Dave Bradwell Springing units

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Hardwicke
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Dave Bradwell Springing units

Postby Hardwicke » Sun Sep 07, 2014 12:11 pm

I've been working on the Dave Bradwell springing units that I bought at Scalefour North (in between exhibiting Kirkcliffe).


Slaters Midland 10T van as purchased second hand. I've started removing the brake shoes. (This is a second van and not the one in subsequent photos)

IMG_1975.JPG


After removing the sole bars I made sure the floor was smooth and flat. The sole bars were too close together for the units and P4.
IMG_1978.JPG



Springing unit awaiting fitting. The axle irons have been filed down to give extra clearance and to improve the look.


IMG_1976.jpg




Solebar with the unit fitted. I've used plastikard strip drilled with a small hole for the wire. The wire is loose in the hole. They have a 'bounce' of about 1mm either way.

IMG_1971.JPG


The floor awaiting the refitting of the sole bar.

IMG_1974.JPG



All back together again.

IMG_1980.jpg



The completed under frame.
IMG_1981.JPG


Everything square.
IMG_1982.JPG


I found the units very easy to set up. These are my first sprung wagons (I have some I bought second hand which convinced me of the superior road holding) and I am very pleased with the results. Since this first one I have converted two Coke hoppers (3H), a K's 6w syphon, a K's 21T hopper, and a Parkside SR PMV. The syphon and PMV needed the sole bars moving out by about 1mm either side. I used Markits shouldered bearings (which needed a lot of cleaning up).
Builder of Forge Mill Sidings, Kirkcliffe Coking Plant, Swanage and Heaby. Still trying to "Keep the Balance".

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Colin Parks
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Re: Dave Bradwell Springing units

Postby Colin Parks » Sun Sep 07, 2014 2:06 pm

Hi Hardwick,

That looks like a simple conversion to a sprung chassis and so much easier than complete removal of the W-irons. I have always wondered how these sprung designs would work if the components have to be painted, but here on your wagon the moving parts are tucked away, so chances of anything getting stuck with paint are minimal.

How much weight will you be adding to get the optimum road-holding on this and your other wagons? I have read that a total weight of 50g for two-axle vehicles is specified, however, that was probably set in the days when only compensation or rigid axles were the choices available. If I were constructing a wagon kit these days (have 70 to convert from 00 to P4! already!) , I'd remove any cosmetic under- floor framing (which usually serves only to create cooling sink marks on the top face of the floor), and make room for some lead ballast between the brake gear.

All the best,

Colin

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Hardwicke
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Re: Dave Bradwell Springing units

Postby Hardwicke » Wed Sep 17, 2014 5:39 pm

So far they haven't any additional weight. They still run beautifully. The Syphon had a couple of bits of lead in it already and they aid it with stability. I'm going to do some experiments as to optimum weight and get back to you with the results.
Michael
Builder of Forge Mill Sidings, Kirkcliffe Coking Plant, Swanage and Heaby. Still trying to "Keep the Balance".

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chrisf
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Re: Dave Bradwell Springing units

Postby chrisf » Thu Sep 18, 2014 6:23 am

Thanks for posting this. I have a Hornby Trout that needs seeing to and this technology has the potential. It seems to be the only way of springing open framed wagons such as those designed for ballast without too much being visible!

Chris

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Tonycardall
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Re: Dave Bradwell Springing units

Postby Tonycardall » Fri Jan 27, 2017 1:28 pm

Although it is now a couple of years since the last post on this subject, was there ever an answer as to the optimum weight? I've come to the conclusion that Bill Bedford's sprung W iron system works best for me but, rather than experiment, if someone has already done the work it would be much appreciated.

Armchair Modeller
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Re: Dave Bradwell Springing units

Postby Armchair Modeller » Fri Jan 27, 2017 2:17 pm

Not sure about optimum weight. My limited experiments do however suggest that sprung wagons require far less encouragement to stay on the track than wagons compensated with rocking W irons.

garethashenden
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Re: Dave Bradwell Springing units

Postby garethashenden » Fri Jan 27, 2017 2:26 pm

I believe the previously quoted 50g is still the recommended weight. The Rumney underframes are designed for that weight and I think most other springing systems are too.

billbedford
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Re: Dave Bradwell Springing units

Postby billbedford » Sun Jan 29, 2017 11:17 am

50gm per wagon is a figure plucked from the air via some very dubious north American logic. The point about springing is that the same riding qualities can be obtained for wagons of different weights simply by adjusting the spring rates, i.e. the thickness, od the spring wires.
Bill Bedford
Mousa Models
http://www.mousa.biz

Alucard
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Re: Dave Bradwell Springing units

Postby Alucard » Sun Jan 29, 2017 12:21 pm

Bill I definitely agree.
I have tried both springing systems and what weight I can fit in to the wagons determines the wire. No problems so far.

Terry

dal-t
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Re: Dave Bradwell Springing units

Postby dal-t » Sun Jan 29, 2017 1:05 pm

billbedford wrote:50gm per wagon is a figure plucked from the air via some very dubious north American logic.


The NMRA Recommended Practice for car weight is actually 1oz (28gms) plus 1/2oz (14gms) per inch of car length (for HO gauge), so somewhere between 50 to 70 gms would be derived values, without adjustment for scale, for a standard short wagon (depending on whether you take 'length' to be body or wheelbase - the RP doesn't specify). Like Bill, I'm pretty dubious about the logic, but 'plucked out of the air' is a little unfair, as NMRA did undertake some extensive empirical trials of roadholding using different weights. I remember reading a tediously long and impenetrable article on the subject in, I think, Model Railroader when I had more patience for such things. Of course, there are many points of divergence from our practice, not just the scale - I believe most of their trials were with bogie wagons, size and shape were more aligned to North America than the UK, track, as far as i remember, was standard production, and they seemed more concerned with running on grades than through points and crossings. But the idea that weight should increase with length is interesting, and other bits of 'egg sucking' advice in the RP, like the danger of mixing lightweight and heavyweight stock, are pretty unexceptional.
David L-T

Philip Hall
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Re: Dave Bradwell Springing units

Postby Philip Hall » Sun Jan 29, 2017 3:50 pm

However the figure of 50 grams was arrived at, I usually like to try to achieve this. I like heavy -ish feeling vehicles, as they seem to hold the road better. I am also very much sold on the idea of heavy carriages, between 175 and 200 grams, mostly because I prefer to run them with the buffers and gangways in contact around 3'6" to 4'0" curves, and with buffer to buffer contact with the engine. I have found this much easier to achieve if there is sufficient weight there to overcome the buffering forces.

Now I have no experience (yet) of sprung vehicles, but I cannot see that not having that weight will help in my preferred application. If the vehicles are very light, springing may help them to keep to the rails, but the lack of weight will do nothing to keep them down when the buffer forces are doing their utmost to pull everything off.

Philip

Phil O
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Re: Dave Bradwell Springing units

Postby Phil O » Tue Jan 31, 2017 1:33 pm

I believe that the biggest problem with vehicle weight, comes when trying to propel vehicles of vastly different weights if they are of broadly similar weight there's no problem, it's when you have a couple of empty plastic wagons between the loco and some heavier wagons things go awry.

Phil.

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jjnewitt
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Re: Dave Bradwell Springing units

Postby jjnewitt » Tue Jan 31, 2017 3:15 pm

To me it doesn't really matter where the 50g figure came from or indeed the reasoning behind it. It's a reasonably achieveable weight for most 4mm wagons. I don't think you could consistently get much more in British 2 axle wagons unless they're covered types. If I could get more in then I would put more in but it's not really practical in a lot of cases and I'm a big fan of consistency in any approach, so I think it's a good figure.

There's an american layout that I'm a big fan of called the Allagash Railway. It's worth googling for the senic work alone which is brilliant. Anyway, he weights his bogie freight cars to 11/12 ozs, way above the NMRA recommendations. Admitedly the layout is straight HO with no suspension systems in sight but he felt that in order to get reliable running his wagons had to be heaver. By all account he has zero derailmentson his layout due to stock misbehaving ...

Like Phil I think mixing light in with heavy stock is asking for operating issues, whatever rate the springs are on the wagons.

Justin

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Tonycardall
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Re: Dave Bradwell Springing units

Postby Tonycardall » Tue Mar 28, 2017 12:22 pm

Thank you guys for the replies. I'm going to aim for 50g and see how things work out

Tribus
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Re: Dave Bradwell Springing units

Postby Tribus » Sun Feb 25, 2018 1:39 pm

Hi Guys. Putting aside the wagon weighting debate, does anyone out there have any more comments about using these units (positive or negative).
I fancy having a go ;)

billbedford
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Re: Dave Bradwell Springing units

Postby billbedford » Mon Feb 26, 2018 9:10 am

dal-t wrote:
billbedford wrote:50gm per wagon is a figure plucked from the air via some very dubious north American logic.


The NMRA Recommended Practice for car weight is actually 1oz (28gms) plus 1/2oz (14gms) per inch of car length (for HO gauge), so somewhere between 50 to 70 gms would be derived values, without adjustment for scale, for a standard short wagon (depending on whether you take 'length' to be body or wheelbase - the RP doesn't specify). Like Bill, I'm pretty dubious about the logic, but 'plucked out of the air' is a little unfair, as NMRA did undertake some extensive empirical trials of roadholding using different weights.


It is 'plucked from the air' as it applies to the length criteria. It was added to the formula to prevent bogie vehicles on long trains being pulled off sharp curves sideways. In general this does not apply to British outline models that use short four wheeled wagons and relatively short trains, and the length part of the formula can probably be safely ignored.
Bill Bedford
Mousa Models
http://www.mousa.biz

Knuckles
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Re: Dave Bradwell Springing units

Postby Knuckles » Fri Mar 02, 2018 5:34 pm

I like the initial post and may try this one day. As far as wagon springing goes I've only tried Bill's units and like them very much.

As I didn't want to put weight in the wagon as a load or even 'wood' scribe a lead sheet I put all the weight underneath and didn't want it visible so settled for 40 grams instead.

Happy with how they behave.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
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Tribus
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Re: Dave Bradwell Springing units

Postby Tribus » Thu Mar 15, 2018 9:04 pm

Thanks Knuckles. I have also used Bill's units several times and, like you, am happy with the results. I'm just fed up with filing and scraping away at solebars to remove moulded w irons etc, when on some of the latest kits these look pretty good as moulded (especially on brake vans etc). :)

Knuckles
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Re: Dave Bradwell Springing units

Postby Knuckles » Fri Mar 16, 2018 7:11 pm

Yeah it gets tedious after a while. Is why I think this looks far easier. Worth a try. Pretty sure Bill's units will give the same result by missing out the W irons and making the plastic slide bits each side as you have done.


One thing I like about these particular P4 conversions is that they are gauge universal really. Rather than conversions they are more like upgrades. As a test I tried swapping some of the P4 wheels back to 00 wheels in the trucks to see how they rode and the result was the same. Vastly improved running, for standard 00 especially where flange hungry frogs are concerned.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
SCC Photon Resin Prints Price list
download/file.php?id=19320


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