,
reversing stem and valve, and a similar bushing in which
this valve works, and as these parts perform practically
the same function in this pump that they do in the other,
any irregularity in their action will produce practically
the same effect. If the reversing-valve stem is too long
between the shoulder and button the pump will pound
and may not be prompt in reversing, and the same thing
will occur after the reversing-valve plate or this shoulder
or stem become badl}^ worn. If the distance between the
shoulder and button be too small, the pump will have too
much clearance and will heat in consequence.

An unequal stroke w^ill result in case the lift of the
upper and lower air-valves wears unevenly.

"Jiggling," or short imperfect stroke, will result in
case anv wear or unevenness causes a movement of the



New York Duplex Tump.— Plate 4.

Diseases of the Air Brake System. 21

reversing- valve (72) at any point other than the Hmit of
stroke, when the shoulder or button of the stem is struck
by the reversing-valve plate.

Of course, the small packing rings in the two heads of
the differential piston will wear out in course of time and
will then have to be renewed. The grooves in which they
are fitted, and the bushing in which the valve works, will
also wear so as to require renewal, but I have not heard
of any of these pumps which have been in ser\^ice long
enough yet to make such treatment necessar}'.

New York Duplex Pump — Plate 4.

The duplex pump not having been in ser^'ice as long
as the Westinghouse 8-inch pump, it is hard to find men
well encugh acquainted with it to say just what are its
weakest points. The point on which the writer found the
most complaint was a noticeable tendency to heat, espe-
cially in case of any carelessness in regulating the quality
or quantity of its oil supply. "An ounce of prevention
is worth a pound of cure, " is a saying that is even more
applicable to this pump than any of the others in avoid-
ing trouble from heat.

Of course, the main pistons and their packing rings in
this pump will wear the same as iti any pump, and after
a long period of serv^ice the cylinders will become worn
out of true and require reboring.

This state of affairs will manifest itself by a blow at the
steam exhaust or a noticeable reduction in the efficiency
of the pump without any apparent reduction in speed of
stroke. There w^ill also be an aggravation of the tend-
ency to heat, due to a part of the air being churned back

22 Diseases of the Air Brake Sys/em.

and forth by the packing rings. Let us repeat here what
was intimated before in treating of the other pumps, that
nothing will cause a pump to heat so badly as leaky
packing rings or too much clearance in the air cylinder.
If there is practically no air left in the cylinder at the end
of each stroke so an entireh^ new suppl}^ ma}- be drawn
in each time from the atmosphere, there will be little
trouble from heating.

If this pump begins to pound very badly the reversing
valves (5 and 6), stems (7 and 8), and plates (20) must
be carefully examined to see if they are worn in any part,
and new ones should be substituted if necessar}-. The
points where this wear is greatest are the shoulder and
button on the stem and the plate itself.

Diseases of the Air Brake System. 23


Before considering the disorders to which the governor
is subject, let us say a word about the use for which it
was designed. This will assist us very materially in
treating any difficult cases.

The necessity which was the mother of the invention
of the governor arose from the large number of wheels
that were flattened on many different roads as a result
of an excessive pressure in the train-pipe. This was
the primary cause. Other causes there were of less
importance; among them being the need of some device
which would prevent, as far as possible, needless w^ear
of the pump and waste of steam.

A governor is a throttle -valve for the pump, operated
automatically by the air pressure. There are many differ-
ent st^des in use, but they all operate on the same general

There is a steam-valve in one end which controls the
flow of steam to the pump, and is attached to a piston
in such a manner as to be operated by the piston in
shutting off the steam to stop the pump. The other
part of the governor is a kind of a safet^'-valve which
controls the opening from the source of air supply to the
piston which operates the steam- valve. This safety-valve
is held shut by a spring under adjustable tension, and



Plate 5. Westinghouse O..U Style Plate D 9.

Diseases of the Air Brake System. 25

when the air pressure accumulates to a sufficient degree
to open the safety-valve, the pressure which escapes
passes to the piston cavity, and forces the steam-valve
shut, stopping the pump. When the air pressure is
reduced the safety-valve closes again, and the air which
is holding the piston against the steam valve, leaks by
till the valve opens and allows the pump to start again.


The first thing to notice about a governor that is not
working properly is the air connection. Find out whether
it is made to the train-pipe, main drum, or some other
place, as this has a great deal to do with its action. It
cannot be expected that the governor will stop the pump
when the main drum has accumulated 90 pounds pressure
unless the air supply to the governor comes from the
drum, and no governor can be blamed for irregularities
in the train-pipe pressure unless it receives its supply of
air from the train-pipe.


Referring now to the governor shown in Plate 5, which
in general construction is a representative of all three
shown, let us consider which parts are most liable to
become deranged. First of all, the diaphragm valve (17),
with its co-acting parts, is the most sensitive, and should
receive the most careful attention. The accumulation
of dirt around the small seat of this valve is the only
trouble with many governors reported defective.

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