Air Braking Systems

Can anyone advise me"Is there a standard Air Brake System in use on NG Railways in the UK"

I have been investigating some systems, and whilst they appear to be similar, they are not identical, which leads to compatability problems with visiting locos etc.
Would it be an idea to try to come up with a compatible system |?

There does not seem to be any opinion on the size of air piping, control valves etc

Is there anyone in the know who can advise

 

Hi
Sorry don't know your name, only your alias!
Fundamentally there are three basic systems in use: single pipe, twin pipe conventional and twin pipe with spring brake (automotive chambers). The latter two are automatic as the control air is used to hold the brakes off and when the air pressure is allowed to drop in the control line the barkes are applied. This can be as a service brake applicationm or separation of the train in an 'incident'. The supply pipe feeds a reservoir and tence to the elay valve which is controled by the (surprise, surprise!) control air line.
Fundamentally the second type is identical to that which is used on Standard gauge main line twin air systems.
The spring chamber system has the advantage of using readily available automotive components including the brake relay valve (RE6) and usually Type 16 chambers.
Yes you are correct that the systems are not usually compatible.
I am not aware that piping (i.e swept air volume) is an issue and most proprietary systems use 10mm plastic or copper pipe and run at about 100psi. The plastic is very easy to use as the range of reliable push fit fittings is large and easily available.
I have even (recently) seen a steamer plumbed with plastic pipe!!
What is your application?

Chris P

 

The CME of the GVLR, Eddie Draper has written this...

/www.gvlr.org.uk/tech_info/air_brakes.html


First tried out, and still working after 26 plus years at the LCLR ( 24 or so idle),

It may be a useful starting point.

Regards

Peter

 

Contact either the Leighton Buzzard or Talallyn Railways as they set a stand up must be ten+ years ago

Colin Rainsbury

 

Deciding on type of air system depends on your use: most railways now seem to be going for twin pipe (with or without spring return). The advantage is that for lines with a lot of gradients such as Talyllyn they can maintain pressure in the coach reservoirs with the supply pipe despite repeated applications, whereas the single pipe system would cause them to lose reservoir pressure as there would not be enough time for them to be recharged.
Generally the working pressures on all systems (1 and 2 pipe) are about 5-7 Bar, same as on HGVs. as they use the same components. You could run higher pressures if greater brake force was needed but all the systems i've seen tend to stick to this.
AFAIK HMRI are insisting that all new braking systems are air (not sure if they want 1 or 2 pipe) but I don't think they have set any standards. You certainly don't want vacuum as that tends to use a load more fuel/steam!
The only other thought would be if you are likely to have visiting locos: the mods for a single pipe loco visiting a two pipe railway are not too difficult but might look a bit odd while there is little problem running a two pipe loco on a single pipe railway. The only issue would be operating pressures, but again these could be adjusted quite easily.

S.

 

Er... Just to comment that the TR is single pipe air; own design (in turn a modification of a Nigel Bowman design) steam compressors using triple valves (ex-Melbourne Suburban electrics and LPTB) rather than distributors. Brake actuators are commercial HGV parts.

Test stand still in situ at Pendre the other week when I trundled through the shed enroute for a brew.

 

Single pipe Westinghouse is used on the Hayling Seaside Railway. Air pumps on the diesels are an off the self item (so that they can be replaced as soon as one fails), and are run off the crankshaft. On our Ruston LBT 'Edwin' 7002/0967/5 an electric motor to run the pump was tried, but it failed on its' first run, so a piece of aluminium was turned up to fit on the fly wheel to run the pump off the crankshaft. Small bore copper pipe is use (about 8mm ish from memory), with larger steel pipe on the outside of locos and carriages for the mounting of the hoses (off slam door stock) to mount to.

With the low speeds of the trains (7.5mph) and the brakes on the locos sufficient to stop the train, the air brake are mainly use to hold the train in the platform when running round and for emergencies.

For the visit of [thread=22767]'Emmet'[/thread] a twin pipe fitted loco, the two air lines where swapped over and the air regulator turned down to match the working pressure on the coaches. Our own hoses were also fitted to match the coaches.

 

The Moseley Railway Trust has just brought the full passenger railway into use. Included in this were some extremely stringent testing of the passenger fleet & our twin-line airbrake system.

This is a refined version of the twin line systems used elsewhere - we have been particularly careful to be as discrete as possible with the installation on the locos/carriages (this is partly dirven by our museum aims). When not in use, you would be hard-pushed to see the system/connectors!

Why not come to Apedale (this coming weeking/Gala is good!) & see the UK's newest 2' gauge passenger railway in operation in all its glory! http://www.mrt.org.uk Yes - a blatent plug.

 

I see what you mean from this photo on your website. But hanging the air hoses over the diesel's headlight was a bit of a give-away.

The connectors on the steam loco are very subtle too - a really clever idea.

Richard

 

Those push fit connectors are what, 1/4" BSP? My concern would be that in an emergency application it would take longer for the air pressure to drop in the brake line and thus longer for the brakes to apply due to the restriction. Of course, also depends on the length of the train.
http://whr.fotopic.net/p66077978.html shows Gelert at the WHR with larger pipework and palm connectors on a single pipe system. The air pump is a converted Weir boiler feed pump.

S

 

Thanks Richard - we can remove the hanging airhoses on special occasions (eg. hauling frieght trains)!! ;-)

All vehicle internal piping is in 1/4" - the hoses are approx 3/8" & connectors are the well proven/expensive Rectus fittings @ 3/8" - 1/2". Thus the hoses/connectors should provide no restriction to the system. The larger the diameter of the pipes, the larger the volume of air that you need to supply for the whole system & putting more load on the compressors. The only penalty paid by using smaller pipes, is the length of time it takes to fully charge the system/tanks from empty. In normal use this is not a problem, as the vehicle tanks are replenished easily after each application - it is mostly based on standard commercial vehicle components.

All vehicles/confgurations have just completed a long period of in depth detailed testing of application timings/deceleration, all have been found to be well within the latest requirements.

I hope this helps.
G