OO gauge GWR Mogul and Prairie

[David Burton]

14 hours ago, melmerby said:

The Hornby 61XX are about 5.2mm apart.

 

What are the measurements for the slide bars & connecting rods on the drawing?

Hornby have 20mm (5'0") long slide bars and 28mm long (7' 0") connecting rods.

Cylinder centres are about 27.5mm or 6' 9"

 

(As my 63XX hasn't arrived yet I can't check that)

On the drawing, the slidebars are 5' 5 7/8" (just short of 22 mm) long, 1 1/2" high at each end and 2 1'2" high where attached to the motion bracket. The width is 5 1/2". The connecting rod should be 6' 10 1/2" (27.5 mm) long between the the big end and small end centres.

 

David

[melmerby]

9 hours ago, Budgie said:

Can you see the difference?

 

 

You can, It results in the tapered slide bar ends. (The only GWR locos that have that have 4 cylinders)

IMHO a little oversize would have been preferable to undersize.

Get them closer to real and there would be much less need to taper them

Hornby on the 61XX are nearer to the drawing and look better.

 

A slight fly in the ointment of an otherwise cracking looking model.

[Mark]

To my eye the slope on the firebox looks far too steep. The drawing in GWJ scales to about 0.5” front to rear. I am not convinced the Dapol model is correct in this respect.

 

Mark

[boxbrownie]

12 hours ago, Neal Ball said:

All fixed now, no thanks to Dapol who I phoned thus afternoon and were not helpful at all.

 

Absolutely no surprise to me at all.........after the farce I had with Dapol they will NEVER get any of my money again.

[Harlequin]

9 minutes ago, boxbrownie said:

Absolutely no surprise to me at all.........after the farce I had with Dapol they will NEVER get any of my money again.

 

Is it fair to keep on characterising Dapol this way because you had a bad experience with a particular configuration of a particular product?

 

I'm not surprised that Dapol were unable to say anything conclusive about Neal's problem because it may have been the first report of these symptoms they heard. It's still early days for this model.

 

[boxbrownie]

1 hour ago, Harlequin said:

 

Is it fair to keep on characterising Dapol this way because you had a bad experience with a particular configuration of a particular product?

 

I believe so.......they have totally ignored a manufacturing fault on a Loco costing almost £250 which has subsequently cost me another £35 to correct the issue myself.

 

 

[rprodgers]

On 23/11/2020 at 16:43, Neal Ball said:

Has anyone had issues with the loco seizing up?

 

Although the instructions say running-in is not needed, thats what I am now doing. It seems to be running better, (on DC), but is still not perfect.

 

There doesn't seem to be any rhyme or reason to where / how its seizing and/or sticking when going round at slow speed on the rolling road.

 

I will preserve and see how I get on tomorrow.

• Hi Neal  I might have a similar problem whilst testing mine on a rolling road it just suddenly stopped. Checking further I discovered that the crank pin on the one leading wheel was caught on the back of the cross head and it had moved the slide bars etc from the horizontal to a diagonal. I moved them back into place but it has happened again. I am wary about using glue there is a “pip” on the top of the cylinder assembly that fits into the bottom of the running board .
• I will try  to post pictures to illustrate what I mean.
• Ps Before this it was running very smoothly, the slow running issues some others mentioned I assumed was down to the mechanism having to overcome the initial “reluctance “ of the fly wheel. Maybe without the fly wheel it would run as slow as some people would want?

Richard

Edited November 25, 2020 by rprodgers
To add pictures

[Adrock]

R.e. the crawling properties, I know one or two have commented how well theirs crawl; they generally seem to be DCC versions. I wonder if the fitting of a DCC chip will change and improve the running on DC? I have previously used DCC, but when I returned to DC I noticed whilst doing like by like comparisons (chip in and chip out on DC) most engines ran slightly differently between the two modes. And the general trend was that they ran better on DC with the chip in there! Obviously hugely depends on the engine and chip configuration, but this was what I found in most of my particular cases.

 

Does anyone have the equipment and set up to test this hypothesis on the 43xx?

[Neal Ball]

25 minutes ago, rprodgers said:

• Hi Neal  I might have a similar problem whilst testing mine on a rolling road it just suddenly stopped. Checking further I discovered that the crank pin on the one leading wheel was caught on the back of the cross head and it had moved the slide bars etc from the horizontal to a diagonal. I moved them back into place but it has happened again. I am wary about using glue there is a “pip” on the top of the cylinder assembly that fits into the bottom of the running board .
• I will try  to post pictures to illustrate what I mean.
• Ps Before this it was running very smoothly, the slow running issues some others mentioned I assumed was down to the mechanism having to overcome the initial “reluctance “ of the fly wheel. Maybe without the fly wheel it would run as slow as some people would want?

Richard

 

Thanks Richard, have a look at the similar photos on my Henley page, where I’ve marked the locating lugs. The motion bracket needs to fit into the corresponding lug. If one is out, it gives the seizing issues we describe - I didn’t realise at the time, but it’s one direction only.

 

Its awkward to get the two together, but once you do your running should be fine.

 

Towards the bottom of page 52: https://www.rmweb.co.uk/community/index.php?/topic/93864-henley-on-thames-gwr-in-the-1930s/page/52/

 

Good Luck.

[Mallard60022]

Quick question please, to the obvious experts here. 6372 in 1960; did it have Steam Pipes?

Thank you,

Phil

[Clearwater]

2 minutes ago, Mallard60022 said:

Quick question please, to the obvious experts here. 6372 in 1960; did it have Steam Pipes?

Thank you,

Phil

Hi Phil

 

no expert but my GW moguls book says it didn’t.

 

cheers

 

david

[Harlequin]

5 minutes ago, Mallard60022 said:

Quick question please, to the obvious experts here. 6372 in 1960; did it have Steam Pipes?

Thank you,

Phil

My book also says, No.

 

[Chuffer Davies]

32 minutes ago, rprodgers said:

 

Ps Before this it was running very smoothly, the slow running issues some others mentioned I assumed was down to the mechanism having to overcome the initial “reluctance “ of the fly wheel. Maybe without the fly wheel it would run as slow as some people would want?

Richard

 

 

HI Richard,

from the picture above it would appear that the crankpin is not fully inserted in the wheel and it is for this reason that it is hitting the crosshead.  I suggest you compare it against the pin on the opposite wheel to double check.  

 

With regards slow speed running I have been able to check the gearing on mine and it would appear to be an unusually low gear ratio at 16:1.  My experence of building kit loco's is that gear ratios usually come in at 30:1 or higher although the Portescap units were more like 28:1 due to the lower revving of the motors chosen for the units.  The lower the motor speed the less benefit will be gained from the flywheel and in the case of the mogul the flywheel is quite small in the first place.  This is by no means a criticism, just an observation.... 

 

Regards,

 

Frank 

[Harlequin]

48 minutes ago, rprodgers said:

• Hi Neal  I might have a similar problem whilst testing mine on a rolling road it just suddenly stopped. Checking further I discovered that the crank pin on the one leading wheel was caught on the back of the cross head and it had moved the slide bars etc from the horizontal to a diagonal. I moved them back into place but it has happened again. I am wary about using glue there is a “pip” on the top of the cylinder assembly that fits into the bottom of the running board .
• I will try  to post pictures to illustrate what I mean.
• Ps Before this it was running very smoothly, the slow running issues some others mentioned I assumed was down to the mechanism having to overcome the initial “reluctance “ of the fly wheel. Maybe without the fly wheel it would run as slow as some people would want?

Richard

The crank pin might just have not been tightened properly at the factory and worked loose. This is quite a common failing for new steam locos in my experience.

Tightening it back up might be all that's needed - if you can get at it...

Edited November 25, 2020 by Harlequin

[Mallard60022]

3 minutes ago, Harlequin said:

My book also says, No.

 

Thank you very much both...in that case, any chance of looking for 6320 as well? Same time period. Apologies but I am not a GWR/WR person, but these two worked diversions through my depicted area in December 1960. I have 7310 and it has Pipes; I will use it unless 6320 had pipes and then I'll renumber if relevant.

P

[Mallard60022]

Should have said how useful this discussion is before setting off to test mine out; thanks all.

Phil

[Harlequin]

2 minutes ago, Mallard60022 said:

Thank you very much both...in that case, any chance of looking for 6320 as well? Same time period. Apologies but I am not a GWR/WR person, but these two worked diversions through my depicted area in December 1960. I have 7310 and it has Pipes; I will use it unless 6320 had pipes and then I'll renumber if relevant.

P

6320: No

 

[Clearwater]

My book says no as well but I wouldn’t take that as an independent confirmation as if @Harlequinis using RCTS, my book is quoting that in its bibliography so probably the same underlying information.

 

David

[Harlequin]

39 minutes ago, Clearwater said:

My book says no as well but I wouldn’t take that as an independent confirmation as if @Harlequinis using RCTS, my book is quoting that in its bibliography so probably the same underlying information.

 

David

Yes, it would be good to have confirmation from independent sources. I'm using "Great Western Moguls and Prairies" by David Maidment, 2016. I can't see RCTS mentioned in the Bibliography...?

 

[The Johnster]

Much more information re the crankpin/crosshead interface, and the gear ratio, thanks, gentlemen.  16:1 is very low and it is therefore a credit to the free running of the mech that it runs slowly at all; I have memories of Triang and Hornby Dublo mechs with 20:1 gearing that were impossible to control at lower than about 20 scale mph.  If you got a good one, like my 748 saddle tank which could take half an hour to cog it's way around  an 8x4, you were lucky but most of my childhood locos were brick sh*thouse stop or go-too-fast.  Proper shunting was impossible.

 

DCC should improve slow running, as 12v is on tap at all times and the current to the motor is not restriced, enabling a mech to be better running at low speeds when rolling resistance is at it's proportionate highest and any compromise to pickup at it's worst, plus the braking effect of the pickup wipers will be at it's greatest; this is part of the intended advantage of DCC, and stayalives do the work of flywheels.  Those of us who use DC often wish we had the advantage of stayalives, and I did some experimentation with capacitors back in the 80s which never led to anything I could use, and this is presumably the rationale behind the use of flywheels.  I was a fan of this idea at one time but now believe that the advantage conferred by a flywheel is insignificant at lower speeds for the reasons stated above, and would prefer to see the space used for ballast which at least improves pickup from the railhead by bearing downwards to it.  The smaller the flywheel the less point there is too it and it must be properly balanced for good slow running as well, which makes it an expensive engineering-intensive addition, something I would tend to be suspicious of in a loco at this price level.

 

And, tbh, I am suspicious by default of Dapol, who have sold me rubbish wagons in the past, in any case.  I do not regard them as a 'safe pair of hands' in the same way as I do Bachmann or current Hornby production (I have no experience of Oxford or Heljan locos but a friend had a Dapol pug some years ago which could not be made to run smoothly, useless jerky lump of junk with a cab full of motor, a loco where good slow running and cab detail revealed by that large side opening is particularly important; this is the model later sold by Hornby, who may have improved it, but I have a long memory and am still wary of Dapol stuff...

 

The gear ratio is another nail in the coffin of my possible future Dapol 5101; the Hornby is well in the lead as things stand, and opening the lead out!  Were I  in the market for a mogul, I think I'd be looking at the Dap for the body tooling but sitting it on a Hornby chassis, which of course makes the cost less acceptable. Even if it is feasible to replace the gears on the Dapol mech with something more suitable at twice the ratio, the models other running faults and especially the splayed slide bars have made the decision for me.  This might mean a sooner appearance of a Hornby 5101 at Cwmdimbath, as there seems less and less point in waiting for the Dapol!  Sorry Dapol, but the Hornby is a reported and by now established  good runner with a good scale appearance.  Kudos, Mr Kohler...

Edited November 25, 2020 by The Johnster

[Miss Prism]

1 hour ago, Chuffer Davies said:

16:1 

 

Good grief. No wonder its startup is so jerky. That's plain bad design.

 

 

Quote

although the Portescap units were more like 28:1

 

Typo for 38:1 I think.

 

[melmerby]

15 minutes ago, The Johnster said:

 

 

DCC should improve slow running, as 12v is on tap at all times and the current to the motor is not restriced, enabling a mech to be better running at low speeds when rolling resistance is at it's proportionate highest and any compromise to pickup at it's worst, plus the braking effect of the pickup wipers will be at it's greatest; this is part of the intended advantage of DCC, and stayalives do the work of flywheels.

Er. No

(Bearing in mind ADrock's comment on decoders in DC locos)

The voltage output is proportional to the voltage on the track (DCC or DC)

If you only have 6v then the decoder will only be operating on a proportion of that.

If I vary the DCC voltage on my track, which I can do, the loco goes faster or slower.

 

I would imagine the better performance is due to the use of high frequency BEMF.

 

Edited November 25, 2020 by melmerby

[Miss Prism]

6372 at Dulverton in 1953, running with an intermediate 3500g tender. I think it was a regular on the Barnstaple line.

 

 

 

6320, not long after nationalisation, probably 1949/50, somewhere on southern territory maybe (there's an 8-wheel watercart tender in the background):

 

 

 

 

Edited February 6 by Miss Prism
images reinstated

[melmerby]

I can't imagine the gearing to be 16:1, that would need a slow running multipole motor to run reasonably at slow speeds.

[melmerby]

8 minutes ago, Miss Prism said:

 

 

 

6320, not long after nationalisation, probably 1949/50, somewhere on southern territory maybe (there's an 8-wheel watercart tender in the background):

 

 

Could be one of several places where the LSWR & GWR met.

Was a Swindon loco at the time.

Edited November 25, 2020 by melmerby