Your article on clinker was something I could relate to.
I’ve been a fireman on the Welshpool & Llanfair Rly for 21 years although my volunteering career started on the Ffestiniog Rly back in 1968.
A round trip on the W&L is 16 miles, the gradient profile is rather sawtooth with some steep climbs followed by a sharp change to a downhill section so route knowledge on the the fireman’s part is vital,as you found out there is no point arriving at a summit with a roaring fire, the fire has to be allowed to burn down before the downhill part of the journey.
Leaving Llanfair, all locos run in reverse to Welshpool,it s easy steaming for about the first 2 miles, then it’s build up the fire for the sharp climb up to Cyfronydd, level through the station, sometimes nonstop, then it’s all uphill to Castle Caereinion about another 2 miles away with a stop to flag the level crossing at Dolaryddyn, if things are not going according to plan this stop is useful to get the boiler pressure and water level back to where it should be. From Castle there s another sharp pull, 1 in 33, level, 1 in 33 to Coppice Lane crossing, then 1 in 38 down for a few hundred yards followed by easier grades to Sylfaen, a distance of about 3/4 of a mile. From Sylfaen it’s about 1/2 a mile on a 1 in 33 to 1 in 87 to Sylfaen summit, then all down hill to Welshpool Raven Square, some of it at 1 in 29.
We also use Welsh coal,when we started using it we were told to keep the rear damper open all the time, this usually prevents most clinker from forming. It also keeps the firebars cool. The fireman who burns out a firebar is not popular with the workshops. Running with the rear damper open is quite usual on the W&L if the fire has been built up, i.e. leaving Raven Square. Sometimes also opening the the front damper helps the fire to start burning. There’s no hard and fast rule, it depends on the quality of the coal – usually fairly good – and train weight.
Approaching Sylfaen on the outward run, the trick is to check the fire: it might need a few small lumps, boiler full for the pull up to the summit. If things are working well the boiler pressure should be dropping to about 140 psi from a maximum of 160. Mind you sometimes things go wrong and the train staggers over the summit with 110 on the gauge and the brakes leaking on (been there done that!). The iron or pricker is run through the fire on the downhill run to Welshpool as there might be a bit of clinker.
Returning to Llanfair on the downhill run from Castle to Cyfronydd, it’s always a good idea to keep an eye on the fire. If it burns down too much a few lumps here and there keeps the fire looking healthy. Leaving Cyfronydd, the grate is covered with a thin layer of coal for the easy run to Llanfair: not too much – don t want the loco blowing off! Just before Llanfair there’s a sharp pull up past Tanllan carriage sheds; easy to come unstuck here. This nearly happened to me a couple of months ago when a trainee driver was on the regulator. I was talking to the driver and let the pressure drop too much. We made it – just!.
The iron is run through the fire at Llanfair. There’s usually some clinker. It’s either punched through the bars or worked to the centre of the grate where it can be lifted out with the firing shovel.
This is all part of being a fireman. Every trip is different. That’s what makes it interesting!