Curious questions - Caledonian Sleeper

[Tomnick]

Thanks, that's what I thought! I've only really understood vacuum brake systems in any depth though, so didn't want to speak with too much confidence!

 

[reb0118]

Let us think of the term failsafe: in effect when something fails it defaults to the safer of the two options. With air braking you need to create air pressure to release the brakes. So if you lose air pressure what happens to the brake?

 

[Tomnick]

Initially the brakes will be applied. However, it's only the air pressure stored in a reservoir that holds the brakes on (rather than a spring) - once this has gradually leaked off, or been drained manually, the brakes will be released.

 

[Peter Mugridge]

I drew a diagram of what happens because I found my own post confusing :P

You should be able to see that there's no way of getting the Edinburgh rake (pink) at the front without either abandoning a rake or trapping the red loco between the two rakes.

One point - the loco off the Edinburgh doesn't head back to Mossend; it waits for the northbound Sleeper to arrive and then takes the Edinburgh portion of that forwards.

 

[MattRobinson]

Certainly with vacuum braked stock, you can release the brakes manually (eg, you want to move a vacuum braked wagon with an air braked loco), I'd assume the same was true with air braked stock?