Weekend Rails

what we do for our kids

Of pumps and manpower

13th May 2012

Back in the 80s, when I was working at Thomas Hills, we had an ultimately unsuccessful deal with the Illinois-based Varlen Locomotive Corporation which brought me into contact with real live Americans. "Kojak" - with Telly Savalas playing the lollipop-sucking detective - was on our TVs at the time and several of our visitors fitted the mould. More than once they would take off their jackets and over their waistcoats I expected to find a leather shoulder-hoster. I learned a few new phrases - "Can we sue?" was one that stuck in my mind perhaps because it came from one of the (I thought) more level-headed of our Transatlantic colleagues.

But "Fancy footwork" - denoting some slick contractual dodge or rapid action - was another. And we had some fancy footwork this week. Our first assumption was that we had a problem with the oil pump on D2128's engine, so after getting a typical reaction from Cummins Diesel ("Can't help you, all we'd do is pack it off to Diesel Recon in Glasgow") it was handed over to a sub-dealers in Chesterfield who agreed to check it out. Andrew spent some time on the phone with Cummins Customer Assistance and gradually uncovered the story that this engine is one of a particular rare sub-type of the long-standing 855 series, being in that period where Cummins had a policy of high oil pressures and in this case "FFC" - full flow cooling. After a few years, it must have become apparent that running at such high pressures tended to scour the white metal off the bearings, so they dropped their working pressures progressively until the later N14 engines were positively Rolls-Roycian. Oh yeah, if you ask the minimum oil pressure for a Rolls C6 or C8, you'd be told "any, provided it has some" and we would often adjust safety switches down to as little as 5psi if it kept the engine working.

But to return to D2128. The oil pump was given a clean bill of health and returned to us on Thursday. Andrew slipped over to Scunthorpe that evening and concluded that our fuel leak had been from a fitting immediately above the fuel stop solenoid, but inevitably when he attempted to release the parts concerned, the fuel pipe thence to the 'heads promptly sheared. As it was a flared end type fitting, we had to source tube and a suitable flare end tool on Friday. Meanwhile Cummins Customer Assistance produced information showing that the oil pressure relief valve was on the other side of the engine, next to the oil cooler. We also had evolved a Plan C, namely a 4.5 bar safety valve arrangement to dump oil from pump back to sump.

By Friday night we were reasonably confident that D2128 had a chance of running and headed over to Scunthorpe for a late night session. While Andrew refitted the fuel pump, I traced and fixed a minor wiring fault on the panel and after we had manufactured a replacement fuel pipe (which our special Flare end tool set struggled to form) we went for a crank.

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The oil pressure of course was pretty much as before, but we had barely cranked when Andrew realised that the point from which fuel had emanated was not the fitting we'd replaced but around the stop solenoid itself. Andrew removed it and found that somehow a sealing O ring was completely missing - the fitting, fuel pipe and flare tool had all been an unnecessary expense.. We gave up and came home.

Saturday morning we headed back with O ring set and sealed it up. I tried Plan C but found that the two possible places Andrew had identified to tap into the oil pressure were either an odd-ball thread or without sufficient space to put the hydraulic pipe fittings. Having opened up the genuine oil pressure relief valve we took out the spring and cranked it without ( we got 1 bar oil pressure but thought that was going a little too far!) we found a suitably sized, thick washer and placed it under the head of the relief valve and thus, with spring eased, it cranked at about 5 bar and as the engine idled, touched about 9. Still high (we'll sort out a replacement spring in due course to relieve at about 6 bar) it was at least tolerable, and as the systems filled we concentrated on dealing with numerous oil leaks, which, of course are all blamed on me. After a quick lunch, and with the loco outside, we borrowed the gas and heated all the remaining door hinges whose pins were still stuck in them, after which I refitted all the remaining doors, and with converter pressures registering and air sufficient to work the brakes, we carefully engaged a gear and - nothing

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The powershift in D2128 came out of a Hunslet loco supplied to BAOR in 1984. In all 5 locos were built - described privately to me by an MoD official as the "most unreliable locomotives the Army ever bought" - they returned to the UK, 14 years old with mileages ranging from 1300 to 6000. Subsequently the Army wrote off the locos but recovered the transmissions, later changing their mind and tendering them. Andrew bought two, and this is the first we've fitted. Although we have a working knowledge of the original BAOR locos and the Twin Disc converter at the heart of them, troubleshooting a petulant powershift was something else and the manual was at home. In the end, after doing the basic checks, we conceded that we could not work a train that day but instead, the loco was worked up to the station for the assembled multitudes to photograph, towed by Yorkshire 0-6-0DE "Arnold Machin", which, as the next train loco, duly dropped in front of the incoming train with D2128 as "pilot" to propel it back to the shed. As the turnout into the shed area was on a downhill grade, they reasoned, we could detach and roll forward into the siding and the train proceed on its way.

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As we reached the turnout, the second train (brake vans) was returning and held nearby until our train had cleared the junction. We uncoupled, but being not to sure how free-running D2128 might be, I and Toby dropped off the footplate and assisted by pushing from behind. If that doesn't end up on you-tube in a few days I shall be very surprised

The train proceeded on its way, while we waited for a light loco to appear and push us back to shed. But "Arnie" had failed half a mile or so way, and things became a trifle chaotic as locos were swapped. Eventually both D2128 and "Arnie" were back on shed, and out of curiosity Andrew went over and asked what the problem with "Arnie" was. After all its engine was running, and having been told that it just "stopped driving" proceeded to check and rectify a defective Pilot circuit fuse and restore "Arnie" to action. If only D2128 could be fixed as easily.

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We reappeared at Scunthorpe on Sunday having detoured via Rowsley to collect a few bits. I made up a short hose and sorted out fittings while Andrew dealt with some (more) leaks, after which we fired up the engine and watched the servo base pressure. According to the manual, this should be in the range 50 to 85 psi, but we were barely scraping 25. ( I apologise to any technical people reading this for my jumping between psi and bars, when some standards agency has declared that we should henceforward all measure pressure in something called mini fruit pastilles [mP] - I am just too old to think in another measurement system having been brought up on farthings and Fahrenheit).

I will not bore the non-technical amongst you with a full blow-by-blow of the day. Suffice it to say that we stripped, cleaned and checked various spool valves, pistons, springs and all manner of pieces that (should) control the powershift but to no avail. We did succeed, with a couple of washers, in raising the servo pressure from 25 to 75, but this had no effect. Our best guess at this moment, is that the solenoid operated valve (which causes the "dump" spool valve to close and thus raise the servo pressure sufficiently to engage the clutches) isn't working, but proving this is rather harder as there are no test points or external bits to observe.

So our sincerest apologies to all those who expected to see D2128 in operation, and by that we do not include it being pushed along by yours truly! We tried and tried to sort out every problem as we encountered it, but had to admit defeat. We do at least, have a working engine that sounds good and should serve us well, once the powershift problem has been solved.


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