Imaginary Locomotives

[Johnson044]

The trailing wheels have balance weights to balance the coupling rods, the experimental locomotive being a withdrawn 2-4-0.

 

Well - yes - but somehow, with all the facilities of Crewe at hand and presumably lots of material from withdrawn locos around somehow I expected FW to have ensured the wheels were balanced- hence my comment on balance weights- I was completely wrong about my suggestion that wheels from a Bloomer might have been re-cycled as @ 6' 6" even those from the Small Bloomers were way too big. Looking at the photo closely you can just see the curve of the crank webs disappearing under the footplate valance at the top. Both driving and trailing wheels are perfectly aligned, almost as if they still had the rods attached, which is curious - when I first saw the photo I thought there were wheels without crank webs.

 

I wonder how the linkage would have worked? Was there a similar idler wheel on the other side? We shall probably never know,and in the overall scheme of things it really ain't important. 

 

[Compound2632]

1 hour ago, Johnson044 said:

The trailing wheels have balance weights to balance the coupling rods, the experimental locomotive being a withdrawn 2-4-0.

 

Well - yes - but somehow, with all the facilities of Crewe at hand and presumably lots of material from withdrawn locos around somehow I expected FW to have ensured the wheels were balanced- hence my comment on balance weights

 

Ah, but economy was the watchword.

[DCB]

1 hour ago, Johnson044 said:

The trailing wheels have balance weights to balance the coupling rods, the experimental locomotive being a withdrawn 2-4-0.

 

Well - yes - but somehow, with all the facilities of Crewe at hand and presumably lots of material from withdrawn locos around somehow I expected FW to have ensured the wheels were balanced- hence my comment on balance weights- I was completely wrong about my suggestion that wheels from a Bloomer might have been re-cycled as @ 6' 6" even those from the Small Bloomers were way too big. Looking at the photo closely you can just see the curve of the crank webs disappearing under the footplate valance at the top. Both driving and trailing wheels are perfectly aligned, almost as if they still had the rods attached, which is curious - when I first saw the photo I thought there were wheels without crank webs.

 

 

 

What Crewe would not have had on the scrap pile by this date was driving wheels without balance weights, the trailing wheels on a straight axle seem to have had weights to balance the coupling rods which were not fitted,   They may have had counter balance weights fitted to compensate for  the lack of coupling rods or someone may well have thought "This is a bloody stupid idea" and chucked any old bits from the parts store/ scrap yard together. 

The idea had huge potential, for wearing flats on the trailing wheels if nothing else but with the problems of the very long coupling rods then coming into service it was probably worth a punt.  I am just amazed he stopped when it proved unsuccessful. But of course it actually led to many thousands of German H0 mechanisms with the same idea only using gears behind the wheels instead of rollers on the tread.  Thank heavens Webb never thought of using gears, or if he did nobody actually got round to trying them on the main line.   Maybe someone could build an 00 (or P4) Webb style Gear driven 0-8-0. or is it  0-2-2-2-2-0(?) in shop grey to bamboozle the experts?

[Compound2632]

22 minutes ago, DCB said:

Thank heavens Webb never thought of using gears, or if he did nobody actually got round to trying them on the main line.   Maybe someone could build an 00 (or P4) Webb style Gear driven 0-8-0. or is it  0-2-2-2-2-0(?) in shop grey to bamboozle the experts?

 

They would have to be gears that could be disengaged once the engine was underway. Webb had very good reasons for omitting the coupling rods from the 3-cylinder compounds, if one looks at the question from the point of view of the technological limitations of the day. Webb was faced with the challenge that heavier expresses running at higher speeds required very much greater power but this had to be achieved at reasonable cost. He wanted much larger grate area than previously; this could only be achieved by increasing the "coupled" wheelbase. But long coupling rods were a challenge given the metallurgy of the day - they had to be of greater cross-sectional area, and hence increased mass, increasing the hammer-blow on the track... Also, machining tolerances, even at Crewe, were such that coupling rods introduced considerable friction (and consequent lubrication challenges) - a loss of energy that could otherwise have gone into moving the train. 

[tythatguy1312]

55 minutes ago, DCB said:

Thank heavens Webb never thought of using gears, or if he did nobody actually got round to trying them on the main line.   Maybe someone could build an 00 (or P4) Webb style Gear driven 0-8-0. or is it  0-2-2-2-2-0(?) in shop grey to bamboozle the experts?

Fortunately Webb was trying to design innovative compound locomotives, whilst geared locomotives of the day were honestly too slow even for most slow goods work. That was both good AND bad, limiting them to heavy shunting or logging work in America, albeit whilst able to start trains that would be too heavy for some Garratts. Given that Webb would've definitely heard of them, I believe he wrote the idea off due to that issue. Even with the obvious increases in power for his 0-8-0's, I doubt such a machine has any hope of exceeding 20mph, when most unbraked goods trains in the UK achieved 35.

Edited May 4, 2022 by tythatguy1312

[JimC]

3 hours ago, Johnson044 said:

Well - yes - but somehow, with all the facilities of Crewe at hand and presumably lots of material from withdrawn locos around somehow I expected FW to have ensured the wheels were balanced-

 

I hunted out some other photos of the Samsons. Most have coupling rods down, but on the others it seems to me evident that the tiny balance weight on that locomotive is far smaller than they were on the coupled locomotives. Just big enough to balance the off centre crank web perhaps?

[Johnson044]

6 minutes ago, JimC said:

I hunted out some other photos of the Samsons. Most have coupling rods down, but on the others it seems to me evident that the tiny balance weight on that locomotive is far smaller than they were on the coupled locomotives. Just big enough to balance the off centre crank web perhaps?

I think that makes sense in theory as he balance weights don't seem to be integrally cast- however, neither do they seem to be diametrically opposite the crank webs - it's difficult to tell. The more I think about it I reckon Compound2632 is right and economy prevailed. They just fitted a pair (or maybe just one?) of idlers to an unfortunate Samson without coupling rods and gave it a whirl. When the poor old thing came to a wheezing halt in a flurry of tortured metal FW called it a day.

[JimC]

2 hours ago, Johnson044 said:

The more I think about it I reckon Compound2632 is right and economy prevailed.

In that case may I challenge one of you to produce an image of 4-4-0 trailing wheels with balance weights as small as that:-) I didn't think there was a chance of that tiny weight doing anything useful vis a vis a coupling rod, but was successfully proved wrong a couple of posts down!

Edited May 4, 2022 by JimC

[Johnson044]

I don't know if LNWR balance weights were just iron segments bolted between the spokes? Maybe they just removed one segment so that having removed the coupling rod the crank web / boss was still balanced? Who knows.

 

 

[Jeremy Cumberland]

Photos of Samsons with the coupling rods up seem to be rare beasts on the interweb, but I've found this one, from http://www.lnwrs.org.uk/Mystery/index.php?display_base_mystery_mobile=235:

 

Here, the rear wheel counterweight looks to me to be exactly the same as on 757, but has to balance the coupling rod and crankpin as well as the boss. From this, my guess is as others have surmised, that the engine is just a Samson with the rods removed and a friction wheel fitted.

[JimC]

Another observation is that they appear to have simply removed the brakes rather than create a new arrangement. So may we guess the idler wheel is one side only and this was a very quick and dirty short term experiment?

[cctransuk]

9 minutes ago, JimC said:

Another observation is that they appear to have simply removed the brakes rather than create a new arrangement. So may we guess the idler wheel is one side only and this was a very quick and dirty short term experiment?

 

If the coupling rod on the other side also remained in place, it might explain why the driving wheels have remained in sync.

 

Perhaps just a quick experiment to see if the principle was mechanically viable?

 

CJI.

[Jeremy Cumberland]

7 hours ago, JimC said:

Another observation is that they appear to have simply removed the brakes rather than create a new arrangement. So may we guess the idler wheel is one side only and this was a very quick and dirty short term experiment?

I think the photo I posted is the only one I've seen of a Samson with loco brakes. They only had tender brakes, as was common at the time. This must be quite a late picture (20th century), with the locomotive in Engineer's use, as you will see from the discussion on the linked web page.

[Compound2632]

19 hours ago, JimC said:

In that case may I challenge one of you to produce an image of 4-4-0 trailing wheels with balance weights as small as that:-) I didn't think there was a chance of that tiny weight doing anything useful vis a vis a coupling rod, but was successfully proved wrong a couple of posts down!

 

Remember that the Samson was a tiny engine compared to any 4-4-0 you may be thinking of, a design dating from the 1860s. With the short coupled wheelbase, the coupling rod was not particularly massive, so not so much weight needed to balance it.

 

16 hours ago, JimC said:

So may we guess the idler wheel is one side only and this was a very quick and dirty short term experiment?

 

That would, surely, be a mechanical disaster? One buckled rod the moment the intermediate wheel was disengaged; the excessive twisting force on the rear axle would probably do for the frames, too.

 

The experiment is described in a little more detail in the caption to the photo in E. Talbot, An Illustrated History of LNWR Engines (OPC, 1985), basically confirming that it was an investigation into combining the free-running properties of a single with the starting adhesion of a coupled engine.

[RedGemAlchemist]

On 02/05/2022 at 15:46, Johnson044 said:

Not sure which thread to post this. Imaginary Locomotives possibly not quite right because it actually existed - but it's pretty wild - this is a new one on me. I've seen an image of an American friction drive loco before but never come across one tried in the UK. Is it just me or is this completely bonkers? I completely see the logic and the difficulty of using gears but rather thought that friction was something to be avoided.

It was a concept, and you won't know if it works if you don't at least test it.

 

On 02/05/2022 at 18:53, rockershovel said:

As ever, Mr Self appears to have something to offer on the subject 

 

http://www.douglas-self.com/MUSEUM/LOCOLOCO/friction/friction.htm

 

I've also seen another loco using the "friction wheel to provide occasional extra drive" but I'm unable to find any details. 

I swear that Douglas Self wills these things into existence by writing about them. There can't be that many bonkers ideas out there.

[PhilJ W]

4 hours ago, RedGemAlchemist said:

I swear that Douglas Self wills these things into existence by writing about them. There can't be that many bonkers ideas out there.

There's probably more than you could ever imagine.

[Johnson044]

It was a concept, and you won't know if it works if you don't at least test it.

 

Absolutely! And the world would be a poorer place without these endeavours. 

[Flying Pig]

14 hours ago, RedGemAlchemist said:

It was a concept, and you won't know if it works if you don't at least test it.

 

I swear that Douglas Self wills these things into existence by writing about them. There can't be that many bonkers ideas out there.

 

There's something very Quantum about that notion and it could equally well be argued that they don't exist until you view the web page. You clearly have a lot to answer for.

[Johnson044]

There can't be that many bonkers ideas out there.

 

Oh I can assure you there are!

[tythatguy1312]

42 minutes ago, Johnson044 said:

Oh I can assure you there are!

In theory, the limits of wild locomotive proposals are limited only by whether they can be realised in any form. Ultimately, the number could be near-infinite, however despite that I'm still left wondering how the Diesel Pneumatic locomotive was among those few realised. Alas, in practice, it was better than its appearance implies and even I'm not blind to that.

Edited May 6, 2022 by tythatguy1312

[Corbs]

I still cannot believe a real locomotive was built with flat-edge wheels rather than round ones.

[rockershovel]

8 hours ago, Flying Pig said:

 

There's something very Quantum about that notion and it could equally well be argued that they don't exist until you view the web page. You clearly have a lot to answer for.

Sounds rather Pratchett-esque. Doesn't one of the Discworld books have a running joke about things coming into existence that way? 

[Johnson044]

11 minutes ago, Corbs said:

I still cannot believe a real locomotive was built with flat-edge wheels rather than round ones.

I heard a tale about a class 37 that took a heavy troop train down the Folkestone harbour branch in the '70's or '80's and the loco was stranded at the bottom until it could be re-wheeled / re-bogied in-situ because the tyres had developed such flats on them due to the sliding along the rails, so if true it definitely had flat edged rather than round wheels!

[tythatguy1312]

16 minutes ago, Corbs said:

flat-edge wheels rather than round ones.

hey, the theory was sound. Well "sound" to the kind of person Holman was aiming to swindle with this thing

[Johnson044]

The German Diesel Pneumatic loco could be Anglicised, maybe using a BR standard as a basis...