4 wheel wagons rigid or non-rigid chassis?

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bordercollie
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4 wheel wagons rigid or non-rigid chassis?

Postby bordercollie » Mon Dec 16, 2019 6:21 am

Hi
I have read through the thread on "P4 wagon compensation(springing)" and elsewhere.

In summary it appears that a non-rigid chassis is desirable but not essential.
It also appears that correct weighting is very important.
As a begginer I want to keep things as simple as possible and at present I am leaning towards rigid construction

I would like to know how easy it would be to convert to compensation or springing latter.

I would like to know if you need to buy specfic W-irons for what ever method you want to use i.e if you choose to use springing are there special W-irons for that method? Similarly for compensation and rigid chassis

Mark Forrest
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Mark Forrest » Mon Dec 16, 2019 6:46 am

I'm assuming you are talking about kit built wagons?
Personally I build mine sprung from the start as it usually requires the solebars to be thinned down which could be much more difficult to do on an assembled wagon.

For converted RTR, I have several which are rigid and work reasonably well. With care you can build a kit that is as square and true as a RTR wagon, but to convert a kit built rigid wagon to sprung, I think you'd end up removing and replacing the underframe.

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jim s-w
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby jim s-w » Mon Dec 16, 2019 10:05 am

I agree with Mark. If you want to go sprung you need to decide at the start, converting later is going to be a bit of a faff.
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davebradwell
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby davebradwell » Mon Dec 16, 2019 10:11 am

I agree but do run an embarrassing number of r-t-r wagons with just the wheels swapped for P4, although a little slogger in the bearings helps the things adapt to small track imperfections. Many of these are 12ft wheelbase hoppers which is pushing my luck but I suggest you don't risk longer wheelbases. If you're planning on pushing long strings of wagons then the rigid ones will always be a weakness (yes Dave F, it's easier in EM).

If you're building a kit, however, then it is quite easy to turn the bearing hole into a 2mm wide slot during construction but very difficult after. Once you've produced a short slot extending slightly above and below the original hole then there are a number of ways of fitting springs - you don't need to change the axleguards. You will probably thin down the plastic ones a little but you must stick them to the floor at the correct spacing for the bearings you've bought and get the axles square to the wagon centreline - an achievement in itself. It's probably easier to spring a wagon than build it flat enough so I would warn against building rigid wagons - there's no point. At least with an r-t-r conversion you're getting something quickly.

Any replacement axleguards can be used for springing as long as you make a slot for the bearing. Don't get drawn into springing that only works downwards ie doesn't allow the ale to rise - the vehicle must sit on it's springs for maximum effect and quiet running.

I'll add that it's important to install the springs so each exerts the same pressure and each system has it's own method of achieving this. 25gms per axle is pretty standard but my empty hoppers are significantly below this. Check weight with cheap electronic kitchen scales.

Essentially, as a beginner you want something that works and quickly. Use r-t-r. You don't want something that might work as you won't know where to start fault finding until you've had some experience.

DaveB

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Noel
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Noel » Mon Dec 16, 2019 11:38 am

I don't fundamentally disagree with anything said so far, but would add a few comments -

I started building wagon kits quite a long time ago, before the parts to use springing were commercially available, so most are 'rigid' but with a SMALL amount of sideways movement of the axles. They have to be flat and square in all axes, or there will be problems. I do have one 10ft wb van which is not quite square, but managed to get around the problem by internally compensating one end, so there are remedies, although these may not be a complete answer. It does require care, and I find a bit of flat glass is useful for checking that all wheels are at the same level.

Whether rigid, sprung or compensated [out of fashion these days!] a set of axle spacing jigs is very useful for getting axles parallel and square to the chassis, I find http://www.brassmasters.co.uk/axle_gauges.htm [no interest other than as a customer]. Don't assume, incidentally, that r-t-r chassis are square and flat; they normally are at present, but older designs especially may not be. If P4 axles won't go in then the back of the axleguard will need to be filed down to give clearance; if the axle goes in but won't turn, and nothing is rubbing, then gently rounding off the sharp points of the ends of the axles with a file will usually solve the problem [don't overdo it - a few strokes should be enough].

In my experience, converting r-t-r or completed kit built wagons to springing will almost certainly mean building a new chassis, as there is rarely [never?] enough room between r-t-r axleguards and springing requires slightly more clearance between the axleguards than rigid or compensated. It may be necessary for other reasons as well; r-t-r manufacturers [not unreasonably given commercial imperatives] do tend to use inappropriate chassis, or ones with inadequate detail, on occasion.

Any ballast added should be as equal as possible about the centre point of the vehicle so that the wagon CofG is close to the centre, otherwise axle loadings will not be consistent, which may cause problems. Sprung buffers are not essential, but may help running as they affect the way adjacent vehicles interact when being propelled.
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Noel

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John Donnelly
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby John Donnelly » Mon Dec 16, 2019 12:04 pm

All my current 4 wheel wagons (whether RTR or kit built) are rigid and they've stayed on the track on both of the shorter layouts I've built so far. Whether they will stay on the 30' main line I'm building at the moment, I hope to find out in the next 12 months...

John

Dave Franks

Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Dave Franks » Mon Dec 16, 2019 12:11 pm

davebradwell wrote:I agree but do run an embarrassing number of r-t-r wagons with just the wheels swapped for P4, although a little slogger in the bearings helps the things adapt to small track imperfections. Many of these are 12ft wheelbase hoppers which is pushing my luck but I suggest you don't risk longer wheelbases. If you're planning on pushing long strings of wagons then the rigid ones will always be a weakness (yes Dave F, it's easier in EM).

DaveB


Ouch! Thanks David, I do have some sprung or compensated wagons though, mainly longer wheelbases but one also has to take into account good flat track and correctly spec'ed pointwork for it all to work in any gauge.

There are etched componants available with inside bearings to convert RTR wagons to compensation (Bill Bedford?) but as others have said full springing is probably the best way.

Dave F.

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Tim V
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Tim V » Mon Dec 16, 2019 12:40 pm

I found on Clutton I could just swap wheels (for good ones!) change couplings, and provided I pulled them, never pushed them, they were very reliable.

If you want to shunt them, then I think that compensation/springing becomes necessary.

For building wagons I can thoroughly recommend the Brassmaster's axle setting jig, though I don't know if it's still available.
Tim V
(Not all railways in Somerset went to Dorset)

Steve Carter
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Steve Carter » Mon Dec 16, 2019 2:07 pm

Tim V wrote:For building wagons I can thoroughly recommend the Brassmaster's axle setting jig, though I don't know if it's still available.


Still shown on their website http://www.brassmasters.co.uk/axle_gauges.htm
Steve Carter

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Noel
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Noel » Mon Dec 16, 2019 2:18 pm

Which is why I included a link... :D :D :D
Regards
Noel

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iak
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby iak » Mon Dec 16, 2019 4:41 pm

The vast majority of the stock I've built over the years, including for Mostyn, is rigid downstairs. Yes, I have started using sprung chassis and sprung w-irons but that is on longer than 10 ft wheelbase or because of aesthetic reasons (hallo Justin...)
Sticking to the principles of everything being in line/parallel/square is simple and most effective, as is using a sensible bit of weight in the right place.
Go with what suits you, it is too easy to get lost in musing about this subject...
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Le Corbusier
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby Le Corbusier » Mon Dec 16, 2019 8:15 pm

iak wrote: is rigid downstairs.
:shock: :o ..... :D
Tim Lee

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iak
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Re: 4 wheel wagons rigid or non-rigid chassis?

Postby iak » Tue Dec 17, 2019 9:08 am

Le Corbusier wrote:
iak wrote: is rigid downstairs.
:shock: :o ..... :D


Easy now... ;)
Unthinking respect for authority is the greatest
enemy of truth....
Albert Einstein


Perfection is impossible.
But I may choose to serve perfection....
Robert Fripp


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