most powerfull loco

[Wellwhynot]

what was the most powerfull steam loco to be used on our railways either before or after B.R

[LCDR]

Power of a steam locomotive can be described in a number of ways but it is usually stated in TRACTIVE EFFORT expressed in pounds (lbs) .

Here are some top examples

LNER  Gresley A4 4-6-2  35,455lbs

LNER Gresley A3 4-6-2 32,910 lbs

LNER Peppercorn A1 4-6-2  37,400 lbs (also applies to Tornado)

LNER Peppercorn A2/3 4-6-2 40,430lbs

LNER Gresley W1 4-6-4 originally, 32,000lbs, as rebuilt 37,400 lbs

LNER Gresley P2 2-8-2 43,462 lbs

LNER Gresley/Beyer Peacock U1 2-8-8-2T 72,946 lbs

LNER Gresley P1 2-8-2 with booster 47,000 lbs

LNER Gresley  O2 2-8-0 36,470 lbs

LMSR Stanier Princess Royal 4-6-2 40,300 lbs

LMSR Stanier Duchess 4-6-2 40.000 lbs

LMSR Stanier 8F 2-8-0 32,428 lbs

LMSR Fowler/Beyer Peacock 2-6-6-2T 42,650 lbs

GWR Collett King 4-6-0 40,300 lbs

GWR Collett Castle 4-6-0 31,625 lbs

GWR Hawksworth County 4-6-0 32,580 lbs

GWR Churchward 28xx 2-8-0 35,350 lbs

SR Bulleid Merchant Navy 4-6-2 33,493 lbs

BR Riddles 8P 4-6-2 39,080 lbs

BR Riddles 7MT 4-6-2 32,150 lbs

BR Riddles WD 2-8-0 /2-10-0 34,215 lbs

BR Riddles 9F 2-10-0 39,667 lbs

When however you come to diesels and electrics you get some larger results.

Class 56 Co-Co 61,800 lbs (max), 53,950 lbs (continuous)

Class 55 Deltic 50,000 lbs

Class 47 60,000 lbs (max), 30,000 lbs (continuous)

Class 45 Peak 70,000 lbs

Class 87 Electric 58,000 lbs (Max)

Class 66 92,000 (max), 58,390 lbs (continuous)

 

[LCDR]

For comparison the American Union Pacific  "Big Boy" 4-8-8-4 had a tractive effort of 135,375 lbs, and a Norfolk and Western J class 4-8-4 had a tractive effort of 80,000 lbs. A Canadian Pacific T1b 2-10-4 was 76,900 lbs.

[ellocoloco]

As LC&DR lists above , the LNER Garratt was the most powerful steam locomotive measured on a tractive effort basis to have operated in the UK - something I remember from my Observers book of Steam locomotives! The only other 'big hitter' missing from the list above is the MR/LMS/BR Lickey banker 0-10-0 which would come in 3rd or 4th.

 

More powerful steam locomotives were built in the UK for export including the 3'6" gauge SAR GL Garratts with around 6000lbs more tractive effort than the standard gauge LNER Garratt. This shows what could have been built to operate to a UK load gauge had the need for more power been required. UK railways tended to have shorter and more frequent trains than railways abroad so massive power was never really needed.

 

Steam locomotive power can also be measured on an indicative horse power basis but there are much more variables. In this case I think either the Duchess's or DoG hold the record. 

 

(Perhaps LC&DR can fill in the rest....I'm reaching the bottom of my knowledge pit....)

 

Maybe next year for Hornby's 101st anniversary we could have the Lickey banker or the LNER Garratt...?

[LCDR]

I think the second and third posts had already 'drifted' so my second was in response to JJ's last line, which was a question.

 

Getting back to the matter of the most powerful real locomotive IHP is certainly a measure of power but difficult to calculate without the output of a dynamometer car and train load, and speed data.  It is a huge topic, and perhaps people interested should read the account of the Locomotive Exchanges in 1948 and the Locomotive Performance articles in the Railway Magazines.

[atom3624]

It then gravitates into coal quality, size, steaming abilities, and general skill of the drivers concerned.

 

Many will say the Coronations were the 'most powerful' in UK through one performance of IHP exceeding 3,200 HP in 1939 - Duchess of Abercorn.

 

In the exchange trials I don't remember them performing as well ...

 

Al.

[96RAF]

There are reports of 9Fs regularly hauling over 600 tons, but from memory in one of my ‘footplate’ books there is a tale of the driver being asked if he could manage 640 tons of carriages over the Shap with a Royal Scot on the front. Again not so much how much horsepower you have, but the skill with which you use it. There is also the visual appeal - a large passenger loco in full cry is more impressive in my view to a more powerful freight dragging a larger load uphill at low speed.

[walkingthedog]

I agree an express in full flow, or mollying along as my dad used to say,  is impressive, but a heavy goods heaving up an incline takes a lot of beating. 

[atom3624]

Think how lucky we are at level crossings in comparison to the Americans, with linked freight trains .....

OK, the longest / heaviest is on record as being in Australia, but literally in the middle of nowhere!!

 

Most powerful models I have are a Dapol 68 and a Hattons 66 - 'beasts' - obviously non-steam.

Hornby 50, 56 and 60 are superb haulers as well.

 

Steamies are more prototypical, perhaps underperforming relatively but there or thereabouts.

 

Al.

[Tony57]

Hi LC&DR

 

Great inforative list out of interest in the D&E list where would the Class 52 Western fit?

[atom3624]

I think it's maximum TE was 72,000 lb wasn't it?

Wiki states 66,700, but I'm certain I've seen 72k somewhere.

 

Very impressive locomotive, even if not particularly liked by the maintenance crews apparently.

 

One of my favourites - looks great.

 

Al.

[Postman Prat]

@ WTD

 

Perfect example of your comment is/was the sight of 2 9Fs flogging their way up to Consett

 

😉

[emutoo]

There was good reason to call the class 60s Tugs. It was a while before the 66s took on the longer oil trains. Dunno how the 70s fare, I've still only seen about 2 in operation.

As a child I remember the Tri-ang dock authority been the best hauler on steel track. Beat all the other locos. Wasn't there an article in the Model Railway Constructor for bashing a clerestory coach into a dynometer car? But you can't beat the sound of a steam loco dragging it's train up a long gradient, makes me feel right nostalgic just thinking about it.

[Anglia998]

In his book "The Duchesses", Andrew Roden states "Another engine in this batch, No. 6234 Duchess of Abercorn, had set a British power record for a steam passenger locomotive of 3,300hp in 1939 that remains officially unbeaten to this day"

[81F]

 Good evening,

 

Just to add to the discussion, I believe tractive effort is a theoretical calculation based on a varietuy of factors includes dividing by the wheel diameter. Consequently if all other factors remain the same, the smaller the wheels the less the tractive effort.

 

I remember reading that initial proposals for the GWR had envisaged 6' 8 1/2" driving wheels the same as the Stars, Castles and Saints but the GWR wanted to beat the 40,000lb mark for publicity reasons so reduced the driving wheel diameter. 

[The Doc]

@81F

I think you mean:  Consequently if all other factors remain the same, the smaller the wheels the more the tractive effort.

 

I don't want to seem too pedantic, but power (force x speed moved by force) and tractive effort (a force) are not the same thing at all.  In simple terms, an overweight bloke could probably exert a similar force (tractive effort) on the pedals of a bicycle by standing up out of his saddle as Sir Chris Hoy, but he wouldn't generate anything like the same power.

 

In railway comparisons, the Class 08 shunter has a tractive effort of around 35,000lb, about the same as Flying Scotsman.  That means it can exert the same force to get a train moving.  However, the class 08 has a power of only 350HP, so although it can get a heavy train moving, it could only move it at about 10-20mph.  Friction in the wheels of the trainling load would prevent it from going any faster, and this friction increases with speed.  FS is much more powerful (I couldn't find precise data but I would guess at over 2000HP on good quality coal).  So it could accelerate more quickly and pull the same length of train at a much faster top speed.  The lack of power of the class 08 is not an issue since it is only intended to shunt loads at slow speeds.

 

I read somewhere that the LMS Duchesses when tested could generate well over 3000HP.  When the LMS diesels 10000 and 10001 came along (1600HP but very similar tractive effort of about 40,000lb), they needed to double head the same trains.

 

The Beyer Garretts had very high tractive effort but I suspect were significantly less powerful than Duchesses or Peppercorn A1s and A2, since the former had smaller fireboxes and were probably less efficient.  All other things being equal, the bigger and more efficient the firebox, the greater the rate at which water is converted into steam, and so the more powerful the engine.

 

I can't remember where I read it (possibly a book by OS Nock) but I think the Duchesses and LNER Peppercorn A1s and A2s were the most powerful locos of the steam era in Britain.

  

[LCDR]

The calculation of the power of a steam locomotive is complex , and requires many inputs.

 

The following copied from “The Locomotive Engineer’s Pocket Book 1935” may be of interest.

Indicated Horse Power (IHP) is the measure of the power developed by the steam in the cylinders. A more meaningful measure is Draw-bar Horsepower (DHP) which calculates the output from IHP minus losses caused by resistance within the engine (and tender where appropriate).

 

To calculate IHP we first need to calculate Tractive Force.

Let  D = Diameter of Cylinder in inches.

p = Mean steam pressure per square inch of Piston

D2 = 0.7854 x p  = Total pressure on piston in pounds

S = stroke of Piston in inches

4 = number of strokes (2 cylinder engines) per revolution of axle

(D2 x 0.7854 x p) x 4S = Work done on pistons in one revolution in inch pounds.

W = diameter of driving wheel in inches.

W x 3.1416 = circumference of Driving Wheel.

W x 3.1316 x F = Work done in one revolution at circumference of wheel in inch pounds

(D2 x 0.7854 x p) x 4S =  W x 3.1416 x F

Or D2 p S = W F

The Tractive Force (friction neglected) being equal to the resistance :-

Tractive force in pounds = T = (D2 S p)/W

Let v = velocity of train in feet per minute

Let M = velocity of train in miles per hour.

Then IHP = (T x v) / 33000  or ((D2 x S x p) / (W x 33000)) x v

Or for a speed expressed in miles per hour the equivalent formula is :-

IHP = (T x M) / 375 or ((D2 x S x p) / (W x 375)) x M

So to obtain the Tractive force of a locomotive having –

Cylinders 18 inch diameter and 30 inch stroke

Driving wheels 6ft 8.5 in diameter

And boiler pressure of 225 pounds per square inch , the mean pressure on the piston being 60% of boiler pressure.

Tractive Force  = (D2 x S x p) / W = (18 x 18 x 30 x 225 x 0.6) / 80.5 = 16,300 pounds,

And then to find the IHP of the locomotive at 30 MPH .

(T x M) / 375 = (16300 x 30)/375 = 1304 IHP

 

Tractive force for 3 cylinder engines

T = (3 x D2 x S x p) / (2 x W)

 

Tractive force for Four Cylinder engines

T = (2 x  D2 x S x p) / W

 

 

 

 

[96RAF]

What impresses me is that many of these (especially early) engines were designed by self taught engineers. How do you work out tractive effort from a blank sheet of paper without formal training about the principles of physics involved..

 

The same goes for early bridge buidlers, although some of the bridges did fall down either from poor maintenance in service, bad design or simple overloading by traffic or weather e.g original Tay bridge.

[atom3624]

Mentioned earlier I'm sure, but based on the OP, the most powerful STEAM locomotive as far as tractive effort was concerned was the LNER U1 2-8-0 + 0-8-2 at 72,000 lb = the Western Class 52 diesel hydraulic C-C.

 

Take a look at 'the Tug' - Class 60!!  106,500 lb - that thing 'hauls'!!

 

Al.

[AndyMac1707817969]

Are you only considering main line locos surely the Lickey Incline Big Berth MR 0-10-0 must be in contention with something like 43,300 lbf tractive effort.

The U1 used on the Woodhead route is quoted 72,940 lbf

[atom3624]

Good ol' Big Bertha - https://en.wikipedia.org/wiki/MR_0-10-0_Lickey_Banker

 

There was also Holden's Decapod: https://en.wikipedia.org/wiki/GER_Class_A55

An interesting beastie - one of my old favourites from an O.S. Nock book I used to have.

 

Al.

[AndyMac1707817969]

Those building the new P2 are claiming it will be the most powerful (express) loco to run on Britain’s Railways. I guess they may mean in existence to day (well when it’s completed). Not a lot of other contenders, slightly misleading but I guess it helps sell the project. Would be interesting to see a comparison between the two projects and if the streamlines version outperforms the original

[atom3624]

I would guess it will be the most powerful 'Steamie' on Britain's railway network once built.

 

There is the Bugatti-nosed (A4-style) rebuilt P2 being built as well, so Britain's Heritage line-up will be quite interesting ... unless Grace Tombstone and her cronies have too much influence, too soon ......

 

Al.