Member postings for David Bothwell 1

My locomotive is a piston valved (two and a half inch Pacific) I have had it running (and not) on various sessions, I think the locknuts somehow moved and caused problems. At present the loco is running ( in full forward gear) but only for a short burst and petering out in a sluggish way. Could this be caused by uneven opening of the valves? Any suggestion gratefully accepted!

Thanks Jeff and mr Hancock, loco has been running but due to return crank movement it has stopped, revolves about 260 degrees"

Please excuse this question in advance! I would like to know if Walschaerts valve gear (on a locomotive model) is self starting, or to put it another way should the loco start from any position (of the valve gear)? I presume it does on full size, Mine won't!!

Of course you are correct Mike, I have looked at the conversion chart and there is a difference between 7b.a. and the "metric" equivalent. thanks for the replies most useful.

Thanks for the replies, I will try the solution in the morning! The nut goes down he thread but there is no tightening up I am fairly sure this is because the bolt is a metric thread and the nut is B.A.. at least I think this is the problem

Came across this problem while re-fitting new return crank, I used a cap head screw (2.5 m.m.) and steel nut, but it will not tighten, just wondering if anyone has a suggestion? Possibly incompatible nut (7ba.) I have copied the original part( and consulted the drawings) but the original builder decided to make a split and fit a nut and bolt to grip it to the shaft. I did have the engine running with this method, but the return crank "moved" (engine would not go!) any suggestion gratefully received. Also is there a "fool-proof" way of setting the return crank in the right position in respect to other parts of the motion? Thanks in anticipation!

Argh! Put the wheel back on and I still cannot get it to turn over! I will no re-measure everything, but most frustrating!

Thanks Mick, already took that route, did not fancy heating it all up. It is Poundshop superglue, but I intend o drill the crankpin hole in gradual steps, see how it goes!

Just an "update" Today I removed the drive wheel and drilled out the crankpin hole. I thought I was being clever mak ing a cast iron insert and pressed this in position. When I very carefully measured and drilled for a new pin it dragged the insert out Yuk. I have now inserted a threaded steel insert with a fair amount of superglue. That is the current position. The thread is a seven sixteenths whitworth! The obvious thing to do here would be to silver solder this assembly?

Hello Mick,

Many thanks for the reply to my problem. The gauge of the loco is two and a half inch. Or is it also known as gauge 3? . I know I bought the drawings for it from the two and a half inch gauge society. To clarify it is a New Zealand loco called Pashendaele, of which there is loads of info on the net. I have nearly got the motion moving again. I seem to recall that I had a similar problem a while back and the solution you suggested at the end of your reply did the trick. I have just noticed this morning that the six drive wheels are pinned between the axle and wheel, but when I drilled out the hole (for the crankpin) in the centre drive wheel there was a"jar" as the drill got "stuck" I do appreciate the time you have (all) taken to help me and I am now confident I can solve it. I bought, or rather "swapped" the engine as I quite liked the appearance. It is definitely well constructed and I was a bit wary of spoiling it!

Hello Mick,

Sorry for the delay, the engine is a 4-6-2 "Pacific" of New Zealand origin. Unfortunately though I have drilled the webs with small holes I somehow made a mess of one. I then removed the crankpin and made another one ( complete with hole) When drilling the hole for the new pin something moved. and after replacing the maincon rod it is tight and I cannot get the wheels to turnover!. Thanks Howard for your reply!

Hello Jeff, Many thanks for the reply, I had considered this but was reluctant to drill the crankpin, but at worst if it is in the wrong place I can always make another

I have been working to complete a small model loco (with Walschaerts valve gear) although I have had the loco running a couple of times. Whenever I have tried again it would not move ( well it span round threequarters of a revolution. I have narrowed the problem down to movement in the return crankl, which is moving. It has a slit and hole for a bolt and nut, but although I have tried it is not tightening ( possibly the small size of bolts and nuts.Tried holding with a toolmakers clamp and the tightening the nut to no effect. Any useful suggestion gratefully received. Just seen on Youtube return crank with the slit runninguo the centre of the crank.He was able to move the return crank by hand?

My thanks to John (and Nigel) for their replies. I will give both suggestions a go sometime this week, still got "sticky" motion to deal with!

Phew! Thanks for that Nigel, quite a lot for me to take in. On the drawing of the loco (side view) it shows a pipe from the pump that is attached to the dome and looks like an "exhaust". I will definitely try all the things you said. Also on that side view it looks like two outlets are piped together.

I have recently acquired a two and a half inch gauge model with a working donkey pump (over/under cylinders) I stripped the pump down and fitted o rings to the piston(s) but I do not know how the pump is supposed to work. There are two pipe inlets but on the drawing it states one to air tank, but having connected an pipe and turned the compressed air on nothing happened. Any assistance most gratefully received!

My sincere thanks to everybody who took the trouble to respond to my problem, I think the problem is solved. To be perfectly honest the engine has "grown" to such a size I think it is going to a new home, more like a small three inch engine and I would say almost impossible for one person to lift and from the point of view not very practical

Thanks Bri, I originally had nitrile balls in the pump (until I bought some stainless ones) the pump does move water away from the engine, i.e. when dunked in a shallow container, it had me thinking it is the pipe work from the tender tank, so I sucked a bit through, also primed it with the plunger at top of the stroke. (without any joy!))

Hi Jason,

The bypass is not connected as this would put water into the boiler, which is not at present required

Hi Brian,

Never thought of that, perhaps they need "seating"? bUt as I said it does work when not on the engine?