Of -not another- birthday

11th October 2020

Maybe this is just lockdown-blues...

Another brief instalment this week: as I mentioned last week today is/was my birthday (depends on when you're reading this). Birthdays start being so important when you're young. Twelve months is a criteria by which your progress to adulthood is measured. 'By age X your child should be...' go the manuals and with it a list of accomplishments. As a parent you go through this list and agonise whether your child is in some way retarded if it hasn't ticked off all the list or bask in self-congratulatory smugness if you spot one on the next year's list that your little cherub has already got under his or her belt. But when you get to a certain age: well, the novelty wears off, and far from marking progress towards some worthwhile goal, you start recognising that your summit was somewhere back there. You may conclude that I am not a particular fan of birthdays, and the family goes along with that

It has though, been a busy week. I seem to have been almost commuting into Sheffield and Rotherham dropping off and collecting components. In fact one day I had to go over to Manchester (take a deep breath before entering the city and try not to take another until you leave) and back to Sheffield to pick up bits at the powder coaters. Andrew too has been busy, from inspecting emu's coming up for hand-over, to courses on re-railing troublesome trains, and skating stuck ones - all suitably distanced of course.

Once again work has been concentrating on commercial jobs: final fittings and hoses to complete altered oil and coolant systems, platework around the radiator to prevent re-circulation (something which, I am sad to say, my old employers at Thomas Hill were strangely blind to), new batteries to squeeze into the battery box and cable up to new battery isolation switches, the list goes on. By Saturday morning we started filling the cooling system - plain water first time to find the leaks and resolve them. Draining out the muck with the water before refilling with precious anti-freeze comes later. We had about 6 leaks to deal with, mostly just clips that weren't quite tight, but a couple of pipes on the Cummins engine where rubber rings failed to seal and had to come out and be changed.

Then on to the transmission system, and start filling the reservoir. You can't really fill the entire system by hand - all you can do is provide a head of oil to the charge pump, get the engine running and then keep topping up the reservoir until base pressure indicates - oh and watch out for leaks. We weren't ready to run the engine just yet, though, as although the air inlet system was in place, the exhaust system was still attached to the casing top. So early this afternoon the loco was dragged outside by Charlie, and the casing top with silencer and ducting carefully put on the loco with the forklift. This was a 'moment of truth'. Not only had I carried out an exchange of one (defective) Cummins 855 for another (hopefully not defective) but for various reasons I had changed the engine mounts from the rigid arrangement of the original manufacturer to an a/v rubber mount arrangement which is a bit more 21st century.

Well actually it's more common sense 20th century. Early diesel engines were designed to be rigidly mounted (those in Class 66s still are), they had big lugs which were machined smooth and true and your loco manufacturer built his frames and either planed them true to suit or spent time and effort adding little shims to offset any deficiencies. Without this accuracy bolting a crankcase firmly down to a loco chassis might set up stresses that would lead to premature wear or even engine failure. By the time of the Sentinel, with faster revving engines producing more hp within a given lump such practices were old hat. How much different were these prime movers? If you want a comparison, the much vaunted 6KT of the class 08, which regular readers will know is NOT my favourite locomotive, produces a whole 350 hp but at about 600rpm, to achieve which it weighs 9 and a bit tons and stands 7ft 10 inches tall if you are bold enough to lift it out of the loco. (You don't take it out because it requires major time and hassle getting it back true and lined up with its generator). Meanwhlle, the 16 litre Rolls-Royce C8SFL fitted to the Sentinel 0-6-0 produced 325bhp at 1800rpm and weighed a little over a ton: later on they turbocharged it and got 350 at the same rpm. And they weren't the only ones - Cummins took their 6 pot 12 litre (743 cu in) supercharged engine, originally a direct competitor to the RR C6SFL fitted in the smaller 4wheeled Sentinel, but then bored it out to 14 litres (855 cu in) turbo'd it and by 1963-4 the newly-christened NT400 was producing 400bhp at 2100rpm in rail traction for a weight of just under one ton. So one ninth of the weight, for more hp at 3 and a bit times the rpm, oh, and better fuel efficiency, less oil to change, etc., etc.

Loco manufacturers were encouraged NOT to mount such engines rigidly, better to install them in rubber mounts which would accomodate any discrepancies in alignments without setting up undesirable stresses. Rolls, I think, came up with a mounting system in conjunction with Metalastik and promoted it widely. For not only was it on Sentinel and Thomas Hill locos, but Hunslet, Barclay, Bagnall, EE and Yorkshire industrials, it even turned up hiding under the floors of BR dmus. Actually it wasn't a very good mounting system. The fronts were OK, but the rear mounts had the engine 'suspended' in rubber and for that reason required an additional bump-stop which added to cost and complication. In fact, all too often you found that the 'real' mounts had weakened over time and the engine was sat on the bump stops anyway. But then Metalastk got bought out by Trelleborg. Long before this all had not been well, Metalastik had trod a lone furrow - no one else was allowed to make their own special mounts. R-R had turned to them naturally for chevron type axlebox mounts for Steelman in the later 1960s, but when we went to them in the 1980s for spares and ultimately new ones for new locos, they had abandoned their own designs for 'industry standard' alternatives which took us down an altogether different path.

Anyway, at or soon after the Trelleborg takeover the rear engine mounts we had used for so long were finally declared obsolete. Under the auspices of YEC I had already repowered 3 or 4 locos using the old Metalastik mounting (I say singular, there were actually two different sizes - for different engines - and you had to have 2 pairs of one size - left and right handed - per installation, plus the bump stops) including the Hunslet repowers I had completed for Balfour Beatty and BNFL. Then I had two locos to supply to Sheerness and for once 'design' was entirely in my hands. By then the man I had talked with most at Trelleborg had gone out on his own, and guided by him I produced a simple mounting system to replace the obsolete Metalastik ones, using a coned mount that was produced by several different manufacturers. The cone meant that the rubber was in compression (not suspension like the Metalastik ones) needed no bump stop, and although 4 were still required, they were identical. Above all, they were cheaper, and the metal bits needed less machining/fabrication so their cost was less than half. It only remained to discover whether it would work as well, and the answer was it did and over subsequent years I have gone on to produce permutations of the basic design to suit different engines and locos. RS8, Adolf, Charlie, Tom, Libby, the 03; all have been variations on the same theme.

But all this is to get blase. The crunch would come for this loco if everything lined up with the fixed parts. Not only right fore and aft, but whether my allowance for settlement of the mounts under weight came out right and it was correct up/down. I already knew that the fan seemed to be in the right place to the radiator cowling, would the exhaust fit? In went the casing top, complete with its silencer, bends and bellows. We presented the final elbow from turbo to bellows and to my relief it went in with little argument. So with batteries connected, oil topped up, we got brave, turned the key and the engine fired and ran briefly. Actually it ran too readily - I had had the fuel system completely apart so it was running on whatever fuel was in the engine pipes themselves. The next few times it cranked and wouldn't run. as the fuel pump drew fuel up from the float tank which I had only just refilled, but then it was away and idling happily, drawing hydraulic oil from the reservoir to fill the converter and cooler system.

And then it wouldn't stop! Cummins idle happily with next to no fuel and air, so blocking the air intake didn't seem to kill it. Eventually Andrew cracked the fuel inlet at the pump and that stopped it. We investigated the fuel cut-off valve and found a spring missing, but by the time it was all back together with a spring salvaged from another donor engine, it was too late to try again. Still, there's enough little bits to sort this week to stop me bemoaning the passing of another year. So stay safe and I'll be back, a little older, next week. See ya then.