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Re: Carriage Underframe Trussing

Posted: Fri May 05, 2017 12:29 pm
by sawdust
John Palmer wrote:
Wed May 03, 2017 12:27 pm
billbedford wrote:
Wed May 03, 2017 10:01 am
JASd17 wrote:
Tue May 02, 2017 2:39 pm
I cannot give definitive information 65447.

But study the top photo on page 138 of LNER Standard Gresley Carriages. It seems to show an extra truss rod down the centre of the carriages in this GE Quad set.

Others seem to suggest more than 2 truss rods, but I am not certain of how many, 3 sets or 4?
There would be 4 sets of truss rods, because there were two inner longitudinals, as well as solebars, where the truss rods were attached to he frames.
My first thoughts were much the same as Bill's, but the picture referred to in LNER Standard Gresley Carriages caused me to have doubts. At page 142 of David Wragg's LNER Handbook there is a clear sideways-on shot of a quad-art on which I can see only three queen posts side by side, again suggesting a three-truss arrangement. I can't see any reason in principle why there could not be a single longitudinal frame member along the vehicle's centre line, or a closely spaced pair of such members with a truss rod sandwiched between them.
There is a reason why there would not be a single centre longitudinal and that is it would get in the way of the drag boxes and bogie pivots.

I've worked on carriages from the 1880's through to 1950 and all have had two centre longs.

Sawdust.

Re: Carriage Underframe Trussing

Posted: Fri May 05, 2017 2:41 pm
by John Palmer
sawdust wrote:
Fri May 05, 2017 12:29 pm
There is a reason why there would not be a single centre longitudinal and that is it would get in the way of the drag boxes and bogie pivots.
Yes, I understand why this would be a consideration in the design of non-articulated stock, but I see it as being potentially applicable only to the outermost pivots and drag boxes on an articulated set.

Further study of pictures of the quad-art set on the North Norfolk Railway reinforces the impression I formed that it is mounted on underframes having only three trusses. I base this conclusion on two photographs in particular: http://www.nnrailway.co.uk/graphics/sto ... turn_1.JPG and http://www.nnrailway.co.uk/graphics/sto ... turn_3.JPG. There is also some useful footage between 6:36 and 6:48 at https://www.youtube.com/watch?v=FPrFVBE_jHs.

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 12:34 am
by swhite01
The attached table is from a quick review of the truss rod underframe drawings I have photographed at the NRM. I am traveling for business at the moment but I will try to post some photos of the drawings to my Flickr page, as the images are too large to post on the Forum. I will post a link when I have managed this.
All the underframe drawings show 2 longitudinal beams on the underframes.

Hope this is of interest,
Steve

www.gnrsociety.com

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 9:28 am
by billbedford
John Palmer wrote:
Fri May 05, 2017 2:41 pm
Yes, I understand why this would be a consideration in the design of non-articulated stock, but I see it as being potentially applicable only to the outermost pivots and drag boxes on an articulated set.
But the underframes for the articulated stock were just shortened versions of standard underframes. Why go to the trouble of redesigning something when you could just 'chop off' one end of an underframe that you knew worked well?

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 9:37 am
by billbedford
John Palmer wrote:
Fri May 05, 2017 2:41 pm
Further study of pictures of the quad-art set on the North Norfolk Railway reinforces the impression I formed that it is mounted on underframes having only three trusses. I base this conclusion on two photographs in particular:
There are four truss rods in each of those photos. The fourth queen post is hidden behind the wheel holding contraption in both photos.

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 12:10 pm
by John Palmer
billbedford wrote:
Sat May 06, 2017 9:37 am
There are four truss rods in each of those photos. The fourth queen post is hidden behind the wheel holding contraption in both photos.
Like this?
NNR quad-art truss rods.jpg
Bill, I don't see any evidence of a fourth truss in either photograph. What leads you to think that this particular species of quad art was mounted on a standard underframe design that was just shortened? Which standard underframe?

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 1:49 pm
by sawdust
I went over to Carnforth with Steve Allen and Clive Morris to help with interpreting the drawings of the Quads during their restoration. At that point all the bodies were off the underframes and I can assure you they all had two centre longs.

Sawdust.

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 2:42 pm
by billbedford
John Palmer wrote:
Sat May 06, 2017 12:10 pm
Like this? NNR quad-art truss rods.jpg Bill, I don't see any evidence of a fourth truss in either photograph. What leads you to think that this particular species of quad art was mounted on a standard underframe design that was just shortened? Which standard underframe?
No, like this:
Quad trusses.png
Not that the queen posts are not evenly spaced, as they would if there were fitted to the longitudinals.

The bogie centres of all articulated stock underframes match the bogies centres of standard underframes, allowing a few inches accounted for by the extra steelwork needed to fit the articulation pivot castings. The exception is the short quad-art brakes which would require a 46' underframe.

Re: Carriage Underframe Trussing

Posted: Sat May 06, 2017 3:45 pm
by John Palmer
billbedford wrote:
Sat May 06, 2017 2:42 pm
No, like this:
Got it, thanks. So, this would translate to something like this, adapting my previous image:
NNR quad-art truss rods (mod).jpg
This now makes sense to me for the Diagrams 72B-74 vehicles in the North Norfolk Railway set, but what about the somewhat longer Diagrams 102-105 vehicles in the quad art illustrated at page 138 in Standard Gresley Carriages? Fourth queen post on 61820 hidden behind the battery box?