[Lindsayts]

The line numbers mentioned are for OR xV2252 using the unix editor vim.

[Serana]

 markus_GE, on 17 May 2014 - 04:59 AM, said:

In Austria we have been using a dual pipe braking system for quite a long time now, which allows for gradual release of the brakes.

For your information, it's not the fact that there's two brake pipes that permits the gradual release. It just allows the brakes to never run out of air since the supply pipe fills up directly the auxiliary reservoir of the wagon while, with a single pipe, the brake pipe is also used to fill the auxiliary reservoir... and since the pressure is low when you are braking, you can't charge the reservoir at the same time.

What brings a real difference is if you have a triple valve or a distributor. The triple valve can't do gradual release while the distributor can.

[markus_GE]

So, paraphrasing your post, you mean gradual release is also possible.e with single line brakes?

Cheers, Markus

[Lindsayts]

 markus_GE, on 04 June 2014 - 06:19 AM, said:

So, paraphrasing your post, you mean gradual release is also possible.e with single line brakes?

Cheers, Markus

In theory one can, in practice one can only use the air supply thats in the rolling stocks auxilary reservoir in a single pipe system and it is not very big so one can run out of brakes real quick.

Lindsay

[markus_GE]

Yeah, running out of air also is a problem with normal triple valve controlled brakes. So, are setups of single pipe with distributor valves used in practice? I know we in Austria, (and Europe mostly, for that matter) use twin pipe brakes with distributor valves.

Just out of interest: Would it also be possible to build twin pipe systems with triple valves? (Not that these would be of any practical use, I guess...)

Cheers, Markus

[Lindsayts]

Distributors have a fall back position if the for some reason the Man reservoir pipe is absent or not working it behaves as a standard triple valve. In fact Triple valves and Distributors often share the same castings, the distributor just having the extra facilties bolted on.

This is almost a universal behaviour in railway braking systems, even most EP systems have such a fall back mode. Some rolling stock, eg the Sprinter DMU's in use in Victoria Australia actual do this by having two seperate braking systems the EP system and a twin pipe setup, if the EP fails the twin pipe and distributors are working in parralel.

Yes, you could put a main reservoir pipe on a single pipe system with triple valves, the driver though I believe would still have to release the brakes completely before they could be reapplied.

Again in Victoria no steam loco's were fitted with the type 26 braking system, all worked with a single pipe setup. But since the 1950's all country pass rolling stock came fitted with a distributor based twin pipe system. This being exactly the same as used on Melbourne's suburban electric train system (note 1). So when ever a steamer hauled these country pass's (which would occur occasional up to the mid 1960's) these pass's worked as a single pipe braking system.

Note 1: In 1956 Victoria introduced what was called the Harris train sets on the suburban network. These originally were made by the Gloucester Railway Carriage and Wagon Company (later examples by Martin and King or the VR workshops). I have been told the VR used its twin pipe braking system on all subsequent country rolling stock that would run in Victoria.

Lindsay

[markus_GE]

Yes, triple valves can´t provide for gradual release, but one could immediately re-apply the brakes with a twin pipe plus triple valve setup, as I understand it.

Quite some interesting info there, :( for sharing :)

Cheers, Markus

[Lindsayts]

The first loco in Victoria, Australia to be fitted with the 26L brake was the X class DE, availible from 1966. The DE's before this had either the 40CL or 6ET, a driver has told me these two were essentially the same except for the way the brake handles were fixed. Unlike the 26L with these valves there was no way to regulate the brake line pressure during release. One simply pushing the handle to service (some docs call this position slow release) until the brake line pressure was what one wanted.

These early DE's did have two brake pipes at the coupling I have not at this stage found the function of the 2nd pipe. It is possible this is a main reservoir pipe only used to connect loco's together when multi heading. The steamers in Vic only ever had a single pipe availible.

In double heading steamers were of course always crewed so one could control the brake system from either loco, this is not the case for DE's, pipe connections being availible to connect the loco's brake systems together to allow all loco's brakes to be controled from one machine. Pipe connections availible for this being two large pipes and 4 smaller ones, it being probable of these latter only ever 2 were used in any instant.

Lindsay

[markus_GE]

And I thought I had understood the majority of things to know about the inner workings of train air brakes... :whistling:

:victory: once more :lol2:

Cheers, Markus