To All

Please be aware that the Westinghouse Air Brake Company Instruction Pamphlet No. 5032-1 June 1938 No. 8-ET Locomotive Brake equipment on pages 126 to 129 goes into a discussion of Quick application and slow application of the independent brakes. The design working pressure by Westinghouse is 45 psi. It is important to understand that the locomotive independent bakes were meant to hold a train while standing on a grade and/or overcome the potential effects of a leaking throttle which is discussed in the operating section on pages 146 to 148.

In The Southern Pacific Company Air Brake Rules and Regulations for 1944, the standard pressure for the reducing valve is 45 psi no matter the type of service the locomotive is in. Further more the instructions for enginemen and hostlers in the second rule in the books is that the “Engine brakes must be cut in at all times and operated in a manner to avoid overheating and loosening of tires or sliding of drivers and engine operated in a manner or prevent wheels sliding.” Therefore by this statement they knew in 1944 that the pressure needed to overcome the forces of a possible leaky throttle and forces created by gravity in holding a train still with the slack in or out. It was known then as now that applying full pressure of the independent will slide the wheels.

Respectfully
Robby Peartree

Curious as to their intentions for driver cut-outs when they wrote that they were not to be used, unless maybe in special circumstances like doubleheading or dead engine moves.

Driver brake cut outs bring a certain liability with them if you were involved in a grade crossing accident from the simple standpoint of could you have missed my client if you had the brakes cut in question. On Grand Canyon Railway the steam ;locomotives were equipped with them while I was there and they were helpful when doing down long grades and you needed to lightly apply additional braking force for a short distance and then needed the additional braking force to disappear. This is a different way to get the effect of a graduated release without messing with the brake pipe in increasing the reduction and then graduating part of it off. When moving GCR 18 light from the canyon in 2002, we heated up the comp brake shoes on the tender and were able to bring the locomotive down the 3% grade from Imbleau (historically known as Apex) to Anita. On the top part of the hill we cycled in and out the driver brakes to control the speed of the decent by cycling the position of the cut out and varying the independent brake pressure. With the driving bakes cut in we had ample brake pressure, so we ran low pressures but reduced the speed of the locomotive to a near stop and then cut out the Driving brakes which then the tender could not initially hold the weight so we increased the braking pressure to help heat the shoes until we reached about 15 mph and then cut the driver bakes back in to slow it down to a walking speed. This cycling gave the tires a chance to cool between brake applications and the tender comp shoes eventually got hot enough to hold back both the tender and locomotive weights.

I watched Mr. Earl Knoob come down Cumbres Pass in October 2001 with a hospital train primarily depending on the compression brake on 489. That was an interesting trip and showed the value of the water brake concept. It is interesting that the Santa Fe used the water brake idea early on Raton Pass and later went to the by pass valve.

For a point of historic curiosity, there is a picture of an early SP cab forward stopped on Donner Pass grade allowing the brakes to cool on the cars from the decent of the pass. They had to have held that train with the independent brakes or have set hand brakes to help hold it back. But then on the cars they set hand brakes the wheels would have cooled at uneven rates due to the brake shoes and would have possibly caused problems with the wheels tempering.

Robby Peartree

This is a paper from the 1903 Air Brake Association proceedings. Unfortunately the illustrations did not survive the coping. If you are interested in the paper with the illustrations or the discussion, I would suggest buying the Air Brake Association proceedings. In 2008 they put 100 years of proceedings on one disc with an index. For information contact Joseph Faust, Secretary/Treasurer of the Air Brake Association. Phone at 801-944-5270 or email: joefaust@comcast.net.

"The Combined Automatic and Straight-Air Engine and Tender Brake.

Mr. President and Gentlemen:
To uphold the motto of our Association it is not only necessary that our members and other readers of our proceedings be kept informed on the long established brake and signal apparatus; how to operate and maintain same in the best and most economical manner, but that they be given the same information on new devices as soon as such are undeniably past the experimental stage and recognized as practicable and desirable.
It is because of these facts that I have been requested to present for your consideration a paper on the Westinghouse Air Brake Company's Straight-Air Apparatus (Schedules SWA and SWB), which with the regular automatic brake parts forms the Combined Automatic and Straight-Air Engine and Tender Brake Equipment.
All who have been in touch with switching and road work are familiar with the complaints about the inadequacy of automatic for switch engines, the frequent use of the reverse lever on engines equipped, the many schemes and devices employed to apply or, at least, hold the driver brake applied when the automatic is in release and the very decided preference expressed by engineers for the straight-air, vacuum or steam brakes on the drivers and tender of switching and freight locomotives. The truth of the old maxim that "Where there is so much smoke, there must be some fire," is here again proven by the remarkable results obtained with the apparatus in question, both in switching and in freight service. It would have been valuable several years ago, but with the increased number of air brakes per train, heavier locomotives, necessity for rapid work and pressure brought to bear to decrease the damage more or less incident to switching and road work, it becomes one of the essentials. The independent brake has heretofore been condemned, and properly so, because it either eliminated or seriously interfered with the automatic, neither of which should be tolerated. This was constantly kept in mind in perfecting the device in question. with the result that the automatic remains as it was, always cut in on both driver and tender brakes and acting with the car brakes whenever the automatic brake valve is used. So, too, is the straight-air cut in at all times, it responding on the driver and tender brakes whenever the straight-air brake valve is used.
Practicability being assured, the natural and very proper question is asked, of what value is the device? The uses of the one in question are as follows:

USES OF THE STRAIGHT-AIR (SCHEDULES SWA AND SWB) FEATURE OF THE COMBINED AUTOMATIC AND STRAIGHTAIR ENGINE AND TENDER BRAKE.

1. To quicken switching and reduce the incident damage to lading and equipment.
With the straight-air brake, drawing its supply from the main reservoir (a), the holding power and possible speed of application never vary from one application to another and thus inspire and warrant confidence in what can be done. (b) So far as holding power is concerned, the release is practically instantaneous. (c) The holding power can be quickly increased a little or much and the maximum possible is not affected by piston travel, unless the full limit is reached, or any moderate cylinder leakage. (d) Where the brake power applied is more than wanted it can be reduced either slowly or quickly any desired amount. (e) Application immediately following release is never delayed, as follows from the overcharged train pipes and reduced auxiliary pressure with the automatic. (f) The driver and tender brake cylinders being connected when using straight-air, the distribution of brake power is not affected by piston travel or cylinder leakage, and there is, therefore, less liability of wheel sliding.
2. To permit of brake release on long trains without danger of slack running out suddenly and train breaking in two, otherwise so liable to occur at slow speeds.
By thus enabling the train brakes to be released with safety at low speed, it in such cases prevents the loss of time and occasional damage incident to starting a train in an unfavorable place at which the only reason for coming to a stop would be the danger of breaking in two by releasing.
3. To prevent change of grade (sags or humps) or curvature from running the slack of long trains in or out so suddenly as to cause severe shocks and train separation.
4. To slow or stop trains where the brake work required is not heavy; thus reducing pump labor, stuck brakes, wheel sliding and the breaks-in-twos incident to an endeavor to start long trains with brake shoes dragging-sometimes brakes stuck-on cars near the rear end, a not uncommon result with freight car brakes held on to the stop.
The reduction in brakes sticking is due to the fact that light applications from full pressure are, in all probability, indirectly the most common cause of stuck brakes.
A light application of all brakes on a long train gives very little return in holding power for the amount of air used. That discharged from the train pipe gives no holding power, and of the quantity it causes to be sent into the cylinders, some little is lost through the leakage grooves and much more in filling the space behind the pistons to the amount necessary to overcome the resistance of the cylinder release springs and brake rigging friction. It is the insignificance of these losses with the straight-air acting only in the two-driver and one-tender brake cylinders which results in the considerable saving in pump labor.
The absence of brake beam springs on freight cars requires some train movement to shake the shoes loose from the wheels where brakes have been held on to the stop. By rendering it safe to release the automatic at low speeds and by avoiding the use of the latter where the required brake power is moderate this dragging of brake shoes can be avoided. In preventing train separation, other less serious shocks and in saving time it is a very important factor.
5. To prevent the slack from running out and aid the car brake retaining valves in controlling the speed while recharging on heavy descending grades.
To prevent overheating of driver and tender wheels at such times the ½ inch cut-out cocks, one being connected between the double check valve and triple valve of each of the two brakes and located convenient for operation while running, should be left open. Thus, while these auxiliary reservoirs are recharged with those of the train, automatic application is prevented, and the engineer is, therefore, able to make the fullest practicable use of the driver and tender brakes. The lower maximum speeds and more thorough recharging of auxiliary reservoirs which this accomplishes increases the train safety far more than is possible with the greatest practicable use of automatic alone on these two brakes.
6. To hold the train or locomotive and keep the automatic brakes recharged when standing on grades; thus having train brakes ready for instant use at the start and increasing the safety when work requires someone to go under the engine. The application position of the straight-air brake valve renders it impossible for the driver and tender brakes 10 leak off. The latter prevents the locomotive from getting away when no one is present, even though the throttle leaks.
To many it would prove a surprising fact that, with the train standing and slack bunched, the straight-air can hold a long train on quite a heavy descending grade. In this its power is far greater than is possible with steam used for this purpose. The starting of undercharged trains, having a reduced pressure through the previous brake application and subsequent leakage, is a dangerous feature too frequently met with in heavy grade service.
7. To control speed while weighing cars. Straight-air facilitates this work and decreases rough handling.
8. To increase mileage between tire turnings and decrease the damage done to frogs and switches by badly worn tires.
9. To decrease the repairs and improve the average condition of the automatic brake valve by reducing the use of emergency position, and, in a lesser extent, of service.

DEMONSTRATED ADVANTAGES AND BENEFITS.

The foregoing are well demonstrated advantages which, more particularly on road engines, will be realized in proportion to the number of locomotives equipped, as engineers must have frequent use to become thoroughly familiar with any device, a requisite not only for developing its possibilities for good, but to avoid its abuse.
Its use requires additional parts, but with the following exception, these reduce rather than increase, the labor and expense of engine brake maintenance.
More frequent adjustment of driver and tender brake piston travel is necessary than with automatic alone, due to the increased labor these brakes perform. To offset this there is, in addition to the advantages already mentioned, less reversing, with the consequent betterment to valves and cylinders.
The double check valve and straight-air brake valve are the only additions to standard brake parts. Long service has demonstrated that these seldom require repairs. When such repairs are needed they mean only the replacement of small leather seats.
While the apparatus can, to a limited extent, be abused in use, as is true of any device of value, yet other manipulated by the engineer requires that he be given so little instruction or that he exercise as little skill and judgment to obtain satisfactory results.
In view of these advantages, it may be asked why switch engines should not be equipped with straight air alone. The reasons are that such engines may at any time be used for transferring where it is necessary to have the use of car brakes; may as helpers have to operate passenger or freight train brakes: may be called upon to move a freight train promptly where same is left in the yard with brakes' set; and when switching loaded passenger cars should use the automatic part of the time. Even this could be accomplished without triple valves and auxiliary reservoirs on the engine and tender were it not that the operation of the automatic brake valve should apply every brake, particularly in cases of emergency.
The value of a device should not be measured by what the most expert and zealous engineer can do with it, but, instead, by the results that will be obtained by engineers in general, whether on regular engines or in the pool. It is the latter that commends schedules SWA and SWB. Engineers do not purposely stick brakes, slide wheels and break trains in two. Hence, if given a device easy to understand and use, not liable to get out of order, one which does not tend toward abuse and which, in addition to reducing very materially the three serious faults first mentioned, in many other ways contributes to good service and their comfort, they will, with such incentives, make good use of it as soon as its advantages arc understood.
The benefits possible with straight air on a switcher, such as quicker work, less damage to cars and lading and elimination of reversing, are so manifest that where it leaves the automatic at all times instantly available without having to cut in or cut out any part so freight and passenger brakes can be promptly released and used, there should be no question as to its desirability, considered alone from the standpoint of whether the resultant economies will make it a good investment.
While the same benefits will be got with a freight road locomotive, yet the amount of switching work done with such is so little as to warrant questioning whether it alone would justify the additional expenditure. Let it be well understood that these and some other of the nine uses given are the incidental advantages, comparatively speaking, of its employment on freight locomotives.
In level freight service, with long freight trains nearly or fully air braked, breaking in two, brakes sticking, wheels sliding and excessive pump labor are frequent and undesirable features of this service, which it has been demonstrated the straight-air will very materially reduce. The damage to draft rigging consequent on a break-in-two is often not confined to the point of separation, but causes fractures, which later are followed by failures without severe handling, and are sure to with it.
Recharging is the critical feature of holding trains down steep grades by air brakes. This problem has to be met after standing on a grade for some time, as well as when running, unless hand brakes are used to hold the train, not to be expected for a short stop, nor always depended on for a long one. It is in these cases that the great holding power of the straight air acting on the drivers and tender is so valuable.
Mainly because of the danger of loosening driver "tires the straight air and automatic cannot both be used while descending a steep grade. Hence, the provision for rendering the automatic inoperative, as previously explained, during such time. This permits of heavy use of the driver and tender brakes while recharging the train brakes, and, as well, guards against possible shocks from slack running out suddenly when the speed has been brought low to aid in recharging. How much wheel treads will be heated by brake application depends mainly on shoe pressure, time over which it acts, and speed. The absence of automatic application on these two brakes, low speed while recharging a heavy train and comparatively short time required permit of a strong straight-air application without danger of overheating.
With slack bunched, the straight air, with the assistance rendered by the retainers, will hold a heavy train standing on a steep grade, permitting it to be thoroughly recharged and kept so. Thus, when ready to move, the maximum safety is assumed and the train can be started promptly without jerking or wheel sliding, the cylinder pressure of all cars being well reduced.

CONSTRUCTION AND OPERATION.

GENERAL ARRANGEMENT OF THE COMBINED APPARATUS.

Fig. 1 illustrates the general arrangement of the combined apparatus. Connection with the automatic is made at three points. The straight-air supply is taken from the main reservoir pipe to the automatic brake valve so as to insure dean, dry air. Before reaching the straight-air brake valve it must pass through the reducing valve, set at 45 pounds, this consisting of a standard slide valve feed valve, as used on the automatic brake valve, attached to a special pipe connection made for the purpose.
A double check valve is inserted on the tender and engine in the pipe leading from the triple to the brake cylinder or cylinders so that in automatic brake operation the pressure will have to pass through this double check valve in getting to and from the brake cylinder.
The pipe leading from the straight-air brake valve has two branches, each entering one of the double check valves at the end opposite the triple valve connection, so that in application and release the straight-air pressure will also have to flow through the double check valves.
The two side openings of the double check valve are brake cylinder connections. They are joined by a cored passageway. If convenient the safety valve may be screwed into one on the tender brake, as shown, or with the driver brake, one brake cylinder may be connected to each and the safety valve in either driver brake cylinder pipe.
Each safety valve should be adjusted to open at 53 pounds, should be in direct communication with brake cylinder pressure, whether automatic or straight air is used, and should either point up or a little above the horizontal so dirt and water cannot accumulate inside.
As the straight air should never give over 45 pounds cylinder pressure, and the automatic not over 50 pounds, a correctly adjusted safety valve will never operate except an improper condition exists, but under the latter guard against a dangerously high cylinder pressure.

Fig. 1 (missing)

The cocks C and D, with their pipes, are for locomotives operating on heavy grades. Cock C should be located adjacent to the gangway so it can be operated when running and D near the engineer's seat. In descending heavy grades both are left open. The driver and tender auxiliaries are recharged with those of the train, but automatic application is prevented on the brakes of the former, thus permitting of the greatest use practicable, without danger of loosening tires of the tender and driver brakes when recharging the train brakes, the critical operation in braking down steep grades.
A and B indicate gauge connections. A gauge for the straight air is desirable, but not absolutely necessary. When employed it should be connected so as to show brake cylinder pressure in automatic as well .1S straight-air application, such connection being indicated by B. With no permanent gauge a tee should be put in the pipe from the straight-air brake valve to the double check valves. It should be near the former so that, by taking out the quarter-inch plug in its side opening and connecting a gauge, the latter can be seen while operating the brake valve and adjusting the reducing valve.

FEED VALVE PIPE BRACKET.
Fig. 2 illustrates the special pipe bracket to which the slide valve feed valve, acting as a reducing valve for the straight air, is connected, inlet port A and outlet port 13 coming opposite the similar ports in the feed valve. The arrow lays across the dividing wall.

SPECIAL HOSE CONNECTION.

Fig. 3 illustrates the special straight-air hose connection between the engine and tender. As it differs from the automatic, a wrong coupling cannot be made. Low pressure and little movement insure long life. The union end being forward permits of cutting off back of that point, by the use of a blind gasket, in case a burst hose or bad order tender brake renders this temporarily desirable.

DOUBLE CHECK VALVE.

Fig. 4 illustrates the double check valve in section, the several connections being there indicated. Between the two seats, a and b, is a piston valve, 2612, having a leather face, 2613, on each end. The piston valve is shorter than the distance between its two seats, and the bush in which it works has two series of ports, c and c. With the piston valve against seat b, as shown, ports c afford a free passage for the air between the straight-air brake valve and the brake cylinder. The opening leading to the triple valve, which is now in release position, is closed so no leakage can occur.

Fig. 2, 3, 4, and 5 (missing)

Now, with the straight-air brake valve in release position, where it should be when not in use, assume that an automatic application is made. The air from the triple, on entering the double check valve, will force the piston valve to the right against seat a, thus preventing any escape at the straight-air brake valve and opening ports c so the air can flow on into the brake cylinder, returning the same way in release.
The double check valve must be in a horizontal position so its piston valve will not be moved except by air pressure. Then the mere act of using either automatic or straight air will cause its piston valve to automatically move to the proper position.

STRAIGHT-AIR BRAKE VALVE.

The distinctly advantageous features of the straight-air brake valve employed, illustrated by Figs. 5, 6 and 7, are: (1) The ability to "feel" when, where and how much it is opening the application and release ports; (2) its uniformity of action, there being no parts which, when dry, cause it to work hard; (3) and the long time it will run without repairs, coupled with the ease and cheapness with which such can be made when needed.
Letters cast on the body indicate respectively its main reservoir, train pipe and exhaust openings. The latter should have only a street ell to turn the discharge in the direction desired, the sound aiding the engineer in operation. The other two connections should have unions near by to facilitate replacement.
The valve should be substantially secured and so located as to be easily operated by the engineer when looking forward or back out of the side cab window, this latter being of the utmost importance in facilitating work and reducing incident damage. Where the cab permits, the best location is against the cab side at a convenient height and a trifle forward of the edge of the side window which opens. The handle should be, in this case, on the boiler side, so that in release it will be nearest the engineer, its motion in operation being parallel to the cab side.
Fig. 5 is a sectional view parallel with the shaft 2, operated by the handle 4, which opens application valve 8 or release valve 9. As indicated by b, b1 and b2, the space above admission valve 8, is connected with the one below exhaust valve 9. The leather gasket 6 makes the joint at the shaft collar.
Fig. 6 is a section across the shaft at application valve 8, showing the connection w by which main reservoir pressure, reduced to 45 pounds, reaches the lower side of valve 8 through cavity a. Fig. 7 is a similar section across the shaft at exhaust valve 9, showing the cavity b2 below this valve, the train pipe connection at X leading to the double check valves and, through them, to the brake cylinders; also, passageway c leading from above release valve 9 out through the exhaust opening to the atmosphere.

Fig. 6 and 7 (missing)

Shaft 2 is slotted out to the middle on nearly opposite sides, and valves 8 and 9 are just enough off the shaft center line that the stem of each valve will end just beneath the flanged portion of the steel tappet piece riveted into each of the shaft slots. As shown by the section of valve 9, Fig. 7, these have steel caps to reduce the wear and are fitted with leather seats.
In the three views the handle 4 is on lap position, valves 8 and 9 being held to their seats by their springs, 10 and 11, and any air pressure below them. Moving handle 4, Fig. 5, toward the reader, which is to the right in Figs. 6 and 7, unseats application valve 8 and allows main reservoir pressure to flow by it from a, pass clown from through b through b1 to b2, which brings it under release valve 9 and in communication with the pipe at X, by which it is carried to the double check valves and, through them, to the cylinders, applying the brakes. Moving handle 4 in the reverse direction and past lap position will, having earlier permitted application valve 8 to seat, open release valve 9 and release the brakes.
The following simple instructions should be observed in the use of the combined apparatus:

INSTRUCTION.

1. Always keep both brakes cut in and ready for operation unless failure of some part requires cutting out.
2. Always carry an excess pressure of 10 pounds or more in the main reservoir, as this is necessary to insure a uniformly satisfactory operation.
3. When using automatic keep the straight-air brake valve in release position, and when using straight-air keep the automatic brake valve in running position; this to avoid driver and tender brakes sticking.
4. Automatic must not be used while straight air is applied; if automatic is then wanted, first release the straight air.
5. Though the use of straight air while automatic is applied will not increase the driver and tender brake cylinder pressure above 45 pounds, yet release of either cannot be assured, while the other brake valve is on lap or application positions.
6. Bear in mind that the straight air on the driver and tender brakes is almost as powerful as the automatic brakes on same, and that each should be used with care to avoid rough handling of trains, or, in holding down a long grade, loosening of tires on drivers. When the straight air is used to aid in recharging trains in motion down steep grades the automatic should be kept inoperative by having open the one-half inch cocks shown in Fig. 1.
7. The straight-air reducing valve should be kept adjusted at 45 pounds and the driver and tender safety valves at 53 pounds. Where a full application of the straight air causes either or both safety valves to operate, it indicates too high adjustment of the reducing valve, that same is out of order, too low adjustment of safety valves or leakage at latter. Have them tested and adjusted.

CONCLUSION.

About the only trouble the beginner in its use may experience is one or both brakes sticking. If, through insufficient excess, the use of the straight air causes a reduction in train pipe pressure, the driver and tender triples will start to apply, thereby filling their pipes up to the double check valves. When straight-air release is attempted this bottled-up pressure will shift the piston valves in the double check valves, thus sticking the brakes. Causing the triples to move to release will overcome the trouble and keeping them there will avoid it as described. But if the straight-air brake valve is left on lap position when automatic is being used, any slight leakage past the piston valve of the double check valve, or the application valve of the straight-air brake valve will result in the piston valves being reversed when automatic release is attempted, thus sticking the brakes. Moving the straight-air brake valve handle to release position will remedy the trouble, and keeping it there when automatic is being used, will prevent it"

For a point of historic curiosity, there is a picture of an early SP cab forward stopped on Donner Pass grade allowing the brakes to cool on the cars from the decent of the pass. They had to have held that train with the independent brakes or have set hand brakes to help hold it back. But then on the cars they set hand brakes the wheels would have cooled at uneven rates due to the brake shoes and would have possibly caused problems with the wheels tempering.

Robby Peartree[/quote]


Rules state that such stops are to cool the wheels, not the brakes. Locations as well as the amount of time train was to reamin standing were specified in timetable special instructions for the territory in question. Rules also state that if the train cannot be held with the independent brake alone, sufficient hand brakes must be applied to hold the train. Uneven cooling of the wheels due to the handbrakes being applied on some cars to hold the train was just a chance they took.

There is also the possibility that retainers were in use on said train. Unless the stop was made at a location where the retainers were to be changed to "direct release" position, they would have held the brakes applied on all the cars while stopped, assuming the retainers had been set at "heavy Holdeing" position. Had they been set in "Slow release" position, the4y would eventually release, which would most likley agin require a few handbrakes to be set to hold the train.

Thermal cracked wheels were not an unknown phenomonon in those days. The railroad and the crews did their best to prevent them, but sometimes you have to do what you have to do.