Fixed or pivoting trailing trucks

[Robin Brasher]

Fixed trailing trucks look ridiculous on a large locomotive running through curves of less than three foot radius. Most other manufacturers make pivoting trailing trucks and the trailing trucks are pivoted on the prototype.

 

Some people think that a fixed mounting looks better and people should not be running Pacific locomotives on less than three foot radius curves.

 

What do you think?

[Guest Midland Mole]

I think the old pivoting trailing truck look ridiculous, but then I also think large locos running on these radius curves look ridiculous anyway.

When I compare my new duchess to the older one, the old way looks even worse. I don't like my locos having a floppy truck with so much space you put a Terrier between it and the cab floor.

 

Now if the manufacturers could make it so that the truck looks like the real thing, barely any daylight but still pivots, fine. But chances are incredibly slim and while some people still have to use unrealistic curves due to space issues, I can't see this argument ever being resolved.

 

Alex

[Titan]

and the trailing trucks are pivoted on the prototype.

 

Many of the prototype pacifics are not pivoted, they effectively have an axle with a lot of sideplay, known as a Cartazzi. Almost all LNER pacifics are like this and I suspect a good many others too, see here:

 

https://en.wikipedia.org/wiki/Cartazzi_axle

 

So having it not pivot is more accurate, but it will of course look poor on unrealistic curves...

Edited November 7, 2017 by Titan

[G-BOAF]

What is really needed is a truck that can pivot on scale curves (in instances where the prototype pivots, but not LNER pacifics, V2s Atlantics etc), but can be locked out with flangeless wheels for tighter curves. I originally bulked at the idea of fixed rear trucks, but given how much better they look than pivoting trucks, especially with the absence of daylight above and in front of the trucks, I prefer them. Bachmann's Cartazzi mechanism is innovative, however suffers from a lack of relief of axle box detail due to extra width.

The Rebuild Merchant Navy was actually very good in getting away with a swinging truck, but benefited that the real thing has distance between the delta truck and the firebox. There is however some daylight visible which detracts from the model (along with the hollow-tooth firebox sides) and is an obvious area improvement for this model (possibly in a Dave Jones King method with deeply recessed full height frames in the centre of the loco).

[cctransuk]

What is really needed is a truck that can pivot on scale curves (in instances where the prototype pivots, but not LNER pacifics, V2s Atlantics etc), but can be locked out with flangeless wheels for tighter curves. I originally bulked at the idea of fixed rear trucks, but given how much better they look than pivoting trucks, especially with the absence of daylight above and in front of the trucks, I prefer them. Bachmann's Cartazzi mechanism is innovative, however suffers from a lack of relief of axle box detail due to extra width.

The Rebuild Merchant Navy was actually very good in getting away with a swinging truck, but benefited that the real thing has distance between the delta truck and the firebox. There is however some daylight visible which detracts from the model (along with the hollow-tooth firebox sides) and is an obvious area improvement for this model (possibly in a Dave Jones King method with deeply recessed full height frames in the centre of the loco).

 

See my post #975 at http://www.rmweb.co.uk/community/index.php?/topic/117259-Hornby-princess-coronation-class-duchess/page-39 .

 

Regards,

John Isherwood.

[Guest Midland Mole]

Also, this is another example of the fact a manufacturer will never be able to please everyone. If half the community want pivoting trucks, and half want fixed, then whatever Hornby do will annoy someone.

 

The challenges of being a manufacturer I suppose, and exactly why I would never want to make a product.

Alex

[cctransuk]

Also, this is another example of the fact a manufacturer will never be able to please everyone. If half the community want pivoting trucks, and half want fixed, then whatever Hornby do will annoy someone.

 

The challenges of being a manufacturer I suppose, and exactly why I would never want to make a product.

Alex

 

Not so - there is an easy solution that will accommodate both camps - see my post immediately before your own.

 

Regards,

John Isherwood.

[Bernard Lamb]

Fixed trailing trucks look ridiculous on a large locomotive running through curves of less than three foot radius. Most other manufacturers make pivoting trailing trucks and the trailing trucks are pivoted on the prototype.

 

Some people think that a fixed mounting looks better and people should not be running Pacific locomotives on less than three foot radius curves.

 

What do you think?

Large locomotives look ridiculous running round smaller than scale radius curves. Forget 3' more like 8'.

Hornby have found a method that looks good on a show case model and provide an alternative for running as a toy train.

Do you really suggest we go back to the dark ages?

My vote goes to Hornby.

Bernard

[frobisher]

What do you think?

To my mind the ridiculous overhang of the front buffer beam is much more noticeable on the Duchess there...

[Grovenor]

Many of the prototype pacifics are not pivoted, they effectively have an axle with a lot of sideplay, known as a Cartazzi. Almost all LNER pacifics are like this and I suspect a good many others too, see here:

 

https://en.wikipedia.org/wiki/Cartazzi_axle

 

So having it not pivot is more accurate, but it will of course look poor on unrealistic curves...

That wikipedia page omits the important feature of the Cartazzi design, that it is not just provided with sideplay but the hornguides are angled, and act as a virtual pivot so that the axle is kept at right angles to the track in the same way as a pony truck.

Regards

[farren]

Hornby can't really say you can't have a pacific cus your too poor to have a large layout can they by making the model unsuited for 3rd radius. Well at the same time trying to keep serious modelers happy. And price control. I think Hornby have done a dam fine job.

 

Didn't Stanier use Bissel trucks on the Princess's.

Edited November 8, 2017 by farren

[uax6]

To my mind the ridiculous overhang of the front buffer beam is much more noticeable on the Duchess there...

Which points to the fact that side control on leading bogies (and pony trucks) is a sorely needed item, which transforms a floppy bogie that is just along for the ride into a bogie that actually performs like the full sized item and guides the drivers into any curve...

 

Andy G

[Hilux5972]

Which points to the fact that side control on leading bogies (and pony trucks) is a sorely needed item, which transforms a floppy bogie that is just along for the ride into a bogie that actually performs like the full sized item and guides the drivers into any curve...

 

Andy G

Next you’ll be wanting miniature people that actually fire it and drive it as you command them. There are limitations to what can be achieved. No one ever forces you to buy a model.

[uax6]

Next you’ll be wanting miniature people that actually fire it and drive it as you command them. There are limitations to what can be achieved. No one ever forces you to buy a model.

 

I'm actually quite pragmatic, and up for all sorts of bodges, but I do fit side control to my kit built locos, as I make them. Its not difficult and transforms the way that they look as they run through curves.

 

As I model a Scottish prototype, there's very rarely anything RTR I actually buy...

 

Andy G

[Dunsignalling]

I much prefer the fixed truck arrangement.

 

Yes the overhang on train set curves does look silly, but the whole loco does; it's the curves that are silly, not the locos. Having a pivoted truck surrounded by half an acre of daylight then swinging out so far that the wheel becomes visible outside the line of the cab looks far worse to me.

 

Whether fixed or pivoted, the only answer is not to look at it while it's happening! 

 

Having established that, whichever kind of truck is fitted, the real problem lies with the layout rather than the loco, what's the solution?

 

IMHO, presentation is the key. If we want anything more elaborate than a simple, straight-line shunting or shed layout, most of us have to tolerate such silly curves for lack of space. If they are unavoidable, the only answer is to arrange the scenery, as far as possible, to inhibit the viewer from gazing directly at them, using tunnels, cuttings, woodland or strategically placed buildings.

 

Having the baseboards at chest level helps in guiding the eye away from the worst excesses, too. The effect is maximised from a "helicopter" viewpoint. 

 

John

Edited November 8, 2017 by Dunsignalling

[Robin Brasher]

For me a Hornby tender driven 'Princess Elizabeth' with pivoting trucks looks more realistic going round 2'6" curves than a Hornby locomotive with a fixed truck.

 

The Golden Age Pacifics have trucks that move realistically and have flanged wheels. I think that they are designed for track which is over three foot radius whereas Hornby Duchess is designed for points and curves over 17 1/2" radius. I think it is reasonable to run any of Hornby's locomotives on a minimum curve of 2' 6" radius although most of the track in the barn at Godlingston Manor is 3' radius.

 

I think that Hornby is the only firm that makes fixed trailing trucks in any scale.

[Hilux5972]

No, Bachmann also makes fixes trailing trucks on its A1/A2 locomotives.

[57xx]

I'd agree with some people, but then Rule 1 applies.

[davidw]

No, Bachmann also makes fixes trailing trucks on its A1/A2 locomotives.

But there is insufficient relief on these compared with the prototype. No easy answer. Personally I prefer fixed but then in my scenic sections I'vve gentle curves

[STRAT'71]

 

I find the Hornby Princess Royals' pivoting truck is very discrete, and any gap is hard to see, whereas the Princess Coronations are not so good.

[Hilux5972]

46207.JPG

 

I find the Hornby Princess Royals' pivoting truck is very discrete, and any gap is hard to see, whereas the Princess Coronations are not so good.

Any gap when looking from above is going to be hard to see. Look at it from side on on and you’ll see straight through it.

[MikeParkin65]

46207.JPG

 

I find the Hornby Princess Royals' pivoting truck is very discrete, and any gap is hard to see, whereas the Princess Coronations are not so good.

Give or take the massive chunk of missing frame behind the rear driver. And the fact that the rear pony looks very little like that or a Princess. Apart from those points itsa really good solution

[bike2steam]

Stanier pacifics very seldom ran over the SSR, so mine stay in the display case - problem solved

[Stevelewis]

Stanier pacifics very seldom ran over the SSR, so mine stay in the display case - problem solved

 

or stick all the  sharp  curves in tunnels

[vitalspark]

Give or take the massive chunk of missing frame behind the rear driver. And the fact that the rear pony looks very little like that or a Princess. Apart from those points itsa really good solution

 

 

Yep your'e spot on.. of course the 6ft gap between the tender and footplate does kind of take your eye away from the issue.