Imaginary Locomotives

[Compound2632]

28 minutes ago, rockershovel said:

I didn't say the 0-8-0 types were unsuccessful, rather that the 2-8-0 was superior. They were faster, 

 

Not really an advantage, where the speed of the class of train worked was limited by the rolling stock.

 

30 minutes ago, rockershovel said:

simple expansion configuration made better use of steam 

 

A well-designed compound working at a steady rate would always make better use of the steam than the equivalent simple.

 

The LNWR had such long-distance goods runs for which clear paths could be found, e.g. Crewe to Carlisle, which was why Webb, alone of 19th century British locomotive engineers, found it worth-while to build compound goods engines. (T.W. Worsdell's Class C 0-6-0s were really what would in later years be called mixed-traffic engines.)

[DenysW]

It is asserted that the original (Midland) methodology also included an allowance (probably empirical and per loco type) for ageing, so that any, say, 2F loco could be assigned to a combination of route and train weight that required  a 2F without worrying about whether the actual condition of the individual loco was too poor for the duty because it was just about to have a major overhaul. Others down-rated their locos as they aged. Neither system seems right or wrong, but the different approaches certainly contributed to the culture wars on Grouping into LMS.

 

Starting tractive effort (TE)  indeed has a simple formula based on pressure, wheel size, & cylinder geometry, but it isn't (all that) helpfull, except as a first stab. Excessive starting TE just makes it easy to spin the wheels on start-up, hence the adhesion factor calcs, and the addition of sanding capability.

[DenysW]

While I enjoy the distraction into classifications, can we, just for the moment, accept the proposition that 2F + 2F = 8F, and 4F + 4F = 11F, and think about what imaginary locomotives designable in 1910 (or so) could have been created at 8F and 11F to reduce/eliminate the sight of  most freight trains on the Midland seeming to be pulled by more than one locomotive.

[cypherman]

Hi all,

I am working on 2 more imaginary loco's.

Just waiting for the final parts to arrive. This is what I have so far.

We have an N2/M7 0-4-4 hybrid and a M7/N2 0-6-2 hybrid. I must admit that the M7/N2 0-6-2 hybrid has taken the M7 which to me always looks like a bit of a podgy engine and makes it look more sleek and greyhound like in appearance. Do not worry about the mint Wrenn N2 body being damaged. It was only used to see if it would fit prior to me buying another tatty body. Which as i have said is on it's way.

Edited July 27, 2021 by cypherman

[BernardTPM]

While overal the M7 body would be OK as an 0-6-2T that front splasher will need replacing as now it is absurdly large.

[cypherman]

5 hours ago, BernardTPM said:

While overal the M7 body would be OK as an 0-6-2T that front splasher will need replacing as now it is absurdly large.

Ah yes Bernard, But absurdly large is what the Victorians did so well......

[BernardTPM]

To go with absurdly large wheels. So I'm hoping you'll be getting six of Lord of the Isles driving wheels for it.  You know it makes sense...

 

Believe it or not, they would have made the splashers fit the wheels. They might have added brass beading, cut 'paddle steamer' slots in it, lined it out in multifarious colous, but it would have still been the right size for the wheel.

Edited July 27, 2021 by BernardTPM

[Compound2632]

10 hours ago, DenysW said:

It is asserted that the original (Midland) methodology also included an allowance (probably empirical and per loco type) for ageing, so that any, say, 2F loco could be assigned to a combination of route and train weight that required  a 2F without worrying about whether the actual condition of the individual loco was too poor for the duty because it was just about to have a major overhaul. Others down-rated their locos as they aged. Neither system seems right or wrong, but the different approaches certainly contributed to the culture wars on Grouping into LMS.

 

Not quite so (on several counts). My understanding is that the power classes were set such that any locomotive in that power class should be capable of working the relevant train - so to that extent the definitions of the classes were cautious.

 

10 hours ago, DenysW said:

Starting tractive effort (TE)  indeed has a simple formula based on pressure, wheel size, & cylinder geometry, but it isn't (all that) helpfull, except as a first stab. Excessive starting TE just makes it easy to spin the wheels on start-up, hence the adhesion factor calcs, and the addition of sanding capability.

 

exactly the same factors enter into the Midland / LMS formulae for tractive effort at 25 mph (goods) and 50 mph (passenger) used to define the power classes. Indeed, there's nothing else one can but into such a formula, it's basically:

 

Work done per revolution of the wheels = force x distance moved per revolution of the wheels = pressure difference x total cylinder volume per revolution of the wheels.

[ScottishRailFanatic]

A mixed-traffic design in the form of a 7MT tank.

[Ramblin Rich]

1 hour ago, ScottishRailFanatic said:

A mixed-traffic design in the form of a 7MT tank.

That looks impressive, like a stretched version of the Maunsell 'Z' class

[BernardTPM]

Might be a good idea to have the buffers at the same height each end though.

[The Johnster]

On 22/05/2020 at 11:40, PhilJ W said:

The GE 1500 class (B12) was a very successful engine. It was designed within the restrictions of the GER, notably the short turntables and weak bridges.

And by a man who had emigrated there from Swindon.

 

On 22/05/2020 at 15:06, JimC said:

I think you need to supply some evidence for that, since everything I know is to the contrary. The GWR started a policy of rebuilding bridges to a 22 ton weight limit at the end of the 19thC. Introducing the Kings on the tight timescale was only practical because enough bridges on the key routes had already been upgraded that the rest could be done quickly. To the best of my knowledge the policy continued, which is why the Kings were able to be used on more lines after WW2. 

As for imaginary wide firebox GWR atlantics, I sketched this one a while back. Its a shortened version of the Bear's boiler on a Star chassis. Goodness only knows what the axle weights would be, but probably King territory.

You could probably get away with dropping the boiler centre line by about a foot on this loco, or increaasing the driving wheel diameter for higher speeds, producing a very handy fast outer suburban loco for Paddington-Oxford or Newbury trains.

[The Johnster]

2 hours ago, ScottishRailFanatic said:

A mixed-traffic design in the form of a 7MT tank.

 

Not really much use as a mixed traffic horse, though; driving wheels too small and weight distribution unsuitable for even secondary or local passenger speeds.  It needs to be a 2-6-4T with room for 5'8" or so driving wheels to cut the mixed traffic mustard, and would probably have been too heavy with the 8F boiler.  Hump shunting or banking perhaps, in which case the tanks need to be slope topped so that the driver can observe the shunter's activities at the front of the loco; this makes it even more like a Z.

[Flying Pig]

2 hours ago, ScottishRailFanatic said:

A mixed-traffic design in the form of a 7MT tank.

 

It would work better as a 2-8-4t with the boiler in its original position relative to the cylinders. Apart from lining up the steam and exhaust pipes that would allow a bigger bunker behind the cab: as it is the water and coal capacity look way out of balance.  

Edited July 27, 2021 by Flying Pig

[cypherman]

Hi all,

Or perhaps something like this possibly ?

[rockershovel]

On 27/07/2021 at 04:10, Compound2632 said:

 

Not really an advantage, where the speed of the class of train worked was limited by the rolling stock.

 

 

A well-designed compound working at a steady rate would always make better use of the steam than the equivalent simple.

 

The LNWR had such long-distance goods runs for which clear paths could be found, e.g. Crewe to Carlisle, which was why Webb, alone of 19th century British locomotive engineers, found it worth-while to build compound goods engines. (T.W. Worsdell's Class C 0-6-0s were really what would in later years be called mixed-traffic engines.)

... but the general design trend was for the 2-8-0 to replace the 0-8-0, so clearly the 2-8-0 offered some defining improvement

[rockershovel]

8 hours ago, The Johnster said:

 

Not really much use as a mixed traffic horse, though; driving wheels too small and weight distribution unsuitable for even secondary or local passenger speeds.  It needs to be a 2-6-4T with room for 5'8" or so driving wheels to cut the mixed traffic mustard, and would probably have been too heavy with the 8F boiler.  Hump shunting or banking perhaps, in which case the tanks need to be slope topped so that the driver can observe the shunter's activities at the front of the loco; this makes it even more like a Z.

Various railways built small numbers of 0-8-0, 0-8-4 and even 4-8-0 tanks for hump yard shunting. Only the GWR built 8 coupled MT tank locos, for their specialised local traffic in S Wales

[rockershovel]

On 27/07/2021 at 04:10, Compound2632 said:

 

Not really an advantage, where the speed of the class of train worked was limited by the rolling stock.

 

 

A well-designed compound working at a steady rate would always make better use of the steam than the equivalent simple.

 

The LNWR had such long-distance goods runs for which clear paths could be found, e.g. Crewe to Carlisle, which was why Webb, alone of 19th century British locomotive engineers, found it worth-while to build compound goods engines. (T.W. Worsdell's Class C 0-6-0s were really what would in later years be called mixed-traffic engines.)

... but remember that all four Grouping era companies produced multi cylinder and twin cylinder simple expansion locomotives for all types of traffic, including the former LNWR and BR would standardise on the two-cylinder simple expansion type. 

[DavidB-AU]

5 minutes ago, rockershovel said:

Various railways built small numbers of 0-8-0, 0-8-4 and even 4-8-0 tanks for hump yard shunting. Only the GWR built 8 coupled MT tank locos, for their specialised local traffic in S Wales

 

But plenty of other examples elsewhere that show how they can be useful. Most of the Paris suburban railways had 2-8-2Ts prior to electrification, generally with relatively small driving wheels for fast acceleration with quite heavy trains. After electrification many became mixed traffic or goods locos outside the suburbs.

 

Another notable example is the DRG class 86 built for mixed traffic on branch lines and built in huge numbers  (over 700 of them) from the 1920s to 1940s. In West Germany they were used on short, semi-fast trains and for heavy shunting until 1974. The class leader built in 1928 survived in service right up until the official end of steam in East Germany in 1988.

 

Cheers

David

 

 

[ScottishRailFanatic]

All very good points raised, so here’s a new version! 
- 2-8-4T configuration

- Slanted water tanks

- Increased driver diameter 

- Coal capacity increase

- Same height buffers (thanks @BernardTPM!)

[ScottishRailFanatic]

Works Document 19/7/54: Fowler-style 0-6-0T

”A small but powerful mixed traffic 0-6-0T with some clear Fowler influence. Designed to assist with heavy work on major branch lines, but equally at home shunting. The lining scheme is strange, but will be altered during its first overhaul if it proves successful. May form basis for new Standard class if successful.”

[Compound2632]

2 hours ago, rockershovel said:

... but remember that all four Grouping era companies produced multi cylinder and twin cylinder simple expansion locomotives for all types of traffic, including the former LNWR and BR would standardise on the two-cylinder simple expansion type. 

 

Something one could hardly fail to notice. The operating conditions endemic on British railways were not such as to enable the best to be got out of compound engines, by and large. In France, with very long-distance runs (by British standards) at a steady rate of work (up hill and down at no more than the legal maximum of 75 mph) compounding came into its own. Webb was able to build compounds for 150-mile runs on the WCML but they could not be used to advantage when displaced onto secondary work as train weights increased. Had Gresley not died in office and had the war not intervened, perhaps the next step in development of ECML express locomotives might have been a Chapelon-inspired compound pacific.

[cypherman]

1 hour ago, ScottishRailFanatic said:

Works Document 19/7/54: Fowler-style 0-6-0T

”A small but powerful mixed traffic 0-6-0T with some clear Fowler influence. Designed to assist with heavy work on major branch lines, but equally at home shunting. The lining scheme is strange, but will be altered during its first overhaul if it proves successful. May form basis for new Standard class if successful.”

Hi, 

I think it is time for you to get a 3D printer and turn these ideas into reality. They look superb. The 2-8-4 could use a Hornby 8F chassis and the 0-6-0 could use a USA 0-6-0 chassis.

Edited July 28, 2021 by cypherman

[PhilJ W]

1 hour ago, Compound2632 said:

 

Something one could hardly fail to notice. The operating conditions endemic on British railways were not such as to enable the best to be got out of compound engines, by and large. In France, with very long-distance runs (by British standards) at a steady rate of work (up hill and down at no more than the legal maximum of 75 mph) compounding came into its own. Webb was able to build compounds for 150-mile runs on the WCML but they could not be used to advantage when displaced onto secondary work as train weights increased. Had Gresley not died in office and had the war not intervened, perhaps the next step in development of ECML express locomotives might have been a Chapelon-inspired compound pacific.

If Gresley had gone down the compounding route Stanier was bound to follow. Or for that matter if Stanier came up with a compound pacific likely as not Gresley would have followed suit. Then would have Bullied considered compounding for the West Country routes? Or Hawksworth for the Cornish routes?

[Compound2632]

46 minutes ago, PhilJ W said:

If Gresley had gone down the compounding route Stanier was bound to follow. 

 

Not necessarily. There were still plenty of people around who had first had experience of Webb compounds...

 

47 minutes ago, PhilJ W said:

Or Hawksworth for the Cornish routes?

 

Churchward had looked closely at the marvelous de Glehn compound atlantics and rejected the compounding aspect of the design, so I doubt it. Besides, I don't think any of the GWR routes really offered ideal conditions for a compound. Too much chopping and changing of the character of the line.

 

50 minutes ago, PhilJ W said:

Then would have Bullied considered compounding for the West Country routes? 

 

Now there's a lad who'd be game to try anything, whether or not it was appropriate to the operating conditions of his railway.