Double header locos, why?
Discussion
I was told some time ago they did this purely for grip on steep inclines, is this true? It was backed up by the fact that steam engines produce so much torque the only struggle is for grip.
I don't think it's so popular these days though, or is it? Maybe all the steep lines have gone, locos have more grip, or are indeed more powerful these days....
Evoluzione said:
I was told some time ago they did this purely for grip on steep inclines, is this true? It was backed up by the fact that steam engines produce so much torque the only struggle is for grip.
I don't think it's so popular these days though, or is it? Maybe all the steep lines have gone, locos have more grip, or are indeed more powerful these days....
We still do it occasionally with some trains, for instance the 'jumbo' train I worked from Crewe to Wembley a few weeks ago had two sets of wagons and two Class 66s in multiple working mode, on arrival at Wembley the train was split in two, with one portion going forward to Bow with another driver, then I took my portion down to Battersea. In jumbo mode it was about 4,000 tons in weight, including both locos, as well as being easier to negotiate the gradients en route, it saves a path too.
In simple terms, double-heading happened when the required power to move the train was insufficient for one locomotive.
That was usually either because the train itself was unusually heavy for the route (so the locos in use were not powerful enough singly to operate it at the required speed) or - more commonly - a section of the route had steep gradients but it would have been a waste to provide one very powerful engine to work over the entire route, so you add a second one for the section where it was needed and detach it once over the difficult ground.
So typically would be a quiet cross-country route, usually only seeing a steady trade in goods trains, slow stopping passenger trains and the odd long-distance service between regional hubs, which then gets flooded with massive long-distance holiday trains on a summer Saturday in August. Instead of the ordinary six-coach train you may need to run a ten-coach monster, packed to the roof with trippers and luggage, and at pretty brisk timings because they need to get there as early in the day as possible. There's no point in building some massive high-power engines that are running at half capacity for eleven months of the year, so the railway just double-heads the exceptional traffic with its standard power.
As in P5BNij's more modern example - a Class 66 can, by itself, handle almost any typical freight job on the British railway network. There would be no sense in building a small class of 5000hp super-locos for the small number of trains that need them, so when the time comes two are used together.
There were some cases where the extra engine was to provide braking rather than 'going' power. Prior to WW2 most freight trains did not have 'continuous' brakes (ones which could be applied along the train under the control of the driver), with the wagons only having manual handbrakes which had to be set from the trackside. The driver on the loco had a brake, as did the guard in the brake van at the back and that was it. On steep down-grades the train would stop, the crew would 'pin down' a proportion of the wagon brakes (enough to hold the train against the gradient) and then drag the whole shebang down the hill, ideally with the loco and van brake being unused except to stop the train at the bottom. In some cases an extra engine was attached to the front to provide more braking power. I know this happened on the old line over Stainmore summit - heavy coal trains heading westward would be 'banked' (shoved up by an assisting engine at the rear). At the summit the banking engine would be brought round and coupled to the front of the engine at the front of the train, and the train would be double-headed down the 10 miles of steep down-grades with the combined braking force of two locos able to keep it under control.
P5BNij also mentioned the Midland Railway, which was distinct in being a strong proponent of double heading. For various complicated reasons the Midland evolved an operating method different from every other British railway company, favouring large numbers of standardised low-power locos, operating short, frequent trains and double heading when the power available from one 'unit' was not enough to do the job. The way the Midland worked made this more cost-effective than running fewer, longer trains and having a diverse fleet of locomotives each tailored to do a specific job. Ironically this is pretty much how modern railways run - standardised and interchangeable units, each of relatively low capacity, running frequent and fast services and which are combined together as capacity demand requires.
I believe in technical railway terms 'double heading' is two independent locos coupled together, each operated by their own crews. This was the only way of having one train with more than one loco in the days of steam, since there was no way of controlling a steam engine remotely. Diesel and electric locos can be connected together and worked by a single driver (assuming they have compatible control systems) and this is 'working in multiple' rather than double heading.
That was usually either because the train itself was unusually heavy for the route (so the locos in use were not powerful enough singly to operate it at the required speed) or - more commonly - a section of the route had steep gradients but it would have been a waste to provide one very powerful engine to work over the entire route, so you add a second one for the section where it was needed and detach it once over the difficult ground.
So typically would be a quiet cross-country route, usually only seeing a steady trade in goods trains, slow stopping passenger trains and the odd long-distance service between regional hubs, which then gets flooded with massive long-distance holiday trains on a summer Saturday in August. Instead of the ordinary six-coach train you may need to run a ten-coach monster, packed to the roof with trippers and luggage, and at pretty brisk timings because they need to get there as early in the day as possible. There's no point in building some massive high-power engines that are running at half capacity for eleven months of the year, so the railway just double-heads the exceptional traffic with its standard power.
As in P5BNij's more modern example - a Class 66 can, by itself, handle almost any typical freight job on the British railway network. There would be no sense in building a small class of 5000hp super-locos for the small number of trains that need them, so when the time comes two are used together.
There were some cases where the extra engine was to provide braking rather than 'going' power. Prior to WW2 most freight trains did not have 'continuous' brakes (ones which could be applied along the train under the control of the driver), with the wagons only having manual handbrakes which had to be set from the trackside. The driver on the loco had a brake, as did the guard in the brake van at the back and that was it. On steep down-grades the train would stop, the crew would 'pin down' a proportion of the wagon brakes (enough to hold the train against the gradient) and then drag the whole shebang down the hill, ideally with the loco and van brake being unused except to stop the train at the bottom. In some cases an extra engine was attached to the front to provide more braking power. I know this happened on the old line over Stainmore summit - heavy coal trains heading westward would be 'banked' (shoved up by an assisting engine at the rear). At the summit the banking engine would be brought round and coupled to the front of the engine at the front of the train, and the train would be double-headed down the 10 miles of steep down-grades with the combined braking force of two locos able to keep it under control.
P5BNij also mentioned the Midland Railway, which was distinct in being a strong proponent of double heading. For various complicated reasons the Midland evolved an operating method different from every other British railway company, favouring large numbers of standardised low-power locos, operating short, frequent trains and double heading when the power available from one 'unit' was not enough to do the job. The way the Midland worked made this more cost-effective than running fewer, longer trains and having a diverse fleet of locomotives each tailored to do a specific job. Ironically this is pretty much how modern railways run - standardised and interchangeable units, each of relatively low capacity, running frequent and fast services and which are combined together as capacity demand requires.
I believe in technical railway terms 'double heading' is two independent locos coupled together, each operated by their own crews. This was the only way of having one train with more than one loco in the days of steam, since there was no way of controlling a steam engine remotely. Diesel and electric locos can be connected together and worked by a single driver (assuming they have compatible control systems) and this is 'working in multiple' rather than double heading.
Routine here in western US. Trains are long and most have two or three engines. I assume due to massive load rather than inclines but they certainly exist here too. I wonder whether there's a convenience factor for shuffling traction units around given that so much of the US is single track.
Another reason could be one loco has failed, or to get another loco down the line without using a (signalling) path.
Triple Headed through Romsey this morning.
https://www.realtimetrains.co.uk/service/gb-nr:H37...
66702 + 66035 + 66848 Each a different colour.
Only saw the first truck, bogie, which had a track panel on it.
Triple Headed through Romsey this morning.
https://www.realtimetrains.co.uk/service/gb-nr:H37...
66702 + 66035 + 66848 Each a different colour.
Only saw the first truck, bogie, which had a track panel on it.
Thats one of the network services that I look after Westbury to Eastleigh.
It wasn't "triple headed" or even "double headed" it was 66702 (GBRF) pulling it with 66035 (DBC) and 66848 (Colas) on the rear dead in tow. It had 8 loaded salmon on it.
Its how people upload them to TOPS, on this occasion all 3 were put into the loco section, some TOPS people put the other two at the start of the consist if though they are at the back, and some TOPS people but them at the back of the consist correctly.
But yeh we move locos dead in tow all the time around the network.
It wasn't "triple headed" or even "double headed" it was 66702 (GBRF) pulling it with 66035 (DBC) and 66848 (Colas) on the rear dead in tow. It had 8 loaded salmon on it.
Its how people upload them to TOPS, on this occasion all 3 were put into the loco section, some TOPS people put the other two at the start of the consist if though they are at the back, and some TOPS people but them at the back of the consist correctly.
But yeh we move locos dead in tow all the time around the network.
Edited by the-norseman on Saturday 24th December 08:58
the-norseman said:
Thats one of the network services that I look after Westbury to Eastleigh.
It wasn't "triple headed" or even "double headed" it was 66702 (GBRF) pulling it with 66035 (DBC) and 66848 (Colas) on the rear dead in tow. It had 8 loaded salmon on it.
Its how people upload them to TOPS, on this occasion all 3 were put into the loco section, some TOPS people put the other two at the start of the consist if though they are at the back, and some TOPS people but them at the back of the consist correctly.
But yeh we move locos dead in tow all the time around the network.
A few weeks ago I took five 66s from Bescot to Crewe, they'd all come off weekend infrastructure work further south. Plenty of weight, but plenty of brake force too. It wasn't "triple headed" or even "double headed" it was 66702 (GBRF) pulling it with 66035 (DBC) and 66848 (Colas) on the rear dead in tow. It had 8 loaded salmon on it.
Its how people upload them to TOPS, on this occasion all 3 were put into the loco section, some TOPS people put the other two at the start of the consist if though they are at the back, and some TOPS people but them at the back of the consist correctly.
But yeh we move locos dead in tow all the time around the network.
Edited by the-norseman on Saturday 24th December 08:58
P5BNij said:
A few weeks ago I took five 66s from Bescot to Crewe, they'd all come off weekend infrastructure work further south. Plenty of weight, but plenty of brake force too.
Think 5 is the max the rule book allows isn't it?We had two dead ones up in Scotland last week for FLHH, took another loco up there to rescue them but there's some stupid rule about max 2 locos over the Forth Bridge at a time so we had to do two separate trips.
P5BNij said:
A few weeks ago I took five 66s from Bescot to Crewe, they'd all come off weekend infrastructure work further south. Plenty of weight, but plenty of brake force too.
If I had a quid for each time I hit my knee on the sharp bit of metal to hold the yellow pipe underneath the buffer of a 66 when coupling up, I'd have enough for a knee replacement.Not sure on the veracity of this yarn, but I heard a few years back there was an incident when 2 loco's were coupled along with the black power coupling, the driver released the parking brake, then for some unknown reason the rear started to randomly put power on, pushing them into a set of stops. Not sure if it is true, but I've not seen coupled loco's running alone and sharing power since.
We frequently send coupled loco's back to the Yard, especially on a Saturday when there's fewer drivers on duty. It's also polite to tell the Signalman that there's 3 attached, to save any problems, as they're sent under the headcode of a single light Engine.
the-norseman said:
P5BNij said:
A few weeks ago I took five 66s from Bescot to Crewe, they'd all come off weekend infrastructure work further south. Plenty of weight, but plenty of brake force too.
Think 5 is the max the rule book allows isn't it?We had two dead ones up in Scotland last week for FLHH, took another loco up there to rescue them but there's some stupid rule about max 2 locos over the Forth Bridge at a time so we had to do two separate trips.
I'm off for a fortnight now, so won't be hearing any 'yinging' in my sleep for a while
P5BNij said:
It was five, but has been amended to a maximum of seven.
I'm off for a fortnight now, so won't be hearing any 'yinging' in my sleep for a while
Quite a sightI'm off for a fortnight now, so won't be hearing any 'yinging' in my sleep for a while
I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
demic said:
Quite a sight
I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
DB Cargo recently ran a 'jumbo' train which was two (unloaded) trains coupled together with the 66 in the middle dead in tow. It reduced the number of paths required and the train was split mid journey.I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
Always assumed it was because the single engine would struggle.
As a boy I lived at the town at the bottom of the incline where a train first achieved 100 mph (that was before my time I’m not that old!) and it was always interesting to see the ‘banker’ or extra loco being attached to go up the hill.
As a boy I lived at the town at the bottom of the incline where a train first achieved 100 mph (that was before my time I’m not that old!) and it was always interesting to see the ‘banker’ or extra loco being attached to go up the hill.
standards said:
Always assumed it was because the single engine would struggle.
As a boy I lived at the town at the bottom of the incline where a train first achieved 100 mph (that was before my time I’m not that old!) and it was always interesting to see the ‘banker’ or extra loco being attached to go up the hill.
The first train claimed to attain 100mph was the "City of Truro" in 1903, but officially that honour goes to LNER A3 class 4472 Flying Scotsman in 1934.As a boy I lived at the town at the bottom of the incline where a train first achieved 100 mph (that was before my time I’m not that old!) and it was always interesting to see the ‘banker’ or extra loco being attached to go up the hill.
"Mallard" smashed this record reaching 126mph in 1938 near Peterborough, which for a steam train, has never been beaten to this day.
demic said:
Quite a sight
I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
tried to do that a few years ago, only had 1 driver coming off a possession for two trains, so tried to combine them like that and was told no. Hopefully that rule has changed.I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
demic said:
Quite a sight
I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
Suspected they were for possession work but they are all still showing in BH this morning and all of the BH possession trains went yesterday. I believe that they’ve also amended the rule book so you can haul a loco dead mid formation if the train is to be split and worked forward as two services? I guess to reduce shunting?
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