OO gauge GWR Mogul and Prairie

[Allegheny1600]

I'd rather wait a while longer for a decent, accurate body and a chassis that WORKS really well!

In fact, I'm more bothered that it runs well than anything else.

[woodenhead]

I'd rather wait a while longer for a decent, accurate body and a chassis that WORKS really well!

In fact, I'm more bothered that it runs well than anything else.

I agree, it's just when it was launched last December it was but a year away.

[7007GreatWestern]

Do any of the GWR authorities on here have any views on the new Dapol CADs? I recall MissPrism came up with a long list of recommendations based on the initial CADs which were sent directly to Dapol. The views of some of the more learned souls on here might be useful feedback for Dapol (MissPrism, Edwardian, Coachmann, Stationmaster Mike, Castle, CoachBogie and others whose names I can't remember....)?

Edited July 19, 2018 by 7007GreatWestern

[woodenhead]

I agree, it's just when it was launched last December it was but a year away.

just read this back to myself, it i sound weary now, thank goodness I'm not in the market for an N gauge 142.

Do any of the GWR authorities on here have any views on the new Dapol CADs? I recall MissPrism came up with a long list of recommendations based on the initial CADs which were sent directly to Dapol. The views of some of the more learned souls on here might be useful feedback for Dapol (MissPrism, Edwardian, Coachmann, Stationmaster Mike, Castle, CoachBogie and others whose names I can't remember....)?

They would tend to feedback via Dapol Digest, whilst Dapol may peruse this site they don't engage after some negativity in the past.

[The Stationmaster]

Last time round I was looking mainly at the prairie and Miss P went to town heavily on the mogul which I hope they took notice of as they're typically GWR 'standard' engines with stuff changing on almost every batch and then with the wind over the years.  So need for lots of checking.

 

The prairie was, politely, an utter abortion, which came into the category of 'I wouldn't start from here if I were you' as some bits were off the wrong series, one fairly important bit was off no series that ever existed at Swindon on a 2-6-2 chassis, and various details were not good.  So if they haven't ditched it they'll be doing a major re-work - I hope (or unless they could get anywhere near a proper job one might hope they've quietly left it on one side for now).

 

The 2-6-0 CAD, no doubt subject to checking and comment on the Dapol Digest of course, looks in CAD terms to be almost ready to go into tooling.  So hopefully if it checks out and provided all the ducks are in a row at each successive stage with the right factory onboard it is possible to go from a CAD at this stage to models on the retailers' shelves in a little over a year.  With no hiccoughs and a decent factory they might even beat that by a month or so but hopefully they won't be rushing anything simply to save a bit of time.

 

The big problem with modelling any GWR engine is to chose what to model.  The basic detail of the Dapol 43XX makes it a model of the batches starting with 5384, the first to appear with the later pattern of motion cross bar frame, running up to 6361 the restarting at 6370 and running up to 7319.  6362 - 69 and 7320 onwards all came with outside steam pipes from new while, apart from one early example, outside steam pipes began to appear on the others from late 1944 onwards.  Dapol will presumably get the right numbers on models they issue but renumbering for a stated period will need checking against the date the prototype engine acquired outside steam pipes; some engines never got them.   Various other minor details changed but the washout plus look right, the support struts from the smokebox to the leading footplate area appear to come off the smokebox (as they should) but we can't see 'the face of the engine which is regrettable as, in my view, it matters and can make a huge differeence.  What ids not clear is whether teh splasher on the right hand side is the pre-modified version of the later one.  But overall, to me at any rate, the proportions look ok. 

Edited July 19, 2018 by The Stationmaster

[7007GreatWestern]

 

They would tend to feedback via Dapol Digest, whilst Dapol may peruse this site they don't engage after some negativity in the past.

 

I'm very happy to summarise feedback on here and put it onto Dapol Digest and I seem to remember MissPrism put his comments there directly.

 

Personally I'm not bothered at all how the information gets to Dapol. What interests me is that if anyone sees any howlers Dapol are told and problems are rectified before they go to tooling. Perhaps if Oxford Rail had shared CADs and been receptive to comment the Dean Goods would have been a better model than it was? There will be no point in us all moaning when faults are spotted 6 months hence......we have an opportunity to make a difference NOW.

 

For what it's worth (and it ain't worth much) I've already commented on the over-sized swan neck for the front vacuum hose on Dapol Digest.

[7007GreatWestern]

Over on Dapol Digest I have posted about a possible fault in the drawings regarding the position and size on the cylinders and smokebox in the new CADs. I'll repeat it here for anyone so interested.......

 

"The problem relates to the width (when seen side-on) of the cylinder block and smokebox saddle.

 

I have marked up the relevant part of your drawing and photographs of the prototype to illustrate my point. (see below)

 

In your drawings the front face of the cylinders meets the horizontal running plate some distance behind the point where the running plate curves downward (red circle). This makes the front end-cover of the steam chest visible. When you look at the prototype photo however the front face of the cylinder meets the running plate at the point where it begins to curve down - NOT rearwards of it!

 

 

 

Also, I would query the line of the front face of the smokebox saddle - it should be immediately behind the point where the buffer beam support struts attach to the smokebox. On your drawing there is a gap between the two (yellow circle).

 

Finally I believe the rearmost face of the saddle should meet the forward row of circumferential rivets that hold the smokebox to the front of the boiler. (green circle). Again, on you drawing there is a gap between them.

 

I have checked in David Maidment's book on the class and can find no photos of 4300s having the cylinder layout shown in the drawing at any stage in their lives.

 

The rearward position of the front face of the cylinders looks correct for the later "Collett Moguls", but not the "Churchward Moguls". (See below)

 

https://goo.gl/images/cePcdh

 

However, the front and rear faces of the smokebox saddle are still wrong with respect the the buffer beam struts and the circumferential rivets."

Edited July 22, 2018 by 7007GreatWestern

[7007GreatWestern]

The above seems to be confirmed by official drawings.....

 

Churchward Mogul cylinder position and footplate profile:

 

 

Collett Mogul cylinder position and footplate profile:

 

 

If you compare the above drawings it seems that on the Collett Mogul the curved drop in the running plate was moved forward relative to the front of the smokebox. On the Churchward Mogul the drop is clearly rearward of the smokebox front. Dapol look to have got the position of the curved drop correct for their model (Churchward Mogul), but the cylinders and saddle both seem to be undersized along the x-axis. The saddle should fill the gap between the boiler-to-smokebox rivets and the bufferbeam support strut...but it doesn't.

 

Dapol Drawing of Churchward Mogul:

 

Edited July 22, 2018 by 7007GreatWestern

[The Stationmaster]

I think part of Dapol's problem is that one of the seemingly most commonly reproduced drawings is of the Collett engine rather than the Churchward engine and then things can easily be compounded by looking at the 'wrong' preserved example (or maybe not looking at any preserved examples at all?).  At least Cyril Freezer drew both, next to each other, in his book of WR engine drawings/sketches.

[Horsetan]

The above seems to be confirmed by official drawings.....

 

Churchward Mogul cylinder position and footplate profile:

 

IMG_0219.JPG

 

Collett Mogul cylinder position and footplate profile:

 

IMG_1438.JPG

 

If you compare the above drawings it seems that on the Collett Mogul the curved drop in the running plate was moved forward relative to the front of the smokebox. On the Churchward Mogul the drop is clearly rearward of the smokebox front. Dapol look to have got the position of the curved drop correct for their model (Churchward Mogul), but the cylinders and saddle both seem to be undersized along the x-axis. The saddle should fill the gap between the boiler-to-smokebox rivets and the bufferbeam support strut...but it doesn't.

 

Dapol Drawing of Churchward Mogul:

 

Dapol 43xx.png

Dapol wouldn't be the first to make an error.

 

Back in the 1990s, Bachmann also got it wrong when (re-)releasing the Mogul in 93xx side-window form - they kept the old Churchward footplate and also managed to shrink the cylinders. Iain Rice wrote a piece in the old MORILL showing how to correct it.

[Dunsignalling]

The above seems to be confirmed by official drawings.....

 

Churchward Mogul cylinder position and footplate profile:

 

IMG_0219.JPG

 

Collett Mogul cylinder position and footplate profile:

 

IMG_1438.JPG

 

If you compare the above drawings it seems that on the Collett Mogul the curved drop in the running plate was moved forward relative to the front of the smokebox. On the Churchward Mogul the drop is clearly rearward of the smokebox front. Dapol look to have got the position of the curved drop correct for their model (Churchward Mogul), but the cylinders and saddle both seem to be undersized along the x-axis. The saddle should fill the gap between the boiler-to-smokebox rivets and the bufferbeam support strut...but it doesn't.

 

Dapol Drawing of Churchward Mogul:

 

Dapol 43xx.png

And on both Churchward and Collett versions, the ends of the saddle line up with the ends of the cylinders.

 

If the one is too short, so is the other, and the front of Dapol's cylinders appear to have been moved rearward to maintain alignment with the front of the saddle.

 

One wonders if this has been done consciously, in order to avoid the need to shrink the profile of the cylinders and permit the pony wheels to swing without hitting them.

 

Does the unwritten industry standard of enabling locos to negotiate 2nd radius curves dictate a choice between making the cylinders too skinny or too short?

 

It seems that Bachmann faced the same dilemma when they made a mogul so, if an r-t-r model has to be tweaked to make it functional, which "adjustment" is least undesirable?

 

John

Edited July 23, 2018 by Dunsignalling

[Killybegs]

Dapol will presumably get the right numbers on models they issue but renumbering for a stated period will need checking against the date the prototype engine acquired outside steam pipes; some engines never got them.  

 ....... and then there were those without steam pipes that had boilers with holes for the steam pipes plated over!

[Siberian Snooper]

....... and then there were those without steam pipes that had boilers with holes for the steam pipes plated over!

Pendant mode on, the boilers didn't have steam pipe holes, the smokeboxes did, pendant mode off.

[Killybegs]

Pendant mode on, the boilers didn't have steam pipe holes, the smokeboxes did, pendant mode off.

How right you are!

[tomparryharry]

Pendant mode on, the boilers didn't have steam pipe holes, the smokeboxes did, pendant mode off.

 

Yes, too right. If you open the smokebox door, you'll see an empty sandwich wrapper, and an empty thermos flask.

 

Swindon? It gets everywhere.....

[7007GreatWestern]

And on both Churchward and Collett versions, the ends of the saddle line up with the ends of the cylinders.

 

 

There is of course a very good reason why the leading and trailing faces of the cylinders and smokebox saddle will always line up - they are in fact the same physical component! Here is a photo of the newly cast cylinder/smokebox saddle for the preserved 2884 No. 3850:-

 

http://www.dinmoremanor.co.uk/news-of-3850s-cylinder-casting/

 

On a real GWR loco the smokebox/cylinders are split in the vertical plane. Only on model trains are the saddle and cylinders separable from one another!

 

I'm pretty convinced that the Dapol cylinders are undersized along the x-axis. The question is, are they also incorrectly positioned? I can't say with total certainty but the vertical centreline of the cylinders does seem to line up with the centreline of the chimney.....which it should. (See dotted red line).

 

   

 

Because the cylinders are undersized in the x-plane, the leading edge of the front coupled wheels is clearly visible behind the piston gland (see orange oval), whereas in the official drawings it is obscured.

 

I haven not yet received a reply to my postings on Dapol Digest regarding the error in the cylinders or the front vacuum pipe swan neck. I'll keep you updated if and when I do. In the mean time if anyone else sees anything erroneous in the drawings please inform us or Dapol. Other pairs of eyes would be useful - I am not an expert!

Edited July 23, 2018 by 7007GreatWestern

[7007GreatWestern]

Over on Dapol Digest I have received a courteous and constructive reply from them regarding the cylinder dimensions. 

 

It seems Dunsignalling was 'on the mark' when he wondered if this was a design decision taken to enable the model to negotiate 2nd radius curves. (see post #412).

 

Richard of Dapol has said that they are going to try to redesign this aspect of the model if possible and will update us with revised drawings. The phrase 'if possible' is significant - it may be the project is too far advanced to make these changes now. If not, then I'm guessing an improved cylinder/bogie design should be practicable for the Large Prairie.

 

Whatever you think of the design decision, I'd like to commend Dapol for actually listening to their customers and engaging positively with well intentioned advice. A marked contrast with some if not all of their competitors!

Edited July 24, 2018 by 7007GreatWestern

[57xx]

If they need room behind the cylinders for the bogie wheel, then why not just put a cutout on the back where it's not visible, not compromise the visible dimensions. It also doesn't explain why the rear end of the cylinder block has been shortened.. Hope it's not too late for them to sort out properly.

Edited July 24, 2018 by 57xx

[7007GreatWestern]

If they need room behind the cylinders for the bogie wheel, then why not just put a cutout on the back where it's not visible, not compromise the visible dimensions. It also doesn't explain why the rear end of the cylinder block has been shortened.. Hope it's not too late for them to sort out properly.

 

Hi 57xx,

 

Creating a rebate on the inner face of the cylinder is precisely what I have suggested to Dapol, as well as using off-centre pivot points to effectively lengthen the swing of the pony truck when cornering. It's a technique used by at least one other manufacturer and seems to be widely acceptable to customers.

 

In Dapol's reply to my post they explain that the rear end of the cylinder block was shortened so that the vertical centreline would continue to line up with the centreline of the chimney.

[phil gollin]

Pendant mode on, the boilers didn't have steam pipe holes, the smokeboxes did, pendant mode off.

.

 

Thanks for that.

 

{ Idiot mode on }

 

What were the pipes from the boiler to the cylinders (or rather valves) called ?

 

{ Idiot mode off, hopefully. }

 

.

[tomparryharry]

.

 

Thanks for that.

 

{ Idiot mode on }

 

What were the pipes from the boiler to the cylinders (or rather valves) called ?

 

{ Idiot mode off, hopefully. }

 

.

Generally known as main steam pipes. On 2 cylinder locomotives, the blast pipe was cast integrally to form part of the smokebox saddle. This is 2-cylinder Western locomotives, BTW.

 

Ian.

[34theletterbetweenB&D]

...Creating a rebate on the inner face of the cylinder is precisely what I have suggested to Dapol, as well as using off-centre pivot points to effectively lengthen the swing of the pony truck when cornering. It's a technique used by at least one other manufacturer and seems to be widely acceptable to customers...

It's not far to look on this site to find significant objections to this scheme (try the Hornby L1 thread). Pony trucks with this arrangement have a tendency to fail to straighten fully after curves,  to go wrong way on facing points, and the mechanism slack may allow the pony truck wheel position to alternate fore and aft by about 2mm whenever direction of movement changes. (The past exponent of this scheme were Hornby, and they have dropped it on their most recent outside cylinder with leading pony truck model the K1, which has a trouble free single pivot truck.)

 

Single pivot is far preferable, with a rebate in the cylinder head if required to accomodate set track curvature; the neat solution is to make the front cylinder head a push fit moulding, with an alternative full cylinder head part for those with larger radius curves.

[7007GreatWestern]

It's not far to look on this site to find significant objections to this scheme (try the Hornby L1 thread). Pony trucks with this arrangement have a tendency to fail to straighten fully after curves,  to go wrong way on facing points, and the mechanism slack may allow the pony truck wheel position to alternate fore and aft by about 2mm whenever direction of movement changes. (The past exponent of this scheme were Hornby, and they have dropped it on their most recent outside cylinder with leading pony truck model the K1, which has a trouble free single pivot truck.)

 

Single pivot is far preferable, with a rebate in the cylinder head if required to accomodate set track curvature; the neat solution is to make the front cylinder head a push fit moulding, with an alternative full cylinder head part for those with larger radius curves.

 

Thanks for that 34theletterbetween.....I wasn't aware of the issues you describe with double pivoting. It will be interesting to see what solution Dapol come up with, assuming the existing design is changed. Please feel free to contact Dapol to suggest a better solution.

 

I agree with your point about making the front cylinder cover a separate, push fit moulding. I have suggested precisely that in my most recent post on Dapol Digest. Perhaps a removable 'half relief' cylinder cover could be fitted to the model in the factory, with an full relief one supplied in the accessory pack for the consumer to fit?

 

Hornby have used rebated cylinders on several of their GWR 2 cylinder models (Grange, 42xx/72xx/52xx, 28xx) though to date haven't supplied alternate covers. A shame, as that would be a nice feature for people without tight radii.

Edited July 25, 2018 by 7007GreatWestern

[eastglosmog]

It's not far to look on this site to find significant objections to this scheme (try the Hornby L1 thread). Pony trucks with this arrangement have a tendency to fail to straighten fully after curves,  to go wrong way on facing points, and the mechanism slack may allow the pony truck wheel position to alternate fore and aft by about 2mm whenever direction of movement changes. (The past exponent of this scheme were Hornby, and they have dropped it on their most recent outside cylinder with leading pony truck model the K1, which has a trouble free single pivot truck.)

 

Single pivot is far preferable, with a rebate in the cylinder head if required to accomodate set track curvature; the neat solution is to make the front cylinder head a push fit moulding, with an alternative full cylinder head part for those with larger radius curves.

You are dead right there. I have had a lot of trouble with the double pivot pony truck on my Hornby 28xx.  Taken an awful lot of fiddling to make it stay on the track at facing points coming out of a left hand curve (quite OK coming out of  a right hand curve) and it is still a bit dodgy at times (and my curves are much slacker than 2nd Radius).  If Dapol fit such a feature, I would have serious doubts about buying one.

[The Johnster]

It would certainly put the mockers on my plan for a large prairie; I will play a long game and see if the model is a good runner rather than jumping in with an order; it'll be only myself to blame if they sell out straight away and I don't get one!