Steam experts - help required

[37705]

Many years ago (1989 to be exact), I went to the Mid Hants steam gala where M7 no. 245 was one of the visiting locos. At some point after the event, I was told that the loco for some reason had only been in light steam, and in effect, had had no real involvement in hauling any of the trains during the day. It was double heading all day with one of the Mid Hants residents, and I was led to believe that the other loco was effectively pushing the M7 along, as well as pulling the train. As a result, I could not claim the loco for haulage.

Somebody else recently told me that, even with a loco in light steam, it still has enough power to start a train, haul a train and stop a train, and that, in effect, both locos on the train can be thought to be working.

Is this true?

 

[960012]

It all depends on how much boiler pressure there is as to whether or not it could provide a helping hand.

I would think that it would have been running on reduced pressure, but would have still been able to pull trains and that it was paired with another engine as a form of insureance. I dont see why they would have steamed it just for show, i would hazard a guess what it was indeed helping in the effort of moving the train.

A similar thing what does with 4771 Green Arrow, they ran with another engine on the back of the train as 4771 was running on a reduced pressure on its last day.

Hope this is of help.

 

[E&W Lucas]

I think this is a superb demonstration of what happens if you loisten to armchair experts standing on the end of platforms!

Light steam is one of those expressions beloved of enthusiasts, that has no real meaning, but I presume you mean just a token pressure?

Without going into this too deeply, was the M7 the leading engine at any point? If so, she had to be creating vacuum. Vacuum ejectors will not work too far below the working pressure, and it is forbidden to have any other loco's ejector turned on. I suspect in this case that a more powerful engine was required to haul the train.

The V2 was hardly a case of "light steam". For the final trip, she was reduced to 160 psi. She'd just about cope at that - essentially, that's borderline for creating a brake with most engines, and you'd regard that as being a "problem situation" normally. However, it made a lot of sense to top & tail that train as an insurance. You don't want a failure trashing your timetable.

Best advice is if you want to learn about steam, go and get stuck in somewhere!

 

[37705]

Yes, the M7 was leading for at least half of the day - unfortunately, the only photos I got of it on the day were both on southbound trains, so I don't know if it was run round individually at Alresford to lead as well on northbound trains. The train I travelled on with it at the front was a southbound working.

My other recollection was that the loco was on loan, was claimed to be "a bit delicate", so couldn't do anything other than be operated in "light steam", but I had been to the Mid Hants 5-6 weeks before, and it was in the yard even then, so it does seem a bit strange for a loco to visit a railway only for them to not run it "properly". It's a shame nobody else who was there 21 years ago can add to this story!

 

[E&W Lucas]

Working an engine "lightly", because it's in a bad way is one thing.

You cannot operate an engine in "light steam". Injectors will not function (ie you will not be able to put water in the boiler!!), cylinder lubrication will not happen, you will not beable to create vacuum, and if the engine is fitted with a steam brake, you will not be able to stop! Hopefully, the above list shouldprovideyou with enough evidence that this loco would have been properly in steam, even if it wasn't being especially taxed.