Pros/Cons Piston Valve and Balanced Slide Valve

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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cyberbadger
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by cyberbadger » Fri Nov 10, 2017 7:40 pm

DetroiTug wrote:Quote: "Some steam engines were not really designed to last that long. I have heard the figure 7 years was the average life of a steam traction engine."

That is not consistent with the level of workmanship that went in to these early engines, or anything I've ever read. It was anything but a throw-away society a hundred years ago. Look at how many of them exist until this day.
Well it was often that a boiler needed replacing before the engine. For boats/ships replacing a boiler is not such a big deal. For traction engines and locomotives the boiler formed part of the chassis, and you might as well get a new one at that point.
DetroiTug wrote: Quote: "Also remember during the eras of steam engines in general you have a lot of variety. Lubrication did not really exist as we know it. So quality was often poor."

Considering the majority of oil came from the Pennsylvania oil fields, regarded as oil of the highest quality, they had very good oil. I think you may be confusing Kerosene and Gasoline being low quality a hundred years ago when refining processes were not perfected.
Well this is a long time period I am talking about. There was a time when it was not uncommon for some steamships/boats to stink to high heaven from rotting vegetable and animal fat.

Quote: "lets be honest now - how many miles/year does the average steam boater today travel under steam? I thought I had a great first season with Nyitra this summer, and I estimate ~30miles for the whole summer."
DetroiTug wrote: I have often traveled farther than that in one day, we did close to 50 miles in one day. In New York we did 63 miles in three days and that was going through several locks and finishing up early in the afternoon - and too going slower at times to keep the group together.
So you have gone further in a day then me - what of it? How many miles/year? We are not running these engines day in and day out like they were.
DetroiTug wrote: Quote: "And we both use steam cylinder oil. But if you ask me, have you ever forgotten oil or ignored it for a while? - the answer is absolutely."

The answer is absolutely not. I will not run any of my engines without oil. I've ran out a few times under way and the Swift oiler can be shut off and filled under way which I did.
Yeah, I refill my swift under way too.
DetroiTug wrote: Quote: "Am I worried about this? A little, but not really. But I would never drive a modern i car with the oil light on - it's needs it much more."

What's the difference? An I/C engine is certainly a much more demanding mechanical operation, but why do some sliding metal surfaces need oil lubrication and others do not? The steam engine can be in a very poor state which would render an I/C engine inoperable and still run seemingly well. My car and boat will both run on very low pressures, the boat will run on 10 psi. The car will pull itself on around 50 psi, which is very low for a car. Neither have shown any sort of degradation of performance over time.
Now that I've kept the the drive ratio, I get similar performance. I the Toledo can turn the prop at 30psi. I'm not seeing degredation myself yet.

The different is "Something is better then nothing". Wet steam is not perfect as a lubricant, but you can get away with it for a long time.

-CB
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by DetroiTug » Fri Nov 10, 2017 9:09 pm

Quote: "Wet steam is not perfect as a lubricant, but you can get away with it for a long time."

In our small plants another thing that needs to be considered, the steam is not always wet. Have you heard your engine squeak when you throttle down? The valves and cylinders are bone dry at that point. If you're ok with that, carry on, I never want one of my engines to do that.

"The steam engine can be in a very poor state which would render an I/C engine inoperable and still run seemingly well." The rest of that is it will have lower power and consume more steam than it should.

Quote: " For boats/ships replacing a boiler is not such a big deal."

You need to call the Navy and tell them they are doing it wrong :) Torching out all those decks. A proper Firetube boiler is rarely replaced, they can be retubed many times.

-Ron
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by cyberbadger » Fri Nov 10, 2017 10:17 pm

DetroiTug wrote:Quote: "Wet steam is not perfect as a lubricant, but you can get away with it for a long time."

In our small plants another thing that needs to be considered, the steam is not always wet. Have you heard your engine squeak when you throttle down? The valves and cylinders are bone dry at that point. If you're ok with that, carry on, I never want one of my engines to do that.
Are you asking if I have heard my engine squeak when I throttle down? Not exactly to my knowledge, no. When I have squeeking I try to address it as best as I possibly can.

Keep in mind, I lubricate using what I believe is pretty good quality steam cylinder oil. Mostly continuous. So you're preaching to the choir if you are directing this at me.

But yes, with Nyitra's Boilers MAWP of 200PSI, I certainly do have to take more care with oil as I operate more in this range. I notice the difference between 150 and 175. Much more violent. That's why I have to improving the mounting situation for the engine....

-CB
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by DetroiTug » Sat Nov 11, 2017 12:58 am

That's a good boiler to hold that level of pressure on a 3X4 twin. Best I can do is 90 psi and that is with very good, very dry wood. The reason I'm switching to a big Ofeldt eventually. I may regret it but it gets a little old staring at the pressure gauge to see if my last firing or water take on was good or not, and not having extra steam if needed. I usually run around 70 psi.

-Ron
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by cyberbadger » Sat Nov 11, 2017 1:32 am

DetroiTug wrote:That's a good boiler to hold that level of pressure on a 3X4 twin. Best I can do is 90 psi and that is with very good, very dry wood. The reason I'm switching to a big Ofeldt eventually. I may regret it but it gets a little old staring at the pressure gauge to see if my last firing or water take on was good or not, and not having extra steam if needed. I usually run around 70 psi.
Thanks. Switching to dry well seasoned hardwood and the new spiral nozzle made a big difference for me. It's hard to exactly explain it, but the boiler can get into this "mode" at higher pressures were the self reinforcement of induced draft change the dynamic considerably - and it's like lets go go go! :) It's much easier to get from 150 to 200psi then 100 to 150psi right now.

-CB
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by Lionel Connell » Sat Nov 11, 2017 2:53 am

I am new here, and when I first started looking seriously at this forum there were 2 things that I found very strange. Firstly is that there are many many more people standing back and viewing a topic than there are people participating and contributing to the topic. Secondly, of the hundreds of people that have registered on this forum, there are really only about 20 people, that continuously get involved in the discussion. There is a very good reason for this phenomenon, too many people on this forum seem only interested in arguing down anything that is posted, and all that they are achieving is to convince everybody else that participating is just not worth the trouble. I would suggest that some people here should spend some time looking at the discussion on the model engineering and model steam loco forums, you will find just as many differing points of view, but the way in which people respond to each other is far more polite than I am seeing here.

Oil in steam engine cylinders....................

Not only were small steam ships successfully run without cylinder oil, they were run with seawater in the boiler and without cylinder oil for quite a number of years. During this period it was believed that cylinder oil caused more problems than it solved. However, they ran their boilers at 60PSI or less. It was only after the discovery that running on super heated steam and higher pressures was more efficient that they found it necessary to use cylinder oil. At very low temperatures and pressures, and with suitably wide piston rings and using slide valves with large bearing surface areas, water was a sufficiently good lubricator when used in conjunction with cast iron that had a very high graphite content.

Steam plants that were run in this manner needed to be run everyday in order to avoid corrosion, so when in port the boilers needed to be kept hot and the engines run for a short time everyday. The salt that collected in the boiler needed to be blown down many times per day. This is not suitable for a hobby steam boat, but it can be done and was done. Running steam cylinders without oil is definitely not confined to hobby steam boaters, and anybody that has spent time reading technical steam engineering books that were written one hundred years ago will know that there have been millions of word printed in technical journals describing exactly how to set up a ships steam engine to run without cylinder oil.

These ship engines ran for thousands of hours and needed to have their crankshaft, conrod, and cross head bearings that were running in oil changed many times more often than the cylinders, pistons or rings that ran without oil needed maintenance.

When somebody quotes a steam engine method that was used one hundred years ago, remember this, 100 years ago was at nearer the end of reciprocating marine steam engine development. There were many methods used before that time that worked successfully and would be more than adequately for the hobby steam boater of today to replicate and use to have fun sailing their boat.

Arguing to the point where there is nobody left interested in listening is not a successful outcome, and that is the course that this forum seems to be sailing on.

Cyberbadger, I have great admiration for your persistence and patience. Keep the good posts coming.

cheer, Lionel
Last edited by Lionel Connell on Sun Nov 12, 2017 4:39 am, edited 1 time in total.
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by DetroiTug » Sat Nov 11, 2017 12:46 pm

I think we have very good educational discussions here and for discussion on full scale steam equipment in a very small niche area of interest, this forum is very active by comparison. When I first joined this forum about 10 years? ago (it was on another domain), there were only about 2 or 3 active contributors and it went weeks without posts occasionally. That's not the case now. The owner of this forum has received awards from the SBA for creating it and it's success. Steamboating discussion boards have been tried elsewhere around the web and most have largely failed. Not because people disagreed with one another, it's because the discussion was not interesting to anyone and it died.

We each have opinions on different aspects of the subject through actual practice and/or historical reference. Through offering a sometimes opposing viewpoint and examining each of those opinions, interest level is maintained and much is learned by all.

Yes, Back to the oil in the cylinders topic. Ships were set up to run with no cylinder oil and seawater in the boiler. Seawater in the boiler destroyed it in a very short time period and no one would do that today. Bill Durham wrote on that very subject and claimed that he had known of boilers destroyed in as little as six months running sea water. I have no written account of it, but I'm certain it was discovered that introducing continual oil (SCO Steam Cylinder Oil with Tallow or just Tallow) in to the steam line vastly improved the longevity and performance of the engine and was an adopted widespread practice, just as boiler water quality maintenance is today vs seawater.

My opinion has been formed by lots of reading, observation and discussion with others involved in the hobby, the conclusion I've came to is, yes, a steam engine can be ran without oil, but it will run much longer with oil.

-Ron
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by fredrosse » Sat Nov 11, 2017 2:10 pm

Lionel Connell provided a good comment about the apparent conflicts on this forum, and replies countered that healthy discussion is present, rather than constant "hissing" contests that one can find on numerous other forums. Yes, there have been a few "hissing" exchanges on the forum, but far far less than on other websites.

With respect to so many members standing back and not joining in on the technical comments, I think that is a good thing. Other forums have so many misinformed opinions presented that the technical information gets lost in a morass of confusion. With the technical and safety implications of high pressure steam plants, better to have the knowledgeable people giving replies.

One statement from Lionel I found difficulty with, "So far I have not come across anybody here that is running a successful business building and selling steam engines or steam boats for a living, so nobody here can claim to be a professional."

In fact, there are several, perhaps many, forum members with legitimate claims to have the relevant knowledge here, and several make a living building or repairing steam machinery, and/or steamboats. However, having a successful business building or selling steam engines/boats does not necessarily form the qualifier for technical knowledge.

I am a steam engineer, have worked with steam plants since the early 1960's, and steam power is still my full time day job. I love steam power, it has been my technical passion since the early 1950's. I have even built a coal fired automatic unattended steam electric plant to power, and heat my house. I collect hundreds of 19th century engineering books, most of which devote the majority of their pages to steam power. I have built a few steamboats, many steam engines, and have served on many US flag steamships.

I try to only comment on subjects which I have proper knowledge, and try to follow the rule that, if a professional engineer makes a statement as fact, it is taken as fact, and if an expert thinks something might happen, then the person should say "I think it may turn out this way", then it is properly taken as an opinion.

When I read a statement here that is clearly incorrect, I usually make a comment about it, especially when it is in reference to potential steam safety issues. When someone is just being hard-headed and presenting misinformed argument after argument about something which he (or she) does not understand, it will make contributing far less productive.

In my view this forum functions well, with members asking questions, being given answers that are valuable, without much in the way of personal difficulties. Of course, that is only my opinion.
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by fredrosse » Sat Nov 11, 2017 2:44 pm

"Back to the oil in the cylinders topic"

It has been the subject of very many well financed engineering studies to eliminate oil in reciprocating engine cylinders, which eventually finds its way into feedwater, due to the big difficulties of oil in boilers.

The most relevant information here comes from the largest fleet of reciprocating engine steamships, built with the highest level of knowledge for steam reciprocating machinery. This is the 2700 nearly identical Liberty Ships built during WWII. While steam turbines dominated naval ships, the shortage of steam turbine manufacture forced the building of these thousands of reciprocating triple expansion steamers.

While it is often quoted that these ships ran without oil cylinder lubrication, that is not actually correct. Yes, with ideal conditions cylinder oil could be reduced to a trifle, but every Liberty Ship fed oil to cylinders on occasion, and every Liberty Ship had an elaborate filter system to prevent oil in the steam condensate getting into the boilers.

I have tried to run my steamer with no cylinder oil, and even though I have very nearly ideal conditions according to literature (low speed, 60 RPM, nearly balanced valves, graphite impregnated rings and seals, 70 PSI wet low pressure steam) the engine gets very unhappy without lubrication. The rock shafts start to groan and use up much power just forcing the valve gear to move. To use another old saying that reflects my opinion here.... "I have heard if basements that are dry, but I ain't never seen one"
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Re: Pros/Cons Piston Valve and Balanced Slide Valve

Post by DetroiTug » Sat Nov 11, 2017 3:16 pm

Quote: "It has been the subject of very many well financed engineering studies to eliminate oil in reciprocating engine cylinders"

One in particular recently that spent ten years and 64 Million dollars trying to develop a modern oil-less steam engine and every design change and material tested has been unsuccessful for long service life. Research "Cyclone Power Technologies". There is understandable and substantial outrage on the web because many investors lost their money, but at the root of it and in between the hoopla and disparaging commentary, there was a legitimate effort to achieve their goals, and they had engineering departments of highly regarded universities and some very sharp folks contributing to the effort, The late Jim Crank who worked with the Besler Brothers and the foremost authority on White and Doble steamplants for one. He was the guy Jay Leno called when they couldn't fix one of their steamcars. Jay Leno spoke highly of him in one of his videos. Referred to him as the "guru".

-Ron
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