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> Hornby Valve gear, another one goes pop
kristopher1805
post 5 Jan 2011, 15:56
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Sorry to report but Bunsen a nice weathered Hornby rebuilt Patriot has had a failure of the valve gear, well really the pin that holds the centre coupling rod and con rod has failed, it fell out last night. Tricky to get back but I cannot pick up the flat sides for the piston valve motion, so it don't go at all well.

One of my 9F's had a pin fall out of the last coupled wheel so that is out of action too.

I have had failures on a King Arthur and Evening Star too.

The pin is a tiny effort one assumes because of realism of the scale, the Arthur was the sector retaining pin, anyone else have these experiences and or fixes?

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34C
post 5 Jan 2011, 16:16
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I loco motorised a couple of Tender drive 9Fs some years ago, and the gear failed pretty regularly under the imposed load after a few years, despite careful lubrication. The motion brackets pulled off the plastic crossbar that holds them to the chassis (3 out of 4) , and the rivets holding on the end rods sheared (5 out of 8). Now, no complaints on my part, because I had modified them. But if Hornby have used the old push along model gear unchanged on the Railroad loco drive model, then about now I would expect enthusiastic operators from the first buyers to be wearing them out...

Fixes for rod pins, I form a rivet from annealed copper wire stripped out of old twin and earth wiring. Very easy to do, lasts several years, is softer than the rod so you don't wear that away...

If a screw on big end crankpin has fallen out of a loco with outside Walschaerts gear, as on your Bunsen, that means the return crank was rotating relative to the crankpin to undo the screw, so the locator in the return crank that should lock it to the crankpin is shot. Had the return crank fail on various Hornby, best to make a new one from a piece of brass or nickel silver sheet. Needs a small flat Swiss file to cut the slot that locks the return crank on the crankpin. Make it in slightly heavier gauge than Hornby use and it will survive much better.

I should add that I really enjoy doing this stuff, the occasional failure out on the line when running a timetable operation is just so realistic. The cripple has to come off the train, and alternative power has to be dredged up. Then the cripple is off the roster while being repaired, which usually means that the next booked turn or two has to be allocated to something not normally seen on that service.
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dwhite4dcc
post 5 Jan 2011, 16:36
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Yes. It is a fairly coarse thread bolt. Most dealers tighten them with a small spanner which is a hex hole set in an ali bar. you cannot really tighten these with pliers as you damage the head and don't tighten it enough. All the Hornby OO stuff seems to use these bolts and all are the same size but I have a feeling that it is BA rather than metric so doesn't fit any of the commercial nut spinners and is too tiny for most model spanner sets.

It always undoes on the left side as going forwards unscrews it.

Once my MN undid only slightly and released the flats of the valve gear rocker. Eventually the whole lot tangled up and snapped. New valve gear fitted.

My Q1 actually lost the screw in the ballast on a running session. A magnet found it. No problems once I realised what was happening and got my dealer to tighten them up.


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Coldgunner
post 5 Jan 2011, 16:52
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The materials for the rods don't seem strong enough, when I have time I might try replace what I can with older more robust ones. I had a brand new Hornby 9F completely buckle on me last week, which was a new model (touch wood the replacement seems fine).


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34C
post 5 Jan 2011, 17:26
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A 2.5mm across flats nut spinner will do the job. On the Expo version of this tool I ground the front taper down so there is minimal lead into the Hex section, so that it will tighten the crankpins enough with no risk of rounding off the head. This tool is generally applicable to almost all the Bachmann and Hornby crankpin equipped locos. Exceptions of which I am aware are the Hornby class 08 (2mm) and Bachmann ROD/O4 which needs 3mm for the big end crankpin only, remaining crankpins standard.
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Simon Smith
post 5 Jan 2011, 17:39
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I got my nut spinner from Eileens Emporium at the Uckfield show. Works a treat. smile.gif
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kristopher1805
post 5 Jan 2011, 20:23
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Hmm well thanks, see what I can do? My failures have all been on the right side of the loco which seems odd, yes I have had buckling valve gear but I have not counted what I can fix, had a lovely jam on a Bachmann B1 a few days back, a perfect locking system.

Hornby are good on warranty but I am here in Oman not Margate so it's a long way to send a loco, postage costs more than the loco, however there are lots of Indian silversmiths and goldsmiths so could see if I can get parts made, Omanis simply do not understand railways and have no idea about model ones but Indians do like their trains.

Meanwhile must be costing Hornby a packet with all these valve gear warranty failures, wonder they do not make the a bit stronger, just maetallurgy not rocket science. I got really very little running out of these failing locos, such high failure rates just a shame.
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34C
post 6 Jan 2011, 10:01
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Perhaps not costing quite as much as you might think. What is the operational life of the typical loco? I believe for many purchases it will be the test run in the shop or on arrival at home - it could well be that much of what is purchased never really turns a wheel - even those that are used don't typically pound up the mileage. It is relatively rare on the various forums to read of people experiencing the wear out failures you have experienced. Yet they do happen if you run the models, even with careful lubrication...

I was thinking about this is in another context quite recently, regarding s/h purchases, many bought unseen. Again and again the mechanisms show no evidence of wear. I get through the wheel plating to the brass beneath on Hornby locos within a month or three of their arrival on the layout, and there are polished tyres and wiper tracks on all wheels, contact witness marks on outside rods, etc etc. on all my loco stock.

As for reliability in service, my experience in OO is that the Bachmann designs since the 'Blue Riband' introduction are very good indeed, essentially trouble free once any minor assembly niggles are sorted out to optimise the mechanism. Item 1, pick up wiper contact... It far outpaces Hornby's comparable product which has a tendency to break parts and other troubles which relate to the mechanism designs. The notable exception among my Hornby purchases has been the Britannia; so far 'bombproof'. Of recent purchases that have not yet done enough mileage for assessment, the Castle looks similarly good, and also the L1 basic mechanism; although on this model I am dubious of the longevity of the expansion link mounting, but can see an easy fix. Hopefully the B17 and B1 will be in the same mould as the Brit and Castle.
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kristopher1805
post 6 Jan 2011, 13:39
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Father (84) says that the L1 is 'tishy' this is a problem with Hornby, the whole lot bends easily and is hard to get back straight, Hornby is generally a good product, Bachmann falls into possibly 3 camps
Old Mainline stuff which need updated chassis, weak everywhere
Early Bachmann Ok but not brilliant
Later items = much better

As for Ebay/secondhand really I have gone off this idea,
1. Ebay make it difficult once 1,700 in purchases have been passed, they want money up front and caused all sorts of problems.
2. You never know what you get, often bodged up jobs, reversed polarities, bitsas, non standard parts all sorts.
3. The life I get from them varies greatly
4. You need a spares bag.

So now I buy new helped by ex pat salary but I expect a high failure rate and being here it is hard to claim warranty.

New locos out of action
Hornby 4MT a Hattons bargain at 69.99 but duff after 3 months, possibly the decoder socket~?
Bachmann 5MT has meshing issues
Hornby Bunsen Rbt Patriot coupling rod pin failure
Hornby 9F coupling pin failure
Bachmann Royal Scot the Rangers, will not run (hardly)
Bachmann Ivatt 4MT mucky duck, - been back twice, no one can fix it

there are more, some of the older locos are part worn out, I rewired a tender drive 9F, my tender drive Evening Star has had the valve gear fall apart, one of my tender drive black 5's has packed up for no known reason, several indestructable Wrenn locos are running erratic (8F x 2, Rbt West Country)

My layout/track has never been better, some locos that used to be trouble now run smoothly, just wear I suppose and as you say you can see signs of wear, I get coupling rods worn through. Mind I have a few Bachmann coaches which are very stiff and make the locos work so I have pulled them.

As you say many locos are never unboxed, get very little running, I wonder if Bachmann and Hornby want a destruction tester?
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