Elvas Tower: Releasing the vacuum brake - Elvas Tower

Jump to content

  • 2 Pages +
  • 1
  • 2
  • You cannot start a new topic
  • You cannot reply to this topic

Releasing the vacuum brake Rate Topic: -----

#1 User is offline   cjakeman 

  • Vice President
  • PipPipPipPipPipPipPipPip
  • Group: ET Admin
  • Posts: 2,857
  • Joined: 03-May 11
  • Gender:Male
  • Location:Peterborough, UK
  • Simulator:Open Rails
  • Country:

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 offline   copperpen 

  • Executive Vice President
  • Group: Status: Elite Member
  • Posts: 3,139
  • Joined: 08-August 05
  • Gender:Male
  • Simulator:MSTS & OR
  • Country:

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 online   steamer_ctn 

  • Open Rails Developer
  • Group: Status: Elite Member
  • Posts: 1,879
  • Joined: 24-June 11
  • Gender:Male
  • Country:

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 

  • Vice President
  • PipPipPipPipPipPipPipPip
  • Group: ET Admin
  • Posts: 2,857
  • Joined: 03-May 11
  • Gender:Male
  • Location:Peterborough, UK
  • Simulator:Open Rails
  • Country:

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 !

#5 User is offline   cjakeman 

  • Vice President
  • PipPipPipPipPipPipPipPip
  • Group: ET Admin
  • Posts: 2,857
  • Joined: 03-May 11
  • Gender:Male
  • Location:Peterborough, UK
  • Simulator:Open Rails
  • Country:

Posted 07 February 2021 - 06:53 AM

Nearly 5 years on and I have another request regarding the same topic (this time from Stuart Kenyon).

Basically, how do I release the brakes on the coaches and get the train moving?

As we can see from the posts above, work has been done (thanks to Peter Newell) to implement vacuum brakes as used on GWR and then the Western Region of British Railways.

As it happens, I recently acquired this route myself. The instructions for starting are to release the brakes with the ; key and then to open the ejector with the J key until the vacuum gauge reaches 25 inches.

If Stuart (or me) follow these instructions, the Train Pipe vacuum gauge remains stuck at 0 ins.

Attached Image: 2021-02-07 14_51_02-Open Rails.jpg

How can I debug this issue?

#6 User is offline   darwins 

  • Superintendant
  • Group: Status: Elite Member
  • Posts: 1,222
  • Joined: 25-September 17
  • Gender:Male
  • Simulator:Open Rails
  • Country:

Posted 07 February 2021 - 08:35 AM

The most likely cause of the problem is errors in the eng file. Have you checked the OR log?

With some old MSTS loco then you might not ever be able to release the brakes in OR unless you drive using simple controls. The reason is that some MSTS eng files have a lot of brake "garbage" in them - usually a mixture of air brake and vacuum brake parameters which totally confuses OR - because it makes no sense in terms of the real life loco.


Also, not all eng files have updated instructions, many are copy and paste. If you are using a GWR loco with an OR eng file such as this one:

CTN Hall Class Loco

You should follow the instructions below.

( There is also a tutorial activity for using GWR vacuum brakes on the CTN website - CTN GWR brakes demo activity )


This is the procedure to release the brakes:

(1) Move the brake handle to the OFF position using the ; key

(2) Turn on the (large) ejector using CTRL+J

(3) When the brakes are released Turn off the (large) ejector using ALT+J - it wastes a lot of steam if you forget this.

(4) Drive off - the GWR vacuum pump will maintain the vacuum when you are moving.



You can download OR eng files for most GWR designs here - Attached File  GWRLocos.zip (382.58K)
Number of downloads: 254

You might want to compare the brake sections of those files with other GWR locos - or simply just use them for your own GWR locos.



#7 User is offline   cjakeman 

  • Vice President
  • PipPipPipPipPipPipPipPip
  • Group: ET Admin
  • Posts: 2,857
  • Joined: 03-May 11
  • Gender:Male
  • Location:Peterborough, UK
  • Simulator:Open Rails
  • Country:

Posted 08 February 2021 - 06:01 AM

Hi Darwin,

Thanks for giving me this background - just what I needed.

View Postdarwins, on 07 February 2021 - 08:35 AM, said:

The most likely cause of the problem is errors in the eng file. Have you checked the OR log?

Nothing amiss there.


View Postdarwins, on 07 February 2021 - 08:35 AM, said:

( There is also a tutorial activity for using GWR vacuum brakes on the CTN website - CTN GWR brakes demo activity )

I missed that - thanks.

OK, I'll give this a go. If I can pin it down to a simple change or addition tor the West Somerset route then I will publish it and contact Just Trains.

#8 User is offline   cjakeman 

  • Vice President
  • PipPipPipPipPipPipPipPip
  • Group: ET Admin
  • Posts: 2,857
  • Joined: 03-May 11
  • Gender:Male
  • Location:Peterborough, UK
  • Simulator:Open Rails
  • Country:

Posted 09 February 2021 - 11:00 AM

View Postcjakeman, on 08 February 2021 - 06:01 AM, said:

OK, I'll give this a go. If I can pin it down to a simple change or addition tor the West Somerset route then I will publish it and contact Just Trains.

The loco that won't pull a train is a GWR Manor class. I've examined the basic ENG file for the similar GWR Hall class published on CoalsToNewcastle and found that a replacement will get the vacuum up from 16 to 25 inHg which I read was standard for GWR.


Attached Image: 2021-02-09 18_53_11-C__data_OneDrive__tmp_wsr_manor_7828.eng - Notepad++.jpg


So the code at the top is now commented out and replaced by the highlighted code. Seems to work, but what is it doing? Also, I notice that the loco now starts with the train brake already released.

Can anyone interpret?

#9 User is offline   slipperman 

  • Foreman Of Engines
  • Group: Status: Contributing Member
  • Posts: 750
  • Joined: 09-February 12
  • Gender:Male
  • Location:North Nottinghamshire
  • Simulator:MSTS & ORTS
  • Country:

Posted 09 February 2021 - 11:58 AM

Hi Chris,
The final value in the Brake_Train line specifies the brake's initial setting.
Hence, 0 indicates 'fully released' whereas the previous version had 0.98, which is almost 'fully applied'.

Sorry, I don't know enough to explain the other settings!

Cheers,
Ged

#10 User is online   steamer_ctn 

  • Open Rails Developer
  • Group: Status: Elite Member
  • Posts: 1,879
  • Joined: 24-June 11
  • Gender:Male
  • Country:

Posted 09 February 2021 - 07:19 PM

View Postslipperman, on 09 February 2021 - 11:58 AM, said:

Sorry, I don't know enough to explain the other settings!

Have a look here.

  • 2 Pages +
  • 1
  • 2
  • You cannot start a new topic
  • You cannot reply to this topic

2 User(s) are reading this topic
0 members, 2 guests, 0 anonymous users