Sunday, 15 January 2017

Maintenance Update (bitumen, valves, snifting, coupling)

Wednesday 11th
There were hoards of us working on 2807 today! Brian, Bruce, Gilbert, John G and John T (oh, and me!) plus half-a-dozen Loco Dept Chap(ess)es, including Alex, Clive, Jeff, Tim and Peter.

Alex (nearest camera) skilfully having not painted herself and two chaps into a corner, applying bitumen paint to the coal space.

Thereafter, the rear section (with dome and filler) had to be painted, too. That was slightly trickier now that there was only one way up onto the back section! There ensued some toing-and-froing with a set of steps (that were being used to access the coal bunker of 4270 at the same time).

Brian dismantled the LHS rocking shaft, while, Gil and Peter looked on, practicing being gophers.

Apart from checking the wear, the intention is to ensure that the brass bearings clamp onto the rocking shaft with zero play. This may mean shaving a few thou’ off the casing (as we did on the RHS). All of this tightening of bearings is in anticipation of getting the valve timing spot on. It had been ‘not bad’, but slackness in various linkages makes it impossible to perfect.

John G and John T spent much of the day cleaning the piston valve heads. Getting the grot out of the grooves in the head turned out to be a challenge - one that required the use of a hacksaw blade!

Peter removed the nuts from the RHS cylinder cover in readiness for the piston to be measured for wear. However, the cover was rather reluctant to come off, so he wisely left this as a job that the Saturday gang can tackle. The cover did come off the RHS valve, though.

Bruce attacked Issue 55, and started to remove the snifting valves that are tucked away behind the
main steam pipes either side of the smokebox.

Although the nuts came off the studs fairly happily, the top of the valve unit couldn’t be lifted clear
of the base … because the cladding round the steam pipe was just getting in the way. Bruce is
indicating where a small amount of cladding will have to be cut away for easy access. The other photo is the top removed, and you can probably just see where the valve and its seat make

I fancied investigating the problem of aligning the three links (draw bars) between tender and loco,
which seem to cause other railways (notably the NYMR) a bit of a problem. First minor problem: the
team of painters in the tender! You see, I needed to part the loco and tender.

Checking that the loco wheels were chocked and the tender handbrake was on, I removed the securing pins from the links. I also put the fall plate back to cover the gap between loco and tender, foreseeing one of the dedicated team inevitably stepping backwards out of the tender and …. Aaagh!

While they were all slapping on bitumen, I decided to lift the wooden floor planks in the cab and give them a good clean. Coal dust and oil get jammed between them and underneath, too. Finally, the tender was gleaming black all over the top and the painters had adjourned. I released the handbrake and pushed the tender back a couple of feet.

Two years ago, NYMR managed to bend the RHS safety link (nearest camera) by getting the securing pin down the side of the link instead of through the hole in the end! This time, it looks as if the main (centre) draw bar must have been too low when coupling up, and hit the loco’s drag box; probably then bouncing up and into its hole. However, the bar definitely appears to have a droop!

Saturday 14th
Alistair, Brian, Bruce, David, Gil, John T plus several Loco Dept chaps were working away, mainly on the LHS valve and the rocking shaft. Alistair, John and I tackled the tender and the main draw bar.

Getting the valve rod back in place can be a challenge. It’s heavy (of course); awkward, and often
reluctant to be thrust back into its chamber. The rings on the valve heads have to be a close fit in
order to seal the steam. Persuading the rod to go into the bush at the far end requires skill plus a
pointy thing. Much waggling and pushing is required to line everything up. Hence, it took much of
the day!

Bruce had taken the snifting valves home to machine the seats and lap the valve head. He refitted
them today, and also wired up the insulation, which had previously be tied with string … which had
not lasted the course! Brian plus a couple of Loco Dept chaps gave the cladding a good clean and
tapped the bolt holes before fixing that back over the steam pipes.

David brought the tool that he has made at home ready to adjust the valve timing. He applied
yellow paint plus a clearly marked “2807” on it. We use yellow paint as a marker for our tools. He
then took measurements of the rocking shaft components that were taken apart on Wednesday,
and has taken the top cover home to machine it down a few thou’ to make a good fit. Thereafter, he
was trying to ream out some bushes in the rocking shaft arm and the intermediate valve rod that
connects to it. However, we could do with some sharp reamers!

You may have heard about a loco and tender becoming separated last year? It was apparently
caused by the large nut that secures the drag link to the tender drag box having a worn thread. The
thread stripped; the safety cotter pin behind the nut held on for a while, but eventually sheared, and
the loco and tender jolted apart, held (fortunately) by the two safety links. As a result, GWSR have
asked loco owners to inspect their nuts and check for any signs of undue wear.

Alistair and I worked on removing the main draw bar. This involved removing buckets full of coal
dust. Vis. there’s even plant life growing in it! Once the centre section was cleared, we could see
the panel that had to be lifted in order to extract the securing pin. That took a while, because it was
happy staying where it was - and I even cleaned and removed a small panel on the other side,
thinking that it was all one piece of metal that goes through … but it wasn’t! The deft use of a
screwdriver and copper mallet persuaded this small panel to lift, and we got the pin out.

Then we could remove the draw bar. By use of a standard-issue broom handle, Alistair
demonstrates how bent it turned out to be. We set up the 50 ton press. Carpo got some heat on
the go. John took over from Alistair, and we got ready to bend the bar back into shape. When it was
well and truly red hot, John inserted a lump of steel in the press and I started pumping away on the
hydraulics. Not a lot was happening! After a bit of puzzling and prodding, we discovered that the
little valve that releases hydraulic pressure had stripped its thread, and was not sealing the fluid.
Hence, I was doing nothing but pumping fluid round in a circle! Activity aborted. Hydraulic press
needs mending.

With part of the tender coal space floor removed, you can get to the nut. Well, you could after the
removal of three buckets full of coal dust, slack and grime! There was up to three inches of grot
lying on top of the vacuum cylinder. This is now a tad cleaner and we can inspect the nut next

On the bright side, I purloined a handful of coal dust/slack, and with skilled use of two sieves I now
have a goodly pile of 00 scale sized coal for my two-year old grandson’s model railway (that I’m
building in my spare bedroom).


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