Steam & Excursion > Question about Big Boy's brakes. . . .

Just what is the reason that "Big Boy's" brakes will not be functional for the trip back to Cheyenne?

Isn't the basic brakes system fairly simple -- just consisting of an air cylinder and brake pads? I realize that there are some pneumatic reservoirs and valves involved -- but that apparatus has to be about the most common mechanical device you can find on a railroad, since every freight car and passenger car has to have a functioning set.

So why hasn't it been feasible to make "Big Boy's" brakes functional?

Narniaman Wrote:
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> Just what is the reason that "Big Boy's" brakes
> will not be functional for the trip back to
> Cheyenne?
>
> Isn't the basic brakes system fairly simple --
> just consisting of an air cylinder and brake pads?
> I realize that there are some pneumatic reservoirs
> and valves involved -- but that apparatus has to
> be about the most common mechanical device you can
> find on a railroad, since every freight car and
> passenger car has to have a functioning set.
>
> So why hasn't it been feasible to make "Big Boy's"
> brakes functional?

If I remember correctly, the number one drive wheel assembly must be removed from each engine, in order to access/remove the main brake cylinders. Thus, without inspected/overhauled/tested, the main brake cylinders can not be functional.

A "dead" diesel-electric locomotive can be moved two ways re air brakes:

1) The "dead" unit can be "MU'd" conventionally with the brake pipe hoses connected AND the MU air hoses connected, so that the "working" units' air compressors can charge the "dead" unit's main reservoirs with compressed air, and the brakes on the "dead" unit should function just like the other units'. In other words, an automatic brake application can be "bailed off" (released) by the engineer, etc.

2) The "dead" unit can be set up in "box car mode" in which its brakes respond like a freight car, in other words, brake pipe reduction causes brakes to apply and brake pipe rise causes brakes to release. This is how a diesel-electric unit moved "in train" instead of coupling "in consist" would be moved and set up.

The Big Boy doesn't have any MU air hoses, for one thing, because it was never intended to operate "multiple unit", so there is no way to bail off an automatic application. I suspect UP has an FRA waiver for this movement with UPP 4014's air brakes cut out and non-functioning, just like a wrecked unit in a hospital train. With is also why additional brakes in the form of cars are on hand.

contactpatch Wrote:
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I suspect UP has an FRA
> waiver for this movement with UPP 4014's air
> brakes cut out and non-functioning, just like a
> wrecked unit in a hospital train. With is also why
> additional brakes in the form of cars are on hand.


That is also what the very long, big red hose is for, i.e. by-pass the brake pipe around 4014 in the train consist.

I just was reading here or on another site that steam engines did not use the brakes on the loco while pulling a train. The only time the steam engine would use its brakes was while running Light. I think it was in reference to the 3751 as the example.

Normal practice with a steam locomotive pulling a train is to make a brake application with the automatic (train) brake, then bail off the independent brake, which releases the driver brakes. As I understand it, this is for two reasons, the engine is heavy and has more braking power and would tend to cause slack to run in if the brakes are applied for more than a brief application and secondly, to prevent overheating of the driver tires.

Michael Allen

trainrider47 Wrote:
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> Normal practice with a steam locomotive pulling a
> train is to make a brake application with the
> automatic (train) brake, then bail off the
> independent brake, which releases the driver
> brakes. As I understand it, this is for two
> reasons, the engine is heavy and has more braking
> power and would tend to cause slack to run in if
> the brakes are applied for more than a brief
> application and secondly, to prevent overheating
> of the driver tires.
>
> Michael Allen

Same procedure applies to diesels and electrics today.

I watched 4014 crew repair at least 1 brake cylinder on a bench. I believe part or all of the engine brakes operate. A compressor is placed in the tender.

Thanks for the info. . . which raises another question or two.

Back "in the day", (or now, for that matter). . . .when two steam locomotives double-headed. . . which locomotive controlled the brakes for the train? How about when there was a steam locomotive pusher at the end of the train. . . .was it connected to the train air system?

Thanks!!

Narniaman Wrote:
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> when two steam locomotives double-headed. . .
> which locomotive controlled the brakes for the
> train? How about when there was a steam locomotive
> pusher at the end of the train. . . .was it
> connected to the train air system?

The generic answer is that, when there is more than one locomotive with a brake stand in a train, any one of the locomotives can be set as being in control, with the other brake stands being cut out.

Usually the locomotive in the lead controls the brakes, because that engineer has the most visibility. But there are exceptions.

In 1992, we had a photo special with 3 C&TS 2-8-2s (two up front, one at the rear) on a freight that stopped to take water at Cresco. As the train approached the water tank, the lead (front helper) engineer controlled the brakes. While his fireman took water, control of the brakes were passed to the second (road) engine, who then spotted his own tender for water. Control was transferred to the pusher, and that engineer spotted his engine under the spout. Finally, control was given back to the lead engine, and the train departed.



Edited 1 time(s). Last edit at 04/18/14 11:29 by johnacraft.

johnacraft Wrote:
-------------------------------------------------------
> Narniaman Wrote:
> --------------------------------------------------
> -----
> > when two steam locomotives double-headed. . .
> > which locomotive controlled the brakes for the
> > train? How about when there was a steam
> locomotive
> > pusher at the end of the train. . . .was it
> > connected to the train air system?
>
> The generic answer is that, when there is more
> than one locomotive with a brake stand in a train,
> any one of the locomotives can be set as being in
> control, with the other brake stands being cut
> out.
>
> Usually the locomotive in the lead controls the
> brakes, because that engineer has the most
> visibility. But there are exceptions.
>
> In 1992, we had a photo special with 3 C&TS 2-8-2s
> (two up front, one at the rear) on a freight that
> stopped to take water at Cresco. As the train
> approached the water tank, the lead (front helper)
> engineer controlled the brakes. While his fireman
> took water, control of the brakes were passed to
> the second (road) engine, who then spotted his own
> tender for water. Control was transferred to the
> pusher, and that engineer spotted his engine under
> the spout. Finally, control was given back to the
> lead engine, and the train departed.

So. . . in your three locomotive train, when the brakes were applied. . . did the air line also set the brakes on the trailing locomotives?

4014 also has a lot of braking available with the trailing truck and tender brakes. Will any of that be working ?

Posted from Android

ddg Wrote:
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> 4014 also has a lot of braking available with the
> trailing truck and tender brakes. Will any of that
> be working ?
>
> Posted from Android

there is no reason to have any brakes working on the hulk. all of the air equipment is decades past due for COT&S. if it works at all (doubtful), what's the point, anyway?

Narniaman Wrote:
-------------------------------------------------------
> So. . . in your three locomotive train, when the
> brakes were applied. . . did the air line also set
> the brakes on the trailing locomotives?

As someone said earlier, if a steam locomotive is on a train, standard practice is for the engineer to keep the driver brakes from applying by 'bailing off' the independent brake.

Maybe Realist or Hot Water can offer a tutorial on the interaction between the train brake and the independent - that's above my pay grade.

John Craft... nice description of how it works for a 3 engine train.

Pretty simple, actually. The engineer of the lead locomotive has control of the automatic (train) brakes. Setting any train brake also applies a proportionate amount of independent (engine and tender) brakes on all locomotives. The lead engineer and all trailing engineers must "bail off" this independent brake application. If they don't, there will be a severe run-in of slack because the independent will apply quicker than the brakes on the cars.

When the run-in occurs, it will slam the engine(s) ahead, which can easily cause a broken coupler knuckle or pull out a drawbar. This will be on top of the vicious slam forward that everyone on the train will feel when it happens. Lot of fun if you are working with sharp knives in the diner when it happens, not to mention spilled coffee and people being slammed to the floor.

RE: Pay grade..

I'll take a stab at a SIMPLIFIED explanation --this is not verbatim from an Air Brake text!

The control valve for the locomotive brakes has two sources of controlling the brake cylinder pressure: The automatic operation of the conventional "triple-valve" for brake application and release, as controlled by the train-line air pressure AND the Independent Brake Valve for separately controlling the loco brakes ONLY.
There are modifications to the 'automatic portion' of the control valve to de-sensitize it to minute changes in brake pipe pressure during normal "service" stops.

The 'old' name for the control valve is the "distributing valve" -- I may fumble and use the term interchangeably...

The other way to apply and release the brakes is by using the 'smaller' engineer's brake handle --the independent handle.

Because this valve DIRECTLY pressurizes the braking system, old timers refer to it as the 'straight-air' brake handle.

[The so-called "automatic brake" INVERSELY controls the pressure in the brake cylinders ---- if BP pressure is reduced, the brake cylinder pressure increases!!!
The 'automatic' feature derives from the fact that any break in the train-lined (pressurized) system causes ALL the brakes on both portions of the train (either side of the break) to Suddenly and MASSIVELY slam compressed air into all the cars' brake cylinders (from each car's "Auxiliary Resevoir"); this quick activity is called an "Emergency" application.

Engineers also can place the automatic brake valve handle in the Emergency position. There are TWO different sizes of air ports, and control mechanisms, that crews refer to as the "little hole" and the "BIG HOLE" --- suddenly applying the brakes in this fashion, from the cab, is called "putting her in the Big Hole!"]

The two controlling pressure sources are separated by a shuttle-valve, called a double-check valve.

The independent brake valve is fed compressed air (Main Reservoir), at a reduced pressure (typically set for 45 PSI), applying 'reference pressure' to a 'relay valve'.
The relay valve supplies massive amounts of air to directly feed the all the brake cylinders with pressure --- up to 45 PSI on the piston face.
Are you with me, so far?

The 'automatic' function applies the brakes every time the BP air pressure is reduced..... the engineers typically send a 'release' signal [to let the air out of the the relay valve], thus releasing the applied loco and tender's brakes. That is achieved by depressing the small handle of the independent brake [at the engineer's left knee] in the engine cab. There is a spring loaded 'push button' under the independent's handle that sends high pressure air --- to command the relay valves to fully open & release.

[Note: on diesel MU air hoses, this 'release-command' air MU air hose is called: the "Actuating" airline -- it "Actuates" the release function of all trailing (MU'd) units].

Some engineer's used a wedge shaped device to keep the Release, 'push-button', depressed and thus, sending an air signal to keep the relay valve from pressurizing the cylinders ---at all times. He removes the wedge when intending to operate the braking function.

So, you have the relay valve that pressurizes the brake cylinder and it is fed to two sources, and released at any time by depressing the independent brake valve handle.
The two brake valves in the cab also function in their 'normal ways' of changing the brake pipe pressure by moving the handles to the right (to apply the brakes) and to the left to send a 'release' command to the relay valves --- which releases and exhausts the brake cylinders and dropping the shoes away from the driver tires.

Under braking pressures, the driver tires warm up dramatically, and become loose on the drivers' wheel centers ----too loose and they flop around and CAN cause a derailment.
It takes VERY LITTLE heat to warm them up!! SO keeping them released over the road is VERY important!

Now, you are ready to crack open your WABCO #6ET loco Airbrakes instruction book!
HA!

Wes C.

It all sounds familiar. When I took Engineer's promotion on the Santa Fe, we had to write out the flow of air through the #6 in every position, word for word, even though engines so equipped were just about all gone, or upgraded by that time. We still had a bunch of power with the 24's, and the rest were all equipped with 26's by that time. But they wanted us to write it for the #6, word for word.

You move this little valve over, the air goes round and round oh ho ho ho and the train slows down.



Edited 1 time(s). Last edit at 04/19/14 09:59 by Frisco1522.

Putting a wedge or plug in the independent to keep it bailed is against all manner of rules, and should be. Anybody too lazy to bail when needed should get another job.

Non-believers usually get converted very quickly by having a break-in-two right behind the power, or between units. He'll think the plug will prevent flattening the wheels or will forget about it completely until most or all of his air has gone out through the valve. When that happens, he'll have nothing left but the hand brakes on the units to stop with.

Seen it happen more than once. Usually followed by engineer throwing the plug as hard and as far as he can.