Weekend Rails

what we do for our kids

Of valves and coolers

20th May 2012

With the AFRPS gala behind us, for better or worse, we had said we would take a break from Scunthorpe as, with the collection spread over so many sites, spending so much time at one is liable to cause issues at another. Nevertheless, determined to get to the bottom of what was wrong, he persuaded me to head over on Tuesday night for a further bit of investigation.

You may recall in last week's entry I suggested that the likely culprit was a "dump" valve, though I should perhaps have given it its proper name of "Neutralling" valve, but first Andrew wanted to "prove" the solenoids, so with a wire dabbed to provide the pos, a screwdriver held loosely in the centre of the core would immediately swing to the side of the coil as power was applied. So we started to strip the valve assembly. Having removed the visible stem on which the coil resides, we were surprised to find a lose o-ring, which, we deduced by comparison with another valve, was supposed to be behind the next part of the valve assembly, sealing it. But there was no obvious means of extracting the valve assembly from the valve block and so we decided to remove the whole block from the transmission. First thing to come off was the cover plate, which revealed the surprising sight that the sealing joint, which has slots to allow the oil to flow, was in the wrong way round, which would certainly restrict flow but probably not inhibit it altogether. Andrew completed the removal of the assembly - a steel block about 6" square and 2 thick but with enough machined out to take on the character of a Gryere cheese - and still could see no way of extracting the Neutralling valve assembly. Meanwhile I had moved to the alternator, which had been on my "don't connect until we've finished welding jobs" list, and proved to my satisfaction that it was an earth return alternator. We don't do "earth return" on locos (not deliberately anyway) so I pulled it off with the intention of getting an alternative sorted.

The transmission valve assembly went to a specialist who confirmed that Twin Disc had a bit of a blind-spot about removing valve assemblies once fitted, or perhaps they wanted you only to buy complete new assemblies at considerable expense. We remain bemused as to what has happened to this transmission. The most likely scenario is that the loco it was in developed the fault we now have whilst in Germany, and being an unpopular machine, somebody in 275 Rly Squadron was tasked with a "sort it quickly or forget it" and inadvertently put the joint in back to front when boxing it back up. Either way, I got a phone call Thursday afternoon to say it was ready for collection, and I would have been back with Andrew Friday evening but for the fact that the alternator - supposedly being overhauled and converted from earth to insulated return - wasn't ready and there'd be no way of safely securing its drive belts. So we must contain ourselves for another week...

Saturday: Over at Rowsley "Libby" has been waiting patiently for us to get on with the various bits we are improving. We went over with the pressure washer and moved the transmission matrix outside before blasting it free of dirt. I then set about drilling out the new holes required for the mounting brackets while Andrew stripped the compressor unloader valve from the 03, which had failed to work. Our first trial of the cooler into position proved that (a) I had not quite allowed enough space when I laid out the installation in the first place and (b) the radiator is a sillimetre or two out of parallel with the running plate. Either way, it would fit if the steel side members were trimmed away a bit, so I did.

One of our auction purchases, probably over 12 months ago, was an Oxford oil-cooled welder, and although residing in the VBA at Rowsley, we had never had reason to try it out, as the MIG was always to hand. But the MIG is over at Scunthorpe, and so we had brought the sticks out from over the boiler at Briddon Towers and gave the Oxford a try. Sadly, it could not produce enough current to get a decent weld onto the thick running plates of Libby, and Andrew, whose welding course has now moved on to stick welding, was totally dissatisfied with the result, so ground the welds out and declared it must wait until the MIG returns. In fact the cooler was lifted out before I had time to get a picture...

We did though, fit the converter reservoir on its brackets in front of the fuel tank, and Andrew cleaned some more of the cab in the ex-cupboard corner. I also decided to see how much extra hosing we'll need to connect the converter to its new cooler, and having re-routed the main 1.25" bore hoses from over the engine to under, was pleasantly surprised to find that they ought to reach with a couple of swept elbows up into the cooler. Add to shopping list...

 
 

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