Mixing vacuum and air braked wagons, running unfitted with a brake van

[Jim]

Hi,

I was wondering if, when vac and air were running at the same time, would they've run a loose fitted train made up of both types with a van on the rear?

I was thinking perhaps a fitted head of the greatest portion then just pull the cords on the rear wagons and run them unfitted.

 

Cheers,

Jim

[Steven B]

In general the head of the train would be made up with the most numerous brake type (assuming the allocated loco could provide it!). The remainder of the train would run un-braked with a brake van on the end of the train. The exception would be for wagons that were through piped. These could be included in the fitted head but there were limitations as to the proportion of through piped wagons in the fitted head.

 

Happy modelling.

 

Steven B.

[Rivercider]

Yes both vacuum and air braked vehicles would regularly have been seen in the same train, sometimes the vacuum vehicles were also air piped, or vice-versa so with careful marshalling the train could still have run fully fitted, otherwise a brake van would be required.

 

31128 arrives at Bridgwater with a mixed vacuum/air train, two vacuum vanfits, a VEA and then some KEVs of coil, 1/5/81

 

 

Initially air braked vehicles were in the minority and while there was still an extensive vacuum braked freight network the odd air braked vehicle would probably have been formed into the unfitted portion. During the 1970s as the air braked fleet increased it was more likely for an air braked head to be formed. When the Speedlink network was being built up around 1980-82 there was still a declining vacuum braked network and for a couple of years the two networks ran in parallel.

 

edit - here is an air braked head on an otherwise unfitted train

Behind 37255 are three VDAs, then an unfitted empty coke-hop and some empty vacuum braked HTVs seen leaving Commonwealth Smelting at Hallen Marsh for Severn Tunnel Junction as 7C42, 5/2/81

 

cheers

[Jim]

Great stuff chaps!

Really useful stuff and excellent photos!

Jim

[Mark Saunders]

The marshalling of the through piped wehicles is subject to a maximum of three marshalled together and in the fitted head no disc braked vehicles should be included!

 

In a lot of cases the train would run unfitted as it would be well within the maximum load for running unfitted!

 

Mark Saunders

[D854_Tiger]

The marshalling of the through piped wehicles is subject to a maximum of three marshalled together and in the fitted head no disc braked vehicles should be included!

 

In a lot of cases the train would run unfitted as it would be well within the maximum load for running unfitted!

 

Mark Saunders

 

 

There was some kind of mathematical rule that applied to mixing braked and un-braked vehicles in the same train that somehow factored in the locomotive type, the weight of the train and the number of vehicles of either type.

 

Inevitably, the calculation went wrong one day and resulted in an accident.

 

A class 40 hauled freight from Merseyside which overran a red light on the downhill approach to Weaver Junction.

 

I don't believe anyone was badly hurt.

 

The trainload contained both whisky and caustic soda and henceforth the crash was referred to as the whisky and soda accident.

[Titan]

 

 

Inevitably, the calculation went wrong one day and resulted in an accident.

 

 

It was not exactly the calculation was done wrong, the driver was told that the train was fully fitted, when only 8 out of the twenty loaded wagons had operational brakes, the others being through piped. The driver also failed to do a running brake test which should have revealed the lack of brake power.

[AberdeenBill]

It was not exactly the calculation was done wrong, the driver was told that the train was fully fitted, when only 8 out of the twenty loaded wagons had operational brakes, the others being through piped. The driver also failed to do a running brake test which should have revealed the lack of brake power.

 

 

And here's the accident report: http://www.railwaysarchive.co.uk/eventsummary.php?eventID=229       I see that it took an incredible two-and-a-half years to investigate and publish this report, does anybody know why it too so long?

 

Thanks,

Bill

[hmrspaul]

Into the 1980s many airbraked wagons were also equipped with through vacuum pipes. The three letter code ending in B (Eg VAB & VBB for the first design on Cov AB http://PaulBartlett.zenfolio.com/brvaa/e10746ce4 ) indicates there is a vacuum pipe as well as air brake.

 

Paul

[Swindon 123]

Basic train calculation was part of the MP12 course for driver training. The basic rule was take the max weight of the wagon with the minimum brake force and add them all up so you got a weight of train and the brake force available. You then went to a brake table for the route concerned, Table F1, all routes being graded A,B,C,D, depending on gradients and the like. You then looked down the table to find the closest match, always lower than your actual load/brake force, which would give you your maximum permitted speed. If the weight of a wagon was known as well as its brake force, then that would be taken into account when calculating the train, if not the default procedure outlined above applied. A lot of wagons up until TOPS era had yellow stickers on them outlining weight and brake force details of the wagon, and that along with the wagon label, which would tell you the loaded state of the wagon, H-Heavy, M-Medium, L-Light, E-Empty, would be used to calculate train weight and brake force. If a wagon didn't have a yellow label then the working manual had tables giving basic wagon details. I have shown a couple I have from 1979.

 

 

Some wagons where not allowed to be used as part of a fitted head, covhops and Cartic 4 being two that readily come to mind, but there where more as laid out in the working manual for Rail Staff. Below are a couple of pages from the Working Manual on how to assess a train, possibly more understandable than the way I've put it, along with a table of brake types and the SLU calculator.

 

 

 

 

TOPS and the elimination of unfitted and later vac fitted wagons eliminated a lot of this calculation and the Working manual.

 

Paul J.

 

[Rivercider]

Into the 1980s many airbraked wagons were also equipped with through vacuum pipes. The three letter code ending in B (Eg VAB & VBB for the first design on Cov AB http://PaulBartlett.zenfolio.com/brvaa/e10746ce4 ) indicates there is a vacuum pipe as well as air brake.

 

Paul

I think this photo by Andy Kirkham may show a Warship hauled fully fitted vacuum braked train including one of the then new air braked vans.

The air braked van construction started in 1969 and the early vehicles had through vacuum pipes.

https://www.flickr.com/photos/52554553@N06/10420877273/in/photolist-oEJRi1-hc883o-gSRHKP-dKfDnj-dPgbd6-dPge1T

820 Grenville passes Malago Vale carriage sidings Bristol with a train of vans in 1972.

The rule for through piped vehicles in freight trains as I first remember it was a maximum of five consecutive piped vehicles,

with a minimum of two braked vehicles (piped up with brakes in working order) on the rear. This formation with two vanfits behind the cov-AB conforms to that rule.  

Later sometime after I joined TOPS in 1978 the rule was altered to be a maximum of three consecutive piped vehicles

with a minimum of three braked vehicles (piped up with brakes in working order) on the rear,

 

cheers

[Jim]

Again great stuff,

I love the working manual...Swindon123

I have used it in the past, leaving ballast sites.

It would be possible to create a "rea"l drivers slip for a model train...I don't know how the model gradients would affect the RA..!

[DY444]

And here's the accident report: http://www.railwaysarchive.co.uk/eventsummary.php?eventID=229       I see that it took an incredible two-and-a-half years to investigate and publish this report, does anybody know why it too so long?

 

Thanks,

Bill

 

There was also an accident on the SR due to a mix up about the number of vac braked and through vac piped ferry vans resulting in an underbraked formation.  Class 71 hauled train at Maidstone East iirc. 

[russ p]

I didn't know the rule was originally two fitted vehicles on the rear I thought it had always been three

[Rivercider]

I didn't know the rule was originally two fitted vehicles on the rear I thought it had always been three

My memory is a bit hazy on that point, but there was a change, probably fairly soon after I went into TOPS in 1978,

I am fairly certain the limit had been five consecutive piped vehicles.

I remember wondering what might happen if a breakaway occurred and the tail of the train was formed

of two or three loaded 80t ferry vans through piped with just a couple of vanfits behind them!

 

cheers 

 

cheers 

[Edwin_m]

My memory is a bit hazy on that point, but there was a change, probably fairly soon after I went into TOPS in 1978,

I am fairly certain the limit had been five consecutive piped vehicles.

I remember wondering what might happen if a breakaway occurred and the tail of the train was formed

of two or three loaded 80t ferry vans through piped with just a couple of vanfits behind them!

 

cheers 

 

cheers 

I presume the theory was that if the rear was underbraked it would decelerate less rapidly than the front and therefore never separate, or if it did separate they would meet again quite soon at a speed difference the buffers could cope with, without causing derailment.  Whether this would work in practice I have no idea, though I don't recall any accidents caused by re-combination of separated train portions, except one involving a non-coupled banking engine which isn't really relevant here. 

[The Stationmaster]

I didn't know the rule was originally two fitted vehicles on the rear I thought it had always been three

 

1972 General Appendix it was two, and still two after issue of the 1978 amendments.

[russ p]

1972 General Appendix it was two, and still two after issue of the 1978 amendments.

Was there an incident which made them change the rule

[101]

I remember around 1980/81 knocking the last two off one day because the second from the rear wasn't working - I remember well because there was an incident with the stop blocks!. I would think it changed to 3 around 83/84 (but I'm guessing really!)

[The Stationmaster]

Was there an incident which made them change the rule

 

I can't recall one offhand Russ although there were several instances of breakaways on fully fitted freights in the late 1970s/early '80s (only a handful, but they happened) and it might be that one of them prompted a change?

[Chameleon]

I remember working a ballast/spoil train on a pway job many years ago (I was still only a second man) the first wagons behind or loco (37) was airbrakes, the whole rest of the train was vacuum. Great bit of planning there! We were allowed to run most of the way to Reston unfitted as it was downhill all the way. But we had to stop to get a class 26 on the track drain up our rear to give us a push. About this time, we had smoke pouring out our rear cab so we had to kill the 37. I swear that Wee class 26 had flamescoming out its arse pushi g us up the hill!

We ended up with two 26s, a dead 37 and a pair of 47s all at Reston that night.

 

I loved those jobs.

[joseph_locke]

I remember working a ballast/spoil train on a pway job many years ago (I was still only a second man) the first wagons behind or loco (37) was airbrakes, the whole rest of the train was vacuum. Great bit of planning there! We were allowed to run most of the way to Reston unfitted as it was downhill all the way. But we had to stop to get a class 26 on the track drain up our rear to give us a push. About this time, we had smoke pouring out our rear cab so we had to kill the 37. I swear that Wee class 26 had flamescoming out its arse pushi g us up the hill!

We ended up with two 26s, a dead 37 and a pair of 47s all at Reston that night.

 

I loved those jobs.

Having spent many years planning engineering train consists, the ratbag of engineering vehicles we had available had examples of every possible combination of brake fittings for vac / air including dual piped, vac piped / air brake and vacuum only,  though majority were vacuum brake / air pipe. Many is the time that we'd crack the puzzle going to site, only to realise we then had to reverse the train to take it away. I was always taught that three braked on the tail was the minimum, including any points along the train where it had to be split. This sometimes required the marshalling of un-used vehicles or surplus plough / brakes on the back!

 

As to smoking locos - spoil train arrives, usual apology of a 31 with 40-odd minerals on the hook. train is duly loaded and second loco arrives on the other end to take it away. Lack of concise communication follows, leading to both locos hooked up. The second (downhill) driver then lets the brakes off and opens the regulator, at which point the first (uphill) driver is jerked awake, sees the train brakes are off and opens his brake valve. The pumps on the second loco still manage to release well over half the train so it moves off (downhill). First driver soils self (as is now moving "backwards", albeit slowly) and opens attempts new record for turns on the loco handbrake. End result - some SERIOUS wheelburns and a happy Monday night shift changing rails ...