Comet Gresley 8'3" bogies

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barhamd
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Comet Gresley 8'3" bogies

Postby barhamd » Sat Nov 05, 2022 3:01 pm

I'm in the process of building a Thompson full brake from a Comet kit. The prototype had 8'6" Gresley Heavy Duty bogies. Unfortunately the white metal casting supplied with the kit have axle centres of 33mm. I'm guessing the master was made the correct size but the castings suffer from shrinkage. Interesting the etched underfame had holes labelled for 45'6" centres at 175mm (should be 182) and 45' at 173mm (should be 180mm). The actual coach should have a bogie wheelbase of 43'6" (174mm).

Ho-hum, looks like I'm jumping into CAD to print myself some sideframes.

Is this uncommon?

David

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BryanJohnson
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Re: Comet Gresley 8'3" bogies

Postby BryanJohnson » Sat Nov 05, 2022 3:26 pm

I've got some Comet LMS 9' wheelbase bogie sides and these were the opposite. There is a pip on the axlebox front which gives an easy pair of points to measure between and instead of 36mm I get:
Rivetted packet #1 36.7mm
Rivetted packet #2 37.2mm
Rivetted packet #3 37.0mm
Welded packet #1 37.0mm
Welded packet #2 36.8mm

I shortened one of the rivetted ones, but didn't think it was worth the effort so I've just lived with the error, although it makes opening the axlebox hole for springing a bit more tricky.

Bryan

Tony Wilkins
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Re: Comet Gresley 8'3" bogies

Postby Tony Wilkins » Sat Nov 05, 2022 4:35 pm

Hi David.
As far as I am aware, the Thompson and Gresley full brakes used 8'0" wheelbase bogies at 43'0" centers as opposed to 8'6" at 43'6" centers for the rest of the main line stock. I discovered this anomaly whilst building a Mallard models etched kit for a Gresley full brake supplied with 8'6" bogies.
Reference: Historic carriage drawings LMS & LNER by David Jenkinson & Nick Campling and Gresley coaches by Michael Harris.
Regards
Tony.
Inspiration from the past. Dreams for the future.

davebradwell
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Re: Comet Gresley 8'3" bogies

Postby davebradwell » Sat Nov 05, 2022 5:55 pm

Well, I've just looked in Harris and all his diagrams for 61ft 6in Gresley stock would appear to show bogies at 43ft 0in centres. I have some real drgs for Thompson stock and they're the same.

As for full brakes he states "The GNR design of 8ft wheelbase bogie was at first used, permitting a max payload of 8 tons. The single bolster bogie used for suburban stock was then adopted for bogie vans and with 10 in by 5 in journals their payload was increased to 10 tons".

This suggests 8ft 6in bogies were used on later diagrams and it is possible the early ones were upgraded. 10 by 5 journals would suggest a heavy type bogie. Another trap was the use of Fox 8ft bogies on some stock but these had smaller journals.

I'm not in my comfort zone here so can only hope someone will step in and tidy this up. Mike Trice is the man as he tracked much information back to real drgs.

As for accuracy of castings and plastic mouldings - yes, they're all over the place due to incorrect shrinkage allowance and, yes, it can be almost impossible to predict. If you are going to print some sides, please use a real drg. Looks like I can do an 8-6 heavy bogie but I believe the light bogie drg is officially reported as "missing". I have an 8ft light and a Fox. Wouldn't like to say if they're single or compound bolster.

DaveB

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Re: Comet Gresley 8'3" bogies

Postby davebradwell » Sat Nov 05, 2022 10:21 pm

I'll add that after checking my drgs, Thompson 61ft 6in stock has 43ft bogie centres - other lengths are available. You'll ned an MJT roof to get the profile right - if you file the gutters down and give a light squeeze in a vice its very close to a Thompson roof, or was on my BZ!

DaveB

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jim s-w
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Re: Comet Gresley 8'3" bogies

Postby jim s-w » Sat Nov 05, 2022 10:54 pm

barhamd wrote:I'm in the process of building a Thompson full brake from a Comet kit. The prototype had 8'6" Gresley Heavy Duty bogies. Unfortunately the white metal casting supplied with the kit have axle centres of 33mm. I'm guessing the master was made the correct size but the castings suffer from shrinkage. Interesting the etched underfame had holes labelled for 45'6" centres at 175mm (should be 182) and 45' at 173mm (should be 180mm). The actual coach should have a bogie wheelbase of 43'6" (174mm).

Ho-hum, looks like I'm jumping into CAD to print myself some sideframes.

Is this uncommon?

David


Are the MJT ones not suitable?
Jim Smith-Wright

http://www.p4newstreet.com

Over thinking often leads to under doing!

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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Sat Nov 05, 2022 11:02 pm

Thanks for the advice. I've started modelling up a bogie side frame. I could buy a set for Isinglass but thought I'd have a go and see what I could do.

8-6bogie.jpg


Dave - are you saying the roof profile from Comet is completely wrong?

David
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davebradwell
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Re: Comet Gresley 8'3" bogies

Postby davebradwell » Sun Nov 06, 2022 9:54 am

If you have a Comet standard roof, and I think they only do one, then it's very different from an LNER roof - the edges curve too sharply.

You must have a dimensioned bogie drg, then?

DaveB

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BryanJohnson
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Re: Comet Gresley 8'3" bogies

Postby BryanJohnson » Sun Nov 06, 2022 11:03 am

I remember going to a talk given by one of the original Comet founders at Scalefour North a good while ago. IIRC, his explanation for the Comet coach roof was that even with all the manufacturing sites in Birmingham, the minimum quantity for forming the roof shape was way too much to allow them to have a range of shapes. I can't recall the exact figure but it may have been a hundredweight of aluminium, which is a lot of single rooves. Their compromise was to go for a profile somewhere between the GWR and LMS profiles as they were likely to be their best sellers.

Bryan

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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Sun Nov 06, 2022 2:04 pm

davebradwell wrote:
You must have a dimensioned bogie drg, then?

DaveB


I have the single, rather indistinct image, from LNER Carriages by Michael Harris but I think I can get close enough for me and certainly better than the wrong length white-metal version in the kit.

David

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Re: Comet Gresley 8'3" bogies

Postby davebradwell » Sun Nov 06, 2022 3:32 pm

That's fine, then, but if you can't read any important dimensions just let me know. Centre section is 13in deep, for example and top is 1 1/8in below top outside axleboxes. Bogie is 7ft 3 1/8in over the flat sides so you can work out how thick to make them to get the width right.

DaveB

Tony Wilkins
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Re: Comet Gresley 8'3" bogies

Postby Tony Wilkins » Sun Nov 06, 2022 9:05 pm

davebradwell wrote:Well, I've just looked in Harris and all his diagrams for 61ft 6in Gresley stock would appear to show bogies at 43ft 0in centres. I have some real drgs for Thompson stock and they're the same.

As for full brakes he states "The GNR design of 8ft wheelbase bogie was at first used, permitting a max payload of 8 tons. The single bolster bogie used for suburban stock was then adopted for bogie vans and with 10 in by 5 in journals their payload was increased to 10 tons".

This suggests 8ft 6in bogies were used on later diagrams and it is possible the early ones were upgraded. 10 by 5 journals would suggest a heavy type bogie. Another trap was the use of Fox 8ft bogies on some stock but these had smaller journals.

I'm not in my comfort zone here so can only hope someone will step in and tidy this up. Mike Trice is the man as he tracked much information back to real drgs.

As for accuracy of castings and plastic mouldings - yes, they're all over the place due to incorrect shrinkage allowance and, yes, it can be almost impossible to predict. If you are going to print some sides, please use a real drg. Looks like I can do an 8-6 heavy bogie but I believe the light bogie drg is officially reported as "missing". I have an 8ft light and a Fox. Wouldn't like to say if they're single or compound bolster.

DaveB


Hi Dave.
You are of course correct about the 43' 0" centers. There are drawings in the Campling book showing a 43' 6" dimension, which I can only conclude is an error.
Regarding the bogie dimensions I believe that I am correct about the 8' 0" wheelbase for the full brakes. MJT lists a heavy duty 8' 0" Gresley sideframe casting and some ex LNER coach underframes were used for conversion to diesel brake tenders. Both 8' 0" and 8' 6" variants were used. The small rectangular batch built at Stratford used the 8' 0" variety. I know because I measured them. They are also visually different.
Regards
Tony.
Inspiration from the past. Dreams for the future.

davebradwell
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Re: Comet Gresley 8'3" bogies

Postby davebradwell » Mon Nov 07, 2022 10:30 am

I discovered when checking through my drgs that the 43ft 6in dimension is correct for coaches having a 63ft body and I also discovered a 42ft spacing on a 59ft 6in body (corridor composite). Nick C gives 40ft 0in for this. I'm unable to add anything to the bogie wheelbase question other than to quote others. Nick C gives 8ft w/b bogies on his planked full brake but I don't have any real drgs for full brakes to confirm or otherwise but the real question is whether they were ever changed.

Roofs have been mentioned and the ellipse given on all my Thompson drgs is: major axis 8ft 8 1/2in, minor 4ft 6 3/4in. Width over cantrails is 8ft 8in with an extra inch over cornices. However, the planked full brake is narrower with vertical sides so roof will be a special. Perhaps an extra squeeze in the vice will do it.

DaveB

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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Thu Nov 10, 2022 9:50 pm

I got around to printing these last night, I think I'm fairly happy with the result and that they will fit onto the Bill Bedford bogies I have with minimal fettling.

aIMG_9884.jpg


The comparison between the Comet whitemetal version and mine is quite interesting.

aIMG_9886.jpg


David
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billbedford

Re: Comet Gresley 8'3" bogies

Postby billbedford » Fri Nov 11, 2022 10:18 am

According to the diagram the Thompson D344 full brakes had 8' 0" bogies and they almost certainly had single bolsters.

Here's two photos that show the difference.

LNER 8ft bogie.jpg


LNER 8ft6 bogie.jpg
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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Fri Nov 11, 2022 12:01 pm

Just to confirm this is the Thompson 63' Full brake Dia 344. The photos would appear to show 8'6" Heavy duty bogies.

David

billbedford

Re: Comet Gresley 8'3" bogies

Postby billbedford » Fri Nov 11, 2022 12:59 pm

Which photos are you talking about?

There is a photo in Michael Harris's LNER Carriages which shows D.344 No E153E with 8', deep framed, single bolster bogies. There is also a photo of a D.198 with similar bogies.

I have a list of all the bogies used by the LNER. Vestibuled full brakes rated at 10 tons used bogies to drawing 5023N, while full brakes rated at 8 tons used 7943N.

LNER Bogies.pdf
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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Fri Nov 11, 2022 1:47 pm

Hi Bill
I was looking at the same picture but thought the bogies were the 8'6" HD. I'll bow to your greater knowledge.

Harris states:-

'The standard postwar bogie van was dia 344, on a 61 ft 6" underframe with a steel panelled body of 9'3" width and with 3 pairs of doors on each side. The payload was 10 tons.'
He then mentions no 10-19 which worked on the Flying Scotsman and had fairings over the solebars.

Comet described their kit as 'British Railways Thompson BR(E) Diagram 344 63' Gangwayed Full Brake'. The box description also mentions the first 10 were used on the Flying Scotsman. The box also describes how the kit comes with 8'6 bogies.

So it appears that Comet think they are talking about the same vehicles but the Comet kit not only came with incorrect 8'3" HD bogie side frames, but also the wrong LNER 8'6 bogies - great.

I'm beginning to think this coach building lark is just too hard. I'll think I'll just put this back in the unbuilt pile and go back to my Macrame as a hobby.

David

billbedford

Re: Comet Gresley 8'3" bogies

Postby billbedford » Fri Nov 11, 2022 2:01 pm

barhamd wrote:Hi Bill
I was looking at the same picture but thought the bogies were the 8'6" HD. I'll bow to your greater knowledge.


If you look at the bolster supports, below the side frames, they are a single piece without the channel bar ends found on double bolster bogies.

Oh, and having worked with some of the people behind Comet, I wouldn't put it past them to market a 6'3" wb bogie as a compromise between the 8'6" and 8'0" ones.

Tony Wilkins
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Re: Comet Gresley 8'3" bogies

Postby Tony Wilkins » Fri Nov 11, 2022 2:05 pm

Hi David.
Don't feel too badly about it. Bachmann and Hornby made the same mistake with their Thompson and Gresley full brakes, probably because they didn't want to go to the trouble of making new tooling just for one type of vehicle.
Yes, the bolster supports are the giveaway.
Nice 3D prints though.
Regards
Tony.
Inspiration from the past. Dreams for the future.

Porcy Mane
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Re: Comet Gresley 8'3" bogies

Postby Porcy Mane » Fri Nov 11, 2022 2:38 pm

Hello boys,
I'm firmly in the 8' 0", heay duty, single bolster camp for the Diag . 344 BG.

Don't know if these are of any help.

Tight crop of a BR official that shows the roof profile quite well.

D344-BG-60032-ELIZABETHAN-B'MANS-Prk©PwD-Collection.jpg


Dtail of an 8 ft HD under a diag. 245 in 1966.

Pigeon-BogieDetail_Tue-28-6-1966©PwD-CollectionEdit.jpg


P
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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Fri Nov 11, 2022 2:41 pm

Does anyone have a drawing or at least the major dimensions of the 8'0" bogie? It should be relatively easy for me to modify my 3D model. I'm presuming that the plate side was not as deep as the 8'6" HD bogie I've modeled? Were they shorter at the ends too or is it just 2mm off the middle?

I can then get some of Bill's 8' bogies from Eileens to fit them on.
Then I'll just need to find another vehicle with 8'6 bogies to fit the ones I've got under.

David

billbedford

Re: Comet Gresley 8'3" bogies

Postby billbedford » Fri Nov 11, 2022 4:40 pm

Does anyone have a drawing or at least the major dimensions of the 8'0" bogie?


Does this help?

LNER 8' single bolster bogie.jpg
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barhamd
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Re: Comet Gresley 8'3" bogies

Postby barhamd » Fri Nov 11, 2022 6:40 pm

billbedford wrote:
Does anyone have a drawing or at least the major dimensions of the 8'0" bogie?


Does this help?



certainly does, thanks
David

Crepello
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Re: Comet Gresley 8'3" bogies

Postby Crepello » Fri Nov 11, 2022 7:51 pm

Porcy Mane wrote:Hello boys,
Tight crop of a BR official that shows the roof profile quite well.

Those trees look familiar. Hatfield south curve by any chance?


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