Hornby Britannia

John Nuttall said the following on 29/09/2006 13:08: Nope, but you can be sure that if it's anything like the current RTR from Hornby, it is going to be bloody good for the pittance that these things sell for.

Have just got the Brittania 'William Wordsworth', looks and runs very well. However, is it me or is the rear pony truck supposed to be a fixed in place item, with wheels with no flanges...??
Ian J.

That is how Hornby have designed it but not how the real thing was built. IMHO one 'improvement' they should not have made. Keith

Ian J. smirked:
No. It actually *was* a pony truck, not a Cartazzi truck like the Gresley pacifics.

"Ian J." wrote
In reality the amount of movement of such a bogie on the prototype would be minimal, and as a result it's not an unreasonable compromise which Hornby have made with the Britannia (and with their recently released models of the ex-LNER A3 & A4 models). The fact that the pony truck wheel is flangeless is not visible when the loco is in use on a layout.
The ridiculous loco to tender draw bar on the A3 & A4 is a much greater issue for me (not actually seen a Britannia yet, but assume that's the same).
John.

Ah, but the Merchant Navy has a 'proper' pony truck, and it works fine, so why did Hornby choose such an obviously wrong arrangement for the Brit? Even on 32 inch curves ( much more than the minimum 438 mm stated for the Brit), the pony truck wheels just aren't in contact with the track properly, so sometimes the wheels aren't even turning... I'm puzzled why the model's been designed this way...
Ian J.

"Ian J." wrote
Much older model, and although it 'works fine' I'd suggest there are grossly overscale gaps between the pony truck & other parts of the loco chassis.
John.

Because that was the Triang way of doing things, and obviously Hornby feel a strong need to return to their heritage.
Next they will be doing a revamp of the Evening Star on an 0-4-0 chassis with a push-along friction motor... keeps the costs down, makes it more accessible to the disabled by making it easier to re-rail (in accordance with the DDA), and gives us something to talk about on this newsgroup.
Cheers, Steve

Because - whilst the truck under the MN probably follows the track OK, it doesn't half look ridiculous, with the huge air gap under the cab:
The model of the Duchess is ruined in the same way, of course:
Horrible. Just horrible.
The A1/A3. OTOH, use the fixed truck with (as standard) flangless trailing wheels (IIRC an alternate set of wheels with thin flanges are available for suitably gentle curves):
and looks much the better for it. No vast yawning air gap where the firebed ought to be.
The new Britannia looks like it's done the same way. The absence of (over-scale :) flanges on the trailing wheels in the new 'un
seems a great advance on the pivotting truck and huge 'orrible air gap of the old 'un:
Um. The Tri-ang Princesses had a pivotting rear truck (and 'uge, 'orrible air gap), so you could say they're finally breaking away from that.
Well, the curves on most model layouts would be strictly for short- wheelbase engines, if translated to 12"/' practice. Your main goods engine would probably have to be something like:
- although I find it hard to see a down-side to that :)

To be honest, I so rarely look at a model at such a direct side-on view that I'd never noticed, and certainly therefore never been bothered by, the gap... Bearing in mind I've not heard or read any complaints about it before, I wonder is it such an issue amongst modellers that it isn't right? Or is this the result of the collector community that rarely runs but frequently looks at locomotives starting to influence model design?
Ian J.

"Ian J." wrote
Having seen some of the junk which is collected I can't believe that market is a factor, but I have to say that I much prefer the A3 & A4 models with the fixed Cartazzi truck, and am happy to sacrifice the flanges on the associated wheelsets for something which looks significantly more prototypical.
John.

Just a thought - I'm neither into OO nor the LNER, but does the combination of outside frame/bearing for the real thing's rear truck, and the narrower gauge leave room for hiding a cheat behind? Like an actual pony truck with limited travel behind cosmetic outside bearings?

"Christopher A. Lee" wrote
Bachmann have managed just such an arrangement with their Peppercorn A1 model. Both that and Hornby's arrangement are perfectly acceptable to me.
John.

Thanks.

There is no need for the vast gaps Tri-ang Rovex left between truck frame and mainframe on a _model_ locomotive. They made allowance for minimum radius track traversing floor rugs, books and the like. With reasonably laid track there is no need for more than about a millimeter of upward movement of the truck. If the model is designed as an 0-4-0 or 0-6-0 (with attached wagons masquerading as bogies) then considerable sideways movement of the truck is required as the entire loco will swing a long way, but if the bogies and trucks are properly designed to guide the loco then very little sideplay is required, particularly if that sideplay is divided amongst all the relevant axles.
As a verification, measure your loco wheelbase from the center of the front bogie to the rear truck axle. Place your rule along a section of snap track with the "0" and wheelbase length against one rail and then with a second rule measure the offset of the rail at the maximum. Half that measurement is the greatest sideplay required of the truck. (in each of both directions)
I bet it's a much smaller distance than you imagine!
Regards, Greg.P.