Just how strong are built-up crankshafts? They're common in very small engines, some of which seem rather highly stressed. They seem less common in larger engines, but those I'm familiar with are high-production types where tooling costs matter less than per-part costs.
For example, if somebody wanted to build a small, one-off diesel engine, say a 200cc v-twin, would a built-up crank have a chance? At the other end of the spectrum, are the cranks in very large marine diesels (think Emma Maersk) built up or monolithic?
Not sure about Harley but MANY Motorcycle cranks are and many 2 stroke cranks. They work pretty good in applications where there is not much chance of impact / shock loads which have a tendancy to twist built-up cranks out of true. They are also used in applications where comnpactmess is required and there is no room for bolted split-cap rods
Just how strong are built-up crankshafts? They're common in very small engines, some of which seem rather highly stressed. They seem less common in larger engines, but those I'm familiar with are high-production types where tooling costs matter less than per-part costs.
For example, if somebody wanted to build a small, one-off diesel engine, say a 200cc v-twin, would a built-up crank have a chance? At the other end of the spectrum, are the cranks in very large marine diesels (think Emma Maersk) built up or monolithic?
Thanks for reading,
bob prohaska
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".. it exceeds 50% thermal efficiency in its maximum economy mode."
The newer Harley motors are using a pressed together crankshaft , the older ones used a bolted assembly with tapered joints located with keys . The newer ones have evidenced a tendency to twist at low RPM/heavy throttle . I know my 1990 has a bolted crank assembly , not sure about the 2009 Sporty but I think it was before the bean counters "improved the profit margin" .
I couldn't find any information on whether the Wartsila engine was a built up crank but the Doxford ship engine was, some info here
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and repairing the damage due to not doing the correct engine starting procedure resulting in slippage of the shrink fit crank
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. I mentioned that incident to a neighbour's friend who had worked for BOC and he said he had been involved in a similar fix in the docks at Bristol UK.
Clever ... I wonder if this sort of repair had been used prior or if the author was the first. If first, I have to admire his willingness to jump in the deep end, so to speak.
I got a chuckle out his titles: "RJF Hudson PhD., BAppSc., DMS., CEng., Extra First Class M.O.T FIMarEST., FIMechE., MCMI."
Clever ... I wonder if this sort of repair had been used prior or if the author was the first. If first, I have to admire his willingness to jump in the deep end, so to speak.
I got a chuckle out his titles: "RJF Hudson PhD., BAppSc., DMS., CEng., Extra First Class M.O.T FIMarEST., FIMechE., MCMI."
------ I suspect that every possible sort of failure had occurred soon after a design was introduced. Prior to WW2 engineering was cut-and-try, strengthen whatever broke.
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"Eventually, in the late 1930s, experimental stress analysis began to be incorporated into the design process."
Hi folks! I haven't stopped in for years, but I was so pleased to see that the political stuff (which drove me out in disgust) seems to be just a whimper now. If I was still writing about metalworking, I'd get back into it. But I'm not, so I'm just saying "hello" and it's nice to see so many of you still around.
Bob, I don't know of any unsupercharged diesel engines -- running on diesel fuel -- smaller than about 300 cc or so per cylinder. I'm not a diesel guy and there may be some such engines, but that's what I've heard from diesel people. They've told me that smaller cylinders quench too much to burn diesel fuel without supercharging. Of course, you can "diesel" with ether and maybe some other fuels, but that's something to check out. Those model "diesel" engines that run on ether don't have injection, so purists don't consider them to be "diesels." Just "compression ignition."
As for built-up cranks, there were racing engines in the 1930s, and probably since, that had built-up cranks. SO I'd guess that they can handle the torsional load if you get the press-fit right.
Good to see ya'll, and without the vile political stuff!
Good to see you're still with us and posting, it has been getting quiet on here as even the metal working related stuff is getting less often. I hadn't noticed a reduction in political/gun/survivalist stuff as my filters kept that under control. I had a Davies-Charlton UK made diesel airplane model engine and took it back to Wichita and asked my chemistry teacher where I could get some ether to make the fuel and she was rather concerned about safety and not helpful, IIRC the fuel was ether, amyl nitrate, and castor oil and easy to get in the UK as a pre-mixed fuel but not common in the US in the early 1980s. IIRC a source for ether is engine start spray and people do use it to repair capillary temperature gauges.
Hiya Dave! I haven't tried to buy ether for decades. I kept a pint can of it in the trunk of my MG when I lived in Michigan, for starting on those 0-temp winter days ( and with a sad Lucas battery), which I guess was like keeping a few sticks of dynamite in the car. Oh well, it worked. and I'm still in one piece.
I see it's relatively quiet here, but the subjects are metalworking-related, like it was when I joined over 20 years ago. It's good to see.
Hi folks! I haven't stopped in for years, but I was so pleased to see that the political stuff (which drove me out in disgust) seems to be just a whimper now. If I was still writing about metalworking, I'd get back into it. But I'm not, so I'm just saying "hello" and it's nice to see so many of you still around.
Bob, I don't know of any unsupercharged diesel engines -- running on diesel fuel -- smaller than about 300 cc or so per cylinder. I'm not a diesel guy and there may be some such engines, but that's what I've heard from diesel people. They've told me that smaller cylinders quench too much to burn diesel fuel without supercharging. Of course, you can "diesel" with ether and maybe some other fuels, but that's something to check out. Those model "diesel" engines that run on ether don't have injection, so purists don't consider them to be "diesels." Just "compression ignition."
As for built-up cranks, there were racing engines in the 1930s, and probably since, that had built-up cranks. SO I'd guess that they can handle the torsional load if you get the press-fit right.
Good to see ya'll, and without the vile political stuff!
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