34theletterbetweenB&D

Strictly, that is an invalid statement. No one has the data to support it, because this is a relatively new alloy. On the evidence to date it appears to be stable for the upper end of a human lifetime, (which to my mind is good enough for the classes of goods made using it) but that's no guarantee of permanently free from degradation.

Not really, it was retired when the Bachmann 9F became available and is now with a friend, and outside the UK.

Usually there is sufficient of the factory grease to tack the driveshft in place to ease reassembly. Without this assistance my arthiritic fingers would be in trouble.

There's a long term pattern of model railway production migration to the next low cost location. No reason to believe China will be any different, it's not if, but when.

I would gently suggest that the engineering challenge of such a mechanism is making the inadvisable into a working proposition. It was very noticeable that diesels with a pair of worm drive bogies for improved traction, wore out far more rapidly than a pair of spur gear drives used in the same way. And those paired worm drives were not directly mechanically coupled... The Bachmann 9F is a proven workhorse as your benchmark. My small fleet is coming up 18 years in service, carrying extra lead ballast, and totally trouble free, will exert 85g force, which was required for a reliable restart with a total 3kg train entirely on a 1 in 80 rising gradient. (I have now revised the gradient to 1 in 160, so nothing like this force is required, but have yet to remove the added ballast on these and other locos, since they are all performing without complaint.)

This was one of Bachmann's products from their initial probe into the UK OO market. The mechanism is a low cost construction with numerous weaknesses, well documented by a good many postings here and elsewhere. That said, the lighter locos - of which this is one - do tend to greater longevity. I'd suggest not going overboard on it, just a decoder to make it a runner, with the proviso that first you open it up to make the modifications essential to isolate the the motor terminals completely from both chassis halves. It is not necessary to take the outside rods off the coupled wheelsets, just take the glued on cylinders off the chassis block stubs and then drop the complete assembly out once the keeper plate has been removed. What you will find inside is hard to predict, it may all be in good condition, or alternatively the many essential plastic components that provide the isolating function between the chassis halves may be failing. And test and test again on reassembly to be certain that both motor conections are fully isolated from the chassis halves I successfuly converted a good number of the LNE group models to DCC about 20 years ago, and they lasted four to six years in intensive operation, with much swapping of any parts with life left in them until I had worn through the plating on all the wheelsets; one exception, a particularly good early A4 mechanism with much heavier plating that still runs, long ago fitted with a Hornby A3 body, that mechanism and body combo is now coming up 30 years old. The motors in all these were good, they appear 'unburstable', and I also salvaged bodies, bogie and trucks, etc. for repurposing, so not a total loss.

Pourquoi? Just in case it is relevant, when I wanted a 9F with real loco traction for outdoor use, I lobbed an Airfix GMR motor from an N2 (five pole job clearly based on the MW 005 motor design) into an early Hornby push along 9F chassis, that had a chassis block with the shaped section to allow an XO4 to drive on the unflanged wheelset. That combination would still slip the wheels when made up to 800g and held back on the track. And after some years very effective service - neither trainload, nor rain, nor adverse gradient, nor headwind, or any combination of same, ever stopped a train it was hauling - it hurled itself off the track. Two wheels had slipped on the axles and the coupling rods were very bent. There would appear to be a limit to how much torque RTR OO friction fit driven wheels will stand, if worked hard for long enough. (The motor and driveline to the axle were all absolutely fine and the mechanism had all damaged parts replaced, it now lives indoors with a regular plastic body and has given no trouble since.)

Also possible, one of the plastic couplers = 'drivecup' that the dogbone ='driveshaft' engages, is slipping, or alternatively a gear in the drive train is either missing, or out of alignment sufficiently that it isn't engaging the gears either side. The driveshaft not present or properly engaged is most likely, exactly as Darius suggests. The items in quotes are Bachmann's terms, and you will find them in the attached spares list. https://Bachmann-spares.co.uk/category/1-branchline-diesel-parts/class108dmu/chassis?page=1&sortby=5&numper=100

The Gresley and Thompson types available from Hornby were secondary service stock; rather than inner suburban stock for which at the southern end of the LNER there were articulated high capacity sets, see below*. Otherwise it is kits at present, other than the dated BR mk1s from Bachmann. Coming soon: *The very very exciting announcement of (GNR/LNER) Quad Arts from Ellis Clark. BR mk1s, from Accurascale, with the very necessary lav compo in addition to BS and S.

Story of my life, two, each in their own way desireable, present themselves. Happily there's no law against bigamy in model railway.

Bought the very lovely Hornby P2 as no 2003 'Lord President', and had it all in pieces after test running was complete, decoder now in Loco, tender wiper pick ups removed, etc.. It's way cheaper than a self build model would be. Does that answer the question? (Overall I rate it very good.) The main motivation was assessing the mechanism for a future project acquisition. Gresley would so have advanced to a 4-8-4 had he been spared...

This culture doesn't trouble me: before there was RTR OO worth purchasing as a model, everything had to be built by DIY using kit components. Now we get fully assembled kits, and happily an increasing proportion of these fully deserve the 'RTR' label: Joy unbounded, I don't have to run the loco, carriage and wagon works, more time for my real interest in timetable operation. But all models that come my way get taken apart to some extent, because improvements and adjustments can be made. Hornby's product typically gets the most extensive treatment, because among the current brands it has the largest content of toytrainium in its offerings, which can be discarded: first to go are wiper pick ups on tender wheels. (They are only fitted to try to help the loco get over the dreadful design set track pointwork, completely unnecessary on a live crossing layout.) And there's much more besides. As far as I am concerned, now that it is generally recognised that scale dimensions and appearance - insofar as that is possible within the necessary OO compromise for UK subject matter - all is generally well. The minor problems and deficiencies can be quickly fixed: HURRAH! Once there's a plain and simple Hornby Black 5 in BR late crest on sale, it'll be in pieces on my bench the moment it's completed infant mortality acceptance testing. Yes, they can in their RTR HO product, which is made to a long time well developed standard, with an extensive range of toytrainium input and performs impressively. And it is so marvellous that 'modellers that can' adopt P87 to get rid of the toytrainium and have true scale models, which - surprise! - won't get around the minimum radius HO set track curves. There's little point in making comparisons between RTR HO and RTR OO, which developed on very different paths reflecting aspects of national character, there ordnung, here gung-ho; the chance of any future convergence is so small as to be ignored...

No external added frames visible on my PC screen. original condition in this respect.

That's better, edging closer to an 'ordinary' unnamed BR late crest version, minus doodads and promotional polished metal work, all ready to be reliveried in LMR standard filth.

Not been aware of any DCC fitted mk1s from Bachmann. What these have is the pick up system on the axle pinpoints, which I think was first seen on the mk1 based Met-Camm Pullman cars, and MU carriages, and performs well both in respect of pick up and free rolling performance; at last displacing the Trix Commonwealth bogie from its position as the most free running RTR OO item. Welcome additions to the mk1 range which further increases the lead of the reigning champion in number of vehicle variations covered from a standard format design.