Elvas Tower: Releasing the vacuum brake - Elvas Tower

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Releasing the vacuum brake

#1 User is offline   cjakeman 

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Posted 15 March 2016 - 10:50 AM

I'm posting on behalf of Roger Malyn who wants to report an issue which affects vacuum-braked steam locos in the UK.

Roger writes:
The brakes on GWR locomotives and come to that nearly all UK steam engines were held off by a vacuum in the brake cylinder and it was usually 25 inches of mercury. Whilst the locomotive was in motion a vacuum pump attached to a steam cylinder cross-head maintained it, on GWR locos this is visible above the motion bracket on the right hand side of outside cylindered locos. Obviously the vacuum is broken when a loco is brought to a stop and to regain it when starting off an ejector was opened to ‘suck’ the air out of the brake pipes until the 25 inches were regained. Once the engine was in motion the vacuum pump took over and the ejector was closed to save steam.

In MSTS with the West Somerset Railway route from Just Trains, the "J" key opens the ejector and without this function the brakes will not release and the loco will not move. The locomotive in the above route was a Manor class loco but I understand the GWR 4300 or 7300 which are very similar and free to download.

Can anyone advise Roger or is this functionality which Open Rails is missing?

Thanks,

#2 User is online   copperpen 

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Posted 15 March 2016 - 01:52 PM

OR currently does not model ejectors, however, I have no trouble in driving vac equipped engines. They appear to be working in a similar way to airbraked engines with the exception that you cannot set and hold a vac level. The problem is that without the ejectors, brakes take forever to release. With a working ejector you can set the brakes, slow down and then hit the large ejector to release the brakes again almost instantly. If a vacuum system is correctly modelled for a steam loco there will also be a small ejector ( vacuum pump ) working while the engine is running that takes care of leaky brake pipes. Diesels that were vac fitted also had ejectors but those were mechanically operated.

There is however a requirement in OR to ensure that all vac stock is properly set up in all eng and wag files. Quite a few use airbrake settings that will not work with vac settings in an eng file.

#3 User is offline   steamer_ctn 

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Posted 15 March 2016 - 01:58 PM

Hi Chris,

I think that this blueprint requests the functionality that you have identified. Does this appear to align with the request?

I think that the "J" key is still free.

#4 User is offline   cjakeman 

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Posted 16 March 2016 - 10:58 AM

View Poststeamer_ctn, on 15 March 2016 - 01:58 PM, said:

I think that this blueprint requests the functionality that you have identified. Does this appear to align with the request?

I think that the "J" key is still free.

Certainly does. Thanks for finding that and I've added a link at Launchpad back to this thread too.

Now we need someone to take it on !

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