What is the ideal weight for OO gauge wagons and coaches?

[6029 King Stephen]

I started laying the track on my Sutton Harbour layout yesterday and having laid a couple of turnouts and lengths of flexi-track I decided to run some kit-built wagons fitted with three-link or Dingham couplings through the trackwork to ensure it was smooth.  When I pushed a couple of Coopercraft wagons through the pointwork, the lead vehicle derailed despite ensuring that I have pushed the tiebar as far over as possible.  The wagons seemed very light, despite having the supplied weight fitted. 

 

I went and used the digital kitchen scales and found that one weighed 18g and the other 28g.  I then weighed a couple of Airfix tank wagon kits that I know to be very heavy having had their tanks filled with plasticine and some fishing weights.  These weighed 100g and 121g respectively.  I then weight a couple of RTR Bachmann brake vans; a GWR toad and an SR Queen Mary - these weighed 48g and 150g respectively.  I then weighed a Comet LMS brake third without interior fitted for a comparison and came in at 182g.

 

I have the Right Track DVD on wagons by Iain Rice and I think he suggests 50g as a minimum and this would seem about right.  Fortunately, I managed to get a bag of used car wheel balance weights and these come in 5g, 10g and 50g, so that I will use these, retrofitted to my kit built wagon fleet to bump up the weight.

 

My question is what is the ideal weight for a OO gauge wagon and coach if the loco pulling them is to have any chance of hauling a prototypical train?  In the case of the LMS coach already mentioned, this will form part of a 9-coach Coronation Scot train so the total weight will be around 1638g and the intended locos will be Hornby Princess Coronation class with loco drive.  Will they be able to cope?  I had thought of building the DJH Coronation loco but at £140 plus wheels, motor and gears it starts to get really expensive.  The prototype loco set a record on the LMS of 114 mph but in daily service I would imagine that 60-80 mph might be more appropriate.  For a goods train, most of the trains on my layout will be short goods not exceeding 10-12 wagons plus brake van with a J94, pannier of small prairie tank engine.

 

Regards,

 

Steve

[Bernard Lamb]

For many years I have worked on a figure of 25 grams per axle.

Got a feeling that figure came from Ian Rice.

It does seem to work for shunting wagons.

Unless you have the odd cast white metal kit, but then it is probably best not to mix these in with other stock.

As for haulage capacity I would refer you to Tony Wright and his comments on the merits, or otherwise, of RTR locomotives compared to kit built varieties.

Bernard

[34theletterbetweenB&D]

How long is the ideal piece of string? Long enough to do the required jobs, and I would suggest it is the same with model railway vehicle weights. Heavy enough to stay on the layout track in the most demanding proposed operation and to ensure autocoupler function, light enough to enable the maximum desired trainload to be moved.

 

There's a whole bunch of characteristics to go into the mix to secure the desired performance, beyond vehicle weight. Minimum radii on the layout, track laying standard, gradients or not, free rolling wheels, consistent buffer and coupler alignment, control refinement, all of them matter. My rule of thumb for OO vehicle weight is in the range 150 - 200g per foot. That generally means that provided the wheels are free rolling OO RTR steam models can realistically move a representation of the full size train they worked in reality, on level track. If there are to be gradients, then weight will usually need to be installed on the locos to increase their traction. (Maximum speed is essentially a function of gearing only if traction is sufficient to get the train moving from rest, because the actual velocity at a scale maximum speed is very small.)

[Dunsignalling]

r-t-r coaches generally weigh around 160g. Most seem to run well and scaling that down according to length seems to provide decent running in wagons.

 

Around 45-50g seems to work well for vans, increasing to 60-65g for long wheelbase vehicles (CCTs, or modern airbrake types).

 

I deliberately make swb coal/mineral wagons a bit on the light side (about 40g empty) to partly offset my removable loads, which weigh about 20g each. Anything with a permanent load gets treated the same as a van. 

 

Take care not to overdo things. Not only can it overtax locos or limit train lengths but adding too much weight to r-t-r wagons can result in unduly rapid wear to the plastic bearing surfaces. In plastic kit-built wagons, excess weight can sometimes cause the axleguards to spread.

 

As so often in life, "Moderation in All Things", seems a good rule of thumb.    

 

John

Edited November 7, 2016 by Dunsignalling

[DCB]

There is no real Ideal weight but ideally every wagon should weigh the same.   It is always the light wagons which derail, you can weight them, or lighten the others but the optimum is all similar wagonl weighing the same, as in all short wheelbase 9ft 10ft 4 wheelers, not Bogie Bolsters or long wheelbase wagons, which should all equally be similar within their type and ideally proportionate to their size.

Weighting wagons causes centre of gravity issues, cutting the floor out of the underframe and replacing it with lead flashing is my preferred method, give two layers of flashing a love tap with a sledge hammer to compact it and cut to size so it hides between the side members of the underframe and does not hang down.

Hornby Dublo seemed to get it right, the 8F will haul well over 40 of their wagons and reverse well over 20 of them over 2ft radius points and that is the benchmark I use, standardising on H/D Wrenn underframes and adding Bachmann etc bodies.  Attempts to weight Hornby and Bachmann wagons have been less successful than straight body transplants mainly due to issues fitting H/D couplings and fine flanges narrow treads which don't like my almost prototypically rough track work  in yards etc

Couplings are a bigger issue than weight,   In 00 the tension lock Bachmann/ Hornby thing is hopeless, I use Peco H/D style which is much more tolerant of misalignment, and if starting again would either use Kadees or N gauge couplers.  Controlling excess turning movement on bogies and sideplay slop on the track also improves shunting.

[johnb]

After some experimentation I settled on 20g per axle for both 4wheel and bogie stock (I treat 6 wheelers as 4 wheel). That is using Peco medium radius points and 3ft rad curves/

I don't have any three axle bogie stock.

 

John

[Yardman]

The NMRA have a standard that basically says a vehicle should weigh one ounce for every inch of length plus an additional half ounce. It is an HO standard but it's near enough for OO. I’ve used the standard for the last forty years and it works.

[teaky]

The NMRA have a standard that basically says a vehicle should weigh one ounce for every inch of length plus an additional half ounce. It is an HO standard but it's near enough for OO. I’ve used the standard for the last forty years and it works.

Is my maths correct?  That sounds like more than twice as much as the 25g/axle or 50g/mineral wagon suggested in earlier posts.

[johnb]

That's about the situation, it is much heavier result. 

 

I've found the NMRA weights rather too heavy for smaller UK layouts. The NMRA standard allows for very long trains with long freight cars on their basement empires, so that they don't pull off on tightish curves and can be propelled with more certainty

 

As I indicated I found that a total weight of  40g(ish) for four wheelers and 90g(ish) for bogie stock is quite adequate, certainly for my layouts and others up to 20ft+ long and 2ft/3ft radius curves.

Essentially I took very light vehicles, and gradually added weight until they stayed on for both propelling and running, then weighted to the nearest 5g/axle above to be safe. That's using code 100 track, Peco points and the latest wheels (probably RP25 standard or nearly so)

 

John

[Dunsignalling]

I've just refreshed my knowledge of the NMRA standard for HO stock weight and it specifies one ounce plus a half-ounce for each inch of vehicle length.

 

Thus a typical UK wagon of approx. 3 inch length should weigh one plus three halves, total 2.5 ounces, roughly 25% over what you get from 25g per axle but in much the same area.   

 

Doing it the other way would make 3.5 ounces, decidedly hefty for a typical 4-wheeler and requiring weight to be added even to most whitemetal wagons. 

 

A very small change in the order of the words makes a big difference.

 

John

[teaky]

Eats shoots and leaves.

 

A lengthy (by most layout standards rather than prototype) mineral train of thirty wagons comes in at 1.5kg (and around 2.5m in 4mm scale).  Quite a weight for RTR locomotives.  I wonder if they are up to it?  It makes me wonder if these guidelines only work for smaller layouts and/or kit built locomotives?

 

Edited 'cos I can multiply but not type!

Edited November 7, 2016 by teaky

[Legend]

Isn't it friction that's the key here , not weight?

[Corbs]

Is it bad that I tend to add as much weight as I can to all of my wagons? I just like seeing the locos struggle!

[Dunsignalling]

Eats shoots and leaves.

 

A lengthy (by most layout standards rather than prototype) mineral train of thirty wagons comes in at 2.5kg (and around 2.5m in 4mm scale).  Quite a weight for RTR locomotives.  I wonder if they are up to it?  It makes me wonder if these guidelines only work for smaller layouts and/or kit built locomotives?

I don't use the NMRA standard as I think it produces weights that are a bit OTT for British wagons, though most r-t-r coaches come out only an ounce or so under it.

 

I've known several people who use the NMRA formula but only measure whole inches then round the answer down to the nearest whole ounce. Typical British compromise but it seems to work well in practice and doesn't require the use of a calculator. For a BR Mk1 that's 6 ounces - actual weight (Bachmann) 5.8. 

 

My own 4-w vans average around 45g each and my Bachmann 9F will start a train of 46 on a 1 in 50 gradient, double what's normal for the layout. That's just under 2.1 kilos and it didn't struggle (I ran out of wagons so couldn't add more) I don't think 25% more would bother it on the level.  

 

A load of 30 minerals, though, was prototypically the province of fairly modest locos. My loaded ones come out around 55g and 30 of them total about 1.6 kilos which is probably just within the capacity of a good r-t-r 0-6-0 on a flat layout with reasonably gentle curves. Mind you, such a train is going to be over 8ft long including loco and brake van and I think most home layouts run up against length limits before our locos run out of power. 

 

John

Edited November 7, 2016 by Dunsignalling

[34theletterbetweenB&D]

Isn't it friction that's the key here , not weight?

 If the layout is genuinely level, yes. A train that is heavy with respect to the available traction, but very free rolling, will reward realistic driving.

 

If there are gradients then the weight starts to matter a lot, as it will limit train lengths. It's quite easy with free rolling stock to end up with a loco that cannot stop a train going down. (Failure to go up is usually not so much a problem in terms of potential accident.)

[relaxinghobby]

For 00 4 wheel wagons, 9 foot wheelbase 25 to 30 grammes.

 

 

Here’s my version of weighting wagons.

 

Some more experienced modellers have been known to pick-up abandoned nuts and bolts and tire weights in the street. Cars are always shedding tiny parts of themselves. These can be used as ballast weights, the larger nuts and bolts in model railway vans and lead tyre weights underneath the floors of open wagons. The tyre weights when they were lead could be hammered flat and squashed with pliers until they fitted in the spaces underneath, must cheaper than liquid lead.

 

Not so easy now that the tyre weight are cast mazdak, but they can be cut down with snipers

 

 

This picture shows to example, the coal on the right has a sort of porridge of glue, liquid lead and wheel weight clippings, then painted grey to seal the lead in.

 

The left hand one has a flat mazdak weight stuck into the middle and smaller spaces filled with lead clippings, painted again to seal it in. Super glue used to fix things.

 

 

 

 

They roll and shunt satisfactorily, I've just weighed them and the flat wagon L/H is 25g and the coal R/H is 30g.

[Andy Hayter]

Isn't it friction that's the key here , not weight?

 

No - at least not entirely.  A free running and light wagon in the middle of a rake of propelled weighted wagons is the one most likely to derail.  Inertia (mass) plays an important part as well.

[RexAshton]

There is no real Ideal weight but ideally every wagon should weigh the same.   It is always the light wagons which derail, you can weight them, or lighten the others but the optimum is all similar wagonl weighing the same, as in all short wheelbase 9ft 10ft 4 wheelers, not Bogie Bolsters or long wheelbase wagons, which should all equally be similar within their type and ideally proportionate to their size.

Weighting wagons causes centre of gravity issues, cutting the floor out of the underframe and replacing it with lead flashing is my preferred method, give two layers of flashing a love tap with a sledge hammer to compact it and cut to size so it hides between the side members of the underframe and does not hang down.

Hornby Dublo seemed to get it right, the 8F will haul well over 40 of their wagons and reverse well over 20 of them over 2ft radius points and that is the benchmark I use, standardising on H/D Wrenn underframes and adding Bachmann etc bodies.  Attempts to weight Hornby and Bachmann wagons have been less successful than straight body transplants mainly due to issues fitting H/D couplings and fine flanges narrow treads which don't like my almost prototypically rough track work  in yards etc

Couplings are a bigger issue than weight,   In 00 the tension lock Bachmann/ Hornby thing is hopeless, I use Peco H/D style which is much more tolerant of misalignment, and if starting again would either use Kadees or N gauge couplers.  Controlling excess turning movement on bogies and sideplay slop on the track also improves shunting.

It's worth remembering though that a Hornby Dublo 8f only actually has two axles in contact with the rails.

[RexAshton]

I think the Scalefour Society used to recommend ½ oz per axle for rolling stock.

[Il Grifone]

It's worth remembering though that a Hornby Dublo 8f only actually has two axles in contact with the rails.

 

This is true, but for traction this makes no difference as friction is proportional to the applied weight. The latter is not lacking in a Dublo 8F thanks to being made of zinc alloy and having a large lead weight in the boiler. Am I correct in assuming that 40 wagons refers to a ringfield example? Mine has the half inch motor and will only manage about 20 Dublo wagons with plain bearings without slipping. Of course the heavy tender doesn't help....

 

I try to aim for at least an ounce for a short 4 wheel wagon. White metal vans are around two to three times this! A Dublo wagon with an alloy underframe is around two ounces. Ideally they should all be the same, but the prototype manages with a ratio of around 3:1 between loaded and empty wagons, so it's not too critical. Too much weight will cause wear in pin point bearings

[DCB]

The Ringfield 8F has better haulage than the 1/2" because the weights on front and rear axles are around the same, I have a Ks ROD on an 8F chassis with a computer motor, the weight is similar to the Ringfield 8F but it is nose heavy and it struggles with around 30 wagons.

 

I have found lightening the smokebox end of 4-6-0s can actually improve the haulage as it increases the weight on the trailing axle.

[Il Grifone]

I think the solution here is to transfer some of the tender weight to the locomotive using a rigid drawbar of some kind. I always mean to experiment with my Dublo Castle and 8F.

[The Johnster]

Persistent derailment is one of the things that'll really interfere with the enjoyment of the hobby.

 

If the problem is derailment of stock when propelling, especially through reverse curves or turnouts. the cause may be one or a combination of several factors.  Before worrying about weight, check that all the wheelsets are running freely, all the wheels are round  and true, and that the tyres are clean and free of crud they might have picked up, and that all of your coupling bars are the same height above the railhead if you are using tension locks (make sure you aren't having buffer lock issues if you are using scale couplings).  Metal t/l coupling hooks sometimes get bent, and will push the adjacent wagon sideways in a curve.  Check your back-to-backs, and aim to standardise on a wheel profile; that may not be as simple as it sounds if you are using rtr stock from a variety of companies produced over a variety of periods, but it's a good thing to aim for.

 

The next thing is to look at the weight, which is not an exact science so long as a) your stock is heavy enough not to be blown off the track by sneezing near it*, and b) all more or less the same weight proportional to the size.  The figures given in the correspondence are about right, but don't lose sleep if you are a few grams out; you can do this by feel or 'heft' and precision weighing is overkill.  You may need to put a little extra weight under conflats or lowfits to compensate for their lightness, as the manufacturers use a standard size ballast weight for all their wagons. Keep the weight centrally balanced on the longitudinal axis, and as low as you can get it without interfering with the sight lines between the frames.  Bogie bolsters are a bit of a problem because they are very light as plastic models in terms of axle load and you have to make sure that the weight is evenly distributed over each bogie, particularly when they are running empty without the steadying influence of a load to hold them down, and empty lowmacs are as well because there is very little space underneath to put the weight.  Tank wagons are problematic as well, because although you can hide weight in the tank, it brings the centre of gravity up a bit.

 

Drive smoothly and slowly when you are propelling or setting back, but be confident and keep the loco pushing and all the couplings compressed; you need to avoid jerking and snatching.  They can sense it if you're nervous, you know...  If the problem is uneven track, the only thing you may be able to do is, er, better next time you build a layout.  If one particular chassis is a persistent offender, and resists all efforts to cure it, withdraw it from service, bin it to prevent using it again, and get on with your life, unless it is a new one in which case take/send it back for replacement.

 

 

 

*not an actual recommendation for testing wagon weight.  Or weathering...

 

(b****r, how I am going to get rid of that mental image now?)

Edited December 17, 2016 by The Johnster

[Passed Driver]

Hi All. I have been reading so much about the shunters truck, I didn’t realise that it was such an old model. I have just purchased the “Recent 38-677 Old Oak Common “ shunters truck??? and was surprised how light it was, derailments here we come? But how can I keep it on track? It hasn’t got the usual wagon type weight on board. I think that it may have been better to convert another wagon ??

Best wishes. Kevin

[locomad]

I think the solution here is to transfer some of the tender weight to the locomotive using a rigid drawbar of some kind. I always mean to experiment with my Dublo Castle and 8F.

Interesting, after spending some time trying to get a locos to haul 100 wagons round my layout, I've discovered or come across more questions than answers.

 

One particular query was having got 2 1/2" 8F's one was able to cope with about 45 Hornby-dublo wagons while the other struggled with about 30.

 

Thanks I think you have answered why, rigid drawbar, I originally fitted a plastic one because been ex 3 rail use the American system of pick up ie tender pick up one side, I also closed the gap.

 

This is a more rigid drawbar so assume places more weight on the back driving wheel