GWR 2721 pannier
Entry posted by Barry Ten
1,116 views
I've recently revisited an old project which I first mentioned back in 2010, a shocking seven years ago:
http://www.rmweb.co.uk/community/index.php?/blog/257/entry-2879-Hornby-2721-class-detailing/
At the time I "improved" an old Hornby 2721 class pannier by substituting a newer Hornby chassis, as well
as adding some additional brake gear detailing.
The model ran better than the original, but truth be told it still wasn't brilliant, and tended to stall on less than
perfect track. It then needed a prod to get going, despite all-wheel pickups. My guess is that the motor wasn't
that hot. It didn't get any better after I fitted a decoder, either. Eventually the decoder was pinched for another
project and the 2721 body languished, chassis-less, in the general jumble heap of locomotive bits.
Vowing to do something about it, I looked at substituting a Bachmann pannier chasis, but was dissuaded since
it seemed to require a fair of hacking to the Hornby body to make room for the mechanism, and I didn't fancy
anything too adventurous. Last year I decided to add a Comet 57xx chassis instead so the basic bits were gathered
together and finally I made a start.
At Railwells (I think) I also bought a Branchlines motor and gearbox which I was told would be a good choice
for a small 0-6-0T. The only remaining thing was to source wheels, and there I thought I had a cunning plan,
in that I had a Triang chassis which - once upon a time - had had correct diameter Romford wheels put onto it.
The wheels were duly liberated and then I ordered some crankpins as I'd run out.
Snag one was that I'd forgotten that the wheels had been modified to fit the Triang chassis, in that two of
the three pairs had had their crankpin holes drilled out to extra clearance, so that the Triang coupling rods
could be retained. That meant that the crankpins were now a loose fit, rather than a screw-in fit, and needed
to be araldited in position, carefully checking alignment as the epoxy set.
Snag two was that I'd ordered the wrong crankpins - or, by some devious twist of fate, had I? By mistake I'd
ended up with threaded crankpins with screw-in retaining bushes. I'd not used these before and was a bit
dubious. However, by not needing soldering, perhaps they were a fortuitous choice after all, as they wouldn't
risk becoming overheated and loosening the epoxy joints? After getting some advice from the loco builders
on Tony Wright's thread, I forged on anyway. The major difference, for me, was that the coupling rods needed
to be reamed out to a much larger clearance to cover the bushes. I found that tricky, and was constantly on the
point of distorting the rods. I much prefer the small clearance that's required for the usual crankpins.
However, once the rods were on, and adjusted, all was well and they look OK enough in my view - even though,
for a 2721, they should be fluted, not flush.
The Comet chassis, I should add, went together well, as did the Branchlines gearbox and motor combo, which
turns out to be pretty much exactly what I'd want for a Pannier in turns of steady, slow-speed, performance.
Oddly enough, the bearing holes in the Branchlines etch were a very sloppy fit for the supplied bearings, not
the usual tight fit which needs to be opened out. This concerned me as it seems to give a degree of hit and miss
regarding the gear mesh, but in practise it's been a lot less hassle than some of the other gearboxes I've made
over the last year or two.
The resultant loco is very happy on the bits of track that the old chassis didn't like, so I consider that a hit in terms
of getting a better performing model, which was the objective. The wheelbase is more correct, too, but that then
throws up a secondary issue in that the front splashes of the Hornby body need realigning, which I'm not quite
sure how to approach at the moment, being (as mentioned) rather reluctant to hack the body about too much.
Is it a 2721, though? The coupling rods are wrong, and the outside pull rods ought to have a crank in them
beneath each axle, presumably for reasons of clearance. I had a dodge planned to achieve this, but by the time
it came to put the brake gear on, pragmatism was winning the day and I decided to keep them as is, on the theory
that painted black, they're not going to be the first thing that catches anyone's eye.
As far as I can tell, the visually very similar 1701 class had fluted rods, so perhaps that would be a more appropriate
number series to go for - but then again, the pull rods would still be wrong! So it is what it is, for now, a representation
of the open-cabbed panniers without being all that accurate a depiction of any particular class!
(Edited - I was confusing the 2021 and 1701 class originally).
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