Model Railway Forum

Again, not sure whether this really qualifies as a review, but here goes.

Santa was very generous to me last Christmas, in the form of a Bachmann SR class H2 4-4-2. The paintwork and detailing on this model are truly superb: clean, fine and properly aligned. Under test the engine ran very quietly and evenly at all speeds and pulled away very smoothly from a stop. (Controller: Codar TEC-88). There was no trace of wheelslip when pulling a test train of four Rivarossi American coaches and three Fleischmann Bavarian wagons, none of which can hold a candle to the new Bachmann ex-SECR coaches for free running, but it's still not much of a load, so it was clear I'd have to reserve judgement on that for the time being. Current collection is very reliable, thanks to pickups on driving, trailing and tender wheels. After that quick test spin on Boxing Day, back into the box she went. Couldn't wait to put her on the new coaches.

It was only when the loco was set back on the track last week (to show her off) that I noticed a very serious (to my mind) - error, for want of a better word. To put it simply, the piston rods don't point to the centre of the driving wheels because the cylinders are not inclined steeply enough. I've admittedly not studied the instructions to see how she comes to bits but I can hardly imagine that the matter can be resolved by tinkering. And in any case, she's new and under guarantee and that would be straight out of the window if I started digging about. I'd hate to have to send her back with Brexit looming.

I would be interested to hear other members' views and experiences with this loco.

Pix on flickr: https://www.flickr.com/photos/53775591@ ... 9646275268

Cheers,
Artur

Brexit should have no bearing on this. At present goods from China (and non-EU) pay duty on arrival in the UK. At present nothing will change until we leave the EU. As things stand no-one knows what will happen.

I cant see a problem with the loco, what makes you think there is a problem.

So I'd have to hurry a bit, Postman, being based in Germany. The worst-case scenario at the mo is that I'd only have till the 14th. I'll call the shop first.

The problem is not a technical one, Brian, but an optical one. The blue line on the photos highlights this. The cylinders are not lined up with the second driving axle, which looks weird, a bit like a clockwork jobbie from the 1920s (or TriAng's first Black Five). Sorry, but Bachmann has boobed. Had I noticed this before I wouldn't have chosen the loco in the first place. I know, caveat emptor instead of blind faith.

Compared to online pics of the real thing it looks fine to me.

Are cylinders always lined up as such?

Looks near enough correct to me, compare with
https://www.railadvent.co.uk/2017/12/th ... ation.html

On the real thing the cylinders are inclined the tiniest amount and to me the model looks fine.

Actually, to be honest, Wtd, in answer to your first question there are rare exceptions. Some of Churchward's locos, for example, had the cylinder centre line slightly above that of the axles for reasons of loading gauge and because he didn't like inclined cylinders (wish I could remember where I read that). But the line of the piston rod was still parallel to that through the axle centres.

Basically, though, the piston must share its centre line with that of the axle carrying the big end crankpin. Or, to put it another way, at back dead centre the centre line of the connecting rod must pass precisely through the centre point of the axle. Otherwise the driving forces will be lopsided. On the Bachmann Brighton Atlantic the two lines diverge from each other, spreading toward the rear. I attach an image I found of H2 running gear that I augmented to show the straight line from the piston rod to the centre of the driving axle. If I infringe copyright with this please let me know and I'll take it down again immediately. Also, on the prototype the slidebars are clearly at a larger angle to the running plate than they are on the model. I say again, the cylinders on the model are not inclined steeply enough. Please compare the two photos. It's a great shame, this fine model spoiled by this one bad detail.

I also saw the photo you mentioned, Mike, but I decided on the full side view. Both were on Google.

Cheers,
Artur

I see and understand what you are saying. I noticed that on some of the pictures on line of the model, the cylinders are angled slightly more, but not on others.