Accucraft NGG16 issues

[JMORG]

Hi guys,
Has anyone come across an issue where the rear unit is sticking?
It makes a very loud knocking noise when it does move aswell BUT I can't find anything fouling the motion or anything.
TonyW you are needed!

[TonyW]

Errr... no.

Sticking, as in the wheels don't go round? If so, is it just a general reluctance to turn, or is there one place where they stop every time?

And if the latter, does it stop at the same place when the wheels are rotated by hand? And do they stop in forwards and backwards rotation? And fwds and back gear?

Mine has yet to have its first run this year. I fitted it with a pair of Barley Pit bullet burners over the winter, specially made for me by Matt as they are much larger than the standard Accucraft burner. Should be interesting...!

[JMORG]

It's a general reluctance to run in both directions, and it isn't in a specific place either.
The loco probably needs a rebuild now because the various mods that have been done are still not enough to make the d*mn thing run like a 3 and a half grand loco should!

[TonyW]

Remind me... is it Batch 1/2 or Batch 3?

[JMORG]

It's batch 2, but the steam lines were modified to the batch 3 design early on

[TonyW]

Ah, OK, so the rear engine doesn't have any superheat. There are two modifications I have done to improve the running of mine. First was to replace the exhaust pipework with larger diameter tube and throw away the exhaust pipe in the smokebox. The second was to rearrange the lubricator pipework, from this:

to this:

The change has finally given the rear engine the lubrication it was needing and it improved power and speed hugely.

[Palmerston]

IIRC one of the rear unit crosshead hits the guidingbar, hence the noise. The pistonrod can be moved up and down. The motion is somewhat jerky. Seems the piston is undersize? My loco is still in bits. Batch 1

[TonyW]

Mine had its first run of the year on Sunday ... and what a transformation! The new burners were, I feel, the final missing pieces of a long and complex jigsaw of upgrades and improvements. It now generates enough steam to do the job without having the burners turned up so high they deafen neighbours in the next street. Extended run time, nice and quiet, loads of steam (runs on the mark, safety lifts when it stops - it has never done that before) gave me the best run this loco has ever had. Here it is romping along with 48 axles on the back...

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