If you take a look at NKP 765, what's that I see in there but a 26 brake valve.
https://tinyurl.com/y4fzvr9g
It didn't come from the factory that way!
gregcwhat are "AB" brakes?
https://ebs.co.uk/history-of-air-braking.aspx
(scroll down). This was standardized in American practice in the early 1930s and, as noted, the current ABDX (and the convertible ECP version) are just improvements on it.
i can understand that steam locomotive brakes could be retrofitted
considering that the Reading T1 was one of the last steams engine designs, does anyone know what model brakes it has?
greg - Philadelphia & Reading / Reading
gregci'm being told the brake equipment described in the Western Pacific note: 26, 24RL, 14EL and 6BL, may only have been used on diesel locomotives, not steam. is this correct?
These brakes were introduced at particular times, and have some features -- independent braking strongly among these! -- that mattered far more to MUed consists than single or doubleheaded steam. As I recall, 24NL was a late-'50s and '60s thing, and FNL a '60s thing, so of course not installed on road steam. On the other hand these were meant to be compatible with 'units' using 6-ET control valves (see the 24-NL Altamont Press discussion) and at least theoretically that could be a steam locomotive with that style of valve...
For those of you who are 'clueless' about 14-ET, it was a variant of 6-ET intended for lighter diesel-electric locomotives. Interested people can read about it here:
https://heritagerailalliance.wildapricot.org/resources/Documents/AIR-BRAKE-WABCO-5046-13-14EL-BRAKE-EQUIPMENT-DIESEL-ELECTRIC.pdf
If you have the money you can install 26-L or later brake valves on steam locomotives, and as I recall many have done exactly that. The modern version of independent control works just fine on big locomotives.
trying to determine a timeframe for various brake equipment.
what are "AB" brakes?
i'm being told the brake equipment described in the Western Pacific note: 26, 24RL, 14EL and 6BL, may only have been used on diesel locomotives, not steam. is this correct?
OvermodI think the only real way to get meaningful numbers, rather than ranges, for a particular steam locomotive is going to be to model the physical layout of the brake gear on that locomotive ...
gmpullmanI used to run an engine equipped with #6 ET brakes. It responded as quickly as the air pressure could build up against the brake pistons (3 in this case) to about 45 pounds. Probably twenty to twenty-five seconds. Half that time in Quick Apply.
It responded as quickly as the air pressure could build up against the brake pistons (3 in this case) to about 45 pounds. Probably twenty to twenty-five seconds. Half that time in Quick Apply.
this is what i'm looking for -- ~20 seconds to reach max pressure (45 psi) - thanks Ed
I think the only real way to get meaningful numbers, rather than ranges, for a particular steam locomotive is going to be to model the physical layout of the brake gear on that locomotive -- the lengths and characteristics of the piping, the size of the cylinders, the type of the foundation beams and rigging -- and then working from the MRP and the orifices in the physical valve figure out how long it takes to various ranges of shoe pressure.
This will be essential for the 'slow application and release' as these are obviously jiggered to be far outside the response time of the equipment on the locomotive. So you'll take the mass flow through the 'slow' orifice and figure out how long it takes for the particular gear to apply effectively, or release effectively, and you'll need to know more than just pressure or flow at the valve to do that.
I am not an expert on 6-ET (or 24NL/FNL) but from what I know, railroads didn't tinker with the 'factory' slow orifice to fine-tune it for particular services, although that would be technically possible between some limits. In a model or 'simulated' world you could just gin up a time delay to full application, and another one for effective slow release, and just imagineer the appropriate "orifice dimensions" that would produce that effect at the brakeshoes.
OvermodThe point being, as Big Jim pointed out, that Greg's actual question involved understanding of current independent operation.
acutually trying to understand the behavior of older equipment which we presumably have the correct manual for and a live engine to evaluate. expecting to extrapolate this understanding to other steam locomotives
various manuals (e.g. Western Pacific) describe operation but not performance. they don't provide any flow rates (cu.ft./min) for any brake line pressure or difference in pressure between main reservoir and brake line. I assume the flow rates differ on different locomotives, but i would expect the time to affect a change in braking % to be similar
since i'm trying to model this kind of behavior in a throttle, i'd like to know those flow rates or how long the brake needs to be in a particular position to achieve some % of max brake application
my understanding of independent brakes is a brake valve directly controls (no triple valve) air flow into and out of the brake cylinders on the engine and tender to increase/decrease brake force. my understanding is it takes time to increase/decrease the pressure in the cylinders.
whether there are two distinct steps, slow and quick, or a continuous range is not important. but i would like to know what the min/maximum rates or times are
as an example, using current flow values our model slows a 1 car passenger train from 10 mph to 0 mph (green) in ~30 with brakes set to SVC for 5 secs resulting in 22% braking (orange) before setting the brake to LAP. this is for air brakes (brake line PSI in cyan). yes it would take longer for a longer train to achieve the same % braking
gmpullmanThe OP's questions originally were regarding a 1946 Victorian operating manual.
Then we got into the whole 'where did this come from?' discussion -- in which, remember, I was participating fairly enthusiastically -- and we tracked down that it was in fact a variant of 6-ET, and the discussion on older independent brakes was off to the races.
The point being, as Big Jim pointed out, that Greg's actual question involved understanding of current independent operation. Which is nothing like 6-ET. And we all confused him by haring off on an (admittedly splendidly documented!) exploration of systems obsolescent since the Sixties.
Don't feel bad for contributing. I certainly don't. But in retrospect it was (as Uncle Butch pointed out in a different thread) a mistake to fill the thread with posts and posts worth of something that actually had Greg looking in a very wrong direction for very mistaken understanding.
OvermodYour post promptly got buried in data downloads of 6ET (and nerd-style digressions about differences between 8 and 6 pedestals, which further confused the matter).
Sorry.
The OP's questions originally were regarding a 1946 Victorian operating manual.
I hesitated even replying to this thread, now I remember why.
Ed
BigJimDidn't I say that in my first post...hmmm?
Your post promptly got buried in data downloads of 6ET (and nerd-style digressions about differences between 8 and 6 pedestals, which further confused the matter). At this point you might as well recap what you said to establish it free of any discussion of 6ET, FNL conversion to 24-series, or whatever might make poor Greg even more confused than I think he still is.
The modern independent brake is stepless, progressive, and self-lapping; it does not need metered 'slow' and 'fast' application and release speeds, or a dedicated center position. The bailoff control while present "on" the lever is unambiguously separate in action from moving the lever to select braking range.
In my opinion, this is (and always has been) superior to the older method of controlling an independent brake, similarity of operation to Westinghouse one-pipe brakes be damned.
Note that while I could bring in a discussion of the 'transition era' of brakes from 6ET through 24NL to 24FNL, I haven't even mentioned the idea until now -- and am as promptly dropping it. There are threads elsewhere on the Web that cover this in sometimes loving detail. But it does NOT belong in a thread asking about current independent-brake operation with improper starting assumptions.
Didn't I say that in my first post...hmmm?
.
Most of our engines (GP-whatevers), if you slap the handle from release to full on, maybe a second to get max pressure? Then another second or two for the slack to run in and knock your coffee off the control stand. I never timed it. Widebodies may be a little longer?
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
zugmann Overmod Zug or other real railroaders can tell you how long it takes for a control-valve change to be reflected in 'shoes biting' or measurable braking-effort change.
Overmod Zug or other real railroaders can tell you how long it takes for a control-valve change to be reflected in 'shoes biting' or measurable braking-effort change.
OvermodZug or other real railroaders can tell you how long it takes for a control-valve change to be reflected in 'shoes biting' or measurable braking-effort change.
Depends on the locomotives, hwo fast you are going, how good the brake shoes are, how they are adjusted, the weight you are trying to stop, grade, how slippery the rail is, and probably a few more I'm forgetting.
Before we go round and round too much more, here is a link containing how familiar and reasonably modern 26-L independent brakes are controlled (p.15):
http://www.tcrc320.org/MEMBERS/2006_LET_complete_Workbook.pdf
Oh joy! I don't need to post any long complicated technical stuff that drives some posters nuts. Here is technical information on 26-L from NYAB (don't bother reading if this stuff doesn't interest you):
http://www.nyab.com/media/nyab_1/documents_1/technical/instructionpamphletsip/ip_074.pdf
Zug or other real railroaders can tell you how long it takes for a control-valve change to be reflected in 'shoes biting' or measurable braking-effort change.
There's a rule that when you start bailing off the independent, you wait at least 1 second for each MUed unit in the consist. (You see this mentioned in a number of contexts.) This is not the same thing as the 'release speed' I think you want.
I have operated this system on old electric engines.
gmpullmanI used to run an engine equipped with #6 ET brakes. The independent was as simple as simple can be. It responded as quickly as the air pressure could build up against the brake pistons (3 in this case) to about 45 pounds. Probably twenty to twenty-five seconds. Half that time in Quick Apply. I don't recall having to use quick application very often.
yes, the green books says A-6-ET
~20 seconds, that's helpful
thanks
I can't quickly find a photo for conslusive proof Ed, but I'm 99.7% that those pedestals would be found on the Ka and Ja steam locomotives locomotives that were still in operation in the late 60s, early 70s.
Cheers, the Bear.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
Thank you, Bear. I'll show you MY pedestal (Yours looks like a No. 8, mine's only a No. 6)
6_ET-pedestal by Edmund, on Flickr
The one I'm familiar with wasn't pedestal mounted, though. It was a 1918, USRA locomotive.
Cheers, Ed
OvermodJust for the record, I think the "Westinghouse" referred to here is the British Westinghouse Ltd.,
I believe that the brake system that Greg is referring to is the A-6-ET, introduced in 1908, and is American as apple pie!
https://en.wikipedia.org/wiki/Railway_air_brake#/media/File:Westinghouse_Air_Brake_piping_diagram.jpg
There is a figure of brake-valve handle positions, in my 1944 copy of the NZGR Air Brake Handbook, similar to the one Ed posted.
the Bear.
I used to run an engine equipped with #6 ET brakes. The independent was as simple as simple can be. It responded as quickly as the air pressure could build up against the brake pistons (3 in this case) to about 45 pounds. Probably twenty to twenty-five seconds. Half that time in Quick Apply. I don't recall having to use quick application very often.
gregcfor example, would quick-application take 5 seconds to go from 0 to 100% braking?
100% braking will just get you flat spots in most cases and probably won't get you stopped any sooner.
6_ET by Edmund, on Flickr
The positions between running and release were spring loaded to return the handle to the running position. Likewise the position between Slow Application and Quick Application was spring loaded to return the handle to Slow Application.
I hardly ever recall using the lap position, maybe a little if you wanted to hold a light application but there was seldom a need to. The independent was primarily used when the engine was running light OR to keep the engine brakes bailed off (there was no bail-off on the automatic) while applying the train (automatic) brakes.
Overheated driver tires were frowned upon.
6_ET_0001 by Edmund, on Flickr
Good Luck, Ed
Just for the record, I think the "Westinghouse" referred to here is the British Westinghouse Ltd., which was run by Metropolitan-Vickers after 1919. It may bear little resemblance to anything the Westinghouse company here offered by 1946.
I can see how desire for foolish consistency might want the locomotive brake to work 'the same' as locomotive-and-train brake -- and how a slow-speed position either side of 'lap' would be a fine answer to having to build a proportional setup.
"my understanding is ithere are 5 independent brake settings: quick-release, slow-release, lap, slow-application and quick-application."
Maybe on steam engines, and early diesels and electric-powered switchers, but not on any engines I ever ran (starting in 1979, and some of them were switch engines dating back to the late 1940's).**
On engines from the late 40's onward, the independent brake had (from left to right)
- release (you could also remove the handle in this position)
- application zone (cylinder pressure increases as handle moved to right)
- full application (handle couldn't be moved any further)
... and that's all. No "lap" at all.
In addition, depressing the handle (at any position) was the "bail off" feature, and would either partially or fully release the engine brakes regardless of the automatic brake application.
** I was on an old New York Central S2 electric once at Croton, dating back to the original NYC electrification of around 1904 (or 06?), and I believe it had an older-style independent with a "lap" position.
Greg,If you are speaking of a U.S. loco, forget all of that crap that you posted in your first post. It does not apply here.
"does that really mean you have 100% braking immediately in the first unit or a single switching loco?"Yes! On a single unit, you will feel every move you make, from full release to full application and everywhere in between, with the independent brake valve as soon as you make it. It is when you add more units with their brakes cut in that you feel the response time slow down.
"The brake application across multiple units is faster than might be expected, since the independent brake includes air relays. Applying the air in the lead loco doesn;t have the same delay if it were actually supplying pressure to the 4th unit back in the cosist "
rrinker,Well, that is a bit confusing! The independent brake is controlled by the lead unit (usually). The lead unit sends an air signal to the control valve of every unit in the consist. That signal has a maximum air pressure of 60 psi. That is why you can have multiple unit operation. That "signal" is then translated by the locomotive control valve, of which there are many types and each operate the brake cylinder at a different pressure. But this is not the point.
The point is, that the "signal" from the controling unit has to pass to each unit that the independent brake is cut in on. Consquently, the more units, the longer it takes to fill the "Apply & Release" trainline in order for the brakes to apply and release.
Just try switching with six units with their independent brake cut in. It takes what seems like forever (although it is really not that long) for the brakes to apply and release. A crew doing the same job with only one unit could out switch you so fast that it would make your head spin! Just because the indendent brake doesn't have to supply valuable signal air to trailing locomotives.
Randy StahlI suspect this is not an MU system.
rrinker If you gently press the brake pedal in a car, you get a gently increasing braking action. The car stops - eventually. If you nail it hard, you get a rapidly increasing braking force. The car stops, pretty quickly. With only two levels of air introduction into the system, you have just those two options - gently add more, or rapidly add more.
you seem to be suggesting that application-slow or quick are two pressures applied to the brake cylinder instead of the "rate" the brake pressure increases.
application-slow will increase the brake % until it reaches 100%. it takes less time with application-quick. you can stop increasing the brake % by moving to LAP
did you look at the link to 26L Brake Equipment in my previous post
BigJim Greg, Where do you come up with this oddball stuff? Now, to answer your question about independent brake response times...the response time is directly proportional to the number of diesel units in the consist that are mu'ed with the "A&R" hose cut in. In other words, the response time of a single unit is immediate, that of five units cut in takes much longer. That is because the air signal between units must travel and fill a much longer air line.
Greg,
Where do you come up with this oddball stuff?
Now, to answer your question about independent brake response times...the response time is directly proportional to the number of diesel units in the consist that are mu'ed with the "A&R" hose cut in.
In other words, the response time of a single unit is immediate, that of five units cut in takes much longer. That is because the air signal between units must travel and fill a much longer air line.
I suspect this is not an MU system.
I have operated brake like this on old electric railway equipment. My guess is it was meant for running trains without an effective trainline.