Of peripherals

22nd August 2022

A late offering, but here 't'is.

Strange to be writing this on a Monday morning, but after getting back home at eight fifteen last night after 7 hours (almost) non-stop driving (weren't long enough at the destination even to turn off the engine), then eating, then a quick trip down to the shed with Andrew for a 'security' check,and  I was ready for an early night.

Normality returned to the Briddon Country Pile on Monday. Barely had we dropped the van in for its new wheel bearing and got back than a van arrived and the washing machine appeared with its re-programmed control board and was back in action. The van was ready just after lunch and was a whole lot quieter.

On Tuesday morning I dashed in to Sheffield - the laser cutters, who, you might recall, I visited last Friday only to find the order still not complete after almost 3 weeks had promised that the last item would be ready on Monday but there I was and it still hadn't been cut. Fortunately this was just a drilling jig I had put in in anticipation of a further job later in the year but nonetheless it was rather annoying having again gone out of my way to collect it and they promised to post it on instead. Despite their e-mails saying that they are endeavouring to improve their turnround it hasn't been getting any better and alternative solutions are being sought.

I had to get back as I had visitors due after lunch to inspect progress on one of my commercial jobs and tactfully pressure me into getting on with it. The loco is largely re-wired but has a couple of air faults to attend to and a problem with the fan assembly. This was an early design of mine but suffered from the shaftbearings being too close together and with the load being imposed by the belts thus having considerable leverage the bearings have failed. The later design (which is 20 years old now) occupies much the same envelople so they accepted my replacing the whole assembly with the later version, parts of which I already have in stock.

When I (first)  finished this loco in 2001, we were struggling against time and cash-flow issues and one of the desk guages was a 'standard' pneumtics industry panel gauge rather than the 'automotive' one in keeping the adjacent duplex gauge and its counterparts on the other side panel. Moreover the clear plastic has discoloured with age. Sourcing some new gauges a few months ago I ordered a spare one to replace this, even though it was not on my scope of work for the loco - now was the time to draw the condition of the old one to the clients' attention and suggest I replace it with one 'from stock', getting it out of its box for comparison. And of course they agree - adding a bit more profit to the job.

Back on 1387, I had hoped to have the hoses that go out and back to the cooler spec'd and sourced by the weekend but although one is fixed, the other was giving some issues at the converter end. The converter is well down in the frames and being an inside frame loco but with springs outboard, i.e. between wheels and frames, the frames themselves are quite close together. Ideally, given the fluid flow around the cooling circuit when things are going fast, you don't want sharp bends in the cooler lines, but the normal swept elbows didn't give a good line but also fouled the traywork I had installed up the side to take the engine multi-cores, starter cables, etc. and I was loathe to re-route. Moreover this line is the outward one with the hot oil and carries the shutdown switches.

(Any interesting point here that I must ponder on sometime. The 'traditional' method is that the port in the body of the converter carries the temperature sender - capillary or whatever - which therefore reads the 'actual' fluid temperature in the converter, whereas the shutdown switch is placed on the exiting pipe to the cooler. OK, an 11500 converter at full speed is pushing some 50 gallons/minute around the cooler circuit, so there isn't much time lag between what the temperature the body sensor feels and the same fluid passing the shutdown switch, but it would be an interesting experiment to put the shutdwown switch on the converter body and the gauge sensor on the outward line.)

Anyway, I went back to the supplier and came away with 45 degree, 'swept' and 'compact' 90 degree elbows and eventually came up with the compact, then the tee for the shotdown switch, and finally the 45 degree to bring the outward line up and clear of the frame side, but still had to cut a piece of the traywork away to clear the compact. Meanwhile a limit switch arrived and the clutch detection switch bracket mounted on the left hand side of the converter. This is based on that I did on RS8, but detects the arm coming down. Hills always used to put a bracket and cam on the operating shaft itself, arguing that the cylinder and arm could become loose and thus not pull the clutch out. To me this was about as likely as the keys in the fork on the operating shaft failing and allowing the shaft to turn without actually moving the clutch plates. Anyway, I had the experience of either the clutch switch coming loose or the cam slipping on the shaft: I was demonstrating a brand-new loco to a customer, and at the far end of the test track shut the engine down (to show the start protection). But it wouldn't re-start. I knew it was the clutch switch, but being suited and having no tools I was in no position to sort it so had to walk back to the works. I promised myself never to demonstrate that protection  (against starting with the clutch engaged) except at the workshops end of the line!. 

Actually the most frequent problem with clutches concerned the internal toggles, sometimes the pins coming out or the toggle plates snapping in two. They didn't all do this together though, and you'd open up the inspection cover to find the pressure plate sitting at an angle with 1 or 2 of the groups (4 in total) detached. Anyway, I'll get some pictures of the whole set up next time as the camera doesn't seem to have done much this week.

At the front of the engine it has been re-secured to its mounts (we left it last week) and plans set for the exit coolant connection to the transmission cooler. Since there need to be connections here for other pipes (water filter and a breather line to the top of the rad) I looked at making a 50mm thick packer to the water pump outlet through which we could put tapped holes, but after a quote of £150 for a water jetted 'lump' I rather went off the idea and we'll weld fittings into thin-walled tube instead. The flexible hose connections though have arrived and line up quite nicely.

Finally I have a quote for the silencer - a hefty beast, the silencer, not the price - which will be an interesting fit within the space available. Many years ago, I ordered up a silencer for Cummins' without getting its dimensions clear beforehand and received a monster that was far too big ever to fit under the casings. It all depends on gas flow and how much noise you want to reduce by. The engine manufacturer doesn't want excessive back pressure - it lowers the turbo performance and reduces power. So the volume required in pipework and the 'box' seems to go up exponentially. Years ago, we had the loco 'George Toms' in from Brush. It wouldn't start, for no obvious reason except that it wouldn't crank fast and rapidly flattened batteries. Eventually, and almost by chance, we had disconnected the exhaust system and the engine cranked at twice the speed. The loco had originally had a water wash exhaust, but someone had replaced it with a silencer. Now it became obvious that the pipework and silencer were woefully under-sized. The back pressure had affected combustion, producing more black smoke (carbon) which had deposited on the insides of the pipework further reducing the effective diameter quite markedly. A new exhaust system and a bit of a de-coke on the manifolds and the performance was transformed. To my shame I managed to repeat the mistake of ordering far too big a silencer for another project later, and the two of them I think lurked for years and maybe to the end of YEC. Silencer manufacturers work on the assumption that you're running the engine at full power continuously, which is rarely the case with a shunter which spends more time idling, waiting, than ever at full bore. Try to explain that to the silencer manufacturer and come to an understanding about how it will perform under variable conditions - in the end you have to make your own value judgement and stand the consequences if you get it wrong. At least CAD made such oversize c***-ups easier to avoid.

Finally the charge pump issue has been sorted. Years ago when you bought your power pack, you got a British made Hobourn-Eaton charge pump, belt-driven somewhere up front. American built converters had a Barnes-built pump - same bolt fixings but different in appearance - and both incorporated a relief valve on the output to limit pressure to about 60psi. On later Rolls' turbocharged engines, they used the supercharger drive provision to give direct mechanical drive to the compressor and charge pump - though the latter required the opposite direction rotation to catch out the unwary. Hobourn-Eaton ceased making the pumps in the 80s, and Hills were offered the rights, tooling, etc to manufacture them ourselves but Hills' management didn't take it up.

Most engines nowadays incorporate a provision for driving a pump directly - be it for power steering or other auxiliary drive, though torque may be limited, that for a pump only producing 60 psi is negligible. The upside is that the pump drive requires no maintenance, the downside is that if the shaft seals fail on the pump, it may pump oil into the sump through the driving gears. On the other hand, I once went out to a loco for Marcoft at Stoke where the charge pump pulley had worked loose, worn the pump shaft to a taper and finally fallen off. I returned with a replacement pump, pulley and belt and it scared the life out of the driver when the loco moved off as son as he released the brakes (without base pressure the loco performance is very poor). The engine in this case came with a pump drive there but was unsuitable for my purposes and having finally identified that the adaptor was to suit an SAE flange I can now sort out a gear driven pump, external relief valve and finish hosing the converter.

So, sorry if that is a bit tame this week, and late. I've written it up this morning in between calls and texts, sorting out transport jobs and trying to organise other bits and bobs. Normal service hopefuly resumes next Sunday. See ya then.