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Steam pressure in engine
Posted by: Mike Clark (IP Logged)
Date: July 26, 2004 07:46PM
<HTML>I’m just putting the H engine back into the car after replacing the broken frame rods and changing over to my new block The Highway speed thread, and particularly David’s last post giving the steam temperature made me think about what pressure is found in the engine and how to measure it.
My frame rod gave out when going very slowly up a 20% grade, just the conditions which I would expect to produce the maximum pressure in the engine, maybe even near to boiler pressure. Obviously the rod was fatigued and ready to let go but it was the heavy load which finally broke it.
Question is should I reduce boiler pressure to say 400psi from 600 to climb this hill and would this be easier on the engine? Or does cylinder pressure never get near boiler pressure? Obviously the cylinder pressure buiIds up with the load to the point where the car moves and thereafter depends on load, speed, and throttle opening as well as boiler pressure. I should say I can’t avoid the hill which is just before my house!
To measure the pressure I am thinking of connecting a gauge in the oil feed line between the winker and the steam pipe. This would give a higher reading than in the steam chest but has the advantage that the pipe would not need to flex with engine movements and does not need another connection into the steam pipe. It would also assure me, in a more certain way than the winker, that the oil line was not blocked as the pressure would vary with the throttle opening and also presumably with the load on the engine.
This won't tell me the actual pressure in the cylinders but it should give an idea of what it gets to and how the load on the engine varies.
Has anyone tried this? Does it need something to damp pulsations or a restricter? It will be interesting anyway.
Mike</HTML>
My frame rod gave out when going very slowly up a 20% grade, just the conditions which I would expect to produce the maximum pressure in the engine, maybe even near to boiler pressure. Obviously the rod was fatigued and ready to let go but it was the heavy load which finally broke it.
Question is should I reduce boiler pressure to say 400psi from 600 to climb this hill and would this be easier on the engine? Or does cylinder pressure never get near boiler pressure? Obviously the cylinder pressure buiIds up with the load to the point where the car moves and thereafter depends on load, speed, and throttle opening as well as boiler pressure. I should say I can’t avoid the hill which is just before my house!
To measure the pressure I am thinking of connecting a gauge in the oil feed line between the winker and the steam pipe. This would give a higher reading than in the steam chest but has the advantage that the pipe would not need to flex with engine movements and does not need another connection into the steam pipe. It would also assure me, in a more certain way than the winker, that the oil line was not blocked as the pressure would vary with the throttle opening and also presumably with the load on the engine.
This won't tell me the actual pressure in the cylinders but it should give an idea of what it gets to and how the load on the engine varies.
Has anyone tried this? Does it need something to damp pulsations or a restricter? It will be interesting anyway.
Mike</HTML>
Re: Steam pressure in engine
Posted by: Jeff Theobald (IP Logged)
Date: July 26, 2004 09:42PM
<HTML>Hi Mike,
On the later cars this is the method of indicating that the oiler is working, athough not marked in psi. usually marked as OIL ON or CYLINDER LUBRICATION, it is just a pressure gauge in the oil line, it pulses as oil is pumped into the steam pipe, with a different reading depending on amount the regulator is opened, there does not seem to be any form of damping, Jeff.</HTML>
On the later cars this is the method of indicating that the oiler is working, athough not marked in psi. usually marked as OIL ON or CYLINDER LUBRICATION, it is just a pressure gauge in the oil line, it pulses as oil is pumped into the steam pipe, with a different reading depending on amount the regulator is opened, there does not seem to be any form of damping, Jeff.</HTML>
Re: Steam pressure in engine
Posted by: Andy Patterson (IP Logged)
Date: July 26, 2004 10:08PM
<HTML>HI Mike
From a physics point of view. The torque produced by your engine going up an incline is dependent on the incline and acceleration. To maintain speed you only need to produce enough torque to over come air drag, rolling resistance and pull of gravity produced by the incline. Torque above that produces acceleration. As you describe it acceleration is not involved here.
Sense you have specific hook up points that remain fixed regardless of boiler pressure. Boiler pressure shouldn't make much differance.
However using shorter non overlaping cutoff might allow pressure build up in the steam chest producing a good punch when the inlet opens and at TDC were the mechanical advantage is the lowest a high stress load could be put on the engine. Damping these palsations would hide the problem. I suppose a pressure gage could be made to have rebound damning averaging the peak pressure.
Best to be running long overlaping cutoff in such a situation.
Andy</HTML>
From a physics point of view. The torque produced by your engine going up an incline is dependent on the incline and acceleration. To maintain speed you only need to produce enough torque to over come air drag, rolling resistance and pull of gravity produced by the incline. Torque above that produces acceleration. As you describe it acceleration is not involved here.
Sense you have specific hook up points that remain fixed regardless of boiler pressure. Boiler pressure shouldn't make much differance.
However using shorter non overlaping cutoff might allow pressure build up in the steam chest producing a good punch when the inlet opens and at TDC were the mechanical advantage is the lowest a high stress load could be put on the engine. Damping these palsations would hide the problem. I suppose a pressure gage could be made to have rebound damning averaging the peak pressure.
Best to be running long overlaping cutoff in such a situation.
Andy</HTML>
Re: Steam pressure in engine
Posted by: Ben in Maine (IP Logged)
Date: July 26, 2004 10:52PM
<HTML>Hi,,,Seems to me,,,not all F engines have cutoff!! The F engine is used in the H car,,,Has annyone seen one marked H next to the # no,,on the engine frame bar?? At tdc the strain is straight,,,the problem occurs as the crank and rod get crossed up and twist the frame,,,good place for Daves brace plates,,that if there is room for them,,,While the exhaust will not give you a pressure number,,the sound is a pretty good indication of whats going on,,,woosh woosh,,,cold engine condensing in the cylenders,,,chif chiff,,,now thats better,,,avoid blue SMOKE in the exhaust,,,,{got a fire in the steamchest] [burnin off excess O/2 ] gotya thinkin again haha ,,,Cheers Ben,,,,Still dont like juce brakes,,cb ,,,,,,p/s the guage in the oil line wont pulse 'cause theres a check at the entry to the steamline [or should be] it looks like a regular fitti'n 'cept its got a smalltiny grove around,,,easy to not see it,,,,The pulse will be that only of the oil pump I think,,,Sorry about the ramble,,,,its late,,BEN</HTML>
Re: Steam pressure in engine
Posted by: Graeme Vagg (IP Logged)
Date: July 26, 2004 11:12PM
<HTML>Mike,
You should not be able to break new rods with any steam pressure up to 600 psi. A pressure gauge anywhere downstream oif the throttle valve will show you the maximum pressure the cylinders can receive. At high flow rates the actual maxium pressure in the cylinder will be a little less due to friction losses, but it will not be higher. If you want to play safe use a lower boiler pressure and long cut off.
All ther best,
Graeme</HTML>
You should not be able to break new rods with any steam pressure up to 600 psi. A pressure gauge anywhere downstream oif the throttle valve will show you the maximum pressure the cylinders can receive. At high flow rates the actual maxium pressure in the cylinder will be a little less due to friction losses, but it will not be higher. If you want to play safe use a lower boiler pressure and long cut off.
All ther best,
Graeme</HTML>
Re: Steam pressure in engine
Posted by: Ben in Maine (IP Logged)
Date: July 27, 2004 01:23AM
<HTML>Hi,,,If you put the engine in good shape,,perhaps it will last another 90 years,,,perhaps not,,so what,,,fix it again,,,,, ,,,,,Lowering the pressure will lower the saturated temperature,,,the steam temp into the superheater will be less,,,,it will come out at a lower temperature TOO ,,, lower everything,,,,,now the water rate goes up,,,more water needed,,,more fire too,,,yes it will run,,,,but that is where the highway speed thread says a lot about what can be done w /maintinin a 90 year old car,,,,Steam is a careful balence of physics,,,and Roper was the first of my knowledge to make it lightweight,,,,,that 1895 bicycle weighed about 100# and had light bike wheels,,,not big ones,,tho the spokes were all solderd together to take out the flex,,,solderd at the crossings,,,Cheers Ben</HTML>
Re: Steam pressure in engine
Posted by: George Nutz (IP Logged)
Date: July 27, 2004 10:27AM
<HTML>Mike,
We have put steam chest pressure gauges on several cars up here and it is a better indication of what is getting past the Stanley very restrictive throttle. At low speeds on a steep hill it get closer to boiler pressure but actually gets there under a static test. The faster one goes the lower the pressure to the steam chest due to increased throttling. A heavy condensing Stanley only requires 100-120PSIG to use all its steam running down the road at 35-40mph. Only on Coburn's Vanderbilt, with its huge throttle, have we seen near boiler pressure at the steam chest. The valves are very restrictive and at any speed the actual pressure in the cylinders iss quite a bit lower than at the steam chest. Agree with Coburn, keep the boiler pressure at 600 and have more reserve for climbing hills. 400PSIG would be easier on the engine but performance would suffer terribly. Never slam the throttle open at standstill or very low speeds--that is your biggest time to twist and break a framerod, open gradually. Also as Ben stated the maximum twisting force on the framerods is with a crank angle near 90 degrees as it is the crosshead force that imparts a very large side/twisting force on the framerods. I believe most of the cars I have worked on have the thermocouple at where the steampipe enters the engine steamchest.
George</HTML>
We have put steam chest pressure gauges on several cars up here and it is a better indication of what is getting past the Stanley very restrictive throttle. At low speeds on a steep hill it get closer to boiler pressure but actually gets there under a static test. The faster one goes the lower the pressure to the steam chest due to increased throttling. A heavy condensing Stanley only requires 100-120PSIG to use all its steam running down the road at 35-40mph. Only on Coburn's Vanderbilt, with its huge throttle, have we seen near boiler pressure at the steam chest. The valves are very restrictive and at any speed the actual pressure in the cylinders iss quite a bit lower than at the steam chest. Agree with Coburn, keep the boiler pressure at 600 and have more reserve for climbing hills. 400PSIG would be easier on the engine but performance would suffer terribly. Never slam the throttle open at standstill or very low speeds--that is your biggest time to twist and break a framerod, open gradually. Also as Ben stated the maximum twisting force on the framerods is with a crank angle near 90 degrees as it is the crosshead force that imparts a very large side/twisting force on the framerods. I believe most of the cars I have worked on have the thermocouple at where the steampipe enters the engine steamchest.
George</HTML>
Re: Steam pressure in engine
Posted by: Mike Clark (IP Logged)
Date: July 27, 2004 08:26PM
<HTML>Thanks everyone - pretty much what I thought - specially your post George. I'll put a gauge on and report back.
The engines I have are F525 and F826 - 1907 and 1908 I guess. The 08 had a hookup when I got it but the 07 did not but has been retro-fitted. This is the one I have been using and I alway use long cut-off up the dreaded hill.
I expect to get it back together in a few days and have great hopes that it will be OK for the next 90 years. Probably see me out at least. I used 4340 steel for the new frame rods. I upped the size to 7/8" from the crank to the block and was able to shorten the threaded length at the other end. Also put some bracing between the cross head brackets.
When I've tried it I will post some pictures so you can see how it was done. It looks much more substantial than before.
Mike</HTML>
The engines I have are F525 and F826 - 1907 and 1908 I guess. The 08 had a hookup when I got it but the 07 did not but has been retro-fitted. This is the one I have been using and I alway use long cut-off up the dreaded hill.
I expect to get it back together in a few days and have great hopes that it will be OK for the next 90 years. Probably see me out at least. I used 4340 steel for the new frame rods. I upped the size to 7/8" from the crank to the block and was able to shorten the threaded length at the other end. Also put some bracing between the cross head brackets.
When I've tried it I will post some pictures so you can see how it was done. It looks much more substantial than before.
Mike</HTML>
Re: Steam pressure in engine
Posted by: George Nutz (IP Logged)
Date: July 27, 2004 08:44PM
<HTML>Thanks Mike,
If you are using 4340 the engine will twist as much with the same diameters(as the steels have the same Modulus of Elasticity) but should last 90 years, so much stronger than the original steel rods. The increase in frame rod diameter will decrease the torsional twisting as a function of the ratio of the diameters to the fourth power, in your case a very wise move. Keep the pressure up.
Let us know how it turns out!
Best, George</HTML>
If you are using 4340 the engine will twist as much with the same diameters(as the steels have the same Modulus of Elasticity) but should last 90 years, so much stronger than the original steel rods. The increase in frame rod diameter will decrease the torsional twisting as a function of the ratio of the diameters to the fourth power, in your case a very wise move. Keep the pressure up.
Let us know how it turns out!
Best, George</HTML>
Re: Steam pressure in engine
Posted by: ted pritchard (IP Logged)
Date: July 28, 2004 07:27AM
<HTML>Hullo,
I guess I am a member of the club that has had a Stanley break one of it's frame rods. [many years ago!] We replaced it with like I guess you other guys did - with a new 55 ton steel replacement.
Here is one tip that could be useful- Re cutting the threads - We used a radius at the bottom of the thread like the Whitworth thread. Beware of the classic American thread with a little flat at the bottom of the thread with sharp corners where the flat joins the sides of the "Vee." The originals may have included the sharp corners which give you a higher stress concentration than the radius does. Used to use a lot of throttle in my young days! - We obtained 35% gravity acceleration as measured with a Tapley acceleration meter.
Best Wishes,
Ted Pritchard</HTML>
I guess I am a member of the club that has had a Stanley break one of it's frame rods. [many years ago!] We replaced it with like I guess you other guys did - with a new 55 ton steel replacement.
Here is one tip that could be useful- Re cutting the threads - We used a radius at the bottom of the thread like the Whitworth thread. Beware of the classic American thread with a little flat at the bottom of the thread with sharp corners where the flat joins the sides of the "Vee." The originals may have included the sharp corners which give you a higher stress concentration than the radius does. Used to use a lot of throttle in my young days! - We obtained 35% gravity acceleration as measured with a Tapley acceleration meter.
Best Wishes,
Ted Pritchard</HTML>
Re: Steam pressure in engine
Posted by: George Nutz (IP Logged)
Date: July 28, 2004 10:24AM
<HTML>Yup,
So right on---rolled threads would be the strongest. If these oversize rods are stepped down from their 7/8" diameter for the threads make sure to have fillets/radius's on the step down as well or there will be a stress concentration factor at that point(where there is much stress already). Remember the article you wrote many years ago on the family Stanley and increasing the steam temperature by 50F??? nearly doubled the performance of the car.
It would bew nice to find that article and read it again.
George</HTML>
So right on---rolled threads would be the strongest. If these oversize rods are stepped down from their 7/8" diameter for the threads make sure to have fillets/radius's on the step down as well or there will be a stress concentration factor at that point(where there is much stress already). Remember the article you wrote many years ago on the family Stanley and increasing the steam temperature by 50F??? nearly doubled the performance of the car.
It would bew nice to find that article and read it again.
George</HTML>
Re: Steam pressure in engine
Posted by: David K. Nergaard (IP Logged)
Date: July 28, 2004 11:44AM
<HTML>When I climbed Mt. Washington in 1999, I had a stem chest pressure gauge fitted. In normal driving on good roads 100-125 psi. at the engine was sufficient to maintian 35 mph. with my HEAVY 1922 condensing Stanley. On grades, the pressure went up a bit, seldom exceeding 150.
On the mountain, it needed 400-450 psi. at the engine in short cutoff to maintain 10-15 mph. on most of the road. The steepest part, a 22% grade, required 450 psi. at the engine in long cutoff.
This was very hard on the heavy type 7 Stanley engine. I had several parts fail in the following two years, from fatigue cracks that could well have started during the climb. On the earlier type 3 (20 hp. engines), I suspect failure would have been immediate.</HTML>
On the mountain, it needed 400-450 psi. at the engine in short cutoff to maintain 10-15 mph. on most of the road. The steepest part, a 22% grade, required 450 psi. at the engine in long cutoff.
This was very hard on the heavy type 7 Stanley engine. I had several parts fail in the following two years, from fatigue cracks that could well have started during the climb. On the earlier type 3 (20 hp. engines), I suspect failure would have been immediate.</HTML>
Re: Steam pressure in engine
Posted by: Caleb Ramsby (IP Logged)
Date: July 28, 2004 06:20PM
<HTML>George,
If you are talking about Ted Pritchard's SAE article it is at:
[www.pritchardpower.com]
A very informative article indead!
Caleb Ramsby</HTML>
If you are talking about Ted Pritchard's SAE article it is at:
[www.pritchardpower.com]
A very informative article indead!
Caleb Ramsby</HTML>
Re: Steam pressure in engine
Posted by: George Nutz (IP Logged)
Date: July 28, 2004 07:04PM
<HTML>Caleb,
Thanks so much for the Prichard link. The article I remember was in "The Steam Automobile" or one of the club publications back then. Similar stuff however. Wonderful work done back then!
Thanks, George</HTML>
Thanks so much for the Prichard link. The article I remember was in "The Steam Automobile" or one of the club publications back then. Similar stuff however. Wonderful work done back then!
Thanks, George</HTML>
Re: Steam pressure in engine
Posted by: ted pritchard (IP Logged)
Date: July 28, 2004 10:20PM
<HTML>Hi again,
Thanks guys for your kind comments. Yes Caleb - there are some steam car stories on the reference you give. There are more stories coming further up-to-date on my web site- www.pritchardpower.com reached via the home pages under the heading - "Achievements" - "Experiences on the road. - Highlights and Lowlights!"
Stanley's design, stressing etc did seem a bit courageous. However, I must say that when we first looked at the Stanley engine I had many years ago, - the one that had a broken frame rod,- the engine had been set up very badly - motion out of line, crosshead lucky to be bearing on one quarter of its area. This would not have helped and could have contributed to the breakage. We then reconditioned the engine.
Best Wishes,
Ted Pritchard</HTML>
Thanks guys for your kind comments. Yes Caleb - there are some steam car stories on the reference you give. There are more stories coming further up-to-date on my web site- www.pritchardpower.com reached via the home pages under the heading - "Achievements" - "Experiences on the road. - Highlights and Lowlights!"
Stanley's design, stressing etc did seem a bit courageous. However, I must say that when we first looked at the Stanley engine I had many years ago, - the one that had a broken frame rod,- the engine had been set up very badly - motion out of line, crosshead lucky to be bearing on one quarter of its area. This would not have helped and could have contributed to the breakage. We then reconditioned the engine.
Best Wishes,
Ted Pritchard</HTML>
Re: Steam pressure in engine
Posted by: ted pritchard (IP Logged)
Date: July 30, 2004 09:36PM
<HTML>P.S. Can I add a postscript? What helped achieve the acceleration of 35% G on a Tapley meter was that my 20 HP Stanley with 4 in bore by 5 in stroke engine, was not the heaviest model. Weighbridge figure was 1.7 tons and somebody called it the 5 passenger model [rather than 7 pass?] Although it had the full 10 ft 10 in wheelbase. Engine no was 740 3887.
Best Wishes,
Ted Pritchard</HTML>
Best Wishes,
Ted Pritchard</HTML>
Re: Steam pressure in engine
Posted by: Mike Clark (IP Logged)
Date: July 31, 2004 07:40PM
<HTML>David,
Thanks for the info. on your Mt Washington climb - pressures at low speed on steep hill are very much as I guessed.
George,
Yes I put a nice fillet radius at the transition from 3/4 to 7/8 and used a spacer to avoid having to bevel out the crankshaft bearing housings.
The 3/4 inch rod is unthreaded right through the bearing thousing to a point about 1 1/2 inches away from the other side of the bearing where a sleeve nut engages the thread. The sleeve portion is a good fit on the plain 3/4 rod and butts up to the bearing. This way the threaded length can be reduced to the minimum and the highly stressed part going through the crank bearing is not threaded and is, for the 1 1/2 inch length, also stiffened up by the sleeve nut.
I'll post a picture.
Mike</HTML>
Thanks for the info. on your Mt Washington climb - pressures at low speed on steep hill are very much as I guessed.
George,
Yes I put a nice fillet radius at the transition from 3/4 to 7/8 and used a spacer to avoid having to bevel out the crankshaft bearing housings.
The 3/4 inch rod is unthreaded right through the bearing thousing to a point about 1 1/2 inches away from the other side of the bearing where a sleeve nut engages the thread. The sleeve portion is a good fit on the plain 3/4 rod and butts up to the bearing. This way the threaded length can be reduced to the minimum and the highly stressed part going through the crank bearing is not threaded and is, for the 1 1/2 inch length, also stiffened up by the sleeve nut.
I'll post a picture.
Mike</HTML>
Re: Steam pressure in engine
Posted by: Peter Brow (IP Logged)
Date: August 03, 2004 10:15PM
<HTML>Hi Mike,
Well done! These caused at least one admiring whistle out here in California. :)
Peter</HTML>
Well done! These caused at least one admiring whistle out here in California. :)
Peter</HTML>
Re: Steam pressure in engine
Posted by: Mike Clark (IP Logged)
Date: August 04, 2004 07:43PM
<HTML>Refitted the engine to the car today - quite a bit of fiddling needed to adapt various things like engine case and my drip feed lubrication system to the thicker frame rods. Its a dry engine remember.
You may have spotted that I would need to alter the crosshead brackets as well - a bit of head scratching led me to make new ones which have an up and down bar each side as well as the cross bars. They were profile cut in one piece from 7/8 plate with all holes and the four lugs for the crosshead slides built in. The front one has a bar across the middle into which plain bronze valve guides are screwed, thus eliminating the cast bronze guide unit and doing away with the need for the 3/8 tie bolts which I never could keep from unscrewing.
All this has gone together with my new cylinder block and has given me a much more solid engine which although not original actually looks very"Stanley". I am keeping my second original engine on one side as a museum piece and will be using the beefed up one to save using up more fragile original bits.
I still have to prove it works so will not put pictures on the site yet!
Mike</HTML>
You may have spotted that I would need to alter the crosshead brackets as well - a bit of head scratching led me to make new ones which have an up and down bar each side as well as the cross bars. They were profile cut in one piece from 7/8 plate with all holes and the four lugs for the crosshead slides built in. The front one has a bar across the middle into which plain bronze valve guides are screwed, thus eliminating the cast bronze guide unit and doing away with the need for the 3/8 tie bolts which I never could keep from unscrewing.
All this has gone together with my new cylinder block and has given me a much more solid engine which although not original actually looks very"Stanley". I am keeping my second original engine on one side as a museum piece and will be using the beefed up one to save using up more fragile original bits.
I still have to prove it works so will not put pictures on the site yet!
Mike</HTML>
Re: Steam pressure in engine
Posted by: David K. Nergaard (IP Logged)
Date: August 08, 2004 10:14AM
<HTML>Mike, When you are satisfied with the "new" engine, would you write it up for the SACA Bulletin? Please.</HTML>
Re: Steam pressure in engine
Posted by: Mike Clark (IP Logged)
Date: August 08, 2004 08:20PM
<HTML>David,
Yup!
Mike</HTML>
Yup!
Mike</HTML>
Re: Steam pressure in engine
Posted by: David K. Nergaard (IP Logged)
Date: August 11, 2004 11:12AM
<HTML>Thanx, Mike. I await your pleasure.</HTML>
Re: Steam pressure in engine
Posted by: Mike Clark (IP Logged)
Date: August 11, 2004 06:50PM
<HTML>Ran it today for the first time - just a few yards to check for steam leaks before fitting the engine case - seems to be spot on. It will "tick over" very smoothly and slowly with the wheels jacked up with just a slight click from the differential bevels, otherwise silent.
Mike</HTML>
Mike</HTML>
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