1 Steam Cars : Phorum
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crankshaft construction
Posted by: Peter Heid (IP Logged)
Date: February 11, 2002 08:07PM
<HTML>To All:
Do any steam engines use crankshafts that are pressed together assemblies such as the modern two cycle engine ? Does anyone have any experience in this direction ? I know you can't make a more compact crankshaft by any other means and pieces are available individually for many makes and sizes of engine. Also the connecting rod crank pin can be located anywhere in the crank cheek by boring a pin hole as necessarry, allowing custom strokes and crank pin spacing. These crankshafts have stood up to the tests of time and are quite reliable even in 300 HP, 1200 CC, V4 configuration. They generally use dual ball bearings on each main journal and needle bearings on the rod journal.
It would be nice if off the shelf parts could be used for this critical & expensive part.
Thanx
Peter Heid</HTML>
Do any steam engines use crankshafts that are pressed together assemblies such as the modern two cycle engine ? Does anyone have any experience in this direction ? I know you can't make a more compact crankshaft by any other means and pieces are available individually for many makes and sizes of engine. Also the connecting rod crank pin can be located anywhere in the crank cheek by boring a pin hole as necessarry, allowing custom strokes and crank pin spacing. These crankshafts have stood up to the tests of time and are quite reliable even in 300 HP, 1200 CC, V4 configuration. They generally use dual ball bearings on each main journal and needle bearings on the rod journal.
It would be nice if off the shelf parts could be used for this critical & expensive part.
Thanx
Peter Heid</HTML>
Re: crankshaft construction
Posted by: David K. Nergaard (IP Logged)
Date: February 11, 2002 08:19PM
<HTML>All Stanley crankshafts were made by pressing center gears and cranks onto the shaft, with a long key to establish alignment during assembly.</HTML>
Re: crankshaft construction
Posted by: George K. Nutz (IP Logged)
Date: February 11, 2002 08:56PM
<HTML>Peter,
Pressed crankshafts are very good for engines that do not have a huge torque applied to them. A local motorcycle/snowmobile shop have seen slippage on souped up engines that are of relatively low torque but 12-14K rpm. The old Saab three cylinder crankshaft used very high press fit forces, an engineer friend at MIT used to rebuild them and said he needed a 50 ton press to work on them. The webs would have to be of a very high yield strength as to not yield with two pins (main and con-rod) were pressed fairly close together and the pins very high yield as well---then there is the factor of stress concentration where the pin suddenly leaves the web and the long term factor of stress fatigue. Certainly useful for a boat engine but rather tough for a car starting on a hill under full torque(pressure). The local shop, that makes these snowmobiles that blow the doors off a Corvette in 1/4 mile time, say they use a special kind of welding of high penetration and little heat to hold them together---not to be taken apart. The Marks engineering handbook give formulas for all of this and the maximum torque for slippage. Make a higher rpm, lower torque steam engine to produce the same horsepower and it would probably be OK---like them myself--- your message reminds me to get back to my 3 cylinder pressed crank boat engine again.
Best, George</HTML>
Pressed crankshafts are very good for engines that do not have a huge torque applied to them. A local motorcycle/snowmobile shop have seen slippage on souped up engines that are of relatively low torque but 12-14K rpm. The old Saab three cylinder crankshaft used very high press fit forces, an engineer friend at MIT used to rebuild them and said he needed a 50 ton press to work on them. The webs would have to be of a very high yield strength as to not yield with two pins (main and con-rod) were pressed fairly close together and the pins very high yield as well---then there is the factor of stress concentration where the pin suddenly leaves the web and the long term factor of stress fatigue. Certainly useful for a boat engine but rather tough for a car starting on a hill under full torque(pressure). The local shop, that makes these snowmobiles that blow the doors off a Corvette in 1/4 mile time, say they use a special kind of welding of high penetration and little heat to hold them together---not to be taken apart. The Marks engineering handbook give formulas for all of this and the maximum torque for slippage. Make a higher rpm, lower torque steam engine to produce the same horsepower and it would probably be OK---like them myself--- your message reminds me to get back to my 3 cylinder pressed crank boat engine again.
Best, George</HTML>
Re: crankshaft construction
Posted by: coburn benson (IP Logged)
Date: February 12, 2002 04:12AM
<HTML>With the torque on a Stanley crank and its size we still see failures [S ] plural,,,When the piston comes disconnected [this only seems to happen w/full head of steam] the piston attempts to kill the front axle,,,,AND you rrreally should NOT safely hide behind said axle haha,,,IF it happens on the down stroke it tangles w/ awhole bunch of even more expensive stuff,,,,,ths is why the owners handbook says to go gently,,,w/care,,,,,But its fun,,,I have found the fun has its price and if youre gonna race ,,BE prepared to pay the fat lady OR the piper,,,Personally,,,er aaaah oh well The whole engine is marginal,,but it gets the job done,,I THINK,,,,,,,OR ARE there enough sports out there to make it worth wile to make a competition engine??? XXXXXXX I have seen a pressd crankpin work in a steel flywheel ,,Polish the hole,,AND it was assembled w/.003 press w/a nut to hold it[Vincent--500] we raced it,,It was fine if we were in 4th place but to to 2nd ,a lot of things became flexable,,ie /crankpin etc After all,I think the useage will dictate the $ put into the mods and the details,, and it still will not be bullet proof,,NOW have we got it together how we're gonna get this monster STOPPED ! ! !I dont think hooking the beake pedal to the reverse will do the trick,,an seat belts ,,,probably not either,,Daytona 2005 is comming soon,,who can we tease to get their gas cars ready,,They'rs no fun to race alone Cheers Ben</HTML>
Re: crankshaft construction
Posted by: Rolly Evans (IP Logged)
Date: February 12, 2002 10:18AM
<HTML>I have used built up crankshafts for years on marine steam engines. They are not subject to the torque of automobiles. I use a split web with a cross bolt. The main shaft is keyed. This system has worked very well for me. Others I know have pressed them together and welded as well, then they have them grounded. You can see a photo of one of my crankshafts on my web site. The page the shaft is on is
[ourworld.cs.com];
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Re: crankshaft construction
Posted by: coburn benson (IP Logged)
Date: February 12, 2002 01:25PM
<HTML>If you use a press fit ,, the welding in close proximity will stress relieve the area and the interference is lost,,,Anything over .003 will re size the hole!!Anything under .001 will fall apart before the 3rd corner ,,MAYBEE ok to go to the store if its flat country,,I realize we have a VERRY varied technical audience here ,,I prefer for now to keep it simple so U dudes can chuckle n/an again,,George an David can give u the TONS per square Kilometer etc,,,My hats off to you[] and the rest]for providing the details,,My work has been in the field examing broken stuff and trying to make old stuff go better,,and find Victorian machinery fastenating,,Do you fellows realize the early race class==1000 kg =2204 # wt of car/anything goes an they made cars up to 1200 cid WOW Thats the early class,,So what if it gets 3mpg,,120mph to average 60w/ flat tires an NO demountable rims up to Renault '07,,,/John ,If I ramble too much let me know,Its your site and I think this is the best interchange of info ive seen in years,, Cheers Ben</HTML>
<b>Re: keepin' it fun!</b>
Posted by: JW (IP Logged)
Date: February 14, 2002 04:48AM
<HTML>- it's all connected somewhere, ...always interesting little vignettes
'tons per square kilo' .....haha!
My work has also found me in a field, [grin] .....on my back under a Stanley with burned fingers and a smoking shirtsleeve, musing at how this service situation was not mentioned in the sales brochures!
Keepin' it fun!
JW
</HTML>
'tons per square kilo' .....haha!
My work has also found me in a field, [grin] .....on my back under a Stanley with burned fingers and a smoking shirtsleeve, musing at how this service situation was not mentioned in the sales brochures!
Keepin' it fun!
JW
</HTML>
Re: crankshaft construction
Posted by: Jim Crank (IP Logged)
Date: February 14, 2002 01:54PM
<HTML>Coburn,
You bring up a most valid point. Welding sure does ruin any press fit.
Pressed crankshafts are fine for high speed low torque gas engines; but not for high torque steam engines for cars.
I wonder why people are so insistant on using crankshafts that come apart? Hasn,t anyone thought of one piece crankshafts and connecting rods with detachable caps?
Just in case you think they are weak, I can post pictures of my old Doble rods with over 370,000 miles on them and they didn,t break.
Our new ones are even stronger. And, yes they are roller bearings.
Briniton Engineering in England made our ten new crankshafts to spec and absolutely perfectly. No one in America would touch them.
Jim</HTML>
You bring up a most valid point. Welding sure does ruin any press fit.
Pressed crankshafts are fine for high speed low torque gas engines; but not for high torque steam engines for cars.
I wonder why people are so insistant on using crankshafts that come apart? Hasn,t anyone thought of one piece crankshafts and connecting rods with detachable caps?
Just in case you think they are weak, I can post pictures of my old Doble rods with over 370,000 miles on them and they didn,t break.
Our new ones are even stronger. And, yes they are roller bearings.
Briniton Engineering in England made our ten new crankshafts to spec and absolutely perfectly. No one in America would touch them.
Jim</HTML>
Re: crankshaft construction
Posted by: Peter Heid (IP Logged)
Date: February 14, 2002 05:02PM
<HTML>All,
I am just on the search for off the shelf parts that would be suitable for use with steam power. I can't yet find a crankshaft of forged 1 piece construction in the size I would require. I don't doubt the strength of a forged 1 piece crankshaft and split rods, after all I ran a Van Norman crankshaft grinder for 11 years. I believe the split rod is just as much at home on an assembled crankshaft as on a solid one. In recent years the production of split connecting rods has gotten easier and cheaper due to the process of spliting them at the parting line by fracturing.
We have been rebuilding crankshaft assemblies since the mid 1970s for customers and our own racing use. We have never welded any crankshaft assembly, nor do we recomend it. It is not necessarry in any application we have seen and failures of welded crankshafts are most comon around the welds. The interference is not usually affected because of the thickness of the materials being welded. The failures seem to result from a weakening of the metals being welded. It is very difficult to to successfully weld such dissimilar metals without compromising the joint or the materials involved.
Not all assembled crankshafts are in low torque applications, untill 2001 most every harley davidson motorcycle produced utilized this method of assembly. Gravely tractors and other small engine manufacturers have successfully used them. As for torque in a snowmobile application, try reving up a 140 HP engine to 4800 rpm and suddenly engaging the drive to turn 10 pounds of gears and chain, 10 pounds of drive shafts and 25 pounds of track. This happens fast enough to propell a stock snowmobile to 60 mph in 1 3/4 seconds on snow or under 10 seconds in the quarter mile. The clutch systems on a snowmobile makes the engine operate at the point of highest torque when driving.
I might end up with a crankshaft of the assembled design for a prototype due to the low cost, easy availability and adaptability. For production a one piece design would eliminate another possable point of failure on a vehicle that should be designed for the longest life at a point that holds the cost in balance.
Peter Heid</HTML>
I am just on the search for off the shelf parts that would be suitable for use with steam power. I can't yet find a crankshaft of forged 1 piece construction in the size I would require. I don't doubt the strength of a forged 1 piece crankshaft and split rods, after all I ran a Van Norman crankshaft grinder for 11 years. I believe the split rod is just as much at home on an assembled crankshaft as on a solid one. In recent years the production of split connecting rods has gotten easier and cheaper due to the process of spliting them at the parting line by fracturing.
We have been rebuilding crankshaft assemblies since the mid 1970s for customers and our own racing use. We have never welded any crankshaft assembly, nor do we recomend it. It is not necessarry in any application we have seen and failures of welded crankshafts are most comon around the welds. The interference is not usually affected because of the thickness of the materials being welded. The failures seem to result from a weakening of the metals being welded. It is very difficult to to successfully weld such dissimilar metals without compromising the joint or the materials involved.
Not all assembled crankshafts are in low torque applications, untill 2001 most every harley davidson motorcycle produced utilized this method of assembly. Gravely tractors and other small engine manufacturers have successfully used them. As for torque in a snowmobile application, try reving up a 140 HP engine to 4800 rpm and suddenly engaging the drive to turn 10 pounds of gears and chain, 10 pounds of drive shafts and 25 pounds of track. This happens fast enough to propell a stock snowmobile to 60 mph in 1 3/4 seconds on snow or under 10 seconds in the quarter mile. The clutch systems on a snowmobile makes the engine operate at the point of highest torque when driving.
I might end up with a crankshaft of the assembled design for a prototype due to the low cost, easy availability and adaptability. For production a one piece design would eliminate another possable point of failure on a vehicle that should be designed for the longest life at a point that holds the cost in balance.
Peter Heid</HTML>
Re: crankshaft construction
Posted by: George K. Nutz (IP Logged)
Date: February 14, 2002 05:29PM
<HTML>Peter,
Do not the racing snowmobiles(that the local NH shop produces) have a infinetely variable transmission with a kevlar filled belt that can handle all this and give great mechanical advantage?? I thought the local soup up shop was talking 140 horsepower at much more than 4800 rpm. But even at 140HP/4800rpm the engine torque is only 153 foot pounds, one-tenth the torque of a 20 horsepower Stanley engine in long cutoff from the starting line with 500psi on the steamchest. Horsepower= torque x rpm divided by 5250---, we can see from this that if the rpm is 1/10th than the torque is 10x to produce the same horsepower. Steam engines are mighty torque beasts and that is what created all the legends in the first place with the old lower speed engines geared directly to the axle. A crankshaft to take all of that must be very sturdy. If one is building a steamboat none of the above applies unless the propellor is stuck in some submerged rocks.
Great Fun, George</HTML>
Do not the racing snowmobiles(that the local NH shop produces) have a infinetely variable transmission with a kevlar filled belt that can handle all this and give great mechanical advantage?? I thought the local soup up shop was talking 140 horsepower at much more than 4800 rpm. But even at 140HP/4800rpm the engine torque is only 153 foot pounds, one-tenth the torque of a 20 horsepower Stanley engine in long cutoff from the starting line with 500psi on the steamchest. Horsepower= torque x rpm divided by 5250---, we can see from this that if the rpm is 1/10th than the torque is 10x to produce the same horsepower. Steam engines are mighty torque beasts and that is what created all the legends in the first place with the old lower speed engines geared directly to the axle. A crankshaft to take all of that must be very sturdy. If one is building a steamboat none of the above applies unless the propellor is stuck in some submerged rocks.
Great Fun, George</HTML>
Re: crankshaft construction
Posted by: Peter Heid (IP Logged)
Date: February 14, 2002 06:35PM
<HTML>George,
Your right the drive is virtually variable to keep the engine at the point where its power is most usefull but the drive ingages at 4800 to 5200 rpm on some production machines. This this allows the engine to reach the the point of useable power at the time of engagement, producing great driveline stresses as the machine accelerates from a stand still. With lots of performance modifications, over 300 HP is not uncomon on engines, engaging the drive at 6000 rpm or more and peak rpms of 10,000. The snowmobile does have two advantages in this respect that combine in benefit. The weight of the machine is far less than an auto which imposes less driveline stresses up to the point of traction loss. The other advantage is reduced traction conditions in most instances, even when running a drag race slick or 200 plus studs on ice, the psi on the traction surface is tiny compaired to that of the driving wheels of an auto on dry pavement. I am not trying to build a legend but I was thinking of a steam powered snowmobile as a good place to enter the vapor market and I'm still looking for off the shelf parts that may serve me in the process of development, budget willing. Gotta love that torque !
Peter Heid</HTML>
Your right the drive is virtually variable to keep the engine at the point where its power is most usefull but the drive ingages at 4800 to 5200 rpm on some production machines. This this allows the engine to reach the the point of useable power at the time of engagement, producing great driveline stresses as the machine accelerates from a stand still. With lots of performance modifications, over 300 HP is not uncomon on engines, engaging the drive at 6000 rpm or more and peak rpms of 10,000. The snowmobile does have two advantages in this respect that combine in benefit. The weight of the machine is far less than an auto which imposes less driveline stresses up to the point of traction loss. The other advantage is reduced traction conditions in most instances, even when running a drag race slick or 200 plus studs on ice, the psi on the traction surface is tiny compaired to that of the driving wheels of an auto on dry pavement. I am not trying to build a legend but I was thinking of a steam powered snowmobile as a good place to enter the vapor market and I'm still looking for off the shelf parts that may serve me in the process of development, budget willing. Gotta love that torque !
Peter Heid</HTML>
Re: crankshaft construction
Posted by: allen blazick (IP Logged)
Date: February 16, 2002 07:33PM
<HTML>I am currently looking into manufacturing crankshafts for light frame 30hp Stanley engines.. I am considering a one piece unit using castings from Bill Ruger. His foundry in N.H. has provided me with outstanding lost wax castings for Stanley front axles using exotic metals and a process known as hipping.. Once the parts were cast they were re-introduced back into a chamber with inert gas then heated to where the metal was almost moltent and the the pressure in the chamber was raised to between 15k and 20,000 lbs. This has yielded a casting that has a much higher tensil strengh that a forging, not only longitudinaly but also lattitudinaly.I am proposing to make the piston rods the same way. Any thoughts. Allen</HTML>
Re: crankshaft construction
Posted by: Ron Parola (IP Logged)
Date: February 18, 2002 01:11AM
<HTML>A word in edgewise if I may, As far as torque taking apart crankshafts ck out the motorcycle racing world, in particular the twins class; one litre V twins, both rods on a common pin pressed together. These bike engines are in the 180 hp range (at the crank) and are turning close to 13K rpm for long distances (500 mile) more for qualifing and they aren't ccoming apart. Yes they do have a fuse, not the clutch but the rear wheel. In the Drag racing world with built up four cylinder cranks, they are pressed together and then welded, but only in a few spots, not all around the pin. Another thing of interest as far as stress goes, notice the Nascar guys, their engines usually expire at the end of long straights, not at max power. The inertia loads on the rods, cranks, and pistons is higher than the expansion loads, a good reason for exhaust compression on a performance steamer??Ron P</HTML>
Re: crankshaft construction
Posted by: Andy Patterson (IP Logged)
Date: April 16, 2004 05:40PM
<HTML>Hi All
On a single throw engine as in a single of V twin arangement there shouldn't be much differance between a solid crank and one with a pressed pin. My worry would be with a multipal throw crank where crank torque is being transfer through the structure. In a single throw the torque is being transfer to the crank from the pin. The stresses are much different then in the multi throw case. Here we have the torque puting a twisting stress through the pin. It like trying to rotate the two ends of the crank in opsite directions.
If course I am picturing a single cylander motocycle crank that only has the pins pressed in. A 3 piece assembly.
Andy</HTML>
On a single throw engine as in a single of V twin arangement there shouldn't be much differance between a solid crank and one with a pressed pin. My worry would be with a multipal throw crank where crank torque is being transfer through the structure. In a single throw the torque is being transfer to the crank from the pin. The stresses are much different then in the multi throw case. Here we have the torque puting a twisting stress through the pin. It like trying to rotate the two ends of the crank in opsite directions.
If course I am picturing a single cylander motocycle crank that only has the pins pressed in. A 3 piece assembly.
Andy</HTML>
Re: crankshaft construction
Posted by: Andy Patterson (IP Logged)
Date: April 16, 2004 05:40PM
<HTML>Hi All
On a single throw engine as in a single of V twin arangement there shouldn't be much differance between a solid crank and one with a pressed pin. My worry would be with a multipal throw crank where crank torque is being transfer through the structure. In a single throw the torque is being transfer to the crank from the pin. The stresses are much different then in the multi throw case. Here we have the torque puting a twisting stress through the pin. It like trying to rotate the two ends of the crank in opsite directions.
If course I am picturing a single cylander motocycle crank that only has the pins pressed in. A 3 piece assembly.
Andy</HTML>
On a single throw engine as in a single of V twin arangement there shouldn't be much differance between a solid crank and one with a pressed pin. My worry would be with a multipal throw crank where crank torque is being transfer through the structure. In a single throw the torque is being transfer to the crank from the pin. The stresses are much different then in the multi throw case. Here we have the torque puting a twisting stress through the pin. It like trying to rotate the two ends of the crank in opsite directions.
If course I am picturing a single cylander motocycle crank that only has the pins pressed in. A 3 piece assembly.
Andy</HTML>
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