weighting coaches

[oldknotty]

I am having a bit of a problem with coaches coming off the rails at times , I have checked the track and also the wheels gauge and they seem ok . i was wondering if adding a little weight to them might help as it has done so with the wagons i use and they run better now . If this is a good idea what should the coach weigh to be accurate ?? Also what are the best wheels to put on them I have changed all my wagons to metal wheels what are good ones for coaches ??

Thanks martin

[brossard]

Martin, do they come off the track when by themselves or when coupled to other coaches? Through points? Do other vehicles of different type or make come off too? Do the coaches come off at the same place every time?

 

Adding weight might help but not too much. Typical weight is ~ 140 gms. I find RTR coaches tend to be right. I also find recent RTR coaches are very good runners - what are yours?

 

Check the condition of the track and in particular the gauge. There should be no sharp transitions or bumps. Are your points in good shape?

 

Wheel back to backs going off are a common cause of derailment. I use a Romford steel gauge - I don't feel the NMRA gauge is precise enough. Should be 14.4 - 14.6 mm (Romford is at 14.5mm). If you don't have a gauge, digital calipers aren't too expensive and a handy tool for modelling. I think Hornby and Bachmann wheels are fine (should be 14mm dia). Get the version that are insulated both sides unless you plan to light your coaches.

 

The coupling that you use could be the source of your problem. Also bogie clearance with the body - make sure it is free to pivot without fouling. Maybe tighten it up if it flops about too much. The coach ends need to be free to swing in curves - make sure nothing is preventing this.

 

As you can see there are a host of potential issues. You will need to patiently go through them.

 

Maybe you could add some detail that would help to narrow it down.

 

John

[Silver Sidelines]

Hello Martin

 

My benchmark are the British outline Bachmann Mk1s which have a weight of around 165gm. They have metal wheels running in plastic frames. Hornby make some very good BR outline stock but their coaches are lighter and I have had problems with the leading coach of a long rake jumping off where the track has both vertical and horizontal curvature. I cured this by ballasting the Hornby coaches with a little lead shot (placed inside the seats) to bring the weight up to the 165gm benchmark.

 

Then of course you will need to ballast the locomotives to pull the additional weight up the gradients?

 

The proof is in the eating so to speak, some Bachmann Mk1s and some Hornby Hawksworth with ballast.

 

 

Regards Ray

Edited September 16, 2011 by Longsheds

[corax67]

Hi Martin - like John I would recommend checking the BTB distances on your wheel sets as a first port of call. i use a C&L Finescale brass gauge on all my stock.

 

As for replacement wheel sets I fit a lot of Hornby ones as they are relatively inexpensive and give excellent free running once they have been tweaked for BTB.

 

 

 

Karl

[jcm@gwr]

Hi Martin,

If you want to get the weight right, check out NMRA's website they have a chart to work out

the correct weight of each wagon/coach relative to it's length.

Cheers, Jeff

[oldknotty]

Thanks guys all good advice and will keep me occupied and out of mischief for a while :-)

[Il Grifone]

Check the ability of the bogies to rock relative to the coach body. It is quite easy to have a slight twist in the track over the length of a coach especially if super elevation is used on curves. I arrange almostall* my bogie vehicles for 3 point suspension - one bogie is free to tilt in all directions and the other only fore and aft (ie only along the length of the vehicle and not side to side). This allows the coach to follow uneven track and gives stablity to the vehicle eliminating wobble.

 

*Alternatively the wheels can be sprung..... I have a few of these on trial.

 

The back to back is unlikely to cause derailments on plain track unless seriously incorrect. Note the critical dimension is the check gauge BtB + flange thickness (see the NMRA site for clarification). Note also that NMRA flanges are thicker than most British 'scale' wheels which are usually to the old BRMSB standard of 0.5mm.

 

I think the NMRA weight recommendation (1oz plus ½ oz per inch length IIRC) is a bit heavy, but this is my opinion.

Edited September 16, 2011 by Il Grifone

[corax67]

I remember reading that the 'optimum' weight for rolling stock was 0.4g per mm - I just cut out strips of lead flashing to go under the seating moulding or fit liquid lead onto the underframe until it feels OK on the track, especially through a set of points.

 

 

 

Karl

[Il Grifone]

I remember reading that the 'optimum' weight for rolling stock was 0.4g per mm - I just cut out strips of lead flashing to go under the seating moulding or fit liquid lead onto the underframe until it feels OK on the track, especially through a set of points.

 

Karl

 

This works out to 28g - about 1 oz for a standard 17' 6" underframe, which is about right IMHO. I usually weight mine to about this figure, or a bit more (about 1 - 1½ oz - more for longer vehicles*). Really it depends how many white metal vans you have, as ideally all the vehicles should be about the same. (Within reason - the prototype wagon varies from around 5 tons empty to around 20 or more fully loaded.)

 

I don't differentiate between 9' and 10' wheelbase or the length - all 'normal' 4 wheel vehicles get treated the same. Equalised or sprung vehicles may need a bit more perhaps as much as 2 oz.

 

Since this thread is about coaches, this formula gives around 100g for a Mk 1, possibly a bit light. (The NMRA formula gives about 6oz (or the 165g mentioned above)).

 

EDIT I've weighed (to nearest 10g below) a couple of coaches to hand:-

 

Hornby Dublo tinplate D12 (BR(M) composite with metal wheels -160g) These are prone to derailment as the bogies are rivetted quite rigidly to the floor and are not very 'flexible'

 

Airfix GWR 'B set' composite fitted with Jackson metal wheels - 150g

 

I find metal wheels provide weight just where it's needed - low down (apart from giving better running than plastic ones and being less prone to picking up crud).

Edited September 17, 2011 by Il Grifone

[asmay2002]

Hi Martin,

If you want to get the weight right, check out NMRA's website they have a chart to work out

the correct weight of each wagon/coach relative to it's length.

Cheers, Jeff

 

The NMRA standards were established half a century or more ago - well before the era of plastic and pinpoint axles. They were intended to at least partly compress 1950's era springs in US freight car bogies. Many modern authorites consider them too heavy. The important thing is consistency of weight between vehicles and this will be driven by the heaviset ones that you have.

[Il Grifone]

Quite possibly, but 1950s Rivarossi cars had both spung bogies (with pinpoint axles) and plastic bodies, and probably were some of the vehicles considered. These run quite welll (possibly a little more weight might improve things further - I haven't tried). Later cars with rigid bogies have 3 point suspension.

I suspect the main reason for the weight was the then standard X2f coupling, which requires mass to avoid derailments through the sideways force of the coupling spring. I find these are almost always far stronger than needed to hold the couplings engaged and benefit from weaker springs. They then work quite well.

[Ravenser]

Reviving this thread from the depths of Antiquity out of curiosity...

 

So what is the appropriate weight for a coach?

 

I ask because I've just been reading a copy of MRJ 277, and an article on coach kits wherein it is stated 

Quote

The completed ballasted weight of the coaches is 280g each, which is a little on the heavy side

 

It struck me as very much on the heavy side, since ever since I started doing "proper" railway modelling I've been working to Iain Rice's rule of 25g/1 oz per axle. That gives 50g for a 4 wheel wagon, which certainly seems right - trying to get rid of stock problems on the Boxfile has shown that opens down at 35g-40g are liable to give trouble whereas at 50g wagons normally have enough mass to stay on the road even propelled into the questionable leg of the point for the back siding. (Some more detail to validate the comments here Boxfile - wagon fettling )

 

So much for wagons, where I'm sure of my ground.

 

But the same rule implies 100g for bogie coaches. That does mean adding weight - a noticeable amount of it - to plastic Ratio coach kits, which is what (along with a couple of Kirk items) I mainly have experience of. For 50' vehicles - which most are, give or take - this seems reasonably heavy.

 

A hasty check with the scales gives

- Bachmann BG (57')                 125g  

- Hornby Gresley CL (51')         105g

- Hornby Gresley BCK (61'6)    125g

 

I have heard of people removing the weights from Bachmann Mk1s ("too heavy") to improve running. Meanwhile the old NMRA  formula would require 6.5 oz = 165g for a Mk1 (see this thread Wagon and coach weights  for reference, though the thread is more about wagons than coaches)

 

So - what is a proper weight for a bogie coach? Below 100g? Over 200g ?  Opinions seem to differ wildly, and it would be helpful to know what people think.

 

For what it's worth, I weight long-wheelbase 4 wheelers (coaches and parcels vans) up to about 70-75g , on the basis that 50g is surely too little for such a large vehicle - and 100g must be over the top. I know of no theoretical justification for this, though...

 

[DCB]

I found the Hornby Hawkesworths to be too heavy and took most of the weights out.  The Bachmann BGs run fine as do my Triang Mk1s from as far back as the mid 1960s one of which I just checked at 125 grams.  The Sleeping cars and Caledonian coaches are only about 115 grams as they lack interiors, which is too light for 64 footers.

I reckon 125 grams for a full length coach is a good target.

Probably more important is wheels correct back to back, and couplers at the same height, even 1mm variation levers the bogies off the track on some of the leading coaches of long trains on my garden line with its 1 in 14 gradients, and also indoors when I go mad and run 20 plus carriage formations.

[Les Bird]

As an aside to this thread, if you are planning to weight vehicles, might I suggest car wheel balance weights? I bought mine on Ebay. They come in 5 and 10 gram sections and are self adhesive. They are also quite flat which makes hiding them easy.

[John Tomlinson]

It seems to me that the answer to this question depends at least in part on user expectations. As this is a railway modelling forum I'll assume that the participants are reasonably serious about the hobby, and that they aren't operating a train set for kids, at a scale 200mph round 18" radius curves.

 

On my own layout, I have hills and like to run reasonably long trains, say 8 coach or 20 2 axle wagons. My minimum radius is 27".  For the coaches, I invariably remove the manufacturers weights, on a Bachmann Mk1 this takes us down from around 160g to 130g. Hornby Maunsells are lighter and IIRC without the weights are around 110g. My kit built coaches are also in this area, and I don't have any full brass and white metal efforts that tip the scales over 200g. So in summary I'm going for something around David's target, sometimes a bit less, sometimes a bit more, but thereabouts.

 

On this basis I have little or no problems in running at all. I was reasonably careful in laying my track (Peco code 75). On my BR and ex.LNER gangwayed stock I use Kadee 5's attached to chassis not the bogies, which I find gives a very smooth ride indeed, so much so that I can propel uphill, round a curve and through facing points without a hitch. (Bet it derails next time after writing this!). Hornby Hawksworths and Pullmans have a fixed bar coupling that I've made up to enable use of the close coupling mechanism, but it is shaped so you don't get a great lump of plastic between the bogies of adjacent coaches. Hornby Maunsells have the close coupling bar replaced by spares from Bachmann Mk1's, then a Kadee 17 which is cranked and more or less sits at buffer height - a real pain to couple up but looks good when done, and I tend to run in fixed rakes. I need to be a little careful with buffer locking coming downhill, and some of my loco tenders have a blackened thin brass bar between the buffers to help in this regard - it isn't really noticeable in operation.

 

So in summary, I don't at all buy this idea that you need heavy coaches to keep them on the track, if they keep coming off look elsewhere for the problem.

 

John.

[melmerby]

Whatever you do don't try using Kadees on Close Coupling Mechs.

That is a recipe for disaster. I leave my rakes coupled using a combination of Hornby & Roco couplers which maintains closeness on the straights but opens out sufficiently on curves to stop buffer locking.

 

[melmerby]

2 hours ago, John Tomlinson said:

 

So in summary, I don't at all buy this idea that you need heavy coaches to keep them on the track, if they keep coming off look elsewhere for the problem.

 

John.

Totally agree.

Mine stay on through reverse curves double slips etc without a problem and at some speed.

If the track is laid properly there should be no problems.

None of mine are weighted above what they come with.

[wasdavetheroad]

I run mixed rakes of Hornby and Bachmann coaches and have removed the weights from the Bachmann ones bringing their weight down to similar to the Hornby's. Can't see the point of having the rolling stock being heavier than it needs to be. A 4 wheel wagon at about 40g and a coach at about 120-130g works for me.

[The Johnster]

They don't need to be any heavier than they have to be to prevent being blown over when you sneeze at them, but on a small BLT I use whatever ballast they came with.  Except for 2 Keyser whitemetal A31 auto trailers; these are insanely heavy, and I've added sheet plastic floors and interiors so they are slightly heavier than they were originally.  I can get a Bachmann 4575 to slip a bit with these if I'm a bit heavy handed starting off!