EQ braking locos deployment and other questions

[D7666]

Were there any loco diagrams, or individual freight trains, specified to be worked by vacuum braked locos with EQ (equalisation) brakes ?

I seem to recall LMR 25s (and 40s ?) based at Buxton for Peak Forest - Northwich hoppers were supposed to be EQ but this a vague memory and I'm not sure of it - and even less certain why it would be.

I believe no dual braked loco was EQ fitted. Was this a technical reason with the braking system ? Or space ? Or weight ? Or cost ? Or simply no traffic use for such a machine ?

Lastly, when did EQ brake fitting of locos commence ? AFAIK nothing was built new ex-factory with EQ, they were all retro fitments.

--
Nick

 

[D7666]

I am stunned by the silence

I was expecting at least one nonsense reply or non-understanding the original question or someone starting a drift

But no reply at all is unusual

--
Nick

 

[feliner]

i think the EQ brake was fitted from when the locos were built,it used to work fine on passenger services to Liverpool st, etc, when i was a second man at Cambridge in the early 80s.

 

[D7666]

i think the EQ brake was fitted from when the locos were built,it used to work fine on passenger services to Liverpool st, etc, when i was a second man at Cambridge in the early 80s.

Definitely none of the pilot batches, of any class, or late 1950s or early 1960s diesel batches again of any class, were built new with EQ.

It might be that the mid 1960s batches of 20s and 25s etc were new with EQ, but I believe not, for the simple reason that you'd then find whole ranges of numbers in the D8128 and D7598 upwards series all with EQ, and that is not the case .... unless depots swapped EQ around between locos.

In turn if they swapped that suggests specific traffic needs, so returns to the original question.

D400s were dual braked from new, as were some of the very last delivered D7600s, but in turn that also returns to one of the original questions.

--
Nick

 

[theblackwatch]

Apologies for being a bit 'thick' here, but what was the difference between Equalisation Brakes and normal Vacuum Brakes?

Checking my copy of 'SHED 78', I agree that judging by the identities of 'EQ' fitted locos, it would seem unlikely any were fitted from new, given that they do not appear to have been fitted in batches numerically.

 

[David Barrett]

EQ was really vacuum brake's last stand and was Gresham and Craven's answer to the ever present problem of too rapid a reduction in vacuum train pipe levels during braking leading to uneven application along the length of a loose coupled freight train. If air was admitted to the train pipe too rapidly (by the driver at the front of the train) then the actual brake application would be characterised by the rear of the train significantly lagging the front and hence a pair shockwaves would be created as each wagon buffer contacted the next, one at the front of the train progressively moving towards the rear and one from the rear moving forwards which could result in an upward thrust towards the centre of the train where the two waves met and a consequent derailment.

As with all systems at the time there were two braking rates: goods and passenger, and in the former the rate of application was slower than with the latter. In the EQ system this was achieved by significantly slowing the rate of train pipe vacuum reduction, but leading to a more EQual fall in vacuum throughout the length of the train, by a system of chokes to the extent that, for a full application, it took around 30 seconds for the vacuum to be reduced to the required level.

It seemed to be effective enough but some drivers were not happy about the degree of control which was taken out of their hands, in comparison with the judgement that had to be exercised with the products of Westinghouse and Davies and Metcalfe then in use, and the slow overall rate of application. For release the chokes were by-passed by the provision of an electromagnetically activated valve controlled from a push button in the cab and I'll leave it to you to muse over the pros and cons of this as opposed to a sprung loaded position on the actual brake handle.

Probably a good idea technically, and most certianly a serious attempt to correct an ever present danger in the face of increasing train lengths, loadings and speeds, but really too late with the imminent adoption train air braking and the gradual phasing out of vacuum systems from the mid 1960s onwards and, as it transpired, came to be G & C's. last attempt to hold off the inevitable.

There was no need for vacuum EQ provision in dual braked locomotives as the brake application rates (air/vac.-pass./goods) were controlled by the choked reduction in air train pipe pressures on the locomotive, even in vacuum as in either mode the air train pipe on the locomotive was the governing medium; i.e. on air braked trains the locomotive air brake pipe was coupled directly to the train air brake pipe and in vacuum the same air brake pipe governed the level of vacuum in the vacuum train pipe through the Air Vacuum Relay Valve on dual fitted locomotives.

I recall no specific workings for which EQ fitted locomotives were diagrammed although that is not to say that this wasn't the case or that there was not any particular working for which a locomotive so provided was not preferable although, from my recollection, it was just another method of control which could be universally applied throughout the system.

I hope that this helps, D7666; I must have missed your original posting, the date of which corresponded with the death of my hard drive.

 

[theblackwatch]

Many thanks for the comprehensive explanation.

 

[David Barrett]

Many thanks for the comprehensive explanation.

I've tried to be as thorough as possible but am relying on memories of a distant apprenticeship and sessions in the C.M.& E.E. training school at Doncaster where Messrs Rowett and Taylor attempted to hammer home such matters to teenage minds often concentrated on other things than the posterior regions of railway rolling stock. I came across EQ brakes reasonably frequently in the 1970s but, if I recall correctly, the last time I climbed aboard a locomotive so fitted was around 1985. I would hope that there might be someone out there to add to this but, by the early 1990s, those of us who had any vacuum brake experience at all were, at some locations, becoming rare indeed.

 

[D7666]

Hi Dave

Thanks for the post.

There was no need for vacuum EQ provision in dual braked locomotives as the brake application rates (air/vac.-pass./goods) were controlled by the choked reduction in air train pipe pressures on the locomotive, even in vacuum as in either mode the air train pipe on the locomotive was the governing medium; i.e. on air braked trains the locomotive air brake pipe was coupled directly to the train air brake pipe and in vacuum the same air brake pipe governed the level of vacuum in the vacuum train pipe through the Air Vacuum Relay Valve on dual fitted locomotives.

I'd kind of figured this out for myself, and more or less convinced myself it was the case.

But before asking the general question here and other forums, I asked drivers I know who had worked vacuum braked trains, passenger and freight, if dual brake locos nulled the need for EQ - - and they all answered vacuum train braking on dual braked loco behaved as conventional vacuum not EQ vacuum.

At this point I became confused on what I thought I had clarified for myself.

I am not a driver and was looking at these things from an engineering point of view and from brake system schematics, inckuding those in drivers training manuals. As a generic system, EQ braking can be thought of as having a vac/vac translator and a dual brake loco on a vac train as an air/vac translator, and their effect would be the same. From that view, I see saw no need for EQ on a DB loco, it would behave as EQ by default, yet drivers contradict this.

I recall no specific workings for which EQ fitted locomotives were diagrammed although that is not to say that this wasn't the case or that there was not any particular working for which a locomotive so provided was not preferable although, from my recollection, it was just another method of control which could be universally applied throughout the system.

I asked the same questions on WNXX, knowing that not all readers read all forums.

I had one answer which is easiest to simply paste :

LMR 25s and some 40s as used on the Tunstead to Northwich ICI hoppers were fitted with EQ brakes to enable the ratio of braking given by the locomotive and the vacuum-braked wagons to be altered. Before EQ the locomotives would take more of the braking force than the wagons leading to increased brake-block change-overs by BR and shifted tyres. Whereas with EQ the wagons took more of the braking force and thus the locomotive brake-blocks lasted longer especially on the long downhill run from Dove Holes to Cheadle Heath where the train had to be braked almost continuously.


That does at least explain I was not imagining things about Peak Forest 25s / 40s workings.

And thanks for the answers, it is a pretty obscure subject.

It is one of those details trainspotters loved to talk about this or that loco being EQ fitted or not simply because (some) spotting books said so, yet they had not a clue what it meant.


--
Nick

 

[David Barrett]

Hi Dave

Thanks for the post.





But before asking the general question here and other forums, I asked drivers I know who had worked vacuum braked trains, passenger and freight, if dual brake locos nulled the need for EQ - - and they all answered vacuum train braking on dual braked loco behaved as conventional vacuum not EQ vacuum.


LMR 25s and some 40s as used on the Tunstead to Northwich ICI hoppers were fitted with EQ brakes to enable the ratio of braking given by the locomotive and the vacuum-braked wagons to be altered. Before EQ the locomotives would take more of the braking force than the wagons leading to increased brake-block change-overs by BR and shifted tyres. Whereas with EQ the wagons took more of the braking force and thus the locomotive brake-blocks lasted longer especially on the long downhill run from Dove Holes to Cheadle Heath where the train had to be braked almost continuously.


--
Nick

Firstly the control of the air train pipe and vacuum train pipe was entirely in the hands of the driver as you rightly point out in the case of the systems then in use, with the exception of the EQ system that is, so it would have been incumbent upon him to allow for the front/rear lag in brake pipe fall although with auto. air/vac equipment there was at least a notched initial position on the driver's brake valve which was intended to give a very slight application throughout the train to ensure that all slack was taken out of the rigging and the blocks lightly applied to all wheels.

I also understand the points made in red as, if my recollections are correct, the actual locomotive brake cylinder goods application timings were indeed very gradual in EQ which would indeed be kinder to the wheelsets and blocks on whatever was pulling, or trying to check, the train although in all cases the locomotive brake cylinder application timings were substantially slower in goods than was the case in pass. I will see if I can dig out my 1974 Maintenance Instructions and have a look at timing variations.

I also have a dim recollection of the proportionality being altered on a few auto air/vac. braked locomotives at some point in time but beyond this I could not comment further.

Your comments re. spotters and technical information ring true; I experienced this at first hand when I found that things were not always simple and clear cut early on during my apprenticeship. I still cringe at some of the conversations taking place overheard whilst out and about on the system even now.

 

[Bill EWS]

They were rubbish and most driver's hated them. I was glad they didn't become more in use. Except in an emergency if you pplied the vaccum brake at a steady rate the vaccum brake worked well. Most of the probems were when/if you applied too much and too fast in the initial stage then found you had to use fast release to ese the brake force you would get uneven braking and most likely bumbing. you would have a smooth and steady braking. Having to concentrate on getting the two needles to equalise with the EQ brake took your attention away from your braking.

 

[D7666]

I also have a dim recollection of the proportionality being altered on a few auto air/vac. braked locomotives at some point in time

Yes.

About ten or so Class 20s I believe, also for Peak Forest work, when they moved in to replace 25s.

I remember this well. There was a railtour (F&W/Pathfinder?) that included a private depot visit (i.e. not open day) to Toton.

Me being nosey read notice boards as well as noting numbers . I found a list of 20s with some sort of brake mod. I passed the numbers to Neil Webster who collected stuff like this. Initially he did not use it. Then several weeks later panic phone call from him as some 20s were being reclassified (to 20/3? - the first time round, not the 20/3 we have today) and he wanted to be first out with a list, but had lost my list. The final list matched well.

--
Nick