Modelling the 1840s in HO

Cramptons were peculiar, in that they had longitudinal frameseither side of the wheels, and the carrying wheels were individually sprung off these  frames without compensation, but the drivers had a transverse spring on the top of the boxes, and the middle of this was mounted on a bracket riveted on the backplate of the boiler. I suppose you could say this gave a bit of compensation. I tried to make one a while back, you had to do it very different from any other loco, but I’m afraid the outside valve gear beat me.

3 hours ago, Nearholmer said:

The Crampton question might boil down to weight-distribution and, therefore, adhesive weight and tractive effort. ...

 

Thanks, Nearholmer and Northroader, the weight / springs / adhesion points are very interesting. A lot of the weight did fall on the Norris's driving axle, which helps explain the design's good performance on demanding gradients. 

So considering Pacific231G's point, were early French lines generally less demanding in their requirements than British ones, I wonder? (Other than the very steep St Germain line with Samuda's atmospheric system, of course.)  I've always assumed they were pretty similar, but that's just my lazy assumption because the same engineers, like Locke, were laying them out.   

Edited February 22, 2019 by Ian Simpson

I’ve seen several references to The American type 4-4-0 being directly derived from the Norris type 4-2-0. The Norris isn’t really much like the Crampton at all, with its leading bogie, firebox behind the driving axle and internal bar frames. 

 

I find that Bury locomotives also had bar frames, but their internal cylinders were never an American design feature - I’m not surprised that Bury’s case for patent infringement failed in the courts. 

Edited February 24, 2019 by rockershovel

On ‎22‎/‎02‎/‎2019 at 18:45, Nearholmer said:

...  The Norris looks to me as if it would naturally want to load the driven axle, and that it would be a matter of careful design, around the exact position of the driven axle, to get sufficient mass onto the bogie to allow it to undertake its steering function.

 

Views?

I'm not sure how Norris managed to get enough weight on the bogie. But I've just read something moderately interesting about the way he distributed weight between the different wheelsets. He arranged the connecting bar between the loco and the tender at an angle, so that it rose upwards towards the loco end. This created a downwards pull at the back of the loco, putting extra weight on the driving wheels. (From P J Long and Rev W V Awdry's 1987 book The Birmingham and Gloucester Railway.) 

On 22/02/2019 at 20:00, Ian Simpson said:

 

Thanks, Nearholmer and Northroader, the weight / springs / adhesion points are very interesting. A lot of the weight did fall on the Norris's driving axle, which helps explain the design's good performance on demanding gradients. 

So considering Pacific231G's point, were early French lines generally less demanding in their requirements than British ones, I wonder? (Other than the very steep St Germain line with Samuda's atmospheric system, of course.)  I've always assumed they were pretty similar, but that's just my lazy assumption because the same engineers, like Locke, were laying them out.   

Sorry for the long delay in responding to this.

I agree that Norris's adoption of a 4-2-0 wheel arrangement to cope with roughly laid American track on the three legged stool principle was for totally different reasons than Crampton's and led to the classic  "American"  4-4-0 arrangement.

 

Apart from the very early St. Germain* and other Paris local lines I think the major difference was always the generally longer runs between population centres in France often on relatively flatter ground. That probably made continuous running at speed more important than accelaration (which also led later to a greater interest in compounding by French loco engineers)  

Crampton had of course been a GWR engineer and, while working with Gooch on his successful large driving wheel broad gauge loco, conceived the idea of getting the same broad gauge advantage of stability at speed on standard gauge railways by achieving a low centre of gravity with a large driving wheel. The reasons why his locos were more successful in France and Germany than in Britain may though have been as much to do with his general understanding of the value of larger steam passages, heating surfaces and bearing surfaces, as to his actual patented wheel arrangement.

 

France's early railways did draw very heavily on British engineering as evidenced by their running on the left and  widespread use of double champignon (bullhed more or less) chaired track.  However, quite apart from the Brunels,  it was by no means a one way traffic  The multiple tube boiler was invented by Marc Sequin in 1828; the  mechanical semaphore (and the name) was developed by Claude Chappe but Britain's railways came to adopt a simplified system of moving arms for almost all its signalling.

 

Ironically, France's use of rotating targets for most signals, seen as very foreign by many British observers, actually came from the GWR. In 1843, The Paris-Orleans simply adopted Brunel's disk clear and crossbar danger signal (I think their engineer had come from the Great Western). In 1845 Benoit Clapeyron, in charge of traffic on the St. Germain and Versailles line modified it to a simple red disc that was presented as a stop signal for five minutes after the passage of a train then rotated to not face the driver when the line was considered free. The "disque"  was widely adopted by othe railways (though its meaning changed as other targets were introduced)  though the PLM had a very British looking three position semaphore (danger, caution, clear) until 1885 when a national signalling code was adopted  and movonmg arm signals were confined to direction indicators and sémaphores which are non absolute block signals. 

 

*The St. Germain line, France's first steam hauled and passenger railway, was fairly flat without undue curves from St. Lazare to its original terminus at le Pecq. The limited power available to early locomotives meant that the final two kilometres up to St. Germain itself, requiring a curved route with a 3.5% gradient, was only made possible by using Samuda's atmospheric system which could haul a train up the gradient at 35km/h (return  was by gravity) . The extension opened in 1847 and, with the odd glitch, operated satisfactorily for twelve years as an atmospheric railway until more powerful locomotives became available. Even then, trains had to banked up the gradient until electrification of the line was completed in 1927.  I've always thought that the successsful use of atmospheric power on this  line gives the lie to the popular view that it was Brunel's great folly. Brunel was not though a good locomotive engineeer so may have underestimated how rapidly the development of steam locomotives would make it obsolete.

 

 

Edited March 25, 2019 by Pacific231G

12 hours ago, Ian Simpson said:

I'm not sure how Norris managed to get enough weight on the bogie. But I've just read something moderately interesting about the way he distributed weight between the different wheelsets. He arranged the connecting bar between the loco and the tender at an angle, so that it rose upwards towards the loco end. This created a downwards pull at the back of the loco, putting extra weight on the driving wheels. (From P J Long and Rev W V Awdry's 1987 book The Birmingham and Gloucester Railway.) 

 

I would have thought that having the weight of the bogie itself, the front of the boiler, smokebox, cylinders and valve chests would do the trick... the piece about the angled drawbar tends to suggest that given the low overall weights and slow speeds, the 4-2-0 type would stand all the weight that could be brought to bear, and pretty much look after its own weight distribution..

 

Thanks for such a full and fascinating post, @Pacific231G  It really deserves a much wider audience than the handful of people reading my blog. The distance-between-towns explanation seems very reasonable to me!  And I agree the atmospheric system was more successful than we often remember today. 

 

@Rockershovel, that's a good point about the weight distribution of Norris's design taking care of itself. As Pacific231G pointed out, the 4-2-0 arrangement is basically a three-legged stool if you are using a leading bogie. Norris's concept was widely copied by other US builders. I wonder if the reason British engineers didn't do the same was the poor performance of the Birmingham & Gloucester own Norrises, which as far as I can see had nothing to do with their wheel arrangement and everything to do with their inappropriate materials for British conditions and with the inexperience of the British enginemen.         

 

Edited March 26, 2019 by Ian Simpson

I would expect that the reason British builders didn’t take to the Norris type, was that its principal advantage - the ability to cope with poor, lightweight track - was of little advantage in the U.K. 

 

British tracklaying and permanent way practices seem to have been quite high from the outset. High population density, short distances and an established culture of foundry work and engineering canals seem to have carried over into the nascent rail sector. American lines needed to cope with long distances, shortages of labour and engineering materials of all descriptions, and did what they needed to do to cope with that situation. 

 

Fair point, @rockershovel After all, the B&GR wouldn't have bought them if it hadn't have the Lickey to contend with. 

2 hours ago, Ian Simpson said:

Thanks for such a full and fascinating post, @Pacific231G  It really deserves a much wider audience than the handful of people reading my blog. The distance-between-towns explanation seems very reasonable to me!  And I agree the atmospheric system was more successful than we often remember today. 

 

@Rockershovel, that's a good point about the weight distribution of Norris's design taking care of itself. As Pacific231G pointed out, the 4-2-0 arrangement is basically a three-legged stool if you are using a leading bogie. Norris's concept was widely copied by other US builders. I wonder if the reason British engineers didn't do the same was the poor performance of the Birmingham & Gloucester own Norrises, which as far as I can see had nothing to do with their wheel arrangement and everything to do with their inappropriate materials for British conditions and with the inexperience of the British enginemen.         

 

Thanks Ian

I've always understood that the three legged stool principle applied equally to the American 4-4-0 type familiar from hundreds of Westerns*. It surely must have done for them to stay on the apalling track originally laid by the UP.  I don't know whether 4-6-0s built on the same principles retained the same ability to handle rough track.

 

*The locos starring in Westerns were often one of three Virginia & Truckee 4-4-0s Nos 11, 18 & 22, bought by Paramount, MGM, and RKO between 1937 and 1947 (they also bought V&T no 25 a Baldwin 4-6-0)  However, the single loco that seems to have appeared more often than any other has been  Sierra RR no 3, a Rogers 4-6-0 that has appeared in over 300 movies and TV shows from the original High Noon  to Petticoat Junction. The Sierra RR had unusually short carriages which is often a giveaway. 

Earlier “American” type 4-4-0s sometimes had flangeless front drivers, so as to assist negotiating sharp curves and preserve the “three legged stool” characteristic.