Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: andywright on January 06, 2010, 07:23:55 pm
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Hi all, asking for help, cannot get my TRV1A to run, have followed the instructions to the letter, tried resetting the timing 180 degrees removed, still no joy. Am a bit baffled as to why steam goes through he system when it is in neutral though, thought it should stop with the valves set to neutral..
Andy
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Hi Andy,
Okay, looks like you have become a little confused. I've never made the TVR1A, but it is a standard slide valve engine (?).
There is no neutral position on a twin cylinder engine- if one valve is at 'exhaust' (typically with the corresponding cylinder at 85-90% at the end of it's stroke, giving slight compression and quieter running) then the other valve will be just entering admission on the opposite stroke.
Greg
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It is a slide valve engine, but try as I might I cannot get it to run, spent about 16 hours just fiddling with the timing, i know that is probably what the problem is.
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I don't (yet) have a TVR1A, but do have the assembly booklet. It looks like there are two adjustments that could cause you trouble; one is the position of the eccentrics that operate the slide valve the other is the throw or position of the valves.
Sorry if this takes you over ground you have already covered, but have you turned the engine over by hand, with the the timing chest covers removed. It is pretty easy to see what is going on and to work out if the valves are doing what they should, when they should.
Can you give us a bit more detail of what the engine is or isn't doing. Apart from the blindingly obvious fact that it is not running <*< (sorry).
Neil
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Ok, lets see if we can talk you through it.......... %%
Starting from one end and working toward the other-
If you roatate the shaft clockwise with the valve covers off as Neil suggested-
The eccentric closest to you, with the nearest piston at TDC, should be at the end of it's exhaust stroke and about 5deg into admitting steam into the top of the cylinder. The other piston, if it's a 90deg. crankshaft, should be at midpoint through it'stroke, with it's valve coming to the end of it's admission (and possibly beginning to turn to exhaust depending on the lap and lead of the valve- you really don't want to know about that until you've got your engine going!!!).
Every engine varies slightly, but a .5deg. adjustment here and there will get you there eventually.
Greg
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I find if I turn the fly wheel it will almost run, but not keep going, the engine feels fairly free, I've felt a stiffer engine which which ran very well. The eccentrics seem to slip slightly on the original settings, the grub screws are very small. Will try a bit more running in with a battery drill and try again, I really can't see any reason for it not running.
Andy
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Have you tightened the main bearings too tight? Or the valve/cylinder bottom glands? Plenty of oil in there? You havn't made the apprentices mistake (longshot here) of timing each valve to the opposite cylinder- so it looks right- but in fact each cylinder is running against each other?
Greg
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sorry to ask, but have you got the steam and exhaust the right way round? Pressure into the valve chests to keep the valve pressed against the port face? Still waiting for mine - left USA 27/12.
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I think he means neutral on the reversing gear,
I had a similar problem with mine,
I could get it to run only with excessive pressure and roughly at that, one cylinder was fighting the other at certain points even following the instructions to the letter. I gave it to a steam guru and he discovered the valve retaining collar on the valve rod inside the steam chest is loctited, a touch of silver solder and it runs nicely now.
Nick
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Have you tightened the main bearings too tight? Or the valve/cylinder bottom glands? Plenty of oil in there? You havn't made the apprentices mistake (longshot here) of timing each valve to the opposite cylinder- so it looks right- but in fact each cylinder is running against each other?
Greg
The main bearings were tight, I shimmed two of them to loosen the crank, it was tight when just screwed to its base, the crank assembly then ran nicely on its own. The engine doesn't seem that tight now. its had plenty of running in with the hand drill. I had thought of the timing issue you mention, will check again. I done the timing so many times I can't remember what I have and haven't done, but It does seem correct. Maybe it would be better to run the crank in on its own before assembling the top end.
Andy
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sorry to ask, but have you got the steam and exhaust the right way round? Pressure into the valve chests to keep the valve pressed against the port face? Still waiting for mine - left USA 27/12.
Yes thats all correct, I know its the stupid things that can be overlooked.
Andy
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I think he means neutral on the reversing gear,
I had a similar problem with mine,
I could get it to run only with excessive pressure and roughly at that, one cylinder was fighting the other at certain points even following the instructions to the letter. I gave it to a steam guru and he discovered the valve retaining collar on the valve rod inside the steam chest is loctited, a touch of silver solder and it runs nicely now.
Nick
I wish I had a steam guru near me (South Wales near Cardiff) I would be there like a shot, there is only so many times you can run through the timing. I am beginning to wonder wether to strip it and start again, though I don't really see the point, just that I may have missed something.
Andy
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Two ideas which may help:
Have you an air compressor - when 'debugging' my (home made) engine I found it was much easier to do on air. You can vary the pressure much easier than on steam AND everything stays cool-enough to fiddle without burning your fingers.
Can you disconnect one cylinder, so as to work on just one end at a time, thereby halving the problem?
Geoff
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Hi maybe try to get one cylinder working with the second cylinder eccentric disconnected and the valve at the top of its stroke , once you get it running on one cylinder you can then move the valve on the second cylinder and should then feel the pressure of the stroke and assuming you are using air you will feel exactly when the second piston is is on the downward stroke I have been up close with these little engines and the are sweet runners when everything is spot on also not a good idea to run in with a drill simply because the valve faces can become damaged due to no pressure against the face in fact some early models had a spring in the valve chest lightly pressing against the valve for that reason ,also wonder why the crankshaft is tight maybe a good place to start and get things free as i am sure they should not need forced running in hope this helps
John
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If you check all the factors already mentioned, also have a look at the seating of the slide valves. Did you prepare the valve faces and the port faces on the cylinder with fine sandpaper as per instructions?
As they come from the factory the slide valves can fit the on valve rod quite tight. If this is the case, they won't sit flat on the cylinder face, which means they won't be steam tight. The slide valve should be just a tiny bit loose on the valve rod. Check it and if needed file carefully the recess in the slide valve where the rod fits, so it doesn't fit tight on the rob. You don't want any play there either, just a loose fit, so the valve falls on the cylinder face by itself (when holding the cylinder horizontally).
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UPDATE.
Stripped the valve gear, re lapped the vavle slider, reset the timing marginally, fired up the steam, the engine wouldn't self start, and it wouldn't run on less than 20psi, (model boiler gauge). There is still a tight spot on the engine, and all my gaskets on the steam chests now leak steam slightly, not much, but still too much, disturbed too many times I think, the seat to the cylinders and valve chest is good, (lapped).
Adjusted the valve sliders slightly with the engine running and got the engine running a bit smoother, but not perfect. All in all the running was lumpy, certainly not smooth enough for me., any way it wouldn't self start, so whats the point in having two cylinders if you still have to spin the fly wheel. I'm a bit peeved because I took my time sorting the bottom end, but there is still something causing a tight spot. I saw one of these engines running on air before I bought mine, and that was tighter, but it ran smoothly, so I'm still thinking its timing that is the the main problem.
I think the next stage is to strip the top from the bottom, and re check the crank, for tight spots AGAIN. And take it from there, rebuild from the bottom up.
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Two ideas which may help:
Have you an air compressor - when 'debugging' my (home made) engine I found it was much easier to do on air. You can vary the pressure much easier than on steam AND everything stays cool-enough to fiddle without burning your fingers.
Can you disconnect one cylinder, so as to work on just one end at a time, thereby halving the problem?
Geoff
No , I haven't got an air compressor, right at this moment would give my right hand for one. So its a pain doing anything, wait for steam pressure, run things ,adjust as much as possible, then let it all cool and start again.
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Hi Andy,
This is annoying me now, so I can't imagine how exasperated you're becoming :o
Stick with it!!!!
New gaskets can be made from thick newspaper and a very thin mix of varnish and oil- can't be dissassembled without destroying though so you'll have to wait 'till youv'e got her running before re-newing them.
As much as I can't comment on the qaulity of the manufacture- I've never built one or seen one in the flesh- i've only heard good things about them, however, if you've followed the instructions to the letter and you feel you havn't missed anything and is all assembled correctly, then i'm left wondering if there is a discrepency in the manufacture?
Perhaps check that the piston rods are the same length?
What are the pistons sealed with- o-rings?
On a different tangent- are you sure enough steam is getting to the valves if it's only stiff on steam, not when turned over by hand?
Does it do a couple of rev's before sticking?
Have you discerned where it's sticking- even which side of the engine?
Greg
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No , I haven't got an air compressor, right at this moment would give my right hand for one. So its a pain doing anything, wait for steam pressure, run things ,adjust as much as possible, then let it all cool and start again.
I have used an air foot pump (for car tyres) when I was adjusting my TVR1A. Doing it on steam is much more difficult as you have to wait for the engine to cool before touching it etc.
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Got it going well now in one direction, nice and sweet, but a bit lumpy in the other direction, now the problem is the tiny screws on the valve gear keep coming undone, so its lock tight when all is sorted. And yes when it stops its always the same place, when one cylinder is top dead centre, still needs almost 20 psi to start, and over 20psi the lumpy way.
Andy
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Hi your engine must be run in on air as stated in the manual as the clearances are not enough to allow expansion of steam even the oil will will interupt the "o rings causing unseen problems
John
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:D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D
Yey!
OK, I would suggest the most minute changes in the eccentrics till you get her running sweet in both directions.
Check the piston if possible- take the cylinder cover off and see if the bore is scored in any place- if not take the piston out and check the piston ring.
Will need quite a lot of pressure until it's run in properly.
Greg
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Andy, I guess this is not what you had in mind when people told you that you would have 'endless hours of fun with a steam engine' >>:-(
Well done for your perseverance, it's nice to be rewarded with a running engine.
Neil
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Looking at things this morning, its all cool and a lot more free, can't be far off now, will check the valve chests today and see if there is any difference making it run sweet one way and rough the other. I'll look back at this post in future and laugh. Just keep running it, going to a friends garage tomorrow, he understands steam and has compressed air so we will see.
Andy
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Hi your engine must be run in on air as stated in the manual as the clearances are not enough to allow expansion of steam even the oil will will interupt the "o rings causing unseen problems
John
Unfortunately I don't have air, I have thought of the pumped up tyre thing, may try that, but the engine is a lot sweeter this morning to turn by hand.
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If it stops with one piston at the top (or bottom) is it actually hitting the cover? Or perhaps a valve rod is, or the con rod hitting the piston rod gland, or the big end rubbing on the crank webs. It is possibly improving because the bearings are wearing to give clearance as a side effect. Is the crankshaft straight?
If you can feel the tight spot when turning by hand then keep investigating that way rather than steaming as that will anyway introduce effects such as trapped condensate.
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Hi Andy,
Checking back over the posts I don't see any mention of Lubrication.
Do you have a lubricator for the engine and are you using proper steam oil?
When you were running it in with the drill were you lubricating it?
Are all the other parts being lubricated?
Regards,
Gerald.
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UPDATE
Well its running a lot better now, still slightly lumpy one way, but as smooth as... the other way, It had a good run last night and was a lot more free after, so its carry on running, now it runs very slow on about 15psi, wheras it wouldn't run at all below 20psi.
Yes its been well lubricated right from building, I have been involved with largish marine diesel engines for the last 30 years so do know abit about lubrication, just lacking in knowledge with steam but learning fast! The lubricator works well.
I'm not out of the woodwork yet, but getting there, I may look around for a small compressor this weekend, it would make things a lot easier.
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Cheap compressor? Dead fridge or dehumidifier compressor unit.
Regards Ian.
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Or use your boiler empty as a reciever for a foot pump.
Greg
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Good idea. Thanks.
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for a reasonably priced compressor see Everythingairbrush.com as recommended in the MB article. But still £60. I'n thinking of getting one so I can display various odd engines I've collected over the years - tho I suppose I should make boats for them!
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Try this firm i have used them a few times , they also have a presence on Flea bay very fast delivery.
http://www.rdgtools.co.uk/acatalog/AIR_BRUSHES_AND_COMPRESSORS.html
http://www.rdgtools.co.uk/acatalog/NEW_LINES_TO_RDGTOOLS.html
peter
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Thanks Peter - straight into my favourites file!
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Hi Andy,
Glad to here it has been properly lubed. I have over the years seen a number of engines that were "run in" dry with a drill. I'm glad to read that " its running a lot better now, still slightly lumpy one way, but as smooth as... the other way," . I guess it just needs a bit more running and a bit of fine tuning with the timing.
Regards,
Gerald.
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UPDATE.
Firstly thank you everybody for your advice and information, the engine is running a lot better now, just needs more running in I think, a friend of mine who used to be a steam engineer at sea (I thought he was a motor man!), had a fiddle with the timing so its quite good now.
Will post any other updates on the TRV1A here. Meanwhile will keep the build post updated.
Thats not to say other constructive critism or advice is to be kept to your self, anything that helps is welcome here, I am sure we all can still learn something new everyday.
Regards Andy
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:-)) Good to hear mate- all the best engineers know about steam...so I don't know why I do %%
Have you got any pics of her assembled then?
Greg
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Brilliant, well done Andy.
Frustrating though machines are, it is very satisfying (and educating) when we finally get them going properly.
Neil
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This is the finished engine fitted in my launch. Further pictures here
http://www.modelboatmayhem.co.uk/forum/index.php?topic=3755.0
(http://i181.photobucket.com/albums/x196/lightshipman/IMG_0606web.jpg)
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[quote I am sure we all can still learn something new everyday.
Regards Andy
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Thats exactly what my Dad said in his speech at his 90th birthday party Andy but he added "the problem arises when it is the same thing as we learnt yesterday!"
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Congratulations Andy, it sure it satisfying to get it to run well.
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Now I've got to finish running it in and also run the shaft in, my shaft is a Mobile Marine Models with bushes rather than bearings. I've allways used them with electric tugs and they are a good product.
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Congrats Andy--Welcome to the satisfying and frustrating world of steam!! She looks great :-))
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I'm now having problems getting the engine to self start again, finding it very tempermental, it will not self start when connected to the prop shaft, and the shaft is very free running, I guess the engine has had about 4 1/2 hours running now on steam. Even when free running the starting is hit and miss.
Andy
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Andy, apologies if I'm asking a stupid question but it's always worth airing all aspects with something like this. Not knowing how the crankshaft is constructed and whether it is solid or fabricated but I have to ask whether the two main piston cranks are 90 degrees apart?
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Richard, Yes the crank looks like its 90 degrees.
Something I just discovered is the pressure relief valve seems to lift at between 25 - 30psi on the gauge, I know these model size pressure gauges are not the most accurate, give or take, but it must be some where near, I have tightened it down a midges and got the engine to run longer, its still a bit lumpy one way though, I will visit John at Miskin models hopefully next week, thats where I bought the kit, he has one of his own and he said he would have a look at it. In the meantime I will try to get the pressure relief valve checked more accurately, there is one running on air on You tube at 40psi, it run for about 4 mins during the video without stopping, instant reverse and forwards as well, I think it could now be a combination of not enough pressure, and still slightly out on timing. On nights tonight so its off to bed for an hour.
Andy
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I have a feeling it's still the timing of the valves which is causing your engine to run roughly. There is a few other things that will cause the same types problems. I've seen worn out piston o-rings cause similar troubles in the past. In fact I've seen small pieces of the piston's o-rings break off and become lodged into the steam ports which has cause erratic running characteristics on some engines. If you wish, you could send the engine to us and we'll be happy to take a look at it and try to figure out what's wrong?
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Also check to see if the D valves are completely flat against the port faces. That's another reason why the engine could be losing power. It may only be running on one cylinder and letting steam leak out the other due to poor valve sealing. It's just another thought.
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UPDATE.
fine adjusted eccentrics one way and the other to find optimum position, then adjusted the sliders so that steam is let in to the top of the cylinders slightly earlier, wound the threaded push rod in 1/4 turn at a time, when running clockwise (forward), this was the lumpy direction, engine now running about the optimum, maybe slightly faster in reverse, will go one more 1/4 turn tomorrow to see if speed evens out, though if this is the optimum at the present setting I will be more than happy, self starting perfectly. Now know a lot more about steam engine timing than I did a fortnight ago, if this is it I will be happy, hopefully have the boat on the pond next week for steam maiden!. Andy
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Now fitted in launch, ran and operated on radio gear, still runs better one way than the other, (very marginally), but can live with that, may order a left handed prop, as thats the way it runs the best, or more fiddling with the timing, but I feel like I've done enough. It runs on absolute tick over lefthanded, and I mean slow, but when running clockwise the same speed it does tend to stop now and again, when I say slow I mean slow, probably 30rpm its hard to tell without a rpm counter.
One thing about this engine it does teach you very rapidly and thoroughly about the workings of a steam engine, i am very happy with the out come, and the engine looks a dream in the boat running, will try to post video on you tube some time. Any way more pics in my build thread.
Andy
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Bit late sorry but I have found this timing diagram quite useful in understanding....
http://homepages.rya-online.net/steamboat/anims01.htm (http://homepages.rya-online.net/steamboat/anims01.htm)
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Got mine run in to the point of just self-starting either way with a bicycle track pump and a soldered up rice pudding tin to act as a receiver. However my compressor arrived from RDG (Great people) yesterday and it is a lot easier!. Strange that RDG sell the quick release couplings but only with one tail fitting - Everything airbrush sell the tails separately and I recommend the ones for the aztec airbrushes as they have a 5mm female thread which you can drill out and silver solder in the sort of pipe diameter we use.