Running a steam loco on a 1/30 grade - does it have to be chimney first?

[enz]

And so a question on locomotives going uphill morphs into a discussion on trains going downhill.  I know thread drift is a thing, it's the sheer opposite of theme that amuses me and I can't help but remark on it.

 

- E

[Hal Nail]

12 hours ago, enz said:

I know thread drift is a thing, it's the sheer opposite of theme that amuses me and I can't help but remark on it.

It always helps on here if you already known the answer to your question, then you can ignore the misleading replies!

[LMS2968]

12 hours ago, enz said:

And so a question on locomotives going uphill morphs into a discussion on trains going downhill.  I know thread drift is a thing, it's the sheer opposite of theme that amuses me and I can't help but remark on it.

 

- E

There is a relationship between the two scenarios: going uphill tender first or downhill chimney first. The same gradient will have exactly the same effect on the water level over the firebox. The fact that the engine might* not be working downhill is irrelevant with a big fire aboard happily scorching the crown sheet above.

 

In any case, the engine might have to be worked downhill: one reason is too many wagon brakes pinned down as already described, but even in ordinary running the driver will try to keep the couplings taut on the downhill section to avoid a snatch when he reaches the next uphill one and has to open up.

[rodent279]

14 minutes ago, LMS2968 said:

There is a relationship between the two scenarios

Uphill is only downhill backwards......

[TEAMYAKIMA]

As the OP on this, my only/main concern was if I ran my USA tank bunker first up my 1/30 gradient on my exhibition layout there would be chuckles/sniggers from the viewing public - or at least from 5% of them, the 5% who know about stuff!

 

I think that I have learnt enough from this thread now to be able to justify such a movement if/when the chuckles/sniggers surface.

 

Thanks to everyone who has contributed.

[kevinlms]

On 19/01/2023 at 23:55, LMS2968 said:

The Lickey certainly had its own rules for gradient working not found anywhere else, such as three or four bank engines coming on the back separately, never coupled together, all carrying a head and tail lamp, and all dropping off independently at the summit. I'd be surprised if they pinned the brakes down with the train stationary though: if enough were pinned down to hold a constant speed on a 1:37.7 gradient, it's going to be a lot of fun getting them rolling again on a fairly level stretch at the top.

I believe that unfitted freight trains DID require stopping at the top, the required number of brakes applied, then the train restarted down the hill. At the foot the train required stopping again, to take all the brakes off.

 

"Descending trains were never accepted unless the line was clear as far as Bromsgrove South, and were strictly required to slow to 10 mph (16.1 km/h) at the top and not exceed 27 mph (43.5 km/h) on the way down. Loose-coupled freight trains had to stop at the top to apply wagon brakes and not exceed 11 mph (17.7 km/h)."

 

From https://en.wikipedia.org/wiki/Lickey_Incline#Operation_in_steam_days

 

My understanding is that with the two stops, these trains took longer to descend the bank, than to go up!

[The Stationmaster]

45 minutes ago, kevinlms said:

I believe that unfitted freight trains DID require stopping at the top, the required number of brakes applied, then the train restarted down the hill. At the foot the train required stopping again, to take all the brakes off.

 

"Descending trains were never accepted unless the line was clear as far as Bromsgrove South, and were strictly required to slow to 10 mph (16.1 km/h) at the top and not exceed 27 mph (43.5 km/h) on the way down. Loose-coupled freight trains had to stop at the top to apply wagon brakes and not exceed 11 mph (17.7 km/h)."

 

From https://en.wikipedia.org/wiki/Lickey_Incline#Operation_in_steam_days

 

My understanding is that with the two stops, these trains took longer to descend the bank, than to go up!

It is often the case - even well into the diesel age - that with loose coupled freights (and partially fitted ones as well) more time would be allowed for descending than ascending steep inclines. Ii've just done a quick comparison for Radipole Bank and descending Class J  loaed coal trains were allowed as much as 7 minutes longer than Class j (empty coal wagon) trains climbing the bank.  The steepest section was a mile at 1 in 50 plus about half a mile at 1 in 52 and a similar section at 1 in 74.

 

We hada similar situation on one of my patches on South Wales where descending trains had to stop both at the top of the incline and the bottom to allow the Guard and the Bank Guard to apply/release wagon brakes.  Train ascending the bank didn't need to stop at all.

[Right Away]

Purely out of interest, here’s an old image of a “Battle of Britain” tender first, climbing the 1:30 from Folkestone Harbour in 1950 on what was purported to be a trial run (inspector on footplate); there is no mention of how many R1s were shoving at the rear.

With the Pacific’s long boiler blowing off at 280lb/sq in, it must have been a very delicate balance to avoid dropping a plug yet not letting her prime!

 

(Light Pacifics worked regularly “right way round” down the 1:36 into Ilfracombe, the station being almost at the foot of the gradient.)

 

Edited January 22, 2023 by Right Away
no correction

[LMS2968]

The propensity to prime would be influenced by the point along the boiler / firebox where the steam was collected. This was usually from a dome more or less central or only slightly offset towards the smokebox, so the change of level at the ends would be less marked at that point. Many early engines had a dome immediately behind the smokebox or collection was from the top of a raised firebox, which might make a difference but they were generally pretty high with a large gap down the the water. GWR and domeless LMS boilers used an upwards-pointing funnel arrangement with admission holes along the top face; this was immediately ahead of the firebox and high up in the barrel so possibly subject to priming if working uphill chimney first. I can't say I recall any actual complaints though.

[TheSignalEngineer]

I think bringing a bit of geometry into the discussion is appropriate. The loco shown in the OP is an S100 clone. Looking at the S100 GA drawing the plug is at the highest point of the firebox which is only about 3ft behind the centre of the fixed wheelbase. The latter is effectively the pivot point of the boiler when on a gradient. This means that the plug will move up or down by approx 1.25 inches on your gradient. The firebox top slopes down towards the back, so going downhill chimney first it will become closer to level. 

On the S100 drawing the lowest indication of the gauge glass is quoted as 3 inches above the highest point of the firebox. That would be over 100% safety margin before the plug is uncovered.

In that case there should be no problem going down chimney first as long as the water is visible in the glass when on the level.

Edited January 27, 2023 by TheSignalEngineer
Typos