The LNWR brown train

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Guy Rixon
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The LNWR brown train

Postby Guy Rixon » Wed Jan 17, 2018 9:10 pm

Among the throng of half-built stock destined for my unbuilt layout, there is the first coach in one of the LNWR's "brown trains": the stock built for the Outer Circle service.

IMG_4498.jpg


It's an unremarkable build of a LRM kit, notable only for being badly built and painted. Except...I felt the need to experiment with the suspension.

The full-size coach has its axleguards outside the solebars and its springs inside the axleguards. On the model, the inner faces of the axleguards are very slightly under 26mm apart, making it rather hard to use 26mm pinpoint axles.

The kit has inside bearings instead, arranged for 3-point suspension. As designed, the "bearings" are slots in vertical, etched plates that enclose a 2mm axle; foldable tabs retain the axle. This is an inherently good design, IMHO, in that it works with any wheels on a 2mm axle and doesn't require the wheelset to be dismantled to fit the axle into closed bearings. However, I wanted to improve a few areas.

1. I wanted a better bearing surface. Not that my coaches will wear their bearings much while sitting in a display cabinet, but I hope to be running these models occasionally for the rest of my life. I don't want to have to rebuild them.

2. I wanted to try and control the slop in the bearing. I have a suspicion that some running problems stem from wheelsets floating with insufficient weight on them where the railhead dips, and a loose bearing will encourage this.

3. I wanted to be able to fit and remove the wheels several times during the build. The etched tabs will weaken and break off after a few foldings.

4. I wanted to fit Exactoscale wheels, because they are properly round, and they have a 1mm axle.

5. I wanted to start development of a system that I can build for myself on scratch-built stock and coaches that don't start with a good suspension design.

Therefore, this:

IMG_5280.jpg


This is the rocking-axle cradle from the kit, lightly adapted. The wheelset is built on a plain axle 22mm long, made of 1mm silver steel from Eileen's. The bearing is a length of C-section brass, also from Eileens, cut to fit accurately between the bushes in the wheels. The plates of the cradle are assembled to their OO spacing, so the distance between the plates is less then the length of the bearing, and the bearing is soldered into the plates. The axle-retaining tabs are not used and have been snapped off. The axle is retained by hoops of 0.35mm wire passing through holes in the base of the cradle.

So far, the signs are good. The axle runs smoothly in the bearing half-tube. It is not as free-running as pin-point bearings, but seems already to be smoother than an Exactoscale parallel axle running in top-hat bearings (I have some wagons built that way and they are a drag). There is no detectable end-float. There is no slop between the axle and the bearing. It was trivial to build, and I could easily build my own cradle for this approach.

I do need to refine the hoops retaining the axle as they are too loose. It will be important, I think, that the axle can't drop away from the bearing by more than a flange depth, otherwise it could unload itself and climb off the rail. It should be possible to get the hoops closer to the axle without actually rubbing on it.

I'll report back when I have the coach runnable.

philip-griffiths
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Re: The LNWR brown train

Postby philip-griffiths » Thu Jan 18, 2018 4:40 pm

I have a need to build similar stock for South Wales so this is an interesting posting, thanks very much. Jol Wilkinson had a hand I think in the kit design and Mike Peascod contributed as well. I drew some of the original diagrams for John Redrup, but I don't think Mike used them.

John said that the under frames were wrong on his kits for the South Wales stock, but I think you would need to look hard to see the differences.

Must order the kits.

regards
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Jol Wilkinson
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Re: The LNWR brown train

Postby Jol Wilkinson » Thu Jan 18, 2018 7:13 pm

Philip,

I wasn't involved in the 4 wheel LNWR carriage design, so know little of their gestation.

I belive some more information has come to light about the South Wales version underframes so there may be some news on those soon.

Jol

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Re: The LNWR brown train

Postby philip-griffiths » Fri Jan 19, 2018 10:04 pm

Sounds good Jol. Please keep me informed. I thought that John never did the underframe for it as there would be few takers.

Regards.

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Jol Wilkinson
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Re: The LNWR brown train

Postby Jol Wilkinson » Fri Jan 19, 2018 10:34 pm

Philip,

I think that John didn't do the SW underframe through lack of information. It was always intention to produce a "full" kit if possible.

Likewise for the LNWR Oerlikons. A superb set of patterns for the underframe castings have now been produced by Clive Croome, so those that bought the body etches can finish their models without scratchbuilding.

Jol

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Mon Jan 22, 2018 8:47 pm

I now have the suspension parts finished and fitted for both axles. The trick to the axle-retaining staples is to make three small-radius bends at the top, close together. This puts the apex nearer to the axle than a single bend of the diameter of the bearing tube. The staples are soldered into the back of the cradle, or above the floor at the non-rocking end, then cut off flush.

The coach rolls smoothly, so I'm satisfied with the technique. I will use it for the rest of the train. The rolling resistance is not as low as with pin-point bearings, but it should be fine for a train of 8 or 9 vehicles.

However, this particular chassis will not be in the finished train. The buffer height as come out too high by about 1.5mm at one end and too low by the same amount at the other. Since my custom bearings don't change the axle positions from the original design, I think that this means the bearing plates are different heights, and I've got them the wrong way round. It would have been really nice if this detail was mentioned in the instructions. Since one set of bearing plates are soldered into the chassis and that chassis is bedecked with brake gear, castings and paint, I don't rate my chances of getting it changed round, so will be writing off this build. Only the special wheelsets will survive. Never mind, only 3 months spare time wasted.

The brakes are also wrong. The kit has the horizontal kind of vacuum cylinder, but LNWR Non-corridor Coaches (which book I only got after building the model) shows the vertical kind of cylinder with a centre crank on the Mansion House stock, and the horizontal cylinder on later 28' stock. So when I start again with a new kit I'll be building some of the brake parts from scratch.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Mon Jan 29, 2018 9:13 pm

Another day, another kit. Having put aside the coach with the mis-assembled chassis for later consideration, I'm moving on with the other two kits I have in stock for this train. One is for a third-class coach, which I got direct from LRM and the other for a first-class coach that I got cheap(-ish) off eBay.

The first-class coach turned out to have a 17'-wheelbase frame, whereas the Mansion-house firsts had 18' wheelbase. This kit is actually configured for one of the Birmingham-district trains of 1894, so I've bought it in error and oops...except that each Mansion house train acquired a strengthening all-third in 1897 and these later coaches had the same underframe as the Birmingham sets. Thus, I swap the underframes between the two kits on hand and all is well. I also get to use the brake cylinder and rigging as designed into the kit on the 1897 third, and this is the one I'll build next.

While celebrating this break-down in Murphy's law, I also note that anybody who does want to build a Birmingham-district set has a problem. The panelling of the first-class coach seems to match the diagrams for the Mansion-House trains and the Birmingham trains had different panelling. The etch claims to do both diagrams, but I can't see how that is right.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Mon Jan 29, 2018 9:57 pm

I started my 1897 third with the chassis. The structural build is quite straightforward, up to the point where the step-boards go on. The two changes I made were the half-tube suspension, described above, and strengthening the trussing so that it is less likely to get bent and stretched.

The strengthening is 0.35mm wire soldered to the rear of the tie-bars. I think this was a good move, but I did it before bending up the solebars and this was a mistake: when clamping the chassis to bend it, the extra relief meant that the tie-bars got crushed and slightly distorted.

IMG_5295.jpg


I hope that it will not look too bad when the chassis is painted black. For the other coaches I'll bend up the frame first and strengthen afterwards; similarly for the horn-plates.

The photo also shows an aid for holding the chassis in the vice while fixing the step-boards. It's just a block of wood that fits between the suspension fittings and bears against the top of the chassis. The board fitting is a harsh process and the chassis has to be held firmly.

Step-boards and their supports are an area of coach building that I find difficult. Since these coaches are modelled in condition of 1909, I only have to fit the top step-boards as the lower ones were removed c.1903. This means that the etched supports, which are way too weak when carrying upper and lower boards, will do very well ... if I can get them attached in the right place. They need to be formed into an L shape, soldered under the board and then soldered to the face of the solebar. This is not a nice thing to do with freehand soldering, and attaching the supports to the first board was a cuss-fest. For the second board I made a jig.

IMG_5296.jpg


It's just a piece of strip-wood (actually a tongue depressor, which can be bought on-line for pennies) with slots filed across its width to take the supports. I have a knife-edge file that happens to make exactly the right width of slot for the supports in the kit! The grooved jig is clamped against a piece of plywood in the vice, the supports are poked in, and the etched board is slid under them. The notches at the ends of the jig help me to align the board along its length.

IMG_5297.jpg


The jig is not burnt in the quick soldering and can be re-used for the other coaches in the set (the brakes may need their own jig; we'll see).

IMG_5298.jpg


Soldering, with the highest-temperature solder I had in stock (ordinary 60-40) was then trivial. Cleaning up after soldering is also easy, because the assembly is protected.

One peculiarity of the kit had to be sorted before the board went on. The instructions refer to castings to thicken the ends of the headstocks. These are mythical: in three kits I found no sign of them. The gap between the brass headstocks and the cut-outs in the step-boards is 0.75mm at each end. I filled it with fragments of 0.8mm plywood glued to the solebars and filled back to fit.

The step-board assembly can then be soldered on using 145-degree solder. This is not easy, and I see no way of making it so. Tiny errors in folding the solebars or assembling the step supports show up and matter here, making it hard to get neat joints. Cleaning up is not easy either, but at least the final assembly is strong. The instructions say to trim the supports so that they stop 0.5mm below the chassis top...but to hell with that, it's way too hard to get right. I cut mine off level with the top of the chassis.

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Re: The LNWR brown train

Postby Guy Rixon » Wed Jan 31, 2018 10:45 pm

The underframe of the D300 3rd is now pretty much complete. All the soldered work is done.

IMG_5300.jpg


The brake rigging is as per kit design, except that I used 0.5mm wire for the pull rods instead of the 0.4mm in the kit (it was on the bench and didn't run fast enough...). I drilled the ends of the vacuum sack 0.6mm to a depth of about 5mm and the pull rods are loose in these drillings, while soldered to the rigging at their other ends. It's just possible to get the rocking cradle out of the chassis for painting with the pull rod attached.

The buffers are tricky on this one. The kit provides castings for the buffer guides, and MJT/AGW rams and coil springs. So far so good, and I can manage these parts: drill through 0.5mm and open the front of the bore out to 1.0mm. Or drill 1mm all through and put in a bush with a 0.5mm hole. However, the full-size buffers were 9" from buffing face to headstock, the trains being close coupled. I reckon the cavity holding the ram and spring needs to extend 6.25mm back from the buffing face (see my rambling about the printed buffers on other threads), and there simply isn't room in the castings. Therefore I've drilled them through 1.0mm and will fit some kind of springing behind the headstocks. This will probably use phospher-bronze leaf-springs for which I don't yet have the strip, so I'm leaving this are open for now.

The buffers and the vacuum sack are soldered in. They are my first attempt to solder whitemetal and everything looks OK so far.

I've also fitted a basic coupling.

IMG_5302.jpg


IMG_5303.jpg


The idea here is to make a basic hook that is rigid to one coach and hooks under the headstock of the next, while disguising it as the vacuum hoses and also representing the bar coupling that would have run between the drawplates in the headstocks. The functional hook is just bent brass wire and passes through a hole in the floor of the coach where it is soldered. The cosmetic bar-coupling is made from a bit of fret waste. It has a hole in its inboard end through which the wire hook passes and then a 90 twist to let it pass through the vertical slot in the headstock. Another twist outside the headstock puts the bar horizontal where it shows as I think this how the full-size fitting would lie.

The underframe now just needs its axleboxes, which will be glued on (craven cowardice!) and battery boxes, which have to be built from scratch because the kit represents the as-built condition only. So far as I can tell, the battery boxes sit on metal platforms suspended from the frame by a rod at each corner, and there are four of them, two on each side. In fact, the coaches seem to have the same number of cells as the contemporary bogie-coaches, which seems a bit generous, given that there are only half as many lamps.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Thu Feb 08, 2018 3:16 pm

I've moved on to the body of the D300 3rd. I'm advised that castings for the battery boxes will be available shortly so I'm leaving the chassis for a while.

I'm chronically bad at fixing door ventilators for coaches, usually managing to get them crooked, or out of line, or too clarted with solder. One of my new years resolutions is to do less Circe-du-Soleil-style freehand soldering and to make more jigs, so I partially jigged the ventilators.

IMG_5307a.jpg


The jig is two medical tongue-depressors (bought cheaply on-line) clamping the side and providing a ledge against which I pressed the bottoms of the ventilators. The M2 screws hold the side while the jig is being lined up and the vice provides the main clamping-force. Inside one of the jig boards is glued a narrow strip of 0.8mm plywood such that it bears on the side specifically at this point and doesn't leave a crack for the ventilators to fall into.

If the ventilators were plain-faced I could sweat them on with the iron bearing on the front. These ones are decorated on the front and are hard to clean up after soldering. Therefore, I drilled two holes in the side at each ventilator position and soldered from the back. The holes are 1.4mm, big enough to poke in the tip of the iron. While soldering, the ventilators were clamped to the coach side with aluminium clips, which aren't as grippy as I'd like for this kind of job; I may seek another kind of clamp for the next coach. Also, this work has to be done before forming the top flange of the coach side as the clamps won't go round the flange.

After the ventilators, I fitted the drop lights. These are the full thickness of the etch where I'd prefer half-etched or custom, paper frames added later, but I used the etched parts as given because they also carry the door hinges. The drop lights are all modelled closed as nobody wants a window open in tunnel on a steam railway. The lower hinges are the traditional L-shaped scraps of brass, and these would have been easier to fit if the inside leg of the L had been made longer. As they stand, there is a tendency for the hinge to overbalance and to slide through its slot under its own weight.

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Le Corbusier
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Re: The LNWR brown train

Postby Le Corbusier » Thu Feb 08, 2018 3:47 pm

Very interesting Guy .. thanks :thumb
Tim Lee

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Thu Feb 08, 2018 3:51 pm

Thoughts now turned to the assembly of the basic body. I always find this bit difficult. It amazes me that anybody finds it easy to assemble four bits of brass foil into a monocoque structure, using only butt joints, while controlling 7 separate degrees of freedom on some of the components (that's displacement in three axes, rotation about two axes and flexure in two planes). Monocoques are hard to get right and that's why they don't appear in construction of full-size land-vehicles until quite late on.

Over the years I've tried various extreme approaches to avoid the monocoque-up (see other threads on this forum for some of them), but this time I tried to stay as close to the kit design as possible.

Insight #1 is that the kit has its body/chassis fixings through holes in the lower flanges of the sides: this makes it self-jigging, if the securing nuts are added before body assembly. This is an excellent design-feature. It removes all the displacemental and rotational freedom from the coach sides during assembly, leaving only the flexure to deal with.

Insight #2 was to use my rolling bars to form the turn-under. They won't actually roll it in - it's too hard to restrict the curving to the bottom of the side - but they can be abused as a kind of press. It helps that the brass in the kit is more malleable than some.

I ended up with sides pressed and finger-tweaked to the correct profile and with the bottom flanges then formed almost but not quite to the right angle. When the sides were bolted to the chassis, they were slightly too wide apart at the top. I closed this gap with finger pressure during the final assembly. Incidentally, it's important in this etch to deepen the relieving slot before forming the bottom flange.

The flanges make the sides stiff enough in one axis so that they don't flex. I was actively using the flexure in the in other axis to correct the alignment. The ends, however, wanted to flex a lot and I needed them to stay flat. I soldered strip of fret waste across the back of the sides and this seemed to stiffen them enough.

IMG_5308.jpg


Also shown in the photo is my approach to stopping the ends from slipping down inside the sides during assembly. I just soldered in a length of 1mm x 1mm brass angle at the end of each side.

Final assembly went like this:

1. Hook the bottom of an end under the body-securing bracket on the headstock and locate it between the sides, against the brass angles mentioned above.

2. With fingers, squeeze the sides together to trap the end, trusting that the latter has been made stiff enough not to warp under the pressure.

3. Tack-solder the top flanges to the end.

4. Inspect the alignment of the end. Cuss a little and re-tack it more accurately. It can't easily get out of position on most axes, but it can be pitched too high or too low relative to the sides and, because the sides are flexible, the end can twist so that it is high one one side and low on the other.

5. Now that the assembly is fixed in place and nothing can move, stand the coach on its end on block of wood and seam-solder the joints on the inside. Press the assembly lightly against the wood during soldering to make sure that the end is fast against the angles.

6. Repeat for the second end.

This approach works because I have a temperature-controlled iron and three kinds of solder: high melting-point to prepare the fittings on the sides; 188-degree (Carrs) to seam the side-end joints; 145-degree to add the details (steps etc.) to the ends after assembly. It won't work reliably with only one kind of solder and it would be harder with a fixed-temperature iron. Also, pre-detailing the ends is not feasible because they have to be pressed into the body for the assembly.

Results are overall acceptable I think; actually outstanding by my own standards.

IMG_5336.jpg


None of the above is very original, but it's only on this build that I've drawn together all the techniques to make it easy and reliable. I've written at length because this is a major turning-point for me in my modelling and overcomes the fears and frustrations of 20 years. I hope that these details can help other beginning coachbuilders can benefit from this.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Fri Jun 08, 2018 11:12 am

I now have some printed parts for the vacuum-brake gear.
IMG_5544.jpg

These replace the horizontal vacuum-sac included in the kits and also include the vacuum reservoir and other Heath-Robinson gubbins that the LNWR used.

I'm extremely pleased with how these came out. Everything has printed nicely and they are quite affordable. One couldn't cast or mould something like this, and personally, I'd have a real struggle to build it up from an etch. This kind of thing is perhaps where printing is at its most valuable.

EDIT: the castings for the battery boxes, dynamo and electrical switch-boxes are now available from LRM and I have these in stock for the first few coaches. They are very nice and even include a casting of the pulley sheave for the dynamo belt.

Alan Woodard
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Re: The LNWR brown train

Postby Alan Woodard » Fri Jun 08, 2018 1:36 pm

They look really good. Who done them for you ? and when you say reasonable, how much per item ?
I have two Brown trains to build so these would be a great time saver.

Cheers.

Alan.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Fri Jun 08, 2018 3:54 pm

I had them printed by Shapeways and they are available there to buy in my shop: https://www.shapeways.com/shops/guyrixon.

Prices in SFDP (né FUD) are £5 per assembly at current exchange and including designer's mark-up. I consider that quite cheap considering the amount of work it saves. It might be possible to make up a train pack of 8 modules (6 without handbrake and 2 with chained handbrake) to suit a full 1890 brown-train. That would save save the handling fee on each module.

Alan Woodard
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Re: The LNWR brown train

Postby Alan Woodard » Fri Jun 08, 2018 6:01 pm

Nice one Guy.
Well worth the price and time saved.
Thanks.

Will be making a purchase when cash flow permits.

Cheers

Al.

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Le Corbusier
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Re: The LNWR brown train

Postby Le Corbusier » Fri Jun 08, 2018 6:24 pm

Guy Rixon wrote:I now have some printed parts for the vacuum-brake gear.
IMG_5544.jpg
These replace the horizontal vacuum-sac included in the kits and also include the vacuum reservoir and other Heath-Robinson gubbins that the LNWR used.

I'm extremely pleased with how these came out. Everything has printed nicely and they are quite affordable. One couldn't cast or mould something like this, and personally, I'd have a real struggle to build it up from an etch. This kind of thing is perhaps where printing is at its most valuable.

EDIT: the castings for the battery boxes, dynamo and electrical switch-boxes are now available from LRM and I have these in stock for the first few coaches. They are very nice and even include a casting of the pulley sheave for the dynamo belt.

They look pretty good guy

T
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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Tue Jun 12, 2018 9:26 pm

I'm still trying to devise a better coupling for this train. It would help if we knew what the full-size coupling looked like, but that information seems to be lost. Therefore, I have fantasised a coupling based on the known distance between headstocks of 18" and the statements in Non Corridor Coaches of the LNWR that (a) there was a screw shackle and (b) it could only be released by a special key not available to the operating staff.

Screen Shot 2018-06-12 at 22.16.29.png


This is effectively the centre part of a normal screw coupling with the links replaced by mountings on the end of bars that run the length of the coach. The pivots are vertical and at 8" centres when the coupling is done up, this distance being taken from the vaguely-similar arrangement on the D13 bolster twins. There is about 3" of adjustment on the screw at each end to slacken off the coupling when braking the train in works. AFAICS, the full stroke of the buffers is only 3", so this should work.

Does anybody think that this looks at all plausible?

If it looks mechanically sensible, I can make scale parts that simulate this (even if I have to print them), but don't flex the same way or actually draw the train. The functional coupling will be a hook disguised as brake-hoses, as before.

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Noel
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Re: The LNWR brown train

Postby Noel » Wed Jun 13, 2018 10:22 am

Guy, I know nothing about LNWR coaches in general, but being interested in south Wales I have a copy of W W Tasker's The Merthyr, Tredegar and Abergavenny Railway. This states that in 1900 the LNWR introduced 5 coach close coupled 4-wheel sets on this line [2 compt Brake Third/5 compt Third/4 compt First & Second/5 compt Second & Third/2 compt Brake Third]. The Second & Third looks like a Third in terms of compartment size. They are in normal LNWR livery, and are presumably electrically lit [no lamp tops].

The book includes photographs of a set, apparently in service, where the gap to the last vehicle [a 2 compt BT] is much bigger than the others in the train, suggesting a loose BT has replaced the set BT. There are a couple of other pictures which suggest a mixture of close coupled and ordinary stock. I don't know if any of this is relevant [the close coupling system could have changed], but the thought occurred that the railway would not have wanted to take a complete set out of service if one vehicle failed in some way. It looks from these photos as if ordinary stock could be coupled to close coupled stock, at least in south Wales, which would make sense as well if vehicles from close coupled sets ever had to be shunted separately.

As I said above, none of this may be relevant, but it suggests to me that the south Wales stock may possibly have had normal coupling hooks, but with special short couplings?
Noel

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Re: The LNWR brown train

Postby dal-t » Wed Jun 13, 2018 2:28 pm

Guy, not an area of my expertise, but worth posing the question on the LNW Soc forum for Philip or A N Other to help you (if Jol doesn't pop along in a minute with the answer). I confess I can't really see from the drawing how the necessary articulation for curves and gradient changes would work on your proposal - the drawbars from the coaches and the coupling 'bottle screw' can't all be rigid, can they? I also suspect Noel has a good point on the likelihood of normal (ish?) hooks being present and only the bit between them being special (and protected from operating staff - what on earth were they expected to get up to?). The LNW was, of course, quite used to 'fixed' sets but the amount of cutting and shutting they experienced is always a lively topic of debate. Close-coupled sets must have been as liable as any others to hot boxes or failed door locks and no-one would want to take four vehicles out of service because one was defective, so it seems to me there must have been an easy means of detaching/attaching, it would only be the closeness of the couplings Management were trying to regulate, to avoid uneven riding. Just wish my collection of LNWRS Jounals, Premier Lines and Premier News had a searchable database to see if this issue has been raised before! DAL-T
David L-T

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Wed Jun 13, 2018 4:30 pm

David, in my hypothesis, the full-size coupling pivots on the two vertical pins in the bit between the headstocks. This is roughly equivalent to the arrangement for the twin timber wagons, the difference being that the screw replaces two plates between the pins. If I made up a model coupling to look like this I think I would make it rigid and let it pivot where it passes through the headstocks: i.e. it would sit loose in the headstocks and wouldn't actually couple anything, that being done by a different McGuffin disguised as brake hoses.

One other possibility is to have half a screw coupling between each pair of coaches. In any one coach, the draw-bar would have at one end a normal-ish hook (possibly the mouth of the hook is closed with a key as suggested in the history book) and at the other a forked fitting as in my drawing. Into the latter goes the screw and on the other end of the screw is a short shackle to engage the hook. If set is divided to expose the hook end of a coach, then a another coach with full-length screw coupling (and buffers) could be coupled and would have a wider inter-coach gap as in Noel's observation. I'll see if I can draw up this arrangement tonight: the issue is whether it can be sensibly fitted into 18" gap between headstocks. If so, then it's a much nice thing to model as it can actually work as a coupling.

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Re: The LNWR brown train

Postby Guy Rixon » Wed Jun 13, 2018 8:46 pm

Here's the second solution I mentioned in my previous post.
Screen Shot 2018-06-13 at 21.20.30.png

One end of the screw coupling is integral with a drawbar and is rigid; the other end flexes and adjusts normally. Coupling and uncoupling is done as normal for a screw coupling.

The drawbar with the rigid end of the coupling is arranged somehow (not drawn) to pivot behind the headstock. Therefore, this drawbar works in a wide slot in the headstock. If I try to pivot it in front of the headstock, the rigid part of the coupling sticks out beyond the buffers and will get wrecked if the coach is shunted against stock blocks; this is clearly wrong.

The other drawbar, with the hook, is similar to normal draw-gear except that the hook doesn't need to stick out as far from the head stock as it doesn't carry its own coupling-link. This drawbar works in a narrow, vertical slot in the headstock.

There is just about enough space to fit all this into the 18" gap between headstocks. It looks a bit like a fancy version of a Dingham coupling!

The LRM kit has the narrow, vertical slot in both headstocks. To add the hypothetical coupling on the kit, I think I'd reduce the non-hook drawbar to a think tab of brass that passes loosely through the headstock slot, can tilt to left and right, and is retained with a pin on the inside. This saves carving out the slots which would be tricky on the vehicles I've already assembled. I'd make the whole coupling rigid except the shackle that engages the hook: this is easier to build that a fully-flexible version and is fine for a set of coaches that is never uncoupled on the layout.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Sat Jun 16, 2018 12:07 pm

Next step on the 3rd-class was fitting the electrical gear, for which I bought castings from LRM at Railex. These "electrification packs" are applicable to many Victorian and Edwardian coaches of the LNWR and they include four cell boxes, a, dynamo a pulley sheave for the dynamo (nice touch, that) and the two connection and switch boxes for Stone's electrical system that go on the end of the coach body.

Here's the parts on the coach:
IMG_5549 (1).JPG

The appearance is quite different to the pre-electrification photo earlier in this thread. The whole chassis is now looking quite "busy". Because of my mutant suspension and 1mm axles, I can't use the pulley casting, so it's gone in the spare box.

Spacing is important here. The electrification kit comes with instructions for placing the parts on a 28' coach with 18' wheelbase: the cell boxes are spaces symmetrically about the centreline with a 4mm gap between the boxes on each side and scale 2'11" from longitudinal centreline. That puts then just over a millimetre in from the etched solebar, so a packing piece is needed while fixing them. The axle of the dynamo pulley is 4' scale from the wheel axle, which just clears the adjacent cell-box.

This model is the one coach in the train with 17' wheelbase instead of 18': it's the later-built strengthening coach. The position of the cell boxes is not symmetrical here; they are offset to the end away from the dynamo. The logic is that the dynamo is in the same position w.r.t the wheel as with the 18' wheelbase and thus 6" nearer the centre of the coach longitudinally. That puts it foul of the nearest cell box, so all the boxes move down the frame by 6" to make room.

In the photo. it look like the cell boxes are leaning outward. They are actually soldered on square, but the truss rod is slightly bent in at the centre. Bending the trusses is a big problem with these models and I hope it won't happen too much when they are finished.

In other news, I managed to get the bearing carriers off the chassis for the brake coach, the one I accidentally built with jacked-up suspension at one end. I've rebuilt (and electrified) that chassis: photos to follow when it's finished.

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Guy Rixon
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Re: The LNWR brown train

Postby Guy Rixon » Tue Jun 19, 2018 11:29 am

IMG_5555.jpg


Here's the chassis for the brake coach after repair. I've added the electric-lighting parts and also the print of the brake bits. The latter are almost hidden by the cell boxes, so it's a case of "because I know it's there". 28' stock with gas tanks would show rather more of the brake bits.

In respect of the brake gear, note that the cruciform crank is on the centreline, so the brake assembly sticks out further from the centre at the end with the reservoir. This means that the other end, with the vacuum sac, has to be next to the dynamo otherwise it doesn't fit. Further, the vacuum-sac end is also the end with the chain to the handbrake, so has to be at the brake-compartment end of the coach. This makes me really glad that I soldered the dynamo in rather than gluing it, because, of course, I first put it at the wrong end.

It's all painted matt black, but I think I should probably weather it to something less intense, some shade of dark grey.


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