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Post by delaplume on Dec 8, 2018 12:44:21 GMT
Just to set the parameters ( Don't want to stray off-piste, do we ??) can someone actually define what we mean by "Miniature Locomotives" within this thread ?? Alan Alan Read HS216, D I thought that had been either superseded or was being held in abeyance pending HSE re-structure ?? I haven't a copy to hand and it doesn't seem to be available via Google but doesn't it cover up to 2ft gauge ?? ( With exceptions for commercial ventures, etc ).. Alan
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don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 960
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Post by don9f on Dec 8, 2018 16:53:58 GMT
I can’t say I totally understand the physics at work during notching up, but I guessed the speed increase I have seen is due to less back pressure, I am thinking due to restrictions in the exhaust. To clarify what I said in my other post though, David is completely correct in that notch back only happens once underway, although it still pulls away in any forward or reverse position when lightly loaded. I am looking forward to see what speedy is like in comparison even with the obvious poor valve events. My first few outings driving were a rather panicked ridden events, I was very (pointlessly it turned out) concerned that I wasn’t putting enough water into the boiler. Keeping the fire going, water topped up and controls in the right place was quite a stressful experience. Now I try to relax more and I am more confident that if I get into trouble I can put the fire down quickly. You are on the right lines with your thinking and the later the “cut-off”, the more exhaust steam has to be got rid off at each stroke....wasteful and not good for high speed running! Also, it can sometimes happen that a two cylinder engine comes to rest with the pistons in certain positions, such that it needs more than 50% cutoff to be able to restart again.....e.g. one piston could be at or close to one of the dead centres and not be able to move it’s crank and the other already around half way along it’s cylinder, so still needs it’s inlet valve open to admit steam. I think that the original Speedy valve gear had a rather limited full gear cut-off of around only 60% which is one of its problems but it’s a long time since I looked into that so not certain. 9Fs are my thing and the real one can give 78% in full forward gear.....good for starting a heavy train! Cheers Don
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Post by delaplume on Dec 8, 2018 17:20:20 GMT
Hi Don,
Yes that's about it in a nutshell-----------although the cranks are set at 90 degrees lead, if one piston is at front or rear centre then the other piston will NOT be halfway along its' slidebars but slightly more --- or slightly less depending on the set up......This is due to Con-rod angularity and happens with all piston / con rod assys... The valve could well be just shut....Not impossible but not a regular occurance
You might well see the Driver operating the reverser back and forth in order to get steam admitted...........
Churchward was amongst the early pioneers of the Long Lap, Long Travel valve to get expansive working.... coupled to Stephensons gear for good distribution.........Additionally Stephensons will start off in full forwards and be in negative lead---ie admission is AFTER front centre and then change to Positive lead as you link up..........
Normal Walshaerts only has a fixed, positive lead ( I think it's Positive ---- definitely fixed though )...
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don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 960
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Post by don9f on Dec 8, 2018 18:03:48 GMT
Hi Alan, yes con rod angularity wouldn’t be a problem if it could be infinitely long!
Myself and a few others from our club have just spent a very enjoyable day, along with other clubs, as guests at the Nottingham SMEE and I was privileged to do a few laps with a very nice 5” 9F “Evening Star”....well known at its Chesterfield home.
Because it was someone else’s loco, on a track with some fairly sharp curves, several changes of gradient, signals often against you and plenty of other trains doing the circuit, I only went steady and it was easy on this occasion to just drive on the regulator, leaving the cut-off fixed at about 60%. In contrast to some other locos I’ve driven, this one had a very good progressive regulator opening, making subtle changes of power dead easy....coupled with a handy extension rod into the tender, thus making it very comfortable to drive on the raised track....Cheers Dave👍
Regards Don
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pault
Elder Statesman
Posts: 1,496
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Post by pault on Dec 8, 2018 21:09:43 GMT
It's quite interesting to see "Driving on the reverser" talked about as if it is witchcraft. My guide to it is as follows.
Firstly you need a loco with valve gear which will stay 4 or 6 square even when near as dam it in mid gear.
On a suitable bit of track when you are at line speed, wind the reverser back into mid gear then gently open the regulator as far as it will go. You should feel little or no change. From now on unless you are stopping do not touch the regulator. If the loco starts to struggle or slow down when you don't want it to simply slowly wind the reverser towards full gear until it is doing what you want. Like wise if it is running away wind it towards mid gear.
It is actually a very relaxing and smooth way to drive.
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Post by suctionhose on Dec 10, 2018 0:35:17 GMT
Miniature loco drivers are often seen thrashing along in full gear! It's one of things that draws my attention when they go by and you wonder is it engine or driver? When you do see one crackle by near mid gear you know your looking a at someone wot knows what he's doing both in the workshop and on the track!
In full size, how much to notch back is always subjective and up to the driver to judge. For a slide valve engine the driver may spare a thought for the valve gear and avoid having the steam chest pressure too high. (I remember the owner of a mainline loco here being upset that "they'd been running his engine notched up too far...").
With piston valve of course you can run practically in mid gear, full throttle, boiler pressure in the steam chest (or damn near it).
Miniatures are different in that the loads applied to slide valves have diminished by the "scale squared" so the same issues of scored port faces and valve gear wear don't occur. (eg a valve 12" sq has 144 sq inches area. A 1/12 model has 1/144ths of the area ie 1 sq inch)
The topic is driving miniatures so let's stay with that. The job of driving relates to controlling the speed and progress of the train. Firing is having the steam available when needed etc. Two quite different jobs - used to be two people - that the miniature loco driver has to do and often with only one hand!
Running conditions are very variable too. light loads, flat tracks provide plenty of latitude where other tracks do not! Even an experienced driver who knows his engine well will take several laps to learn the road and figure out how much water to have at a certain point on the circuit and the best firing technique for the circumstances. This is why you can't learn to drive without driving! It's a matter of judgement and no two days are the same!
There's many useful tips to file away in mind for 'things to try when its not going well'. My loco - a 5"g 0-6-2 Fowler - has very short valve travel and a full gear cut off of 70% (I designed it at 75% but its slightly less in practice) I would like 80%+ because it does have difficultly starting a 2 ton load on a tight curve and grade. Once she gets a few revolutions up she's off and can be notched back to 55% which is only a single notch on the reverser because the expansion link is also very short!
The Fowler is just a contractors loco and not designed for the mainline-like running that we ask of it as a miniature. You can imagine that every loco is different and an understanding has to develop between it and the driver. Can't write any hard and fast lessons other than "be prepared to learn" no matter how experienced you are!
So if the guard has pulled us up - kids dragging feet or derailment - and we're having trouble pulling away on a curve, we back up a few feet: a) it gets the engine's cranks to a different place but more importantly b) you get all the flanges away from the inner rail. The flanges will soon start dragging again but by then the engine will have got her feet and be pulling away nicely...
Also, if I've got a orange caution signal and the next is at stop I might chose to pull up well before the signal if it gives a better start from rest when the signal clears. These re the tricks that makes you a driver. Can't get it from a book - you pick them up from other drivers who have been there before!
On firing, you have to sense what is needed by learning the engine, track and conditions. Fuels different types vary widely and honing your technique is simply trial and error. If you're blowing off all the time you're probably over firing. Running out of steam? could be many things including bad planning - low steam and low water together is hard to recover from. Some people let it go too far with no way to get it back.
Of course forgetting the injector's on at the station while you oil round or do photo's with kids is a regular oversight! Too much water and no steam! Oops, and there's the rightaway - deal with it on the run in the next two minutes or you won't get up the approaching grade... You need to know your engine and the conditions for meeting these demands successfully. It's not something you just hop on and away you go.
So how to teach someone. As condescending as it may see, a new driver, even one that has driven before has to be prepared to listen and learn. They have know how to handle your engine carefully and not do damage. I had a fellow snap my brake valve off in a panic because it takes a few seconds for the train brakes to bite. They need to circulate in relaxed circumstances and get the feel of it.
As the trainer, you need to let things go wrong in a controlled way so the trainee 'get's the experience'. Can't get experience by talking about it. So it may take several hours of experience before you trust somebody with your engine and that's only the beginning. Learning to deal with injector problems, lubricators, oiling round, having a sixth sense about something not right...
It looks like the driver just pulls the lever and sits there but there's more to it and that's what makes steam so enjoyable.
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Post by delaplume on Dec 10, 2018 1:18:10 GMT
Blimey Ross------ that's pretty much it I would say....Very comprehensive indeed and enjoyable to read....
Couple of supporting points if I may ??
A distant semaphore signal is actually Yellow.........I know a lot of modern-day folk refer to it as orange...My guess is that they are car drivers 90% of the week and drive a model train on a Sunday....
I try to put a single round of coal on just as I'm approaching the station.....usually when I crack the blower on...and wash the footplate down as I coast in.......
This will avoid a smokey platform area plus give you more time to monitor the pressure/ gauge glass readings.........also, if you have about 1/2 glass and are just about to lift the safeties you can now sit there with NO smoke, keep the safety under control with the odd shot of water, a hot fire as that coal has now burn through and is giving off some useful heat, and by now 3/4 glass with full pressure......Oh yes--- don't forget that clean footplate !!.........Always take water at any opportunity, answer a few questions ( Did you build it yourself ?? = No )... top up lubricator, adjust the Red, spotty neckerchief ( a bit of swank by me !!) and we're ready for the "Right away!" again..
Alan
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Post by David on Dec 10, 2018 9:53:58 GMT
I'm glad someone else cleans the footplate! If there was nothing else to do on the boat I'd sweep the floor in my space. I do the same on the little loco when it looks too messy. I don't have a hose I can't wash it with though, that's pretty fancy.
Ross, why does notching up cause problems for slide valves? Is it because there is more steam pressure in the chests, because less of it is flowing into the cylinders?
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Post by delaplume on Dec 10, 2018 19:07:08 GMT
"I don't have a hose I can't wash it with though, that's pretty fancy" ----- Hi David, I use a 1/2" paintbrush with the bristles cut down to half length on my models... On the full size GWR ones I fired the L/H live steam injector outlet has a tapping for a pipe to feed an on/ off valve situated just under the Fireman's wooden seat....Attached to this is a small rubber hose pipe ( I think abut a 1/2" bore ) which has a wire binding around it for protection....This hose is long enough such that the Fireman can stand on the fall plate and hose the coal down on a hot & dusty day....When not in use this hose pipe can be seen dangling down alongside the L/H loco steps....... There would normally be a galvanised bucket which I'd keep half full of water plus a small yardbroom... As you approach the last station OR}--- If the next station was were your "Relief" Fireman would be then I'd want the footplate and boiler to be in acceptable condition... In my snap bag would be a fresh neckerchief, clean dry towel and a bar of soap.....I would be in as clean a condition as the Footplate on handover... PS}--- At the SVR this was "Normal " practice handed down from the Ex-BR and EX-GWR lads.. Here is a photo of Ex-GWR 6430 Pannier's footplate where you can see quite clearly the ON-OFF water cock ....NB}--- The cab inner is GREEN whilst the roof appears to be White or Cream....
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Post by Deleted on Dec 10, 2018 19:21:54 GMT
8 wheeled Lner had a galvanised buket that sat halfway into the wooden floor. Is also had a tap above to fill with cold water. The A1,A3,A4's alsohat a tap for hot water.
I can't work out how to post a picture using my phone...however, you can see the general layout for the tender on page 37 of my thread
Pete
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Post by delaplume on Dec 10, 2018 19:32:43 GMT
8 wheeled Lner had a galvanised buket that sat halfway into the wooden floor. Is also had a tap above to fill with cold water. The A1,A3,A4's alsohat a tap for hot water. I can't work out how to post a picture using my phone...however, you can see the general layout for the tender on page 37 of my thread Pete Cheers----------will have a look Alan
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Post by suctionhose on Dec 10, 2018 22:23:07 GMT
Ross, why does notching up cause problems for slide valves? Is it because there is more steam pressure in the chests, because less of it is flowing into the cylinders? The higher steam chest pressures loads up the valve. It's a necessary evil because you couldn't keep coal or water up to a full size running everywhere in full gear. Neither issue presents in miniatures on account of the scale effect mentioned.
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Post by delaplume on Dec 11, 2018 4:21:20 GMT
Hello everyone, I've been trawling around in my photographic collection and found this one..........it's a much younger version of to-day's "Auld Pharty-bagz" and shows the 5" parallel Scot during it's cosmetic re-vamp...... The track is the now defunct Rugely MES one and the location is at the "Station" which was the rear of the Changing rooms building.......I'm not sure of the year but it has to be more than 20 years ago.... This was only a test train as I'd normally carry at least 3 trucks.. I've posted this because I've been banging-on about how to drive so i'd best prove that I can.....I also have one of myself firing 75069 at the SVR on it's very first train after restoration..... but I can't find it at the mo !!
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Post by Steve Purves TBLR on Dec 12, 2018 9:25:31 GMT
I'll just leave this here...
Steve
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Post by suctionhose on Dec 12, 2018 11:02:27 GMT
It is always a personal pleasure to see people enjoying a locomotive in any situation! It is a unique and exemplary indulgence unsurpassed by anything mere mortals may experience.. OMG the slightly intoxicated 4am's I have enjoyed...! Here we are, in more subdued circumstances, enjoying the same... I am on the leading engine, the second, built by the driver is also an exceptional machine. We did a few laps for the enjoyment of all present on the day... www.youtube.com/watch?v=n9uELxC0A3U(you may have to copy paste to your browser)
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Post by delaplume on Dec 12, 2018 12:44:45 GMT
I'll just leave this here... Steve Hello Steve----Blimey, that was a few years ago----Joyce and I appear to have only just lost our dark hair..LoL ..... Thanks for posting, I'll add that to my collection...... PS}--- Despite dieting, dancing and generally eating "Rabbit food" , drinking white water, etc-- I still look like that !! Cheers !!
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Post by delaplume on Dec 12, 2018 13:26:07 GMT
Hello Ross,
OH ---- just lovely !!!
That's just how I like a train to be}----- Double headed, 12 trucks with 25 passengers, a bit of a damp day by the looks of it ??.... 2 locos in great trim ( Both sets of exhaust beats sounded crisp and well spaced )..and the crew at the top of their game !!
EXCELLENT !!!
The track looks good with plenty for the passengers to look at---and plenty to keep both Drivers on their toes as well...
It's a great thing that thanks to youtube and e-mail images, we now can "meet" the forum member who is otherwise just a nondescript Avatar at best....
In the video above this Joyce and I are giving that Red Devil a bit of work-out before buying it and taking it back home........With a Polly I'd normally expect 2 trucks and 8 to 10 passengers..
Best regards
Alan
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 12, 2018 13:37:21 GMT
Well, if we're posting pic's to show we've done it, here's one of 7 year old me in the back yard: And about 10 years later: Not particularly good photo's, and there's nothing more recent; both because I'm good at hiding from the camera, and because it's been a while.
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,906
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Post by JonL on Dec 12, 2018 13:53:57 GMT
I've just got X's up where the photos should be, could be my internet though...
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Post by Steve Purves TBLR on Dec 12, 2018 15:02:09 GMT
These have been posted elsewhere... Nothing of me but my 5 year old seems to have the hang of it!
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