Locomotive Performance and Tractive Effort Discussion

Maximum indicated horsepower depends on how much steam the boiler can produce (over some specified time period) and how efficiently the cylinders can use it. As the P2's boiler will be the same as Tornado's, its maximum output should be the same, unless the draughting of either is sub-optimal. The poppet valves may allow the steam to be used slightly more efficiently.

Going back to the Claughton, however, exactly the same philosophy could be applied as is being done for the P2. Build a new one, looking just like the originals but with a few design tweaks.

 

Indeed, a 350hp diesel shunter of class 08 has about the same starting tractive effort than an A4 …

Tom

 

There's always Big Bertha too!

 

Not this 'Bertha', one assumes...

 

No, 22290, later 58100! it once had to rescue the U1 when it died on the Lickey

 

All things being equal the amount of sustained output from these machines depends on how much energy coming from their identical grate areas is converted into steam by the boilers and converted into work by the engine. the big pro for the Duchess is its larger boiler may allow its output to exceed its input for slightly longer periods, The p2 may have a more efficient engine by virtue of its valve gear and draughting. A duchess may have its power 'sweetspot' at a higher speed, the P2 is less likely to loose its feet. But at the end of the day there isnt going to be much in it. Cant think that i have seen anything anywhere that suggests Tornado's boiler is an outstanding steam generator compared to say a Merchant or the Duke...

 

The quality of the exhaust system is more important when all other factors are nominally equal. You point out the steam generation of Tornado and there is nothing to suggest that it cannot equal a MN, Duke or Princess Coronation if required to do so. The smaller boilers and significantly superior outputs of the French Chapelon compound Pacifics should tell you that improved SSC can easily overcome superior evaporation.

 

Child memories! Thanks for posting it Green Howards.

Knut

 

If i`m correct there was a similar statement in steam railway about the B.R. standard Clan class.

 

I would have suggested that the South African Garratt in the Manchester museum is the most powerful loco in the UK at present.

 

Is it operational?

 

Nope. Stuffed and mounted as the saying goes.

 

It was a rhetorical question, to be fair - I saw it there twenty years ago so it's largely a moot point as to how powerful it is.

Serious question: do we have facilities to test the power output of locomotives any more? I'm assuming we wouldn't be shoving people in a wooden box in front of the smokebox these days.

 

Whereas the old dynamometer cars contained complicated mechanical gubbins, with modern instrumentation it shouldn't be too hard to install the necessary bits in an otherwise normal support coach. However I'm not sure how you could ensure that the tension in the coupling represents exactly the TE from the loco and no extra force countering residual pressure between the buffers.

 

A steam engine indicator measures the position of the piston and the pressure in the cylinder. The two values are drawn onto a graph the graph line forms a loop. The power being developed is calculated from the area enclosed by the loop.

If we wanted to do the same thing today we would fit pressure and position transducers to each cylinder to be indicated. They could probable be linked by wireless to a laptop. I expect the results recorded on a spreadsheet and the graph and input produced from this.

I wonder if the men in the indicator took any other readings?

Sent from my SM-A105FN using Tapatalk

 

I've done a bit of engine testing in a former life, admittedly internal combustion and not steam, but similar principles apply. It might not be realised that you can indicate a petrol or diesel engine, two- or four-stroke, but the results look very different to a steam diagram.

 

I’d be quite interested if they’d taken regular heart rate readings!

Tom

 

I think it was H.G. Ivatt who discovered that he could happily smoke a pipe with his head above the top of the indicator shelter, because the bluff front typical of the classes he was on meant he was standing in a large stagnation region in the airflow. So I suspect his heart rate was reasonably under control.

 

They had such a lax attitude to health and safety in those days. Can you imagine nowadays being allowed to smoke while at work!

Tom

 

I don't know, some of the vapers I've seen would have people reporting significant front end steam leakage...