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Frame rod failure
Posted by: Kobus van Jaarsveld (IP Logged)
Date: March 28, 2004 07:21PM
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One of these broke just behind the top left nut holding the crank bearing cap recently. I have read everything on this subject in this excellent forum and the information gleaned was invaluable in choosing the material for the making of the new rods. The cause of failure and steps to stiffen the assembly is similarly of great interest, but I would like to describe what I think really caused the fracture of the bolt in my EX.
Out of curiosity I placed the crank assembly between the centres of our lathe and to my surprise found that the drive gear and the ball races on both sides of it were waltzing about quite markedly while the assembly was rotated. Clearly the central shaft on to which the whole kebab of crank throws, ball races, eccentrics and the drive gear are pressed had bent. The resulting continious movement of the frame rods at the point where the bearing caps bolt on finally fatigued the bolts.
I don't know when and how the shaft bent. I did not perform this check when the engine was assembled previously and chances are that it was bent all along. We are making a new shaft out of EN 24 but any views on how to prevent this from happening again, other than driving softly and slowly, will be appreciated.</HTML>
One of these broke just behind the top left nut holding the crank bearing cap recently. I have read everything on this subject in this excellent forum and the information gleaned was invaluable in choosing the material for the making of the new rods. The cause of failure and steps to stiffen the assembly is similarly of great interest, but I would like to describe what I think really caused the fracture of the bolt in my EX.
Out of curiosity I placed the crank assembly between the centres of our lathe and to my surprise found that the drive gear and the ball races on both sides of it were waltzing about quite markedly while the assembly was rotated. Clearly the central shaft on to which the whole kebab of crank throws, ball races, eccentrics and the drive gear are pressed had bent. The resulting continious movement of the frame rods at the point where the bearing caps bolt on finally fatigued the bolts.
I don't know when and how the shaft bent. I did not perform this check when the engine was assembled previously and chances are that it was bent all along. We are making a new shaft out of EN 24 but any views on how to prevent this from happening again, other than driving softly and slowly, will be appreciated.</HTML>
Re: Frame rod failure
Posted by: Ben in Maine (IP Logged)
Date: March 28, 2004 07:59PM
<HTML>Hi Kobus,,,The bigest strain is likely to be a slug of water while in short cutoff,,,cold of course,,,,BUT the ex doesnt have a cutoff??? I'm curious to hear what else is bent,,,,Is there any chance this occurd on assembly???,,,,In long cutoff these engines will pass a lot of whatevr,,,But in short,,the link motion gives compression and that will blow em apart,,,,If the rods an' all are Ok,,,I would consider it likely an assembly problem,,,Hows the weather over there,,,,Ocean temp is now up 2* at Portland Me [37] an climing, ;} Cheers Ben</HTML>
Re: Frame rod failure
Posted by: Peter Turvey (IP Logged)
Date: March 29, 2004 11:42AM
<HTML>I belive there was an article on strengthening frame rods in a recent edition of The Steam Car, magazine of the Steam car Club of Breat Britain. Don;t have th exat reference to hand I am afraid.</HTML>
Re: Frame rod failure
Posted by: Kobus van Jaarsveld (IP Logged)
Date: March 29, 2004 05:25PM
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'Evening Ben,
You are right, the early "dasher" EX does not have a cut-off. Con rods etc are all well. The frame rod failure manifested itself through the drive gear stripping some teeth off the bronze differential gear. This was caused by the engine slewing out of alignment after the bolt broke. The crunching that went on was horrible, but fortunately I had just pulled away (gently) after stopping momentarily at the end of a long drive on an open road when it all happened. I stopped immediately. I am convinced that the shaft had been in it's bent state for a long time before this event.
Weather in Johannesburg is glorious this time of the year. Calm sunshine days, night temperature ±14șC and daytime around 24șC. Leaves beginning to fall.
Regards, Kobus</HTML>
'Evening Ben,
You are right, the early "dasher" EX does not have a cut-off. Con rods etc are all well. The frame rod failure manifested itself through the drive gear stripping some teeth off the bronze differential gear. This was caused by the engine slewing out of alignment after the bolt broke. The crunching that went on was horrible, but fortunately I had just pulled away (gently) after stopping momentarily at the end of a long drive on an open road when it all happened. I stopped immediately. I am convinced that the shaft had been in it's bent state for a long time before this event.
Weather in Johannesburg is glorious this time of the year. Calm sunshine days, night temperature ±14șC and daytime around 24șC. Leaves beginning to fall.
Regards, Kobus</HTML>
Re: Frame rod failure
Posted by: Ben in Maine (IP Logged)
Date: March 29, 2004 09:15PM
<HTML>Hi Kobus ,,If the engine was running w/a bent shaft I think it would make a irregular noise [hum] while running down the road ,,,,Was the shaft bent in a way that it would change the depth of engagement,on every 1/2 revolution ,,I am very curious where the CENTER of the bend is,,when you get it all apart, this will also indicate where the major strain was,,,,Best of luck and good wishes to get the ole girl back on the road again,,,,Cheers Ben</HTML>
Re: Frame rod failure
Posted by: SSsssteamer (IP Logged)
Date: March 30, 2004 03:21AM
<HTML>Dear Kobus, Do your self and the EX a favor and lower your steam automatic cycling off pressure from the 550 pounds that you are presently running with, down to 425 pounds cycling off pressure. Also, do not dump the throttle on from a stop, ease off with a slight bump of the throttle and once you are rolling about 5 mph then consider rapidly increasing the throttle if needed. Drag racing an EX from a dead stop using 550 pounds steam pressure will break an EX just about every time. Even with our 1914 Stanley 606, I would not consider using a boiler pressure over 425 pounds. Even at 425 pounds, I have broken crank pins, piston rods, pistons, wrist pins, etc. Only because our type 6 10 HP engine has heavier engine frame rods than your EX, the engine frame rods are about the only things that I haven't yet broken in 22,000 miles of steaming. Yes, a cold slug of water while first starting out will put any Stanley engine in the repair shop. Sincerely, Pat Farrell</HTML>
Re: Frame rod failure/pressure
Posted by: Ben in Maine (IP Logged)
Date: March 30, 2004 01:01PM
<HTML>Hi Kobus and Pat ,,,,The original owners manual is fairly strong on the point,,open throttle slowly,,use caution while backing,,,,they just dont tell you why,,,,[its good for business [car sales,,,parts sales ]] I disagree on lowering the pressure,,,,Heres the deal,,,,at the lower pressure the steam is at a lower TEMPERATURE,,,,the superheater puts in the SAME amount of heat, temp rise ,,,SO the steam at the engine will be cooler,,,NOW this all uses MORE water,,,,that means more fire which you dont have,,,so the system becomes unbalenced,,,Yes the car will run but,,,,,Just open the trottle easily like the book says,,,,Just remember there is a finite price to pay for passing corvettes,,,, Cheers Ben</HTML>
Re: Frame rod failure
Posted by: Kobus van Jaarsveld (IP Logged)
Date: March 30, 2004 05:16PM
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Hi Ben and Pat, Yes, there was a mild Rrrr-Rrrr that could be heard on the overrun. All is stripped now and the problem revealed. Looking at the engine from the rear, the main carrying shaft was almost twisted off against the drive gear on the right hand side. This is also the centre of the bend. The direction of the twist is for normal rotation of the engine when the car is moving forward. The twist is such that the key passing through everything was sheared off at this point , the pieces have moved about 1.5 mm circumferentially along the shear plane.
In my defence I must say that I have given the engine lots of steam at high pressure on a number of occasions and made some very spirited starts, the effect is wickedly delightful in concert with the most glorious sounds... But I never "dumped" the throttle at standstill.</HTML>
Hi Ben and Pat, Yes, there was a mild Rrrr-Rrrr that could be heard on the overrun. All is stripped now and the problem revealed. Looking at the engine from the rear, the main carrying shaft was almost twisted off against the drive gear on the right hand side. This is also the centre of the bend. The direction of the twist is for normal rotation of the engine when the car is moving forward. The twist is such that the key passing through everything was sheared off at this point , the pieces have moved about 1.5 mm circumferentially along the shear plane.
In my defence I must say that I have given the engine lots of steam at high pressure on a number of occasions and made some very spirited starts, the effect is wickedly delightful in concert with the most glorious sounds... But I never "dumped" the throttle at standstill.</HTML>
Re: Frame rod failure
Posted by: SSsssteamer (IP Logged)
Date: April 01, 2004 07:27PM
<HTML>While I was attending the last steam car tour held in McCall, Idaho, Bob Edwards from Arizona had brought both his newly restored1900 Mobile steamer and his trusty old 1910 Model 61 Stanley touring to the tour. This was his Mobile's first tour and Bob thought that it should have the same boiler pressure as his trusty 1910 Stanley. His Stanley ran well at 425 pounds, so should the Mobile, right? In the parking lot, he rasied his Mobile's steam automatic from 200 pounds on up to about 400 pounds. His Mobile was snappy and Bob was all smiles. Smart idea huh? His smiles only lasted about 30 minutes. After he had raise the steam pressure and while performing in the parking lot, he soon twisted his left crank throw from the crank shaft. This story sounds very familiar. I often let other people drive my Stanleys. They all do not know how to start out slowly, and sometimes I too forget when I jump out into fast traffic. To prevent damage to my 90+ year old cars, I will error on the side of safety and run a lower steam pressure. Pressures that there were designed to run. Thank you.</HTML>
Re: failure
Posted by: Ben in Maine (IP Logged)
Date: April 01, 2004 09:30PM
<HTML>Hi,,,,Oh I hope he had a Stanley boiler in there NOT a un/wraped shell ,,,Cheers Ben</HTML>
Re: Frame rod failure
Posted by: Peter Turvey (IP Logged)
Date: April 02, 2004 11:27AM
<HTML>Interesting....for Stanley 607 #7644 we got John Goold to fit a new crankshaft and cranks, crankpins during the engine rebuild. We have also retained the lower gearing ratio with a 30 tooth gear on the crankshaft. Fingers crossed this should enable us to run at 500psi and smartly climb the steep hills out of Marlborough UK without problems. The car is still in bits so it will be a while before we can put this to the test.</HTML>
Re: Frame rod failure
Posted by: Ben in Maine (IP Logged)
Date: April 02, 2004 05:33PM
<HTML>To clearify,,,,The EX engine is a mutch more FRAGILE engine than the later 607,,,,1910--1914 engine,,,,its 3 X 4 and the later engine is 3 1/4 X 4 1/4 [I think],,,,funney thing they used film sizes,,,,er,, mmmm,,,,the frame rods are heavier etc Cheers Ben,,,,,ps ICE storm this morning,,,but it wont last,,,, :] CB</HTML>
Re: Frame rod failure
Posted by: Arnold Walker (IP Logged)
Date: April 03, 2004 02:07PM
<HTML>May be a dumb question.....but assuming the boiler can handle the extra pressure.....is it possible to adjustable the stop for max. cutoff shorter by the amount that wouldn't destory the engine.</HTML>
Re: Frame rod failure
Posted by: Ben in Maine (IP Logged)
Date: April 03, 2004 05:41PM
<HTML>Lets see if I can get the words in the right places,,,1,,//Long cutoff will use more steam[water] but will have a lower chest pressure,,,2,,// Short cutoff will use less steam , by virtue of expansion,,but will have a higher chest pressure for the same work,,,3,,// The manual advises long cutoff to reduce the chest pressure to save the valves,,,in climbing hills [there is another reason also],,,4,,//Some old timers spoke of just putting a wedge behind the pedal,,,for cutoff,,,,there would be some thrashing,,,Ideas on this,,,was it a real story???? 5,,// If one needed to limit chest pressure,,the simple way I think would be to put a safty valve in the pipe to the engine,,,It will speak to ya when you over pressure the engine,,! ! ! [Put the oil pipe on engine side of the T ,,,] 6,,// Again I stress the engine has compression in short cutoff,,,,and a slug of water in cutoff will not be nice,,,boiler too full on start up is one way,, dont forget the ex pipe is on top , so on start up you need enough steam through the engine to blow out the water,,,Seems like I forgot somethi'n,,,,oh well post this before it eats it,,,,,AGAIN,,,,,Grrrr !!! Hope this helps,,,,Cheers Ben ppp///sss ON HILLS In short cutoff,,at nearly stall,,,,if it stalls,,,,{wow] an the engine rolls back just a bit ,,,IT WILL pull the eccentric straps back into the direction the engine is going,,,,BACKWARDS,,,wowww so now you are going open throttle down hill backwards,,,,I knew I had foorgot somethin,,,,Cheers Ben,,,,GO SLOWLY<<<KEEP UP PRESSURE ,,,KEEP UP PRESSURE ,,,</HTML>
Re: Frame rod failure
Posted by: Ben in Maine (IP Logged)
Date: April 03, 2004 05:47PM
<HTML>GO SLOWLY<<<KEEP UP PRESSURE,,,,,KEEP UP PRESSURE,,,CB,,,,,THING cut off t wice this WAS on the above message,,,,Some daye long time from now,,,,,,,CB</HTML>
Re: Frame rod failure
Posted by: Ben in Maine (IP Logged)
Date: April 03, 2004 07:05PM
<HTML>Go Slowly,,,,Keep up the pressure,,,,Keep up the pressure,,,,,,,//what happened to this ending last 2 times??? CB</HTML>
Re: Frame rod failure
Posted by: Arnold Walker (IP Logged)
Date: April 08, 2004 01:37PM
<HTML>While looking for a foundry to do some parts ......I ran across one that does cast stainless.Question how would stainless cranks compare to iron cranks.</HTML>
Re: Frame rod failure
Posted by: Mike Clark (IP Logged)
Date: April 08, 2004 09:43PM
<HTML>Arnold - badly must be the answer if compared to steel. Stainless does not match the mechanical characteristics of high grade alloy steels so only use it where heat and corrosion resistance is more important than strength. Wouldn't generally think of cast iron, even SG (malleable) cast iron or cast steel for cranks - much better to use forged steel or machine from solid alloy steel. Same goes for connecting rods.
Mike</HTML>
Mike</HTML>
Re: Frame rod failure
Posted by: Andy Patterson (IP Logged)
Date: April 09, 2004 02:10PM
<HTML>Hi Arnold
It would depend on the stainless aloy. There a lot of stainless types. You can find a bit of info on them in a mechinist hand book.
Andy</HTML>
It would depend on the stainless aloy. There a lot of stainless types. You can find a bit of info on them in a mechinist hand book.
Andy</HTML>
Re: Frame rod failure
Posted by: george Nutz (IP Logged)
Date: April 09, 2004 05:16PM
<HTML>Arnold,
Being old fashioned I still prefer Ductile(mallable) iron castings as they come in very strong tensile strength ranges exceeding 100K psi and are quite machinable.
George</HTML>
Being old fashioned I still prefer Ductile(mallable) iron castings as they come in very strong tensile strength ranges exceeding 100K psi and are quite machinable.
George</HTML>
Re: Frame rod failure
Posted by: SSsssteamer (IP Logged)
Date: November 01, 2012 12:51PM
Kobus will be missed by all of us. SSsssteamer
From: Kobus van Jaarsveld
Sent: Wednesday, October 31, 2012 10:28 PM
Subject: Kobus
My beloved Kobus passed away yesterday morning quietly in his sleep.
Best wishes
Ali
From: Kobus van Jaarsveld
Sent: Wednesday, October 31, 2012 10:28 PM
Subject: Kobus
My beloved Kobus passed away yesterday morning quietly in his sleep.
Best wishes
Ali
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