Removeable firebars - how neccessary are they?

[David]

The method Jim used, sliding out sideways, seems relatively common down here for wide fireboxes where the grate is over the frames. I'm sure my father-in-law used it for his 38 class, and another club member used it on his 59 class.

I didn't understand Steve's grate was hinged at each end so it could open to drop the fire. I guess if you can stand doing whatever is necessary every 10 years to replace it perhaps you can live with it.

The other disadvantage I can see is not being able to experiment with different styles of grate, or sizes of the features in the one you decide to use. We have a lot of experimentation going on down here to see what works for the various fuels we can get hold of. That may not be such a problem in the UK.

[oldnorton]

Jan 2, 2020 7:36:53 GMT springcrocus said:

..... it appears to becomes possible to drop the entire frame, truck, ashpan and grate away with minimal work. 

Adam is right in that the cab needs to be considered, and the tender water connections are a major rethink, but I think you are looking at a positive way forward by investigating a novel idea.

The cab, and all associated items, would need to be carried by the firebox and backhead clothing, and that is pinned to the firebox by various blind bushes like the firebox door supports so will be strong enough. Hanging off the back, around the drag box, would be brackets for water supply and injector valves. The prototype cab was fully supported off the firebox as well!

You could arrange for the frame break lines to be just behind the rear driving wheels and leave the existing bolts where they are. This is perhaps the biggest engineering challenge - how to make those joints strong enough to resist the stresses, but simple enough to break and rejoin in, say, 30 seconds a side.

Perhaps investigate a four section grate while thinking about the above? Each piece could be deep and strong, nice centre drop doors, four lengths to hook out is a trivial extra to three lengths.

Norm

[springcrocus]

Jan 2, 2020 11:01:51 GMT oldnorton said:

Jan 2, 2020 7:36:53 GMT springcrocus said:

..... it appears to becomes possible to drop the entire frame, truck, ashpan and grate away with minimal work. 

... but simple enough to break and rejoin in, say, 30 seconds a side.


Norm

I think it's worth investigating but it's workshop maintenance we're considering here, not a Formula 1 pitstop.

But thanks for the encouragement.

Regards, Steve

[springcrocus]

Jan 2, 2020 10:44:40 GMT David said:

The method Jim used, sliding out sideways, seems relatively common down here for wide fireboxes where the grate is over the frames. I'm sure my father-in-law used it for his 38 class, and another club member used it on his 59 class.

I didn't understand Steve's grate was hinged at each end so it could open to drop the fire. I guess if you can stand doing whatever is necessary every 10 years to replace it perhaps you can live with it.

The other disadvantage I can see is not being able to experiment with different styles of grate, or sizes of the features in the one you decide to use. We have a lot of experimentation going on down here to see what works for the various fuels we can get hold of. That may not be such a problem in the UK.

The problem that I see with a slide-out rosebud (or any slide-out type for that matter) is that it's below the foundation ring, not inside it. The point Alan made about top air comes into play but I wouldn't know how important that is, having never fired or driven a steam loco myself.

Regards, Steve

[delaplume]

Hi Steve,

Thanks for highlighting this point......Slight correction if I may ??......."Top Air" is that air which enters the firebox ABOVE the firebed and in a CONTROLLED manner....ie through the firehole doors, operated by the Fireman...It's main use is to complete the combustion process as the burning coals do not give a 100% burnt gasses situation.....

If the firegrate is not fitted fully into the foundation ring area then some air will pass over the burning coals without adding to the combustion process.........Gasses, like fluids and electricity take the path of least resistance.........Some localised burning can happen at the various places where this air is being admitted causing damage to the copper sheet or foundation ring....The overall result is that the firebed does not achieve its' full temperature with resultant poor steaming and some smoke at the chimney lip...

This air will also take heat away from the firebox with possible leaking tubes etc ( Full-size locos)...


Have a look at Stoichiometric air}-------   www.lesman.com/train/webinars/Webinar-Slides-Air-Fuel-Ratio-Control-101-2014-12.pdf

[jma1009]

A steam locomotive grate both in miniature and fullsize - plus the ashpan - must be able to be cleaned and emptied.

In a miniature locomotive I would consider this of especial importance due to the problems caused by poor quality coal compared to 20 plus years ago.

You only need one dud lump of coal broken up to sit on the grate as rock being heated up, and sitting there as rock, and not reducing to ash, and killing the fire.

You only need the sides of a wide firebox ashpan grate to have ash build up underneath the firebars to cause the firebars to overheat and distort and burn.

I ran a 3.5"g LBSC 'Maisee' Atlantic, rebuilt by myself, for 12 or so years as an LBSCR H2 Atlantic. You could drop down most of the middle grate via a hinge, but the sides required very careful cleaning out with an air compressor jet at home after a steam up, otherwise it would not steam at all.

I would assume that most 5"g Brit builders realised the deficiencies of the Perrier design, and probably omitted the inner rear frames altogether, but I never took much notice of this, so is supposition on my part, but would be what I would do if I were building a 5"g Brit - not that I would ever consider doing so as bending over the tender whilst driving a few gave me very bad back ache!

Cheers,

Julian

[springcrocus]

Jan 2, 2020 23:45:32 GMT jma1009 said:

I would assume that most 5"g Brit builders realised the deficiencies of the Perrier design, and probably omitted the inner rear frames altogether, but I never took much notice of this, so is supposition on my part, but would be what I would do if I were building a 5"g Brit

Cheers,

Julian

I think you must have missed (or misunderstood) half a dozen posts. We could always use a piece of string to couple up the tender, I suppose. 

Regards, Steve

[andyhigham]

My thoughts on this. The removability of the grate falls into two areas
1) Routine maintenance, the grate and ashpan should be removable without a major strip down
2) During running, I don't believe it is a game changer if the grate cannot be "dropped". Most of the fire can be raked through at the end of the days running and an airline or vacuum will shift the rest. It is ESSENTIAL that the ashpan is designed to avoid ash build up under the grate or be easily accessible for raking out.
2A) Emergency!!! pop a rag or something in the chimney and slightly open the blower with the fire door closed, it will kill the fire in seconds

[andyhigham]

I have been spoiled by a loco that the grate can be removed complete with fire, repair the fire and put it back in

[springcrocus]

I think I have found a way to make the sides of the ashpan removeable, allowing the grate to be dropped onto the top of the tunnels and then slid sideways for removal. If so, this allows me to make the grate as designed and just modify the support brackets which fit to the sides of the ashpan. The grate will still have the drop-down centre section and the lower ashpan doors will be retained for cleaning out.

I also plan to refill those ridiculous cutaways for the cylcock operating rod and replace this mechanism with some sort of Bowden cable arrangement which will pass below the ashpan, rather than through it.

Amazing how the suggestions of colleagues encourage further thought from the builder. Thank you, Gentlemen, for your inspiring comments.

Regards, Steve

[delaplume]

Hello Steve,

Quote}--"Amazing how the suggestions of colleagues encourage further thought from the builder. Thank you, Gentlemen, for your inspiring comments."---

I'm happy to second that thought !!.........It's what this Forum is all about, after all..

[Cro]

Steve,

As interesting as that sounds to see being made it sounds like major overkill and complication for the simplicity of 3 sections taken out the firehole door. Don’t forget you would typically have a fair amount of pipework either side of ash pan plus the ash pan design does contain a lot of ash and prevents if from getting into the motion, opening the sides sound messy as hell.

I like things simple so just thought I’d say something so you hopefully take one last look at that option. If you are at the stage where you can pop Ashpan under the boiler, on the chassis would be even better, than make up 3 grates out of card or wood or whatever you have and see how it goes trying to put them in?

Good luck,
Adam

[gwr14xx]

On my Winson 9f I am still using the original grate, but have modified the ashpan to have the side raking ports (as full size), but without the doors! The draught now keeps the corners of the ashpan clear, resulting in no dead spots in the fire. I now have no need to remove the side sections of the grate - just rock the centre section to drop the fire - then when cool enough, vacuum out the remains of the fire.

Regards,
Eddie.

[springcrocus]

The thing is, you chaps have all driven locos and, thus, tended the fire. I never have and, maybe, misunderstand some of the neccessities of the job. So let me try another question.

As designed, the grate has a centre section that drops down, hinged at the back. Why?

Is it to assist in cleaning the fire? Or is it to drop the fire in an emergency? Is it a feature worth retainlng? I have no idea!

If the drop grate is a desirable feature, then lift-out bars will probably be too complicated. It will have to be four sections, three just will not fit through the firehole and a double, dropping section would be somewhat complicated. If the drop grate is a gimmick, then it is easy to make four fixed sections and lay them across a pair of permanent cross members at the top of the pan.

So far, I've been trying to retain the drop-grate feature but maybe I'm wasting my time.

Back to you guys.

Regards, Steve

[oldnorton]

Jan 5, 2020 7:32:47 GMT Cro said:

..... the simplicity of 3 sections taken out the firehole door. 

Won't work Adam because (fire grate width)/3 > firehole door width. It will need 4 sections.

[oldnorton]

Jan 5, 2020 9:23:56 GMT springcrocus said:

As designed, the grate has a centre section that drops down, hinged at the back. Why?

In the ideal world, at the end of a lovely day's steaming, it is best and quickest to drop the remains of the red embers out of the loco and into the ash bucket at the steaming bay, then open the blow down valve and attend to other tidying up jobs.

If you cannot simply drop those embers then you have to shovel them out, or wait half an hour for the fire to die. This all starts to ruin the ideal day. 

You will want to drop the embers in the simplest and cleanest way. We are all debating how to achieve this on a Britannia (or 9F) that has frame members running through the ashpan. If you have a reliable centre drop door mechanism, and all the fire falls through the open ash pan door, with a bit of raking around, then ideal world is maintained. If the drop door jams then you switch to plan 'B' which is to fish the sections out (messy) and achieve it that way.

Back in the workshop, next day, it will be best to get those sections out anyway, vacuum it properly, and see that the drop door is still free to move.

The grate door is not there for emergencies; as others have said block the chimney and blower on to kill the fire (and produce a lot of carbon monoxide so be careful !)

You really do not want any design that could possibly jam with lumps of ash or clinker because, sure as lollipops, it will. You also don't want a system that will spread fire and ash far and wide under or down the side of the engine.

Norm

[oldnorton]

Steve

In case this helps visualise your grate options, here is a picture of my three sections. It is quite heavy and strong being TIG welded from 12mm x 3mm stainless bar. The hinge pins are permanently affixed when it is welded together. The centre section has a hook at the front to catch under the forward ash pan cross bar. This is needed because as the actuating arm swings forward and up to hold the door from below, it would otherwise lift the grate section. The grate mass holds the back down. When putting in through the firedoor the centre section goes in last and it has tapered cross bars that bear down on taper ends on the outer sections to help hold and stabilise them. It is quite simple to locate feeding it in nose first and pointing down to engage with the ashpan cross bar

I think the centre section could be made into two, with the two drop doors having a pair of bars between them; this will not stop the fire falling through. These centre pieces could both hook onto the ashpan cross bar and perhaps engage with each other in some way to enhance stability.

Norm

[oldnorton]

I did not use any of the Perrier design but worked out my own ideas. The trickiest part was getting the lift arm in the right place to achieve the lift, but not obstruct the ash door opening. This crude sketch (sorry, no posh drawings!) might show what is going on.



I used taper pins to hold the arm to the cross bar as I would not trust grub screws under the fire. The one weakness I have is that the grate lift arm has to be held in its upper position at just the right angle in order to hold the grate level. I have fixed an adjustable bracket to secure that lift arm. The ash door lever at the bottom will probably have a pull rod running back up to the cab.



Like you I also deleted the daft slots for the drain cock lever. My lever runs directly under one of the frame extensions where it is out of the way of the ash doors.

[springcrocus]

Thanks, Norm.

Unlike you, I don't have the equipment (or ability) to TIG weld so anything I do will be bolted together. This will, unfortunately, make things a little more cramped. However, I won't be munching metal until Easter, this is all theoretical right now just studying the drawings indoors in the warm.

I need to get my head examined! I originally planned to build this loco exactly as per the drawings but now I'm starting to modify things more and more of late. At this rate, I will be making something to the original works drawing before the blasted thing is finished.

Regards, Steve

[Cro]

Norm, 3 or 4 either way same idea applies. The 9f I actually have two fixed either side and just a middle section lifts out.

The hinge is just for simplicity, not emergency. With a loco this size something drastic has to happen for you to need to pull the plug that quickly and as other say, rag in chimney trick will be far quicker.

All I do at the end of the run is shove the poker in and lift the bars and out the door. Ash falls out the bottom dump door and then rake the worst out of the sides and hoover out when cold.

I’ll be putting ashpan back under the boiler of 9f on Friday so can get photos if that’s not too late?

Hope that helps,

Adam