European Railroad Discussion > Brake question

As a retired Canadian Locomotive Engineer (driver) , wondering about railway operations in Europe.  Is there still a "guards van" on the rear of freight trains, if not is there anything equivalent to what we have here in North America on the rear of a train SBU (sense braking unit) rear end device,  that indicates brake pipe continuity, brake pressure or vacuum and can the Driver put the train into emergency from the lead locomotive via the SBU on the rear???  Also if vacuum brakes are still used, does the train go into emergency if the brake pipe is separated?  I've always been curious how the vacuum brake system works and if it is still in use.  Doug

No guards van, no ted, a painted red-white disc, in Germany rectangular, in Austria a circle only. Often they do not change the disc on boarder, so you find both discs in both countries. Passenger have 2 red lights integrated in the rear of the car bodies, switched on when the train is assembled, not switched by the engineer.

No pics because it is a point of honor making pics from coming trains not from leaving ones. Now i see i must change my mind.

brake pipe in continuity is indicated by pressure loss.

Emergency brake occurs when brake line is separated.

Vacuum brake not in use except some narrow gauge lines.

I am not a locomotive engineer but that is what i know.

Erwin from Austria


 

Thanks for your reply. I would assume that in your country air brakes are used rather than vacuum brake. I wonder if that air brake is used on freight (goods) trains throughout Europe and Great Britain. Odd that there is no "Fred" on the last car indicating air pressure and movement on the tail end car such as we have in North America.  Doug

I am wondering if the shorter train lengths in Europe might be a factor in not requiring an "end-of-train" device ...

 

Will MacKenzie
Dundas, ON

thehighwayman Wrote:
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> I am wondering if the shorter train lengths in
> Europe might be a factor in not requiring an
> "end-of-train" device ...
>
it is.
And i forgot to say that high speed passenger trains are equipped with electric-pneumatic brake lines so all cars release air immediately and brake effect is in all cars without delay.

Erwin

hoggerdoug Wrote:
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> Thanks for your reply. I would assume that in your
> country air brakes are used rather than vacuum
> brake. I wonder if that air brake is used on
> freight (goods) trains throughout Europe and Great
> Britain. Odd that there is no "Fred" on the last
> car indicating air pressure and movement on the
> tail end car such as we have in North America. 
> Doug

Air Braked is standard for all UIC registered freight rolling stock. There might be some vacuum braked stock somewhere in MOW service,  but not likely.

spandfecerwin Wrote:
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> No guards van, no ted, a painted red-white disc,
> in Germany rectangular, in Austria a circle only.
> Often they do not change the disc on boarder, so
> you find both discs in both countries. Passenger
> have 2 red lights integrated in the rear of the
> car bodies, switched on when the train is
> assembled, not switched by the engineer.

Erwin, thanks for the summayry.

Actually, Germany used to use both signals: The round tail disk on a dead-in-consist locomotive and the rectangular one on a train (even if the trailing car is a dead-in-consist locomotive, like in my third picture below). Right now only the squared tail disk is still in use in Germany.

Attached are tree pictures showing the disks and their usage. Sorry, no real train from my side as well ....

E111
 

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I was just riding a bunch of the meter gauge line in the mountains of Switzerland. The those trains have a two brake pipe system. One is the train line as we know it and the other is the resevoir charging line. I'm not an engineer either but I was speaking with a local rr employee whose English is excellent and that is his explaination.   Jeff Pape

You will find vacuum brakes day to day service in some parts of the world, and on preserved operations in the UK. The auto vacuum brake is very simple, to apply the brakes you release the vacuum. In steam locomotive days the vacuum brake used less power than the Westinghouse air brake, hence it's popularity, royalties weren't paid either, which was also popularp! Some British railway companies, particularly those with frequent stops and starts were enthusiastic adopters of the Westinghouse brake - the London Brighton and South Coast for instance. 

Here is a southbound intermodal train rear car passing through Carnforth, England, a few mile north of Lancaster on the West Coast Main Line in early May.
I have no information on the device, just giving the others a visual to refer to.

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The DB Class 120 electric loco is one of my favorite locos.  Thanks for showing!

Your questions about air brake line continuity and SBUs (or "FREDs") have been answered, but I think I can add something about vacuum brakes. These were quite popular in steam days because the trainline vacuum was developed by a steam-operated device called an "ejector", which uses steam blowing through one or more "cones" (tapered orifices) to pull air out of the train pipe, thus developing negative pressure, also known as a vacuum (actually just a partial vacuum; most railroads used a vacuum level somewhere between 18 and 22 inches, or 454 to 562 mm, of mercury). The ejector has no continuously-moving parts, just a valve to control the amount of steam admitted, so maintenance is minimal, although it does consume a fair amount of power in the form of steam. Still, the ejector is simpler, smaller, lighter and less expensive than an air compressor.

This advantage of the vacuum brake disappears when electric or diesel locomotives are used, because then some form of pump (reciprocating or rotary) is required to generate the vacuum; these vacuum exhausters are very similar to air compressors (in fact, the WABCO and Gardner-Denver machines I am most familiar with are basically air compressors with the intake and exhaust manifolds switched so that air is pumped out of the system instead of into it), and so cost about the same to buy and maintain.

For the cars, the vacuum brake has the advantage of not needing a control (triple) valve, because the brake cylinder does this job on its own. Most  vacuum brake cylinders are vertical; they have upper and lower chambers, separated by a piston with a sealing ring or diaphragm that seals in both directions, and by a ball check valve that allows air to flow out of the upper chamber, but not into it.. So, when in "Release" position, the ejector sucks air out of the train pipe and therefore out of both chambers of all the brake cylinders; when vacuum levels (negative pressures) are about equal in both chambers, the weight of the piston makes it drop to the bottom of the brake cylinder, thus releasing the brake. To apply the brake, the ejector handle cuts off the steam supply and opens the train pipe to atmosphere, allowing outside air to flow into the train pipe and from there into the lower chamber of each brake cylinder; but the check valves on the cylinders block air from entering the upper chamber, so the upper chamber vacuum "sucks" the piston upwards, pulling on the piston rod and the brake rigging to apply the car brakes; all quite simple and, with small cars and short trains, quite effective. The main problem is that the maximum effective pressure available is 1 Atmosphere, or 14.7 psi; that is, only one-third to one-tenth of the pressure range available with compressed-air brakes. So air flow is slow because of the lower pressure "head", and as cars grow in size, the brake cylinders get very large, heavy and unmanageable (Indian Railways' 80-Ton ore cars required two 24"-diameter vacuum brake cylinders, where a single 10" air brake cylinder would do the same job); and this very large volume of air has to all be pulled out through a single 2" train pipe, making for very slow applications and releases. In practice, these limitations restrict train length to about 1600 feet (500 meters), or about 35 eight-wheel cars -- which was acceptable in steam days, but is not very efficient when diesel or electric traction is available.

In the late 19th century, and into the early 20th., the vacuum brake was widely used in Britain, Ireland, Austria, Spain, Portugal, Argentina, Uruguay, Paraguay most British and French colonial territories, and many European narrow-gauge lines (and likely a number of places I'm forgetting right now -- remember, I'm an old geezer!); but most of these have either converted to air brakes or the lines have been shut down. In some countries, the vacuum brake is still used on passenger trains, but heavy-duty freight services now use the air brake.

Hope this helps a bit.

Roger Lewis (airbrakegeezer)    

airbrakegeezer Wrote:
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> In the late 19th century, and into the early
> 20th., the vacuum brake was widely used in
> Britain, Ireland, Austria, Spain, Portugal,
> Argentina, Uruguay, Paraguay most British and
> French colonial territories, and many European
> narrow-gauge lines (and likely a number of places
> I'm forgetting right now -- remember, I'm an old
> geezer!); but most of these have either converted
> to air brakes or the lines have been shut down. In
> some countries, the vacuum brake is still used on
> passenger trains, but heavy-duty freight
> services now use the air brake.

South Africa still has a lot of vacuum brake freight service and about as much air brake freight service. Freight trains are diagrammed for one or the other. Drivers must have a separate (higher) qualification for air brake trains.

TAW

Actually an interesting discussion. I have always wondered why the two brake hoses, and how that system works. I've also always wondered why there is no FRED type unit on the rear of freights myself, but they have been that way since the first time I've seen European trains, and maybe the shorter train length does indeed account for it not being needed.

In regard to the square disc markers shown above, I believe the Swiss use the same. But the Italians, as far as I know, use two flashing red lights mounted on the last car to show the end of the train - based on watching many YouTube videos. It has always made me wonder that the others feel safe operating with no light up markers on the rear of the train at night, but apparently it is not a problem or issue.

Twin pipe brake systems are more suited to frequent applications and quick release, both are characteristics of much European operation. One pipe is jsut to maintain pressure in the auxilairy reservoirs, the other is used for control purposes.

I cannot recall seing any trains, passenger or freight, without some form of red light after dark, often stroboscopic. Am I right in thinking that the various plain discs and plates are only for daytime use? I suspect the need for a "smart" ETD is much reduced in Europe by the shorter train lengths, with many fewer air pipe connections and couplings, and the two pipe system which is inherently less vulnerable.



Edited 2 time(s). Last edit at 05/27/15 04:42 by spflow.