Weekend Rails

what we do for our kids

Of floors and filters

21st July 2013

No sooner had I pressed the publish button on last week's blog than my phone rang. It was Ben Riley letting me know that the pieces of hardwood I'd passed him had now been transformed into the subframe for the Drewry's cab floor. I popped down one evening with Andrew to take a look, and sure enough the necessary longitudinals, cross-members and uprights were present and correct. Andrew did some painting on Libby's casing parts.

But as he has been away again for the latter half of the week, when it came to Saturday I was actually on my own and decided to make a start on the Drewry, after all, it is due to take part in the "Warring 40s" event not many weeks hence.. Amongst the arrivals from the last auction were M6 x 55 bolts and a number of right-angle brackets of indeterminate purpose. I hunted them out from the container and having run out the 110V supply to the Drewry, started drilling and clamping the whole lot together. Ben still had two loose battens that bolt to the battery box. He brought these up to me after a while and I had some M8's to secure them, but had to take one back for some minor amendments which, with the tools of the LMSCA at his disposal, took less time to alter than for me to walk down with them. By 6pm I had them in place, all bolted up and the old lifting panel roughly in place to give myself a slightly more practical work surface. I had also cut and loosely positioned the first two flex conduit sections to take the starter cables from battery box to master switch.

On Sunday Andrew came home from Norfolk, passing Steph on her way down to take over looking after his partner and our grandson while the former continues recuperating from her broken wrist. Once back in Derbyshire, we headed back to the container for some pipe fittings and then up to Rowsley.

While I made a start threading the 70mm cables from battery box to master switch, Andrew set to work on "Ashdown" disconnecting the superfluous reservoir and its attendant dmu-special valves. He removed the vac isolating valve from under the cab floor and replaced it with a filter/snifter assembly, which this locomotive appeared to be lacking. Further attention will also be required in due course because we realised that the "double-check valve" (that's rail-speak: in normal compressed air speak it is a shuttle valve) is an automotive one and only 1/4" bore which will tend to slow brake response by unnecessarily restricting the 1/2" bore lines.

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It was also apparent that the proportional valve, instead of having a proper vac res to balance it, it plumbed to the suction line to the exhauster (and from which, apparently, the vac res gauge line is also connected). These are all rather inappropriate variations from normal installation but without a doubt, the lack of filter was the worst, but before we got that far, Andrew had come over and aided me threading the new cables to the starter motor through the original metal conduit before I could get the lugs on and finished.

By the time I came to join him on Ashdown, he was just squeezing the filter assembly under the cab floor, and we broke off for a cuppa. But when Andrew fired Ashdown up, apart from me confirming the sad news that the charge circuit is u/s (time for another solid state conversion) the vac barely rose to 5" and then fell away again. We felt the air delivery side of the exhauster - we couldn't quite agree but it clearly wasn't delivering properly, so couldn't be sucking.

The casing box that goes over the compressor is merely secured to the original casing door hinge points, which was fortunate as the exhauster is so far up in the air that the cylinder head cannot be removed with it in situ. We lowered the box down and while Andrew removed the cylinder head nuts I went over to the Mattersons to photograph the motor brakes. Although our set is in good condition overall, the rainwater has obviously penetrated the brake units and when the power cuts off, the motors spin down - they should stop dead. Mattersons are being very helpful, a gentleman in the Service department recognised the serial number and confirmed what we knew of their past history, plus that the set had been built new for Stanton, suggesting that it might have been installed at the Ironworks that lies between Junctions 25 and 26 of the M1 and where a fleet of Sentinel 0-6-0 and 0-4-0 DHs once worked.

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When we had disconnected the flexible suction hose from exhauster to frame piping, a small cloud of rusty dust had escaped. Without a suction filter this was scarcely a surprise. but when we lifted off the cylinder head, we had little sandcastles over the piston crowns. If you don't put a filter in the suction line, and then run the system top-n-tailing with a steam loco, this is what you can expect. The pistons cleaned up easily, but peering in the 2" ports of the 'head, everything was covered in dirt.

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For the moment at least, a replacement cylinder head was the easiest, and while Andrew cracked on with this, I went back to the Drewry and manufactured the final bits for the train brake handles. By the time I was back, Andrew was ready to run "Ashdown" and sure enough the vac came up immediately - in fact he had to tweak the snifter to bring it down to 21"!

By now the train service had finished so we boxed Ashdown back up. Its original cylinder head will be returned to it in due course, but will be a homework job to soak and sort it.

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