This page is to provide an overview for cleaners and firemen of the technical details required to perform their tasks on the B12 without embarrassment!
Locomotive Background
The flagship locomotive of the North Norfolk Railway was built in 1928 as part of the last batch of 10 B12/2 locomotives, by Beyer Peacock in Manchester. They were all rebuilt during 1932 - 1944 to enlarge the boilers and replace the original Belpaire fireboxes with round-top boxes, and this variant was termed B12/3.
These B12/3s were the most powerful and longest lived of the class and survived until 1961 hauling services between Norwich and Cromer. B12/3 number 61572 was the last to be withdrawn, on the 20th September 1961, almost two years later than other B12s. It was stored at Stratford prior to purchase by the M&GN JRS in 1963.
She currently appears on the NNR in LNER apple green livery, carrying LNER number 8572.
Notes for Cleaners
Design work on the GER S69 class locomotives (become the B12 under LNER) started in 1908 so it is no surprise that the locomotive shares little of the relative sophistication of the WD or the BR Standards. It does have a drop grate - or at least, part of the front grate drops - but it is so difficult to get it back into position that it is not used. Therefore, the grate is cleaned by climbing into the box with a brush, a torch and a jemmy, protected with a dust mask, and removing a few firebars.
There is ashpan is fixed and is cleaned through the dampers.
The ashpan is situated over the middle axle and as such has to be cleaned from both ends. This is the front - open the damper to swab down and rake out the ash, taking care to wash the ash off the hump over the axle:
This is Fireman Tony cleaning out the rear of the ash pan - notice that it faces the front and you will have walked under the front damper to get to it - do the rear first if you don't want to get wet, and make sure the person operating the dampers knows what you want opened and when - you don't want the front opened when you are cleaning the back, or you will get water or hot cinders down your neck.
Fireman's Controls
The fireman's controls are very traditional, but as usual there are a few things to be aware of.
Note the driver's side injector steam valve is right under the regulator handle - you will get in the drivers way when you operate it. Note also the position of the blower valve - protect your hand when you use it, it gets hot.
The steam heat valve is in the middle of three brass wheels on top of the boiler:
Fireman's side injector water valve - this is actually an exhaust steam injector, though the exhaust is not piped in. The valve on the left is the water valve, though you don't need to use it as the B12 has an automatic water valve on this injector - the handle on the right trims the combining cone:
This is the drivers side - isolation valve on the right. The valve on the left is there to allow you to close off the injector overflow - doing this allows water to pass directly from the tender tank to the boiler, and was used to fill the boiler by gravity. It is actually one to be wary of - it is loose, and will rattle closed.
This is one of the injector steam valves. Beware the square headed valve above the wheel - it is a stop valve which stops the water on it's way into the boiler. When you dispose the locomotive, you have to shut these two valves and if you forget to open the square one, you will be panicking and wondering why there is no water going in. The purpose of these valves is to close up the boiler, which prevents leaks and allows you to service the clack (the big hex nut) with pressure in the boiler.
Lighting Up
The big issue with the B12 for most inexperienced fireman is the length of the firebox. There's 8' between the firehole and the tender coaling plate, and the box is about 8' long so the front of the box is a long way from the coaling plate. It pays when you are lighting up and the flame scoop is out to make sure the front is well covered.
Secondly, where the drop grate starts over the middle axle the grate starts to slope downwards, and it is easy to leave a hole here - in fact, whilst you can fire the front with sufficient energy in your swing, getting coal part way down the box is a lot more tricky - you need it all covered.
Having said that, the B12 has large dampers and once it is covered it will light easily with sufficient wood and rags. Be wary if it is cold - too thick a fire will result in an hour of thick smoke belching from the fire hole.
Firing the B12
The B12 grate is relatively level at the back, but a third of the way along from the front it slopes downwards sharply. At one time, this portion of the grate dropped for cleaning the fire. The best way to fire this loco is to create a level fire - that is, with the sloping section at the front filled up, and run it with the front damper closed. You can control the fire with the rear damper, and if you want it to remain cool the middle third of the grate can be allowed to thin and go to holes - this will steady the pressure at about 150 psi if you maintain a thick thermal mass at the front. Keep the back relatively full to provide constant heat around the foundation ring. When you are building the fire ready for the next run, top up the front and back, fill in the sides and when you want to make steam quickly, fill the middle in.
Difficult bits - as I said, front corners... the 'between frames' box is narrow and easy to fire to the sides but when the flame scoop is in you really need to concentrate on your aim - look at the grate below the firehole as you start your swing and hopefully you will be rewarded with the sound of the coal hitting the front. If you don't make it, you will start a hole forming at the front, cold air will come in, the boiler pressure will start to drop and you are in trouble.
The B12 safety valves lift just below 180 psi - just below the red line on the gauge. The Brake Ejector struggles to make 21" vacuum if the boiler pressure falls below 150 psi, so the brakes are close to coming on - you want to keep it above 150 but below 170 at all times.
The second issue is the flame scoop or deflector plate. If you don't get the shovel well into the firehole, the coal will hit the end of the flame scoop and will start to form a little hill in the middle of the grate, preventing any more coal from getting to the front. You can fix this with the bent dart if you have to - just push it forward when you can get 10 minutes with no-one else on the footplate.
The other hazard to contend with is the heat shield that protects the driver's leg from the fire - loss of concentration, or fatigue, will have you hitting that with the shovel which usually sends coal all over the floor...
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