Weekend Rails

what we do for our kids

Of locos at Scunthorpe

10th February 2013

There have been over two hours of phone calls this week between me, our transmission experts and Twin Disc over in the USA. One of the outcomes is that it may be that our low base pressure on D2128's powershift is the result of the charge pump not delivering sufficient oil. In the manuals we had with the transmission (or to be exact, the manuals that Hunslet supplied with the original locos when they were delivered in 1984) there was no reference to oil delivery rates for the transmission, only acceptable grades.

The charge pump that was with the transmission (and had come off the original loco) was a gear pump of about 26cc/rev, but was seized so early last year I ordered up a tandem gear pump, one for the converter and one for the powershift, the latter being 26cc/rev, and - I thought - got about the same drive belt ratio (engine speed to pump speed) that Hunslet had fitted. Just in case, I sited the pump drives at the accessible end of the auxiliary drive shaft so that if we had to "fine tune" the drive ratios it would not be too hard. Now from Twin Disc we have the definitive answer that the powershift needs a minimum of 5 US gallons (just over 4 imperial gallons or about 20 litres) per minute, and the test rig at our experts was happily delivering 20 gpm when on test prior to return to us. Calculations based on our present drive ratio and estimated idling speed (there being no working tacho yet) suggest we are some way below this, so it looks like we may have to "uprate" the drive by changing the pulley sizes and possibly substituting a larger capacity pump for the powershift. In which case I'll probably switch from 2 belts to 3 to transmit the extra power and longer term review the suction filter for higher flows.

Also on D2128, the throttle cable has progressed, leaving me a few dimensions to obtain off the loco so that a "special" can be manufactured early next week. Although I blew the dust off the file for the electronic throttle (which I must get around to for "Libby") I would rather have the time to play with the chips before installing, and as the main throttle position sensor is on a month's lead time I was rather glad to make progress on a traditional means. Thus an order went in to the profilers late in the week for various brackets for D2128 as well as the exhauster mounting on Beverley, which I'll be collecting next week sometime. Andrew is now anxious to get the vac installation on Bev finished for Easter, which, given that a considerable time is now - rightly- being spent with his new son may prove difficult.

Indeed, on Saturday he was again away with mother and baby and Steph and I actually had time to wander around Matlock shopping, like normal people do on a Saturday. He was back by late that night however, and reasonably early on Sunday we were back on the road to Scunthorpe armed with, among other things, the hand tacho. A few weeks ago Andrew agreed to sell the Palvan, subject to carrying out a minor roof repair, and we had hoped to get a look at it last week, but time did not permit. So it was first job of the day, and in a deja vu from last November, the AFRPS's Yorkshire 0-6-0DE "Arnold Machin" was officially out of action, whereas the Bagnall 0-6-0DM merely had flat batteries, but Janus No.1 fired up and we shunted it across with that. I left him to it while I made a start on tapping the holes that I had drilled a couple of weeks back to M10 to receive the bolts that secure the cab front to the casing top. After assessing the damaged bit of roof cladding on the Palvan for repair, Andrew emptied more of its contents into the van and then we shunted the Palvan back. Eventually we decided it was time to brave D2128 and having added an optical target to the viscous damper, we fired up the engine. Idle, it transpires, is currently 550rpm and maybe I was reading the gauge wrong last week but we now have a steady 40psi at the powershift. But at this speed we are only delivering 14 litres a minute (or about 3.75 US gallons) so we eased the throttle open to just over 728rpm which on paper is the point at which we deliver 5 US gallons. Pressure rose to 45psi - at that rate we would need to rev the engine at 2000 rpm just to get pressure, but lifting the rpm another 160 made no difference to the pressure. Having repeated and recorded the results we shut it down for further consultation.

With two nice old Butlers headlamps (they were a well made, pressed steel 5" headlamp that all the industrial loco manufacturers seemed to use - well Thomas Hill and Sentinel at least - but Lucas took them over and discontinued it) available for fitting, I turned to the back of the 03's cab and mounted the first, then removed the wiper arms and trial fitted a Trico arm in place. Soon I must carry on fitting the wiring in the 03's cab to the wiper motors, cab light and external lights, supremely confident that we'll sort out why the transmission doesn't co-operate quite soon.

Meanwhile, Andrew started assembling his bits of 2" pipework ready to have a blitz on the vac fit on Beverley as soon as we can get the loco back inside!

In conference on the drive back we decided that as an interim measure, we will swop the driving pulley for the charge pumps on D2128 so that we are getting 5 US gallons at idle and try it again. If that still leaves us without sufficient pressure, we may unilaterally adjust the regulating valve like we did before.

And finally

I am quite used now to magazine correspondents plagiarising or précising this blog or news pieces on Andrew's website (which I also write) for bits to print in their respective columns, and indeed, we are happy to co-operate with those who approach us direct for news. But I do think it is beholden on such people to condense my prose reasonably accurately. One of the March issues has caused us to pull our hair out (Andrew can afford to do this, I cannot) having used content from this blog's entry of the 18th November last year (yeah, really up-to-the-minute, I know). Apart from attributing all the work done at Scunthorpe to a single loco numbered D2128 and called "Beverley" (!) the contributor has proceeded to juggle bits incorrectly or out of context as to make Andrew and me look incompetent idiots. In my experience such people often have little or no mechanical understanding and make their living by "commentating" on others. Meanwhile their Editors may rail about train operating companies "not co-operating" with the press. There may be a moral here, somewhere.

composite 10feb13

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