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O Gauge kit-built loco weight...


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  • RMweb Gold

I've finally got round to (hopefully) finishing a build of an O gauge Agenoria 'Jinty', and I was wondering what a good weight for it would be. I've currently got it up to about 800 grams (a shade under 2lbs in old money). What's a good weight to aim at for a 0-6-0 tank?

 

Thanks!

 

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Perhaps I should add that this is my first loco build (excluding a couple of N gauge body kits).

The chassis has been complete for some time... 

 

20210520_161714.jpg.ed40fd7e8e2ec40b2fe15d29ed31207e.jpg

 

...and runs beautifully, even if I say so myself :)

Work on the body, however, had stalled, and I've only recently picked it up again...

 

20210520_161816.jpg.5bd6e70368424fe6c0cd4d91eec87485.jpg

 

The extra weight has been glued inside the tanks, you might just be able to make it out. There's room for more, but I don't want to overdo it... :unsure:

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Unless you have a full scale layout of the St Pancras carriage sidings, I wouldn't worry too much. If you have, then you might be needing a much larger motor too. Built as per instructions, the Jinty should be able to manage a couple of medium weight coaches or a dozen lightly weighted wagons. Enjoy.

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4 hours ago, doilum said:

Unless you have a full scale layout of the St Pancras carriage sidings,

 

Well I do have quite a big garden... :lol:

But seriously, I guess I've added enough then. At least it will aid pick-up.

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A flywheel of that size will require quite a bit of power to accelerate it, which means the motor will have to work hard (equals heat). The benefit is the flywheel will smooth the motor acceleration and deceleration, which is good for realistic running.

 

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Whilst I normally opine that there is a special place in purgatory for those who obsesse about the brake horse power of their road car or individual wagon axle loadings, this has got me thinking. I am happy with the weighting of my locomotives but couldn't actually quote a number. So I braved the rain and grabbed the first Austerity to hand, Antwerp a scratch build on Slater's wheels. On to the kitchen scales which tipped at 13oz. The kitchen is an imperial domain with baking tins and recipes going back three generations. Antwerp is perhaps a tad light but runs well. Given a large colliery layout I might add another three or four ounces. For comparison, I put my J72 on the scales. This is an early Piercy model in white metal and enters the ring at 2lb 1oz or 33oz. Your Jinty will be fine!

The only locomotives I have spent a lot of time ballasting are those unbalanced classes like the 0-4-4 G5 and the long wheelbase N1&2 which tended to lift and derail at the front.

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I built my old Vulcan 8750 pannier back in 1991 (when I was 16!) and put loads of Lead in it and made it really heavy (don't remember how much - maybe 4lb).

 

I used to run it regularly round the test track in Cardiff bay - part of the old Industrial  & Maritime museum (demolished to make way for the Millennium Centre - the museum is now in Swansea - test track was destroyed by arson).........

 

Anyway.... the pannier used to happily trundle around with 40-50 wagons behind it......I later took all the weight out - this made no difference - it still pulled the same load happily!

 

My conclusion was that weight is useful but in this instance it was more the case that the chassis was perfectly square and had beam compensation so it was firmly planted - even without the weight (if that makes sense).

 

We could always go into a discussion about scale weight and getting a realistic slip when starting - but I think that's one for another month!

 

Jeff

 

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2 hours ago, Scorpio7uk said:

I built my old Vulcan 8750 pannier back in 1991 (when I was 16!) and put loads of Lead in it and made it really heavy (don't remember how much - maybe 4lb).

 

I used to run it regularly round the test track in Cardiff bay - part of the old Industrial  & Maritime museum (demolished to make way for the Millennium Centre - the museum is now in Swansea - test track was destroyed by arson).........

 

Anyway.... the pannier used to happily trundle around with 40-50 wagons behind it......I later took all the weight out - this made no difference - it still pulled the same load happily!

 

My conclusion was that weight is useful but in this instance it was more the case that the chassis was perfectly square and had beam compensation so it was firmly planted - even without the weight (if that makes sense).

 

We could always go into a discussion about scale weight and getting a realistic slip when starting - but I think that's one for another month!

 

Jeff

 

Good point. I once, following a viewing of the austerities at work on you tube thought about trying to replicate this in 7mm. It didn't take long to realise that !the forces and strain on a miniature electric power train are very different to a full size steam loco and that I might be constantly destroying mechanisms. That said, my childhood Triang Scotsman did a perfect wheel slip with five or six coaches attached.

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40 minutes ago, Ian Rathbone said:

 Multiply the prototype weight (in tons) by 0.435 to get the model weight in ounces. (It is coincidence that the factor is 0.435 and the scale 1:43.5). So a Jinty at 49 tons should weigh about 21 ounces.

 

Ian R

 

I've probably overdone it slightly then, but not enough to worry about... besides, I've soldered the tank inner sides on now!

 

But thanks anyway... ;)

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The correct gearing is a very important factor in both the prototype and models.  The gearing should be matched to the intended duties of the model.  Look at the prototype.  There are a lot of factors at play, which modellers ignore, because they aren't really relevant, but in the real world they are very important.  Some of the factors, in a steam locomotive, are boiler pressure, cylinder size, steam flow, wheel size and rolling resistance.  Locomotives are designed to be as light as possible for a given duty to give maximum traction at the rail for the minimum rolling resistance.  There comes a point where additional weight, both in reality and model, only increases rolling resistance giving no extra benefits and expending energy uselessly.

 

Roja

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  • 4 weeks later...
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Having started this thread, I suppose I should carry on showing progress...

 

IMG_1576.JPG.2284e54ce88477f4c7595f37d02e6dbd.JPG

 

...besides, I know everyone likes a gratuitous photo!

Now substantially complete, a few odds and ends to finish, then paint. Far short of the standards seen elsewhere on this forum, but I'm really pleased with the result so far. I might have to build another loco one day...!

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