Class 2, in Blue - S&DJR 2P

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MarkS
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Class 2, in Blue - S&DJR 2P

Postby MarkS » Thu Jul 17, 2014 7:28 pm

After the long "Great 3F build off" saga, http://www.scalefour.org/forum/viewtopic.php?f=20&t=2019 I wanted to build something easy, a project that would last a couple of months, not years.
I have built 5 CSB/sprung locos and in each case the chassis has been scratch built or at least heavily modified to enable them to be sprung.
Whilst they all work very nicely, there was a fair amount of time and effort for me to get them there. (Thank goodness for High Level jigs!)
I wished to build a chassis that was "designed" to be sprung, (in this case by Ted Scannell/Bill Bedford) as opposed to "fudged" by me.

I have wanted a 2P for a long time, so a couple of years ago I acquired an old Mainline version for the right price, and then went about collecting a chassis, wheels etc.
Generally I try to work on one loco at a time, so the 2P waited for the 3F saga to end, but I did take time to prepare my checklist for the build, so that when it is time to build, I could just get on with it.

What has amazed me so far is how fast this project has progressed. Admittedly, I only had to do some minor modifications to the RTR bodies, but the chassis has been a joy to build so far.
After a couple of evenings work -
2P chassis.jpg
2P chassis.jpg (42.58 KiB) Viewed 9816 times
at which point I checked how they fit into the bodies.

The loco is a perfect fit, the tender needed a little bit of carving for the wheels to fit:

2P tender chassis.jpg
2P tender chassis.jpg (67.24 KiB) Viewed 9816 times


A week later the bodies have been stripped and detailed:
2P loco body.jpg
2P loco body.jpg (43.95 KiB) Viewed 9816 times
2P tender.jpg
2P tender.jpg (35.66 KiB) Viewed 9816 times


and since we have a nice dry day today, I primed it... now I shall return my attention to the chassis while the primer cures...
2P Primer.jpg
2P Primer.jpg (61.54 KiB) Viewed 9816 times
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Thu Nov 06, 2014 5:27 pm

Continuing on, I spent the next 3 months riding my bike, since the weather was not too hot, too cold or too wet.
However, snow threatens once again, so to the railway room I go...

The body has received a coat of Prussian blue and lining has been blocked in, it will be tidied up in due course.

The brakes are a bit of a let down in an otherwise excellent kit. they don't line up well with the wheels.
On the tender, this is not a big problem since they are hidden behind the frames, but on the loco, it looks like they were drawn to fit EM flanges... :shock:
P1050038.JPG
Brake pads look worn out...
P1050038.JPG (110.41 KiB) Viewed 9607 times

P1050043.JPG
Once painted, not very noticeable.
P1050043.JPG (94.69 KiB) Viewed 9607 times


On the tender, the brake gear can swing away should it be necessary to, as can be seen.
I use tiny brass pins and .8mm ID brass tube soldered into the frames to attach the gear.
P1050039.JPG
Tender frames
P1050039.JPG (43.71 KiB) Viewed 9607 times

P1050040.JPG
Brake gear swings away.
P1050040.JPG (54.79 KiB) Viewed 9607 times


P1050041.JPG
2P continued...
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

Simon Glidewell

Re: Class 2, in Blue - S&DJR 2P

Postby Simon Glidewell » Thu Nov 06, 2014 7:07 pm

That really looks the business Mark

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Wed Dec 14, 2016 10:53 pm

SDJR 2P.jpg
The 2P is almost complete, the major items to resolve being:

1) finding time to work on it, :?

2) The tablet catcher to fabricate, since I have run out of my collection of Iain Rice castings,
3) Bogie brakes - does anyone know of a casting? I will probably have to fabricate these too...

4) And finally, it is difficult to get weight into the loco, but stuffing the smoke box will not do much good.
The centre of gravity is just behind the leading driver, and it does not have much tractive effort weighing only 150 grams.
Being a Bedford chassis, fully sprung with CSB, any suggestions as to improving it?
Obviously find room for more weight or tender drive, but are there any ideas as to playing with spring rates on the drivers and bogie perhaps?
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

David Knight
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Re: Class 2, in Blue - S&DJR 2P

Postby David Knight » Thu Dec 15, 2016 1:58 am

Hi Mark,

Just a thought about the bogie brakes, would the shoes from a wagon or coach kit serve as a starting point?

Cheers,

David

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Paul Willis
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Re: Class 2, in Blue - S&DJR 2P

Postby Paul Willis » Thu Dec 15, 2016 6:49 am

MarkS wrote:SDJR 2P.jpgThe 2P is almost complete, the major items to resolve being:

1) finding time to work on it, :?

2) The tablet catcher to fabricate, since I have run out of my collection of Iain Rice castings,


Very nice indeed :-)

I don't know if there is a prototypical similarity (I believe there is, from something I read a while ago in a BRJ or Midland record), but Andy Kopp lists Manson Tablet Catchers in his Lochgorm 4mm range. You'll find them on page 6 of the catalogue for a grand total of £2.50.

http://www.lochgormkits.co.uk/assets/applets/Lochgormkits_text_catalogue_4mm_October_2015.pdf

I think I may have a few sets kicking around at home where they have been tabbed on the edges of 5522 Models artwork. I'm afraid I won't have the chance to check for a couple of days though due to various work commitments.

Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Paul Willis
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Re: Class 2, in Blue - S&DJR 2P

Postby Paul Willis » Sun Dec 18, 2016 4:33 pm

Flymo748 wrote:
MarkS wrote:SDJR 2P.jpgThe 2P is almost complete, the major items to resolve being:

1) finding time to work on it, :?

2) The tablet catcher to fabricate, since I have run out of my collection of Iain Rice castings,


Very nice indeed :-)

I don't know if there is a prototypical similarity (I believe there is, from something I read a while ago in a BRJ or Midland record), but Andy Kopp lists Manson Tablet Catchers in his Lochgorm 4mm range. You'll find them on page 6 of the catalogue for a grand total of £2.50.

http://www.lochgormkits.co.uk/assets/applets/Lochgormkits_text_catalogue_4mm_October_2015.pdf

I think I may have a few sets kicking around at home where they have been tabbed on the edges of 5522 Models artwork. I'm afraid I won't have the chance to check for a couple of days though due to various work commitments.

Cheers
Flymo


And here's the 5522 etch for a tablet catcher. If it's of use to you, let me know and I'll pop one in the post to you...

5522 HR tablet catcher.JPG


Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Sun Dec 18, 2016 5:46 pm

Flymo, thank you for your generous offer, but apart from changing the shape of the main component, I suspect I would still have to fabricate quite a bit... after all we want to "get it all right" ;)

Here is the Whitaker S&D version (also M&GN) - (the ring is attached to the pouch being exchanged)
S&D tablet catcher.jpg
S&D tablet catcher.jpg (26.02 KiB) Viewed 8681 times

As you can see it is a different shape to the Manson one (less duck bill, more shark tooth), plus I have seen at least 4 different arrangements to attach to tenders, these are both on a 2P...

2p tablet exchange 1 .jpg
2p tablet exchange 1 .jpg (60.58 KiB) Viewed 8681 times
2p tablet exchange 2 .jpg
2p tablet exchange 2 .jpg (31.37 KiB) Viewed 8681 times

The different apparatus could be pushed out, flipped up, swivelled up & out, there is quite a variety - I'm glad I don't need to make them work...
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

garethashenden
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Re: Class 2, in Blue - S&DJR 2P

Postby garethashenden » Sun Dec 18, 2016 11:24 pm

Can you rig up the tender in such a way that it transfers some of its weight to the rear of the locomotive? Put a hinge near the back of the tender body so that the tender body and chassis are connected at the back but the body can be hung on the engine. There's a description of how to do it in one of Guy Williams' books.

John Palmer
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Re: Class 2, in Blue - S&DJR 2P

Postby John Palmer » Mon Dec 19, 2016 1:33 am

A splendid unit of motive power to head 'the Diner'! I'm impressed by how well your combination of components captures the character of the engine.

As to the tab catchers, I assume you have Peter Cattermole's1982 monograph on the subject, which includes a detailed drawing of the catcher. I think this is a sitter for a 3D printed component - could Alan Butler of Modelu be persuaded to take this on? Hitherto I have fabricated my own in metal with mixed success, but I'd replace all 3 if an accurate replacement were to become available (and would have some spares as replacements for breakages).

Spare a thought for the firemen who had to fit the outgoing pouch in the catcher's jaws, somehow clinging to the the tender and exposed to the engine's slipstream as they did so. I find it amazing that, to the best of my knowledge, only once did a fireman sustain serious injury whilst so engaged.

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Will L
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Re: Class 2, in Blue - S&DJR 2P

Postby Will L » Mon Dec 19, 2016 11:11 am

MarkS wrote:...Being a Bedford chassis, fully sprung with CSB, any suggestions as to improving it?
Obviously find room for more weight or tender drive, but are there any ideas as to playing with spring rates on the drivers and bogie perhaps?


The CSB chassis will ensure that the weight that is available is equal shared between the drivers. The support of the bogie will ensure the loco stays level. My post CSBs a question of Gravity goes over all this and explains how you can work out how much weight will sit on the drivers using the relationship between the location of the CofG, the distance between the centre of the CSB chassis and the bogie, and the relationship between the two. Playing with the spring rates won't change/improve any of that.

As for adding weight, we can't tell about how much space you have around the motor to put weight so it is hard to comment on what can be done there. A tender drive, so you can pack the fire box with lead, certainly will help, or weight transfer from the tender can add weight and move the effective CofG further back. Failing that a nice heavy cast metal crew will help, and you will often find a fair bit of space between the frames which can be used to add weight.

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Mon Dec 19, 2016 7:23 pm

John,
thank you for you kind comments, I find that locos with tall driving wheels look so much better in P4 since the wide "steamroller" look is eliminated, plus Bills chassis makes the area around the bogie look "all right".

I don't have the Cattermole monograph, I suspect it would be very hard to find here in Canada, but photos and the internet will do for the moment. However, I fully agree that a 3D print would be useful.

I can imagine being a fireman had its challenges, hanging off the side of a rollicking tender being one of them, walking back to find a dropped tablet pouch being another!
But then, that was part of the job...
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Mon Dec 19, 2016 8:12 pm

Gareth,Will,
I'm not sure if I can effectively use the weighted tender method here since it is fully sprung, as opposed to compensated with a solid rear axle.
I used the method on my 2-4-0 (viewtopic.php?f=19&t=1277) and it worked well, but the tender has a solid rear axle.

I've filled the area between the frames with lead, and I might be able to get a little bit more in above the motor.
The CofG is between, but close to the leading driving axle, so I need move it a bit further back toward the rear driving axle so that both wheel sets have similar grip...

...This loco may need an overweight inspector in addition to a well fed crew.
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

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Will L
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Re: Class 2, in Blue - S&DJR 2P

Postby Will L » Mon Dec 19, 2016 9:26 pm

MarkS wrote:..The CofG is between, but close to the leading driving axle, so I need move it a bit further back toward the rear driving axle so that both wheel sets have similar grip...


As I said before, the CSB on the drivers will share the weight equally between then, what is at question is how much is carried by the bogie and how much by the driving wheels. The whole post is worth a read if you want to understand what's going on.

An inspector on the footplate is a good idea.

Philip Hall
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Re: Class 2, in Blue - S&DJR 2P

Postby Philip Hall » Mon Dec 19, 2016 11:02 pm

Re the weighted tender idea, it's not necessary to have the tender with a rigid axle at the rear. Although I use compensation, my method for both rigid and compensated tender chassis (where weight transfer is involved) is to have the tender body bearing down on the chassis at a point midway between the centre and rear wheels. I usually arrange this with a beam across the chassis top which bears on two small plates either side which protrude from the body. This allows some weight on all tender wheels, maybe not completely evenly, but enough to keep the wheels on the track and keep them turning against pickups. The front of the tender is hung on the back of the engine using a right angle hook on the tender and a short horizontal bar under the engine footplate. I usually concentrate the extra tender weight to the front and centre.

I have used this on kit built tenders, and most recently on modified Hornby T9 tenders, where the separate chassis moulding can be arranged to pivot in a similar way. The engine behaves much more steadily with a bit of weight hung on the back, and in the case of the (rigid) Hornby T9, been able to haul 9 or 10 quite heavy and far from free running carriages. I have no experience of doing this with a CSB sprung engine, although if Will says it can be done, I'd go with it because he knows far more about it than I do.

Philip

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Tue Dec 20, 2016 10:51 pm

OK Will,
I read further down the page, and the snow is clearing slightly.
I went back and carefully checked where the CofG is for the loco - about a millimetre behind the leading driver axle.
So, since there is a bogie upon which some weight rests, the effective CofG is probably between the bogie and the leading driver?

And that is probably not a good thing...

Time for a glass of red and a think.
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

billbedford
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Re: Class 2, in Blue - S&DJR 2P

Postby billbedford » Wed Dec 21, 2016 7:45 am

MarkS wrote:4) And finally, it is difficult to get weight into the loco, but stuffing the smoke box will not do much good.
The centre of gravity is just behind the leading driver, and it does not have much tractive effort weighing only 150 grams.
Being a Bedford chassis, fully sprung with CSB, any suggestions as to improving it?


How much tractive effort do you need?

If the loco weighs 150gms and the centre of gravity is somewhere ne the leading driving axle it is safe to assume the weight on the drivers is around 100gms.
CBS frames are around 20% efficient, i.e. you can expect the drawbar pull to be around 20gms.
The pull needed to move a free running coach is of the order of 2gms, therefore this loco should handle around 10 coaches depending on track geometry..
It is only a 2P, does it need to handle more than 10 coaches? is there room on your layout for longer trains? and with a light loco you have the added advantage of prototypical slipping with longer trains and heavy handed drivers.
Bill Bedford
Mousa Models
http://www.mousa.biz

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Wed Dec 21, 2016 8:24 pm

Bill,
the problem is it struggles pulling even 4-5 coaches on the level... My Dapol Pug can pull that!

I suspect it is a case of balance - ie too much weight, too far forward, so that the drivers have less than 100 grams on them.
It sounds like I won't need a lot of weight, it just needs to be in the right place...
I pulled the body off, and the area behind the motor has room for a flywheel, or some lead.
So I should be able to make it work.
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."

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Will L
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Re: Class 2, in Blue - S&DJR 2P

Postby Will L » Wed Dec 21, 2016 11:00 pm

MarkS wrote:...I pulled the body off, and the area behind the motor has room for a flywheel, or some lead.
...

Fixed lead will be much better for your loco weight distribution than a flywheel
1. because the weight of the fly wheel will mostly ends up on the driven axle and for best results you need it shared across both driving axle
2. you'll get a lot more in if it doesn't have to spin.

You should make sure the loco chassis is really sitting level, if not that will effect the weight distribution on the drivers. If it isn't level you will need to adjust the bogie privet point till it is. But before you do that, get as much weight in as you can, find out where the CofG is, use the calculation in that post of mine to find out how much weight is on the drivers and use the spreadsheet to work out what size the CSB wire should be. Then the driving wheels will be at the right hight in the chassis before you check for overall level.

billbedford
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Re: Class 2, in Blue - S&DJR 2P

Postby billbedford » Thu Dec 22, 2016 9:05 am

MarkS wrote:Bill,
the problem is it struggles pulling even 4-5 coaches on the level... My Dapol Pug can pull that!

I suspect it is a case of balance - ie too much weight, too far forward, so that the drivers have less than 100 grams on them.
It sounds like I won't need a lot of weight, it just needs to be in the right place...


Yep

I don't understand why the front end is so heavy. Has someone glued a plug of lead in there?
Bill Bedford
Mousa Models
http://www.mousa.biz

billbedford
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Re: Class 2, in Blue - S&DJR 2P

Postby billbedford » Thu Dec 22, 2016 9:06 am

Will L wrote:But before you do that, get as much weight in as you can,


It doesn't need more weight, it just needs it in the right places.
Bill Bedford
Mousa Models
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Will L
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Re: Class 2, in Blue - S&DJR 2P

Postby Will L » Thu Dec 22, 2016 10:19 am

billbedford wrote:
Will L wrote:But before you do that, get as much weight in as you can,


It doesn't need more weight, it just needs it in the right places.


Bill is right it not about absolute amounts, it is about getting it in the right place. My point was that you should have settled the overall weight before selecting the right CSB wire as this effects how high the chassis sits etc etc.

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Tim V
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Re: Class 2, in Blue - S&DJR 2P

Postby Tim V » Thu Dec 22, 2016 12:26 pm

What part does the bogie play in road holding? If the bogie is holding up the front (rather than going along for the ride), then even if the COG is in front of the first driver, some weight will still transfer to it.
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Will L
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Re: Class 2, in Blue - S&DJR 2P

Postby Will L » Thu Dec 22, 2016 6:38 pm

Tim V wrote:What part does the bogie play in road holding? If the bogie is holding up the front (rather than going along for the ride), then even if the COG is in front of the first driver, some weight will still transfer to it.


Yes it will.

A CSB chassis sitting level will act pretty much like a bogie does, i.e. it will act as if the weight is applied at the centre of the wheel base and it is shared across the wheels equally, assuming a normal CSB set up. So if you work out
1. the distance between the centre of the driving wheel base and the bogie centre (lets call that L),
2. the distance from the centre of the driving wheel base to the CofG (let call that L1)
3. The loco weight (less the unsprung weight of the wheels and motor if you want to be picky) (W)

Then the weight distributed through the driving wheels is W*(L-L1)/L, and the rest of the weight is carried by the bogie.
See the diagram, borrowed from a previous thread which, I know, appears to complicate things with an extra driving axle but in practice it works the same for any number of driving axles under a CSB. Nor does it make any difference if the bogies is sprung or not

CSB gravity 3.jpg
CSB gravity 3.jpg (139.05 KiB) Viewed 8105 times


This is all assuming the CSB chassis is designed to distribute the weight equally as they usually are, and that it is sitting truly level. Then the springs over each wheel will deflected by an eqaul amount and thus will be transmitting the same amount of weight. If it is not level the maths will get a lot more complicated. It isn't all that easy to see if a loco is really sitting level, to check put a strait edge central along a bit of the footplate that should be level and measure the offset to rail head is the same at both ends of the strait edge.

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MarkS
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Re: Class 2, in Blue - S&DJR 2P

Postby MarkS » Thu Dec 22, 2016 6:59 pm

2p bogie 2.jpg

Tim, here is the bogie, the chassis sits directly on the rubbing plate, so yes it bears some of the weight of the loco.
Bill, there is about 20 grams immediately ahead of the motor, in the boiler - over the leading sandbox seen in the photo.
On plate glass, with a straight egde, the loco sits level, and the buffers are at the correct height.
It will stay on some of my worst trackwork. The chassis is not at fault, stuffing enough lead and a motor into the firebox is the challenge. The ashpan is full of lead.
One observation, and I believe the prototype was similar, it has a lot less traction in reverse.
So to Will's point, I think the Loco CofG is too far forward.
Cheers,

Mark.
"In the end, when all is said and done, more will have been said than done..."


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