Building up air with brake in emergency - HST

[diego1234]

Hi,

Could anyone quickly explain to me how before
moving an HST (or I believe any train for that matter)
that may not have been mobilised for a while and hence
sufficient air will need to be built up, why putting the train
brake into the emergency position will allow the system
to build up air. Is it the case that if you left it in step 2 after starting
it, you won't build your main res air up but rather lose it?


I'm a little confused!

Thanks in advance..

 

[156441]

Can't talk for HST's but Sprinters and Pacers do not need the brake in emergency to build up air. However (and isn't that word popular on the railway) if you activate the compressor speed up switch to speed up the engine revs in order to build air more quickly, the emergency brake will apply itself as the CSU switch is on the brake circuit 'train wire 4'. Any break in this circuit (which runs through 16 other safety systems, passcoms,doors etc) will apply the emergency brake.

As I say loco stock may be a lot different but that's the view from a unit drivers perspective.
--- old post above --- --- new post below ---
Could also be a local procedure. At Northern if with have 0 main res and 0 brake cylinder pressure we have to remain in the cab to apply the spring applied park brake should the main res start to rise but the brake cylinder pressure doesn't. (This would release the park brake from the train when the pressure reaches 1.5-1.7 bar allowing the train to roll away.)

 

[Hairy Bear]

Leaving it in emergency stops the E70 unit trying to create a brake at the front whilst the rear unit is destoying it when its at the critical pressure of the main res gov not being made due to insufficient air.The trick is to wait until at least 6.5 bar is in the main res pipe and tanks and create the brake slowly, one notch at a time.