Brake vans - why?

[driverd]

Hello all,

Just one of those questions that popped into my head today - may seem quite a simple one, so I'll provide some context.

On mk1/2 rakes it was the norm to see a brake vehicle, be it BSO/BG etc. I understood these vehicles essentially had a handbrake to prevent the stock rolling during uncoupling etc. However, these are notably absent from mk3/4 rakes.

It's my understanding that, should the main res be dumped on even these older carriages, the brakes would automatically apply on that vehicle (albeit a parking brake, but a brake none the less). So simply, why even bother with the handbrake? Why not just mrpic the leading vehicle and dump the air before uncoupling? Or an even simpler solution, just use one/a few parking brakes (assuming rolling stock has a parking brake application cock)?

Secondly, I presume this is the method used in depots when marshaling vehicles, is this correct? If not, how are mk3s secured (I'm reasonably confident I've seen them without wheel chocks, and there must be a way to secure during shunting)?

It also interested me that handbrakes were a feature of 1st gen DMUs - is this something to do with vacuum brakes as opposed to air?

Any enlightenment much appreciated - its something I've often wondered but never found a satisfactory explanation for.

 

[hexagon789]

Hello all,

Just one of those questions that popped into my head today - may seem quite a simple one, so I'll provide some context.

On mk1/2 rakes it was the norm to see a brake vehicle, be it BSO/BG etc. I understood these vehicles essentially had a handbrake to prevent the stock rolling during uncoupling etc. However, these are notably absent from mk3/4 rakes.

It's my understanding that, should the main res be dumped on even these older carriages, the brakes would automatically apply on that vehicle (albeit a parking brake, but a brake none the less). So simply, why even bother with the handbrake? Why not just mrpic the leading vehicle and dump the air before uncoupling? Or an even simpler solution, just use one/a few parking brakes (assuming rolling stock has a parking brake application cock)?

Secondly, I presume this is the method used in depots when marshaling vehicles, is this correct? If not, how are mk3s secured (I'm reasonably confident I've seen them without wheel chocks, and there must be a way to secure during shunting)?

It also interested me that handbrakes were a feature of 1st gen DMUs - is this something to do with vacuum brakes as opposed to air?

Any enlightenment much appreciated - its something I've often wondered but never found a satisfactory explanation for.

Because of leaks. Left standing for a while the brakes will leak off and therefore a handbrake is required to hold to train stationary when it's parked up. Look up Lac Mégantic for what happens when the brakes naturally leak off on a parked train and where the air compressor is disabled by the engine being turned off due to a fire and insufficient handbrakes are set to hold said train.

Mk3s do have brake vehicles - there are the 3 BFO plus the DVTs (in earlier years a Mk1 BG would usually be used instead) and Mk4s have DVTs as well. A DVT performs the function of a brake vehicle in this case and on HST sets the power cars did originally and later the TGS.

 

[Supercoss]

Mark 4 sets ran with DVTs which acted as brake van and had handbrake and Mark 3 stock ran with 110 mph rated "BG" brake vans prior to introduction of Mark 3 Driying Van Trailers . Coaching stock usually maintained in sets Depot shunting using wheel scotches to secure detached individual vehicles of simply coupling them to something that is handbrake fitted
Back in the day a single mark 3 sleeper coach ran away at Willesden when the loco ran round an empty stock wolverton to old oak common move left unsecured during run round , it went a fair way passing a level crossing and ending up round near Kensington Olympia
don"t forget those nice mark 3 bfo 17173 to 17175 built for intercity Pullman sets now in use on night sleeper sets .

 

[43096]

A DVT performs the function of a brake vehicle in this case and on HST sets the power cars did originally and later the TGS.

TGS vehicles are not brake vehicles.

 

[43096]

don"t forget those nice mark 3 bfo 17173 to 17175 built for intercity Pullman sets now in use on night sleeper sets .

The Mark 3 BFOs were ordered for the electric HST. When the power cars for that were cancelled they found another use for them.

 

[driverd]

Because of leaks. Left standing for a while the brakes will leak off and therefore a handbrake is required to hold to train stationary when it's parked up. Look up Lac Mégantic for what happens when the brakes naturally leak off on a parked train and where the air compressor is disabled by the engine being turned off due to a fire and insufficient handbrakes are set to hold said train.

So is there no parking brake on stock?

I've only ever worked with MU stock (built from 1980ish onward), where you get "air released, spring applied" parking brakes. Ie; when air pressure drops below 2.5 bar the parking brakes apply - to prevent exactly this type of incident.

Just surprises me that stock wouldn't have something like this - seems an easier solution than having to use a very specific vehicle on each train.

 

[DanNCL]

So is there no parking brake on stock?

I've only ever worked with MU stock (built from 1980ish onward), where you get "air released, spring applied" parking brakes. Ie; when air pressure drops below 2.5 bar the parking brakes apply - to prevent exactly this type of incident.

Just surprises me that stock wouldn't have something like this - seems an easier solution than having to use a very specific vehicle on each train.

Not on many passenger hauled stock in the UK. As mentioned above with the Mark 3s the only ones with handbrakes are the three BFOs and the DVTs. With the Mark 4s it’s just the DVTs. With the sleeper Mark 5s it’s just the seated carriages. The Mark 3s are the only ones it’s ever really posed an issue with, as the Mark 4s only ever run with DVTs and the sleeper Mark 5s always run with at least one seated coach.

For the Mark 1s and Mark 2s a brake vehicle (such as a BSO, BFO or BG) doubled up as somewhere with a guards office and a luggage/parcels compartment so would generally have been desired in the formations anyway regardless of any other vehicle in the formation having a handbrake. It wasn’t uncommon to see multiple brake vehicles in one formation of Mark 1s and Mark 2s.

Modern freight wagons have a handbrake which is why brake vans aren’t seen on freight trains these days.

 

[3973EXL]

Modern freight wagons have a handbrake which is why brake vans aren’t seen on freight trains these days.

The reason you don't see Brake Vans on the rear of freight trains today, is that the vehicles are fitted with an automatic air brake system.

Manned Brake Vans at the rear of freights were used on partially or unfitted trains to enable the guard to stop a break away or provide additional braking such as on gradients.
Trains could be made up of vehicles with no auto brake, fitted head (air/vac) with incompatible/unfitted wagons.

There are other special uses for vans on fully fitted trains.

 

[Bill57p9]

The reason you don't see Brake Vans on the rear of freight trains today, is that the vehicles are fitted with an automatic air brake system.

Manned Brake Vans at the rear of freights were used on partially or unfitted trains to enable the guard to stop a break away or provide additional braking.
Trains could be made up of vehicles with no auto brake, fitted head (air/vac) with incompatible/unfitted wagons.

There are other special uses for vans on fully fitted trains.

However if left uncoupled the handbrake must be applied as air/vacuum brakes will bleed off over time. As @hexagon789 stated above, look up Lac Megantec on Wikipedia to read about what happens when insufficient handbrakes are applied and the air pressure bleeds off.

 

[3973EXL]

owever if left uncoupled the handbrake must be applied as air/vacuum brakes will bleed off over time. As @hexagon789 stated above, look up Lac Megantec on Wikipedia to read about what happens when insufficient handbrakes are applied and the air pressure

Quite true, stabled freight trains should be secured as per the Method of Working for the location. I was only referring to
the use of freight Brake Vans was due to not having a through auto brake and not the lack of handbrakes, which even unfitted vehicles had.

 

[jopsuk]

with the Mark 5 sleeper stock, is the seated car a Brake Vehicle, as was the case with the mark 2 seated vehicle on the previous formations (with mark 3 sleepers)? And with the 5As for TPE, I guess the driving trailer is one?

 

[Bill57p9]

with the Mark 5 sleeper stock, is the seated car a Brake Vehicle, as was the case with the mark 2 seated vehicle on the previous formations (with mark 3 sleepers)? And with the 5As for TPE, I guess the driving trailer is one?

The mk5 sleeper stock, yes it's the seated coach.
Not sure about the mk5a stock but it would make sense for it to be the driving trailer.

 

[hexagon789]

So is there no parking brake on stock?

I've only ever worked with MU stock (built from 1980ish onward), where you get "air released, spring applied" parking brakes. Ie; when air pressure drops below 2.5 bar the parking brakes apply - to prevent exactly this type of incident.

Just surprises me that stock wouldn't have something like this - seems an easier solution than having to use a very specific vehicle on each train.

On the continent, passenger coaches usually do have their own handbrake, hence a separate guard's van is not required and any such vehicles are usually referred to as baggage vans rather than brake vans.

In Britain this was not adopted, perhaps when automatic braking for passenger trains was mandated it was decided that was sufficient for all needs except holding a parked up train.

 

[driverd]

Interesting replies - thanks all!

I'm interested as to why we don't see parking brakes (as per most MUs since 1980) on rolling stock? To be clear, it's quite normal for multiple unit trains to drop all their air and have the parking brakes as the only thing holding them (and this isnt something anyone has to do anything about - they go on automatically as the air drops, and come off as the air pressure builds again).

Is there a reason this isn't the prefered method on rolling stock? I presume mk5s would have this, given the TPE ones are in essence, CAF MUs?

 

[Bletchleyite]

An interesting difference from Continental (RIC) stock is that on those every vehicle has a handbrake - I wonder why the UK and Europe went a different way?

 

[hexagon789]

An interesting difference from Continental (RIC) stock is that on those every vehicle has a handbrake - I wonder why the UK and Europe went a different way?

I'm not sure of the history, the only thing I could think of - did the UK mandate full automatic brake provision throughout passenger trains earlier than the continent?

 

[Gloster]

I'm not sure of the history, the only thing I could think of - did the UK mandate full automatic brake provision throughout passenger trains earlier than the continent?

I would have thought that the Continent would have been earlier than the UK. Could it be that the power of the private companies and their reluctance to spend money meant that the Board of Trade were unable to push through as thorough a change as they wished?

 

[hexagon789]

I would have thought that the Continent would have been earlier than the UK. Could it be that the power of the private companies and their reluctance to spend money meant that the Board of Trade were unable to push through as thorough a change as they wished?

I have no idea if the continent (that is to say all the better off countries, rather than just one of them or the entirety of Europe) was earlier than the UK.

Googling several search queries did not produce any dates other than for Britain.

 

[36270k]

I would have thought that the Continent would have been earlier than the UK. Could it be that the power of the private companies and their reluctance to spend money meant that the Board of Trade were unable to push through as thorough a change as they wished?

Automatic brakes ( Vacuum or Westinghouse ) were mandated in the UK in 1889.
Not sure of the exact date on the continent but there was a runaway of a heavy passenger train in France in 1917 that only had the Westinghouse brake on the first 3 coaches.

 

[AndrewE]

An interesting difference from Continental (RIC) stock is that on those every vehicle has a handbrake - I wonder why the UK and Europe went a different way?

I would guess that they had so much portion working, with odd through coaches being dropped off and attached all over the place, that you couldn't rely on a braked vehicle (or a pilot loco) being coupled to any particular portion all the time, so each individual coach needed its own handbrake.
We used to have it (to a more limited extent) but continental trains retained through coaches to a wide variety of destinations long after BR went to the single "block-train" principle for passenger trains as well as freight.

 

[hexagon789]

Automatic brakes ( Vacuum or Westinghouse ) were mandated in the UK in 1889.
Not sure of the exact date on the continent but there was a runaway of a heavy passenger train in France in 1917 that only had the Westinghouse brake on the first 3 coaches.

I had the Saint-Michel-de-Maurienne incident in my mind when I was thinking about the brake situation abroad. I have no idea however whether such arrangements were permitted in France at the time or if that was untypical and simply needs must because of the war.

 

[Oxfordblues]

I'm reminded of an incident when I was working at Preston station in the 1970s. There was a serious runaway when shunting the Liverpool/Manchester-Glasgow/Edinburgh train. The portion involved had no loco attached and no brake vehicle and ran away southward from Platform 4, getting halfway to Ribble Sidings before being abruptly stopped by the pilot loco. All we could do was look on in horror, but fortunately there were no serious casualties.

 

[hexagon789]

TGS vehicles are not brake vehicles.

Does the guard have no access to a handbrake/brake valve beyond a passenger emergency brake on HST sets then?

 

[Ken H]

Does the guard have no access to a handbrake/brake valve beyond a passenger emergency brake on HST sets then?

brakes in the power car which shoule be the adjacet vehicle in the train

for modernisation plan DMUs, the parking brake was used when they were left in a station with no driver, but with engine running. Any idea why. They had dual pipe vacuum brakes.

 

[43096]

Does the guard have no access to a handbrake/brake valve beyond a passenger emergency brake on HST sets then?

Not in the trailers, no. Parking brakes are applied in the power cars: on the power cars built with guard's accommodation (43002-152) there were parking brake controls in the guard's area; on 43153-198 this was re-located to the clean air compartment.

 

[jopsuk]

I would guess that they had so much portion working, with odd through coaches being dropped off and attached all over the place, that you couldn't rely on a braked vehicle (or a pilot loco) being coupled to any particular portion all the time, so each individual coach needed its own handbrake.
We used to have it (to a more limited extent) but continental trains retained through coaches to a wide variety of destinations long after BR went to the single "block-train" principle for passenger trains as well as freight.

especially in central and eastern Europe through coaches to multiple destinations are still very much a thing

 

[trebor79]

brakes in the power car which shoule be the adjacet vehicle in the train

for modernisation plan DMUs, the parking brake was used when they were left in a station with no driver, but with engine running. Any idea why. They had dual pipe vacuum brakes.

Because the vacuum brake will leak off over a period of time.

 

[Ken H]

Another point of brake vans on an unfitted train is if, on an incline, if the train were to accidentally divide, the guard could apply his brake and stop the runaway portion. Not sure that would actually work with a heavy train, mind.

 

[norbitonflyer]

And I thought modern train brakes were "fail safe" - leaky pipe means loss of compressed air (or vacuum) means brakes come on. So how can the brakes on a parked train with no power source leak off?

Another point of brake vans on an unfitted train is if, on an incline, if the train were to accidentally divide, the guard could apply his brake and stop the runaway portion. Not sure that would actually work with a heavy train, mind.

It didn't at Armagh in 1888, even though the the handbrake was applied when the train was actually stationary, before it was (deliberately) divided.

 

[edwin_m]

Because the vacuum brake will leak off over a period of time.

The engine running will maintain the vacuum, but if unattended there is always the risk that the engine will stop and nobody will notice. That was also contributory to Lac Megantic - the one locomotive left with engine running caught fire and the engine was shut down by the fire brigade, after which the air brakes leaked off and not enough hand brakes had been applied to hold the train.