Bulleid Light Pacifics - How did their axle load compare to smaller locomotives?

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alexl92

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I remember reading somewhere that the Bulleid Light Pacifics were so light on axle load that they were sometimes used on branch line services that were normally operated by much smaller locomotives. I just wondered how light they actually were compared to other locomotives - were they lighter than any tank engines for example? What were the lighest routes they worked? I don't really fully understand how routes were rated for route availability/axle load etc so if anyone can explain that too I'd be grateful!

Thanks!
 
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Irascible

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Essentially ( and simplistically ) Route Availability is a) does it fit? ie will whatever you're testing physically fit through bridges/tunnels/stations/other infrastructure ( while moving, too ), and b) will it destroy the infrastructure? ie will it weaken the track/bridges/other permanent way features or even just are they strong enough to cope. The last one is mostly axle loading which is a concentration of force in one spot ( which isn't always all pointing down either ), but in steam days you'd have to account for hammer blow too, although not sure if that really had an effect on where anything was cleared for.

The Westcountry pacifics were, as the name suggests intended to be used in the south-west - and yes, there's plenty of photos around of them hauling services on the branch lines down here with a load that's probably less than the locomotive itself. Not so much replacing tank engines ( the lines were lightly used but generally long & hilly - which is not to say there weren't any used ), but N1/U1s ( moguls ) and T9s, which dated from the turn of the century & lasted forever. Using a huge pacific in those cases was just as wasteful as you'd imagine.

The E1/R tanks in the south-west were rebuilt from a class originally from the 1870s, which makes the T9s look modern. You can see why the pacific idea came about.
 
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Harvester

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I remember reading somewhere that the Bulleid Light Pacifics were so light on axle load that they were sometimes used on branch line services that were normally operated by much smaller locomotives. I just wondered how light they actually were compared to other locomotives - were they lighter than any tank engines for example? What were the lighest routes they worked? I don't really fully understand how routes were rated for route availability/axle load etc so if anyone can explain that too I'd be grateful!

Thanks!

The unrebuilt Bulleid Light Pacifics were around 20 tons heavier than the N1/U1 moguls, so not particularly light. They could however be used on most of the branches operated by the southern region in the West Country. (The rebuilt Light Pacifics could only be used on the Exeter to Plymouth route). Some of the lines the unrebuilt engine worked were to Bude, Padstow and Ilfracombe.
 

Ash Bridge

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Yes it was apparently quite the norm for a Westcountry or BoB light pacific after arriving on the Atlantic Coast Express to be afterwards employed on a single coach evening service between Wadebridge and Padstow, and also occasionally work local services of no more than 2 coaches between Okehampton and the latter. Undoubtedly plenty of other examples on the former “Withered Arm” lines also.
 

UrieS15

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I learned during the Bulleid weekend at the Swanage railway some years ago that the rebuild programme had always planned to leave a group of unrebuilt WCs for use on the Ilfracombe line because of the parlous state of the bridge at Barnstaple, however events overtook the plan. How true this I am not certain.
 

Harvester

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I learned during the Bulleid weekend at the Swanage railway some years ago that the rebuild programme had always planned to leave a group of unrebuilt WCs for use on the Ilfracombe line because of the parlous state of the bridge at Barnstaple, however events overtook the plan. How true this I am not certain.
Yes I have read somewhere that this was the case. Around twenty or so would have remained in unrebuilt form based at Exmouth Junction, to work routes the heavier rebuilt locos could not.
 

30907

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Yes it was apparently quite the norm for a Westcountry or BoB light pacific after arriving on the Atlantic Coast Express to be afterwards employed on a single coach evening service between Wadebridge and Padstow, and also occasionally work local services of no more than 2 coaches between Okehampton and the latter. Undoubtedly plenty of other examples on the former “Withered Arm” lines also.
The 1954 workings I have access to have 2 Bulleids stabling at Wadebridge, one for the (summer) ACE and one for the stopper that was the winter ACE. Both of those would have been reasonable loads though not heavy at the Exeter end, and as for Saturdays....

They were rare at Bude, common to Ilfracombe and Plymouth.

I think the most weight-restricted route they worked regularly may have been Swanage where they were limited to 40mph, but they weren't barred altogether from many.

I have the restrictions booklet if you want a list... tomorrow.
 

Gloster

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They were rare at Bude, common to Ilfracombe and Plymouth.
Were they passed to run to Bude? I think that 21C106 reached the town for naming, but was that the only occasion? I don’t know if 34097 reached Holsworthy.
 

Irascible

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Yes it was apparently quite the norm for a Westcountry or BoB light pacific after arriving on the Atlantic Coast Express to be afterwards employed on a single coach evening service between Wadebridge and Padstow, and also occasionally work local services of no more than 2 coaches between Okehampton and the latter. Undoubtedly plenty of other examples on the former “Withered Arm” lines also.
How big was a Padstow portion of the ACE ( in summer, lets say. )? . Not big enough to really neec a WC outside of an exceptional day, I'd think.
 

30907

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How big was a Padstow portion of the ACE ( in summer, lets say. )? . Not big enough to really neec a WC outside of an exceptional day, I'd think.
Leaving Exeter in 1960 it was 6, 8 in the summer peak, plus twin restaurant on summer Fridays. So the second longest train of the day after the Brighton-Plymouth.
 

zwk500

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Essentially ( and simplistically ) Route Availability is a) does it fit? ie will whatever you're testing physically fit through bridges/tunnels/stations/other infrastructure ( while moving, too ), and b) will it destroy the infrastructure? ie will it weaken the track/bridges/other permanent way features or even just are they strong enough to cope. The last one is mostly axle loading which is a concentration of force in one spot ( which isn't always all pointing down either ), but in steam days you'd have to account for hammer blow too, although not sure if that really had an effect on where anything was cleared for.
I don't know if it was different in SR days, but RA today is strictly about Can the bridges & track take the weight? The question of not hitting anything is dealt with by loading gauge.

I don't really fully understand how routes were rated for route availability/axle load etc so if anyone can explain that too I'd be grateful!
Today's RA system is based on an LNER or LMS system, I think, so this may not be strictly applicable but here goes. Today's RA system assesses the strength of bridges and the maximum weight the rails can bear at a single contact point. From that an RA rating of 0-10 is given, 0 being the lightest/weakest. All locos/unit are then assessed for how their weight is distributed between axles and along the length of the loco, and an RA rating given in the same scale. Any loco with an RA number equal to or lower than the route may pass without restrictions (unless specifically noted in the paperwork), any loco with a higher RA number than the route will need special permission which may include slow speed over bridges or even outright refusal. Especially weak bridges may have further restrictions on the number of other trains allowed on them at any one time, and minimum length between locos on the same train.

FWIW, 34046 Braunton is listen in TOPS (Number 98746) as RA6.
 

341o2

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Yes it was apparently quite the norm for a Westcountry or BoB light pacific after arriving on the Atlantic Coast Express to be afterwards employed on a single coach evening service between Wadebridge and Padstow, and also occasionally work local services of no more than 2 coaches between Okehampton and the latter. Undoubtedly plenty of other examples on the former “Withered Arm” lines also.
While this may sound extravagent, you had a loco in steam at the right place and time, rather than firing a second loco and using a second crew. The fireman would also be running the fire and boiler pressure down to suit the light load, aiming to end the duty with as little fire and steam as possible, to come on shed literally at the last puff
 

Merle Haggard

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Route restriction isn't just based on static axle load (i.e. weight) but dynamic forces ('hammer blow').
Bulleids had chain driven valve gear which replaced the reciprocating masses with other types. Although that's small compared to the con-rod etc., it must have made a reduction.

It might be worth mentioning that, after nationalisation, the southern region received a large number of LMS design and BR standard 2-6-4Ts (the latter were even 'designed at Brighton'). Controversial, but maybe that was what was really wanted, rather than Pacifics.
 

341o2

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Yes I have read somewhere that this was the case. Around twenty or so would have remained in unrebuilt form based at Exmouth Junction, to work routes the heavier rebuilt locos could not.
But the lines were dieselised in 1965 and only Salisbury - Exeter - Plymouth and Exeter - Ilfracombe had loco haulage
 

Taunton

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You can't really blame the use of Pacifics of Wadebridge-Padstow shuttles as schedule inefficiency; the end of the line was at Padstow but the shed was at Wadebridge. There were some light engine movements as well between the two.

I don't recall such a large train at Padstow, nor with restaurant cars, which didn't normally work west of Exeter or sometimes Plymouth. The ACE dropped a Bude portion at Halwill, and although such portions normally had a tank loco take them on, I've also seen pictures of a WC running tender first on the Bude branch with a single coach. Between two and four coaches seemed normal for Padstow, I don't think Padstow platform, or the intermediate ones, would hold much more than that plus the loco.
 

DelW

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How big was a Padstow portion of the ACE ( in summer, lets say. )? . Not big enough to really neec a WC outside of an exceptional day, I'd think.
I remember staying with my parents at a B&B at St Kew Highway near Wadebridge in August 1964, and going into the garden in the late afternoon or early evening to watch the down ACE pass. It consisted of a Bulleid Pacific and just three coaches, a fact I remember because on my Tri-Ang 00 gauge model railway I ran a (Stanier) Pacific (Princess Victoria) with the only three coaches I owned, so I was pleased to see a similar consist in real life, albeit with different stock.
 

Irascible

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I don't know if it was different in SR days, but RA today is strictly about Can the bridges & track take the weight? The question of not hitting anything is dealt with by loading gauge.

You're probably right & I was mixing route clearance with availability - it's been a hard week. Out of curiosity I did once check into how the SR decided what could run on the local lines ( given they managed Pacifics & the GWR used 43xx at the largest ) but that was years ago - I'll go dig something up again if I can.
 

Harvester

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But the lines were dieselised in 1965 and only Salisbury - Exeter - Plymouth and Exeter - Ilfracombe had loco haulage
Yes but I was referring to the time of the rebuild programme, when the secondary lines and the Pacifics had a future in the region. This all changed from September 1962 when the lines were transferred from the Southern to the Western region.
 

30907

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I don't recall such a large train at Padstow, nor with restaurant cars, which didn't normally work west of Exeter or sometimes Plymouth. The ACE dropped a Bude portion at Halwill, and although such portions normally had a tank loco take them on, I've also seen pictures of a WC running tender first on the Bude branch with a single coach. Between two and four coaches seemed normal for Padstow, I don't think Padstow platform, or the intermediate ones, would hold much more than that plus the loco.
The 11am SO Up was booked 11 coaches ex Padstow in 1960 - much too long for the platform, certainly; the longest SO Down train was load 7. But that was just a few days in summer.

Back to weight restrictions: in 1954 they were barred from various minor lines across the region, plus slightly busier ones like Sheerness, Holborn and Topsham to Exmouth, all of which I think would have been due to specific weak bridges. They were permitted to New Romney and Westerham, but not Allhallows or Three Bridges-Ashurst Jn.
 
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Ash Bridge

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While this may sound extravagent, you had a loco in steam at the right place and time, rather than firing a second loco and using a second crew. The fireman would also be running the fire and boiler pressure down to suit the light load, aiming to end the duty with as little fire and steam as possible, to come on shed literally at the last puff
That was my understanding too. After arriving with the ACE at Padstow; uncouple then light engine back to Wadebridge to pickup a Bulleid BCK (or similar) work the 6:13 service to Padstow thence back to Wadebridge drop off the coach then onto the shed for a well deserved service?
 

341o2

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Yes, just to correct one thing in my post, the Exmouth Junction crew would work the 6pm Padstow back while a local crew would work the Padstow - Wadebridge journeys
 

Ash Bridge

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Yes, just to correct one thing in my post, the Exmouth Junction crew would work the 6pm Padstow back while a local crew would work the Padstow - Wadebridge journeys
Thanks for adding that, it had me wondering previously whether the Exeter crew would have perhaps lodged at Wadebridge as it would have been getting rather late to perform a return Exeter working if they had also operated those local turns?
 
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