Guest stuartp Posted May 16, 2012 Share Posted May 16, 2012 I wonder how much of this is a Cross-ism It could well be a Cross-ism, I confess I took it at face value until now, maybe someone at Ayr was pulling his leg. The 'Twins' seem to have worked both ways round though, there's at least one pic of them coming past Annbank Jcn tender first. Link to post Share on other sites More sharing options...
Highlandman Posted May 17, 2012 Share Posted May 17, 2012 There was a very good article about running tender first in The Railway Magazine April 2009 edition. Fortunately this can be read online and can be found here http://www.exacteditions.com/read/railway/april-2009-4983/18/2/ Link to post Share on other sites More sharing options...
cary hill Posted May 17, 2012 Share Posted May 17, 2012 There was a very good article about running tender first in The Railway Magazine April 2009 edition. Fortunately this can be read online and can be found here http://www.exactedit...2009-4983/18/2/ Well worth a read and some excellent photographs including an SR Q1 with couple of ancient coaches running in reverse. Link to post Share on other sites More sharing options...
Edwin_m Posted May 17, 2012 Share Posted May 17, 2012 Thanks for the link. In case anyone was struggling as I was to read the blurry text, you can click on the page to get a proper resolution. Seems to work a lot better than other digital mags too! Link to post Share on other sites More sharing options...
RMweb Gold PhilH Posted May 17, 2012 RMweb Gold Share Posted May 17, 2012 Obviously on the MHR we have equal amounts of running both ways. There should be no reason why timekeeping etc. should suffer, the things go just as well backwards as they do forward, indeed some seem to go better (imperfect valve events). As far as water level is concerned it can be easier running backwards whilst working hard as the water level is artificially dragged down with the regulator open, so as long as it's in sight you know it will come back when the regulator is shut. Conversely when running chimney first you get an artificially high water level, and it can be a bit of a shock when it all disappears as you shut the regulator - especially if you're about to go over the top of a summit and it all runs up the front anyway! It can be uncomfortable, especially in summer/ dry weather when coal dust can be a menace - a good fireman will use the tender spray / pep pipe at every opportunity or risk a few sharp words from his driver - they do on my footplate anyway, I will not have dust! Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted May 17, 2012 RMweb Gold Share Posted May 17, 2012 The West Somerset Railway also find the time keeping for engines running tender first is harder and is more likely to make the trains run late than when going chimney first so was this a problem when running pre preservation as well. Why? If you're running at relatively low speeds - as all the leisure/heritage railways are - I can't really see why running tender first should result in delays compared with running chimney first, for all the reasons Phil has already noted. True tender first running can be uncomfortable but it's not so bad if you keep a clean footplate and make liberal use of the pep pipe; does the Severn Valley lose time when running tender first (under arguably more arduous conditions than the WSR)? Back in the days of real railways my local branch saw tender first running (usually light engine but sometimes on ecs and passenger trains) on a daily basis (SX) and the timings were no different for a 'Castle' running tender first from those for a 'Castle' running chimney leading; and from what I observed travelling in the trains the actual performance also didn't vary. Again we're talking relatively low speeds and 28Xx and 'Manors' made occasional appearances on ecs trains - all running in the same timings and all having to run tender first in one direction as the turntable was long out of use and in any case regarded as a waste of time when subsequent movements off the branch meant there was no need to turn. Link to post Share on other sites More sharing options...
RJS1977 Posted May 17, 2012 Share Posted May 17, 2012 Referring to the post above on the use of 0-6-2T on the Welsh Valley lines, I suspect that the reason for running boiler first uphill was to reduce the risk of the boiler water level falling below the fusible plug at the top of the firebox. Running bunker first on an uphill grade or boiler first on a downhill has the small risk of the water adopting "level", so higher at the smokebox end, lower at the firebox end. While not a lot, with a "mortgaged" boiler it could mean the difference between smooth run and disaster. I think it was a common practice on some steeply graded narrow guage lines. Also hot gases rise so it's easier to draw the heat from the fire uphill than downhill... Link to post Share on other sites More sharing options...
RMweb Gold PhilH Posted May 17, 2012 RMweb Gold Share Posted May 17, 2012 Also hot gases rise so it's easier to draw the heat from the fire uphill than downhill... ?????? Link to post Share on other sites More sharing options...
buffalo Posted May 17, 2012 Share Posted May 17, 2012 ?????? I'm glad you said that, Phil. As one whose understanding of steam engines is more theoretical than practical, I had the same reaction but wasn't prepared to comment. I can only assume an invisible smiley was intended. Nick Link to post Share on other sites More sharing options...
RJS1977 Posted May 17, 2012 Share Posted May 17, 2012 If there is an uphill gradient from firebox to smokebox, the tendency of the hot gases to rise will aid draughting along the boiler tubes, as the smokebox will be higher than the firebox. Conversely if there is a downhill gradient, there will be more of a tendency for the hot gases to stay in the firebox, opposing the draughting of the loco. As an analogy consider filling a watering can (or a teapot) with a spout pointing upwards. In order to get water in the spout, you have to first fill the can (or pot) up to the level of the bottom of the spout. From then on the spout will gradually fill up under pressure as you continue to fill the can, but you need to add a lot of water to the body of the can to get a little bit of water in the spout. However if the can had the spout pointing downwards water will flow down it quite happily - such that you can't ever fill the can up!. Now imagine an (empty) can turned upside down over a fire. If the spout is now pointing downwards, smoke from the fire will build up above the spout hole and smoke will only get into the spout through pressure as the can fills with smoke. However if we consider turning the second can with the downwards spout upside down (so the spout now points upwards) smoke will find its way up the spout relatively easily. (I know, this has probably confused you even more!) It's probably a small effect as even the steepest railway gradients are more "along" than "up" but even so a boiler will probably be slightly more efficient running uphill chimney first than cab first. Though the issue of keeping water over the fusible plug is of course more important! Link to post Share on other sites More sharing options...
buffalo Posted May 17, 2012 Share Posted May 17, 2012 ...It's probably a small effect... Compared with the draught from the exhaust steam, I would have thought even "small" is a gross exaggeration. Negligeaible might be a better term. Is it even measurable under working conditions? Nick edit: at least RJS can spell negligible Link to post Share on other sites More sharing options...
RMweb Gold PhilH Posted May 17, 2012 RMweb Gold Share Posted May 17, 2012 If the gases 'stay in the firebox' then you're in trouble - as soon as the door is open they will exit onto the footplate and ignite, it's called a blowback and it will kill you. The volatile gases must exit through the tubes and up the chimney, this is why, for instance, the blower must be opened when the regulator is shut. Uphill or downhill, per se, has no effect on the steaming of a loco. Link to post Share on other sites More sharing options...
buffalo Posted May 17, 2012 Share Posted May 17, 2012 Phil, it's clear to me that you, as a down-to-earth practical sort of chap, lack a complete scientific understanding of the machines you drive almost every day. Surely, it is well known, at least amongst us theorists, that it is the rising airflow in the cab resulting from the body heat of the crew that leads to blow backs when the door is open? Nick Link to post Share on other sites More sharing options...
RJS1977 Posted May 17, 2012 Share Posted May 17, 2012 Nick, Phil - thanks for your clarifications. And apologies for adding to my post after you'd posted those clarifications - I was so busy adding my analogy that I didn't see them come in! Suffice it to say that a brief back-of-the-envelope calculation has confirmed to me how "small" (the word my university lecturers used when they meant "negligible!") the effect would be. Link to post Share on other sites More sharing options...
RMweb Gold PhilH Posted May 18, 2012 RMweb Gold Share Posted May 18, 2012 A bit of a thread hijack but the workings and management of a steam loco boiler are a bit more complex than most people realise - primary and secondary air considerations, not creating black smoke, keeping a water level in no matter what the attitude of the boiler, firing to the road and the biggy, how not to kill or maim yourself whilst on the footplate. For instance. no matter how the thing is steaming you don't have the rear (or leading in the direction of travel) damper fully open when running tender or bunker first, especially if you have a bit of a black fire - a sure way to force combustible gases out through the firehole and onto the footplate when the door is opened.......Boom! Link to post Share on other sites More sharing options...
scotcent Posted May 18, 2012 Share Posted May 18, 2012 My recollection, in the Glasgow suburban area in the 1950's is that locos on local trains were used whichever way round they happened to be facing -- I can remember a very sparkling run round the Cathcart Circle behind a backwards Jumbo 0-6-0. But it could be difficult on these services to get at a turntable, and I also recall that drivers of tender or tank locos, when they had the opportunity, would always turn to run chimney first. Allan F Link to post Share on other sites More sharing options...
Castle Posted May 19, 2012 Share Posted May 19, 2012 Hi All, The Australian adventures of our Didcot restoration project loco, No.4079 Pendennis Castle, provided some 'exciting' tender first running. There were no turning facillities on the Hamersly Iron Ore Railway where she was running between 1978 and 1994 and as a result spent as much time in reverse as she did in forward gear. The difference between UK practice and Australian preservation practice being that she was often made to go as fast in reverse as she was in forward gear. Speeds of over 70 mph were not uncommon apparently! This is scary enough from a certain perspective but becomes more so when you realise that at the time she was propelling a second tender in the form of a water carrying and air pump vehicle... Makes you think doesn't it? All the best, Castle Link to post Share on other sites More sharing options...
buffalo Posted May 19, 2012 Share Posted May 19, 2012 Flicking through Ivo Peters' Somerset & Dorset in the Fifties, I was reminded of another reason for tender-first running and the extent to which it was sometimes avoided. Engines arriving at Bath (Midland/Queen Square/Green Park) from either the Midland or S&D lines were invariably turned before taking another train out of the terminus. In April 1953, the turntable at Bath was out of action for a week. During this time, trains of four or five engines were assembled and ran ten miles west to Mangotsfield for turning on the triangular junction. Of necessity, the out and back runs were entirely tender-first (except, of course, for one leg of the triangle). Nick Link to post Share on other sites More sharing options...
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