Smoke box door handles

[steve howe]

Just completing a brace of rather work weary 57xx panniers, and fitting the smokebox door darts today, (these are the Alan Gibson product) it occurs to me they are rather long... so referring to Russell and various other sources seems to show that not only did the length vary considerably, but the 'angle of dangle' did as well. Before I get the cutters out, does anyone have an opinion as to how big these things should be?

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DSCF3593.JPG

Steve

[davebradwell]

I suppose the "official" length will be on the GA. I've made many NE ones over the years and sometimes you'll find that they've broken off and the fitters have just welded in a bit of parallel bar so really it's down to a photo. At least the ones you have look to be the right sort of diameter - I set the tool to start turning at about 0.45 dia and taper down from there. Check the backing disc isn't too thick on a casting - this is better made as part of the smokebox door or added separately.

DaveB

[davebradwell]

PS - the front handle should lean forwards, not back. The rear one hangs vertically.

DaveB

[John Palmer]

In case it might be thought that the rear handle is dangling free... The reason for it being vertical is to ensure that the 'key'-like projections at the inner end of the dart, having a known alignment relative to the rear handle, are at right angles to the slot in the internal smokebox crossbar through which the dart passes and against the inner face of which those projections engage. The front handle engages the thread at the outer end of the dart; winding it in draws the door towards the crossbar, thus the rim of the door is drawn tight against the smokebox face ring in order to provide the required air-tight seal. With the door tight against the face ring the rear handle is locked in position.

[davebradwell]

Absolutely, John but I'll throw in that as the rear handle mounts onto the dart on a square, it isn't entirely beyond the bounds of possibility that it ends up at 3, 6, 9 or 12 o'clock. The front one, as explained, can end up anywhere although the way the human body works does give preference to certain positions. In desperate situations, the coal hammer would be brought into use. One's locos should show a variety of positions.

DaveB

[John Palmer]

Yes indeed, Dave, and I'd guess that the rear handle most often pointed downwards because that was the position it would naturally adopt under the influence of gravity when being fitted onto the squared section of the dart.

My clumsy reference to a 'known alignment' was because I gathered from one my elderly books on British locomotive practice that there were smokebox designs that had a vertical crossbar, though I've never seen an example of this. Can't think why anyone would adopt such a design as it's so much easier to provide suitable mountings for a horizontal crossbar.

Coal hammers, heh! Look for the discoloured patch on the lower part of the door where hot char has been allowed to accumulate, the heat then probably distorting the door as a consequence. That's when you hope that slogging the front handle will pull the door tight enough to seal it, but all your hammering may be in vain.

[Will L]

Just completing a brace of rather work weary 57xx panniers, and fitting the smokebox door darts today, (these are the Alan Gibson product) it occurs to me they are rather long... so referring to Russell and various other sources seems to show that not only did the length vary considerably, but the 'angle of dangle' did as well. Before I get the cutters out, does anyone have an opinion as to how big these things should be?

They lookly over long to me too, but then I know B all about the GWR. As Dave said you need to have a look at drawings/photos. Which brings me to the point. Guy Rixon produced this internet tool for pulling dimensions of drawings displayed on a PC screen.

See here https://people.ast.cam.ac.uk/~gtr/drawi ... er-v2.html

I find this incredibly useful driven as I am by GER drawings published as pdfs. As it works on jpgs its also good for pictures.

For example I can tell you that on a Comparable GER loco (J69) the handles are 12 inches long and the disk behind is 6 inches across (or close enough)

[andrewnummelin]

These may be useful.
https://steamworkshopstores.com/products/gwr-5700-0-6-0-pannier-tank-locomotive-drawing-smoke-box-and-super-heaters
https://hmrs.org.uk/hmrs-38205--class-57xx---smoke-box.html

[Dave Holt]

The rear handle might well be on a square shaft allowing, in theory, four possible positions at 90 degree intervals, but I can't remember ever seeing a photo of a loco with it anywhere other than vertically down. On our loco, there's a lug with a locating notch to ensure it stays there when tightened up.
Dave.

[Will L]

The rear handle might well be on a square shaft allowing, in theory, four possible positions at 90 degree intervals, but I can't remember ever seeing a photo of a loco with it anywhere other than vertically down....

What ever Dave says, I don't think that's true. On every smoke box I've seen, the dart is of a rectangular section not square and goes through rectangular slot not a square hole so only vertically up or down would work. And then slotting it in with the handle vertically up would just be perverse and probably rather difficult to achieve against the weight of the handle. Thus always seen vertically down.

Preserve- Perverse. A dyslexic like me would never see the difference, at least I got all the right letters in it, but yes Keith you were right that is what I ment

[david_g]

On the Swindonised smokeboxes I'm familiar with it's not just gravity or ergonomics which determine the position of the inner handle: there is a raised notch on the back of the handle towards the centre which engages with a nib on the ring on the smokebox door, preventing the inner handle rotating as the outer handle is tightened.

I'm prepping an engine next Sunday so I can take some photos inside and outside the smokebox to illustrate the points made in this thread.

[david_g]

So, smokebox door show & tell time...

Although narrow gauge and built by Beyer Peacock 822 and sister engine 823 were sent to Swindon around 90 years ago and emerged from the works heavily Great Westernised.

IMG_0341[1].JPG

The main changes to the loco were around the boiler and smokebox. The Beyer Peacock smokebox door either gained new furniture or a new door was fitted, the original had shorter hinge straps on the door, no outer ring and the dart had a handle and wheel. I can imagine some apprentice being sent to the stores for a set of "Smokebox Door Fittings No. 2". Of course the smokebox gained a copper capped chimney in place of the stovepipe original, because that's how they roll at Swindon.
The od of the outer ring of the smokebox door is 40" approx; the inner "positioning" handle is 13" centre to tip and the outer "tightening" handle is 12" centre to tip.

IMG_0344[1].JPG

In the side view of the handles slackened off you can see the inner handle is free to slide on the square section; the outer handle is on a thread on the end of the dart. Also visible is the projection on the inside of the inner handle and the nib which it engages with on the middle smokebox ring. I assumed this was a standard Swindon feature but a dive down the rabbit hole that is A Beginners Guide to Pannier Tanks on the internet shows this is only present in a minority of photos. With one exception all the photos show this handle in the downward position, the exception being the first photo on the website of 8791 at Swindon works in ex-works condtion. Whoever put it there probably didn't have a driver casting a baleful eye over it. Without the nib & projection the inner handle ends up at some quite jaunty angles in the photographs, anything up to approx 20deg from the vertical; this could either be the result of a "near enough is good enough" approach by firemen or the handle could be dragged round by friction when the outer handle is tightened.

IMG_0345[1].JPG

This is the dart on the inside, as you can see it is is rectangular in section.

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This is the locking bar inside the smokebox. Note the slotted hole in the middle; the dart goes through this, is rotated through 90 degrees then the door is pulled in by the tightening handle against the sealing ring round the circumference. The locking bar rests on horizontal brackets either side of the smokebox door aperture. There are short upward projections at the rear to prevent the locking bar getting knocked off if the dart misses the slot.
The screens behind are spark arrester screens,

IMG_0347[1].JPG

The locking bar has been removed and is leaning against the wall of the shed. Other orientations of locking bar have been mentioned in this thread, horizontal is simple and effective as gravity holds it in place, I think any other orientation would require something more elaborate to hold it in place.

IMG_0348[1].JPG

This is the view inside the screens, blastpipe, blower ring and an awful lot of char.

[david_g]

Forgot to add this showing an alternative arrangement of handles on Lok Zwei of the Zillertalbahn. Here Krauss, the builders, have put the positioning handle on the outside, fixed to the dart by a pin and the tightening wheel is on a threaded section on the inside and bears directly on the smokebox door rather than through the positioning handle. There are also 4 dogs around the circumference.

IMG_0350[1].JPG

[Will L]

So, smokebox door show & tell time..... the inner "positioning" handle is 13" centre to tip and the outer "tightening" handle is 12" centre to tip.

The GER dimensions was typical then.

[Hardwicke]

Simple when you think about it and obvious.

[JFS]

So, smokebox door show & tell time...
This is the view inside the screens, blastpipe, blower ring and an awful lot of char.

Very nice Lempor nozzle there - bet that does a fine job Shame about the crxp fuel ... in March I bought a tonne of Welsh for a small fortune. Now it is worth a huge fortune - as a museum piece!

Many thanks for posting.

[david_g]

Very nice Lempor nozzle there - bet that does a fine job Shame about the crxp fuel ... in March I bought a tonne of Welsh for a small fortune. Now it is worth a huge fortune - as a museum piece!

Many thanks for posting.

Well spotted!

The Lempor was put on about twenty years ago ( not a volunteer then but I remember reading about it in the Journal) and by all accounts transformed the steaming and reduced fuel consumption - all the things a Lempor is supposed to do. Subsequently all the W&LLR fleet were equipped with Lempors and having fired the Kerr Stuart Joan while still in service, that would steam on hot firebars. When The Earl went to Aberystwyth for overhaul in 2019 the Lempor was deemed "not necessary"; on it's return to service it certainly didin't steam as well as before which was just about tolerable when we were burning Welsh steam coal.

When Wales' finest started to disappear and we were experimenting with coal substitutes the indifferent steaming became an issue. Fortunately provision had been made to allow the Lempor to be refitted so a series of tests were carried out using a u-tube in the cab to measure smokebox vacuum with and without the Lempor (there was an unofficial competion among crews to see who could produce the highest number). Needless to say the Lempor won hands down. As someone who was around the first time we went round the loop remarked: "Who knew?"

(Apologies for the thread drift)

[Hardwicke]

Today I've ordered some Silver Tay Models smokebox door handles. They look the part and I'll report back when they arrive.